/stubby4j

An HTTP server for stubbing external systems in both Docker and non-containerized environments for integration, contract & behavior testing.

Primary LanguageJavaMIT LicenseMIT

stubby4j is an HTTP server for stubbing external systems in both Docker and non-containerized environments for integration, contract & behavior testing.

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stubb4j

It is a highly flexible and configurable tool for testing interactions of service-oriented (SoA) or/and micro-services architectures (REST, SOAP, WSDL, etc.) over HTTP(s) protocol.

Please refer to Key features for more information

Why the word "stubby"?

It is a stub HTTP server after all, hence the "stubby". Fun fact: in Australian slang "stubby" means beer bottle

User manual for stubby4j v7.3.1

Table of contents

Key features

  • Emulate external webservice in a SANDBOX for your application to consume over HTTP(S)
  • HTTP request verification and HTTP response stubbing
  • Request proxying - ability to configure a proxy/intercept where requests are proxied to another service
  • Regex support for dynamic matching on URI, query params, headers, POST payload (ie:. mod_rewrite in Apache)
  • Dynamic token replacement in stubbed response, by leveraging regex capturing groups as token values during HTTP request verification
  • Record & Replay. The HTTP response is recorded on the first call, having the subsequent calls play back the recorded HTTP response, without actually connecting to the external server
  • Dynamic flows. Multiple stubbed responses on the same stubbed URI to test multiple application flows
  • Fault injection, where after X good responses on the same URI you get a bad one
  • Serve binary files as stubbed response content (images, PDFs. etc.)
  • Embed stubby4j to create a web service SANDBOX for your integration test suite

Quick start example

This section explains how to get stubby4j up and running using a very simple example Hello, World, without building stubby4j from locally using Gradle.

Minimum system requirements to run stubby4j archives hosted on Maven Central

  • version >= 4.0.0: JRE >= v1.8
  • version >= 3.0.0: JRE >= v1.7

Setup

-  request:
      method: GET
      url: /hello-world
 
   response:
      status: 200
      headers:
         content-type: application/json
      body: Hello World!
  • Execute the downloaded stubby JAR using command java -jar stubby4j-x.x.xx.jar -d <PATH_TO_LOCAL_YAML_CONFIG> (also see Command-line switches and Splitting main YAML config in to sub-includes)
  • Navigate to http://localhost:8882/hello-world to get the stubbed response Hello World!
  • Navigate to stubby4j admin portal at http://localhost:8889/status to see what has been stubbed & other useful data

That's it!

For more information and more complex examples, please dive into the rest of documentation, especially Endpoint configuration HOWTO

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Running in Docker

stubby4j Docker images are hosted on https://hub.docker.com/r/azagniotov/stubby4j.

Alternatively you can build your own image locally using one of the project's Dockerfile under:

Navigate to one of the above desired directory and run the following command to build from the master branch, e.g.:

$ docker build --rm --no-cache -t stubby4j:latest .

or the following command to build from a specific tag, e.g.:

$ docker build --build-arg REVISION=v7.3.1 --rm --no-cache -t stubby4j:latest .

Refer to https://hub.docker.com/r/azagniotov/stubby4j README How to use this image section regarding how to use the built image

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Why would a developer use stubby4j?

You want to:

  • Simulate responses from real server and don't care (or cannot) to go over the network
  • Stub out external services in a Docker based micro-service architecture
  • Third party web service your application suppose to contract with is not ready yet
  • Verify that your code makes HTTP requests with all the required parameters and/or headers
  • Verify that your code correctly handles HTTP error codes
  • You want to trigger response from the server based on the request parameters over HTTP or HTTPS
  • Support for any of the available HTTP methods
  • Simulate support for different types of HTTP Authorizations: Basic, Bearer Token & others
  • Support for HTTP 30x redirects
  • Provide canned answers in your contract/integration tests
  • Enable delayed responses for performance and stability testing
  • Avoid to spend time coding for the above requirements
  • Concentrate on the task at hand

Why would a QA use stubby4j?

  • Specifiable mock responses to simulate page conditions without real data.
  • Ability to test polling mechanisms by stubbing a sequence of responses for the same URI
  • Easily swappable data config files to run different data sets and responses.
  • All-in-one stub server to handle mock data with less need to upkeep code for test generation

Building

stubby4j is a multi source-set Gradle v6.8.3 project

Run ./gradlew command to:

  • Clean
  • Run unit, integration and functional tests without JaCoCo code coverage
  • Build (the generated JAR artifacts will be located under <PROJECT_ROOT>/build/libs/)

Run ./gradlew clean jacocoTestReport command to:

  • Clean
  • Generate JaCoCo report under the <PROJECT_ROOT>/build/reports/jacoco/html/index.html

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Third-party dependencies

Adding stubby4j to your project

The following are the stubby4j artifacts that are hosted on Maven Central:

  • stubby4j-x.x.x.jar - an uber/fat JAR containing all the 3rd-party deps
  • stubby4j-x.x.x-no-dependencies.jar - a skinny JAR containing no 3rd-party dependencies at all
  • stubby4j-x.x.x-no-jetty.jar - an uber-ish JAR containing all the 3rd-party deps except Jetty binaries
  • stubby4j-x.x.x-sources.jar
  • stubby4j-x.x.x-javadoc.jar

Gradle

compile("io.github.azagniotov:stubby4j:7.3.1")

or by adding a classifier to the JAR name like no-dependencies or no-jetty, i.e.:

compile("io.github.azagniotov:stubby4j:7.3.1:no-jetty")

Maven

<dependency>
    <groupId>io.github.azagniotov</groupId>
    <artifactId>stubby4j</artifactId>
    <version>7.3.1</version>
</dependency>

or by adding a classifier to the JAR name like no-dependencies or no-jetty, i.e.:

<dependency>
    <groupId>io.github.azagniotov</groupId>
    <artifactId>stubby4j</artifactId>
    <version>7.3.1</version>
    <classifier>no-dependencies</classifier>
</dependency>

Installing stubby4j to local .m2 repository

Run ./gradlew installToMavenLocal command to:

  • Install stubby4j-7.3.2-SNAPSHOT*.jar to local ~/.m2/repository
  • All the artifacts will be installed under ~/.m2/repository/{groupId}/{artifactId}/{version}/, e.g.: ~/.m2/repository/io/github/azagniotov/stubby4j/7.3.2-SNAPSHOT/

Now you can include locally installed stubby4j SNAPSHOT artifacts in your project:

compile("io.github.azagniotov:stubby4j:7.3.2-SNAPSHOT")

or by adding a classifier to the JAR name like no-dependencies or no-jetty, i.e.:

compile("io.github.azagniotov:stubby4j:7.3.2-SNAPSHOT:no-jetty")

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Command-line switches

usage:
java -jar stubby4j-x.x.xx.jar [-a <arg>] [-d <arg>] [-da] [-dc] [-ds] [-h]
       [-k <arg>] [-l <arg>] [-m] [-o] [-p <arg>] [-s <arg>] [-t <arg>]
       [-v] [-w <arg>]
 -a,--admin <arg>             Port for admin portal. Defaults to 8889.
 -d,--data <arg>              Data file to pre-load endpoints. Data file
                              to pre-load endpoints. Optional valid YAML
                              1.1 is expected. If YAML is not provided,
                              you will be expected to configure stubs via
                              the stubby4j HTTP POST API.
 -da,--disable_admin_portal   Does not start Admin portal
 -dc,--disable_stub_caching   Disables stubs in-memory caching when stubs
                              are successfully matched to the incoming
                              HTTP requests
 -ds,--disable_ssl            Does not enable SSL connections
 -h,--help                    This help text.
 -k,--keystore <arg>          Keystore file for custom TLS. By default TLS
                              is enabled using internal keystore.
 -l,--location <arg>          Hostname at which to bind stubby.
 -m,--mute                    Mute console output.
 -o,--debug                   Dumps raw HTTP request to the console (if
                              console is not muted!).
 -p,--password <arg>          Password for the provided keystore file.
 -s,--stubs <arg>             Port for stub portal. Defaults to 8882.
 -t,--tls <arg>               Port for TLS connection. Defaults to 7443.
 -v,--version                 Prints out to console stubby version.
 -w,--watch <arg>             Periodically scans for changes in last
                              modification date of the main YAML and
                              referenced external files (if any). The flag
                              can accept an optional arg value which is
                              the watch scan time in milliseconds. If
                              milliseconds is not provided, the watch
                              scans every 100ms. If last modification date
                              changed since the last scan period, the stub
                              configuration is reloaded

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Endpoint configuration HOWTO

This section explains the usage, intent and behavior of each property on the request and response objects.

Also, you will learn about request proxying to other hosts, regex stubbing for dynamic matching, stubbing HTTP 30x redirects, record-and-replay and more.

Click to expand

Here is a fully-populated, unrealistic endpoint:

-  description: Optional description shown in logs
   uuid: fdkfsd8f8ds7f
   request:
      url: ^/your/awesome/endpoint$
      method: POST
      query:
         exclamation: post requests can have query strings!
      headers:
         content-type: application/xml
      post: >
         <!xml blah="blah blah blah">
         <envelope>
            <unaryTag/>
         </envelope>
      file: tryMyFirst.xml

   response:
      status: 200
      latency: 5000
      headers:
         content-type: application/xml
         server: stubbedServer/4.2
      body: >
         <!xml blah="blah blah blah">
         <responseXML>
            <content></content>
         </responseXML>
      file: responseData.xml

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Stub/Feature

description (optional)

  • Description field which can be used to show optional descriptions in the logs
  • Useful when you have a number of stubs loaded for the same endpoint and it starts to get confusing as to which is being matched
-  description: Stub one
   request:
      url: ^/one$
      method: GET

   response:
      status: 200
      latency: 100
      body: 'One!'

-  description: Stub two
   request:
      url: ^/two$
      method: GET

   response:
      status: 200
      latency: 100
      body: 'Two!'

-  request:
      url: ^/three$
      method: GET

   response:
      status: 200
      latency: 100
      body: 'Three!'

uuid (optional)

  • Useful when you want to specify unique identifier so it would be easier to update/delete it at runtime
-  uuid: 9136d8b7-f7a7-478d-97a5-53292484aaf6
   request:
      method: GET
      url: /with/configured/uuid/property

   response:
      headers:
         content-type: application/json
      status: 200
      body: >
         {"status" : "OK"}

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Request

This object is used to match an incoming request to stubby against the available endpoints that have been configured.

Summary

In YAML config, the request object supports the following properties:

url, method, query, headers, post, file

Keep on reading to understand their usage, intent and behavior.

Request object properties

Click to expand

url (required)

  • is a full-fledged regular expression
  • This is the only required property of an endpoint.
  • signify the url after the base host and port (i.e. after localhost:8882).
  • must begin with /.
  • any query paramters are stripped (so don't include them, that's what query is for).
    • /url?some=value&another=value becomes /url
  • no checking is done for URI-encoding compliance.
    • If it's invalid, it won't ever trigger a match.

This is the simplest you can get:

-  request:
      url: /

A demonstration when not using regular expressions:

-  request:
      url: /some/resource/that/will/be/fully/matched

A demonstration using regular expressions:

-  request:
      url: ^/has/to/begin/with/this/

-  request:
      url: /has/to/end/with/this/$

-  request:
      url: ^/must/be/this/exactly/with/optional/trailing/slash/?$

-  request:
      url: ^/[a-z]{3}-[a-z]{3}/[0-9]{2}/[A-Z]{2}/[a-z0-9]+$

method (required)

  • defaults to GET.
  • case-insensitive.
  • can be any of the following:
    • HEAD
    • GET
    • POST
    • PUT
    • POST
    • DELETE
    • PATCH
    • etc.
-  request:
      url: /anything
      method: GET
  • it can also be an array of values.
-  request:
      url: /anything
      method: [GET, HEAD]

-  request:
      url: /anything
      method:
         -  GET
         -  HEAD

query (optional)

  • can be a full-fledged regular expression
  • if not stubbed, stubby ignores query parameters on incoming request and will match only request URL
  • stubby accommodates for HTTP requests that contain query string params with no values
  • query params can be specified regardless of their order in incoming request. In other words - order agnostic
  • query params can also be an array with double/single quoted/un-quoted elements: attributes=["id","uuid"] or attributes=[id,uuid]. Please note no spaces between the CSV
-  request:
      method: GET
      url: ^/with/parameters$
      query:
         type_name: user
         client_id: id
         client_secret: secret
         random_id: "^sequence/-/\\d/"
         session_id: "^user_\\d{32}_local"
         attributes: '["id","uuid","created","lastUpdated","displayName","email","givenName","familyName"]'
  • The following will match either of these:
    • /with/parameters?search=search+terms&filter=month
    • /with/parameters?filter=month&search=search+terms
-  request:
      url: ^/with/parameters$
      query:
         search: search terms
         filter: month
  • The following will match either of these:
    • /with/parameters?search&filter=month
    • /with/parameters?search=&filter=month
-  request:
      url: ^/with/parameters$
      query:
         search:
         filter: month
  • The following will match:
    • From the browser: http://localhost:8882/with/parameters?term=boo+and+foo
    • From the browser: http://localhost:8882/with/parameters?term=boo%2Band%2Bfoo
    • From the browser: http://localhost:8882/with/parameters?term=boo and foo
    • From the browser: http://localhost:8882/with/parameters?term=boo%20and%20foo
    • From the code: String request = "http://localhost:8882/with/parameters?term=boo+and+foo"
    • From the code: String request = "http://localhost:8882/with/parameters?term=boo%2Band%2Bfoo"
    • From the code: String request = "http://localhost:8882/with/parameters?term=boo and foo"
    • From the code: String request = "http://localhost:8882/with/parameters?term=boo%20and%20foo"
-  request:
      url: ^/with/parameters$
      query:
         term: "boo and foo"
  • The following will match:
    • From the browser: http://localhost:8882/with/parameters?term=['stalin+and+truman']
    • From the browser: http://localhost:8882/with/parameters?term=['stalin+and+++++++++++truman']
    • From the browser: http://localhost:8882/with/parameters?term=['stalin%2Band%2Btruman']
    • From the browser: http://localhost:8882/with/parameters?term=['stalin and truman']
    • From the browser: http://localhost:8882/with/parameters?term=['stalin%20and%20truman']
    • From the code: String request = "http://localhost:8882/with/parameters?term=%5B%27stalin%2Band%2Btruman%27%5D"
    • From the code: String request = "http://localhost:8882/with/parameters?term=%5B%27stalin+++++and+truman%27%5D"
    • From the code: String request = "http://localhost:8882/with/parameters?term=%5B%27stalin and truman%27%5D"
    • From the code: String request = "http://localhost:8882/with/parameters?term=%5B%27stalin%20and%20truman%27%5D"
-  request:
      url: ^/with/parameters$
      query:
         term: "['stalin and truman']"

post (optional)

  • Represents the body POST of incoming request, ie.: form data
  • can be a full-fledged regular expression
  • if not stubbed, any POSTed data on incoming request is ignored
-  request:
      url: ^/post/form/data$
      post: name=John&email=john@example.com
-  request:
      method: [POST]
      url: /uri/with/post/regex
      post: "^[\\.,'a-zA-Z\\s+]*$"
-  request:
      url: ^/post/form/data$
      post: "^this/is/\\d/post/body"
-  request:
      method: POST
      url: /post-body-as-json
      headers:
         content-type: application/json
      post: >
         {"userId":"19","requestId":"(.*)","transactionDate":"(.*)","transactionTime":"(.*)"}

   response:
      headers:
         content-type: application/json
      status: 200
      body: >
         {"requestId": "<%post.1%>", "transactionDate": "<%post.2%>", "transactionTime": "<%post.3%>"}
-  request:
      method: POST
      url: /post-body-as-json-2
      headers:
         content-type: application/json
      post: >
         {"objects": [{"key": "value"}, {"key": "value"}, {"key": {"key": "(.*)"}}]}

   response:
      headers:
         content-type: application/json
      status: 200
      body: >
         {"internalKey": "<%post.1%>"}

file (optional)

  • holds a path to a local file (it can be an absolute or relative path to the main YAML specified in -d or --data). This property allows you to split up stubby data across multiple files instead of making one huge bloated main config YAML. For example, let's say you want to stub a big POST payload, so instead of dumping a lot of text under the post property, you could specify a local file with the payload using the file property:
-  request:
      method: POST
      headers:
         content-type: application/json
      file: ../json/post.payload.json
  • please note, if both file & post properties are supplied, the file takes precedence & replaces post with the contents from the provided file.
  • if --watch command-line argument was supplied during startup, then any modifications to the supplied local file in file (e.g. file: ../json/post.payload.json) will cause the whole configuration to be reloaded.
  • if the local file could not be loaded for whatever reason (ie.: not found), stubby falls back to post for matching.
  • please keep in mind: SnakeYAML library (used by stubby4j) parser ruins multi-line strings by not preserving system line breaks. If file property is stubbed, the file content is loaded as-is, in other words - it does not go through SnakeYAML parser. Therefore it's better to load big POST content for request using file property. Keep in mind, stubby4j stub server is dumb and does not use smart matching mechanism (i.e.: don't match line separators or don't match any white space characters) - whatever you stubbed, must be POSTed exactly for successful match. Alternatively you can consider using regular expression in post
-  request:
      url: ^/match/against/file$
      file: postedData.json
      post: '{"fallback":"data"}'

postedData.json

{"fileContents":"match against this if the file is here"}
  • if postedData.json doesn't exist on the filesystem when /match/against/file is matched in incoming request, stubby will match post contents against {"fallback":"data"} (from post) instead.

headers (optional)

  • can be a full-fledged regular expression
  • if not stubbed, stubby ignores headers on incoming request and will match only request URL
  • if stubbed, stubby will try to match only the supplied headers and will ignore other headers of incoming request. In other words, the incoming request must contain stubbed header values
  • headers are case-insensitive during matching
  • a hashmap of header/value pairs similar to query.

The following endpoint only accepts requests with application/json post values:

-  request:
      url: /post/json
      method: post
      headers:
         content-type: application/json
         x-custom-header: "^this/is/\d/test"
         x-custom-header-2: "^[a-z]{4}_\\d{32}_(local|remote)"

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Request proxying

See REQUEST_PROXYING.md for details

Regex stubbing for dynamic matching

stubby supports regex stubbing for dynamic matching on the following properties:

  • request url
  • request query param values
  • request header name values
  • request post payloads
  • request file names & payloads.

Under the hood, stubby first attempts to compile the stubbed pattern into an instance of java.util.regex.Pattern class using the Pattern.MULTILINE flag. If the pattern compilation fails and PatternSyntaxException exception is thrown, stubby compiles the stubbed pattern into an instance of java.util.regex.Pattern class using the Pattern.LITERAL | Pattern.MULTILINE flags.

Please note, before using regex patterns in stubs, first it is best to ensure that the desired regex pattern "works" outside of stubby. One of the safest (and easiest) ways to test the desired pattern would be to check if the following condition is met: Pattern.compile("YOUR_PATTERN").matcher("YOUR_TEST_STRING").matches() == true.

The latter would ensure that the stubbed regex pattern actually works, also it is easier to debug a simple unit test case instead of trying to figure out why stub matching failed

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Regex stubbing for XML content

XML is not a regular language, it can be tricky to parse it using a regular expression (well, sometimes it is not as tricky when XML regex snippet is simple. But, most of the times this will cause you tears), especially when dealing with large XML POST payloads. XML is very complex: nested tags, XML comments, CDATA sections, preprocessor directives, namespaces, etc. make it very difficult to create a parse-able & working regular expression.

Click to expand

Therefore, stubby4j uses under the hood a full-fledged 3rd party XML parser - XMLUnit.

XMLUnit enables stubbing of XML content with regular expressions by leveraging XMLUnit-specific Regex match placeholders. Placeholders are used to specify exceptional requirements in the control XML document for use during equality comparison (i.e.: regex matching).

How to stub XML containing regular expressions?

  1. Using vanilla regular expressions
  2. Using XMLUnit regular expression matcher placeholders
Using vanilla regular expressions

Consider the following examples of stubbed request that have XML regex snippets under post:

- description: rule_1
  request:
    url: /some/resource/uri
    method: POST
    headers:
      content-type: application/xml
    post: >
      <\?xml version="1.0" encoding="UTF-8" standalone="yes"\?><idex:type xmlns:idex="http://idex.bbc.co.uk/v1"><idex:authority>(.*)</idex:authority><idex:name>(.*)</idex:name><idex:startsWith>(.*)</idex:startsWith></idex:type>

In the above example, do note that the ? in <?xml .. ?> are escaped (i.e.: <\?xml .. \?>) as these are regex specific characters.

- description: rule_1
  request:
    url: /some/resource/uri
    method: POST
    headers:
      content-type: application/xml
    post: >
      <\?xml version="1.0" encoding="UTF-8"\?>
      <person xmlns="http://www.your.example.com/xml/person">
          <VocabularyElement id="urn:epc:idpat:sgtin:(.*)">
              <attribute id="urn:epcglobal:product:drugName">(.*)</attribute>
              <attribute id="urn:epcglobal:product:manufacturer">(.*)</attribute>
              <attribute id="urn:epcglobal:product:dosageForm">(.*)</attribute>
              <attribute id="urn:epcglobal:product:strength">(.*)</attribute>
              <attribute id="urn:epcglobal:product:containerSize">(.*)</attribute>
          </VocabularyElement>
          <name>(.*)</name>
          <age>(.*)</age>
          <!--
            Hello,
               I am a multi-line XML comment
               <staticText>
                  <reportElement x="180" y="0" width="200" height="20"/>
                  <text><!\[CDATA\[(.*)\]\]></text>
                </staticText>
            -->
          <homecity xmlns="(.*)cities">
              <long>(.*)</long>
              <lat>(.*)</lat>
              <name>(.*)</name>
          </homecity>
          <one name="(.*)" id="urn:company:namespace:type:id:one">(.*)</one>
          <two id="urn:company:namespace:type:id:two" name="(.*)">(.*)</two>
          <three name="(.*)" id="urn:company:namespace:type:id:(.*)">(.*)</three>
      </person>

In the above example, do note that the:

  1. ? in <?xml .. ?> are escaped (i.e.: <\?xml .. \?>) as these are regex specific characters, and
  2. [ and ] in <![CDATA[ .. ]]> are escaped (i.e.: <!\[CDATA\[(.*)\]\]>) as these are regex specific characters
Using XMLUnit regular expression matcher placeholders

XMLUnit placeholder ${xmlunit.matchesRegex( ... )} to the rescue. Consider the following example of stubbed request:

- description: rule_1
  request:
    url: /some/resource/uri
    method: POST
    headers:
      content-type: application/xml
    post: >
      <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
      <idex:type xmlns:idex="http://idex.bbc.co.uk/v1">
          <idex:authority>${xmlunit.matchesRegex(.*)}</idex:authority>
          <idex:name>${xmlunit.matchesRegex(.*)}</idex:name>
          <idex:startsWith>${xmlunit.matchesRegex(.*)}</idex:startsWith>
      </idex:type>

In the above example, the regular expressions defined in post XML will match any values inside idex:authority, idex:name and idex:startsWith elements.

Please refer to the following XMLUnit Placeholders guide or/and their unit tests for more information.

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Authorization Header

-  request:
      url: ^/path/to/basic$
      method: GET
      headers:
         # no "Basic" prefix nor explicit encoding in Base64 is required when stubbing,
         # just plain username:password format. Stubby internally encodes the value in Base64
         authorization-basic: "bob:password" 
   response:
      headers:
         Content-Type: application/json
      status: 200
      body: Your request with Basic was successfully authorized!

-  request:
      url: ^/path/to/bearer$
      method: GET
      headers:
         # no "Bearer" prefix is required when stubbing, only the auth value.
         # Stubby internally does not modify (encodes) the auth value
         authorization-bearer: "YNZmIzI2Ts0Q=="
   response:
      headers:
         Content-Type: application/json
      status: 200
      body: Your request with Bearer was successfully authorized!

-  request:
      url: ^/path/to/custom$
      method: GET
      headers:
         # custom prefix name is required when stubbing, followed by space & auth value.
         # Stubby internally does not modify (encodes) the auth value
         authorization-custom: "CustomAuthorizationType YNZmIzI2Ts0Q=="
   response:
      headers:
         Content-Type: application/json
      status: 200
      body: Your request with custom authorization type was successfully authorized!

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Response

Assuming a match between the incoming HTTP request and one of the stubbed request objects has been found, its stubbed response object properties are used to build the HTTP response back to the client.

Summary

In YAML config, the response object supports the following properties:

status, body, file, headers, latency

Keep on reading to understand their usage, intent and behavior.

Response object properties

Click to expand
  • Response configuration can be a single response or a sequence of responses under the same - request definition.
  • When sequenced responses is configured, on each incoming request to the same URI, a subsequent response in the list will be sent to the client. The sequenced responses play in a cycle (loop). In other words: after the response sequence plays through, the cycle restarts on the next incoming request.
-  request:
      method: [GET,POST]
      url: /invoice/123

   response:
      status: 201
      headers:
         content-type: application/json
      body: OK


-  request:
      method: [GET]
      url: /uri/with/sequenced/responses

   response:
      -  status: 201
         headers:
            content-type: application/json
         body: OK

      -  status: 201
         headers:
            content-stype: application/json
         body: Still going strong!

      -  status: 500
         headers:
            content-type: application/json
         body: OMG!!!


-  request:
      method: [GET]
      url: /uri/with/sequenced/responses/infile

   response:
      -  status: 201
         headers:
            content-type: application/json
         file: ../json/sequenced.response.ok.json

      -  status: 201
         headers:
            content-stype: application/json
         file: ../json/sequenced.response.goingstrong.json

      -  status: 500
         headers:
            content-type: application/json
         file: ../json/sequenced.response.omfg.json


-  request:
      method: [GET]
      url: /uri/with/single/sequenced/response

   response:
      -  status: 201
         headers:
            content-stype: application/json
         body: Still going strong!

status (required)

  • the HTTP status code of the response.
  • integer or integer-like string.
  • defaults to 200.
-  request:
      url: ^/im/a/teapot$
      method: POST
   response:
      status: 420

body (optional)

  • contents of the response body
  • defaults to an empty content body
  • can be a URL (OAUTH is not supported) to record & replay response from a remote host (see Record and Replay). The HTTP response is recorded on the first call to stubbed URL, having the subsequent calls replay back the recorded HTTP response, without actually connecting to the remote host again.
-  request:
      url: ^/give/me/a/smile$
   response:
      body: ':)'
-  request:
      url: ^/give/me/a/smile$

   response:
      status: 200
      body: >
         {"status": "hello world with single quote"}
      headers:
         content-type: application/json
-  request:
      method: GET
      url: /atomfeed/1

   response:
      headers:
         content-type: application/xml
      status: 200
      body: <?xml version="1.0" encoding="UTF-8"?><payment><paymentDetail><invoiceTypeLookupCode/></paymentDetail></payment>
-  request:
      url: /1.1/direct_messages.json
      query:
         since_id: 240136858829479935
         count: 1
   response:
      headers:
         content-type: application/json
      body: https://api.twitter.com/1.1/direct_messages.json?since_id=240136858829479935&count=1

file (optional)

  • similar to request.file, holds a path to a local file (it can be an absolute or relative path to the main YAML specified in -d or --data). This property allows you to split up stubby data across multiple files instead of making one huge bloated main config YAML. For example, let's say you want to render a large response body upon successful stub matching, so instead of dumping a lot of text under the body property, you could specify a local file with the response content using the file property (btw, the file can also refer to binary files):
response:
      status: 200
      headers:
         content-type: application/json
      file: ../json/response.json
  • please note, if both file & body properties are supplied, the file takes precedence & replaces body with the contents from the provided file
  • if --watch command-line argument was supplied during startup, then any modifications to the supplied local file in file (e.g. file: ../json/response.json) will cause the whole configuration to be reloaded.
  • if the file could not be loaded, stubby falls back to the value stubbed in body
  • if body was not stubbed, an empty string is returned by default
  • it can be ascii of binary file (PDF, images, etc.). Please keep in mind, that file is preloaded upon stubby4j startup and its content is kept as a byte array in memory. In other words, response files are not read from the disk on demand, but preloaded.
-  request:
      url: /
   response:
      file: extremelyLongJsonFile.json

headers (optional)

  • similar to request.headers except that these are sent back to the client.
  • by default, header x-stubby-resource-id containing resource ID is returned with each stubbed response. The ID is useful if the returned resource needs to be updated at run time by ID via Admin portal
-  request:
      url: ^/give/me/some/json$
   response:
      headers:
         content-type: application/json
      body: >
         [{
            "name":"John",
            "email":"john@example.com"
         },{
            "name":"Jane",
            "email":"jane@example.com"
         }]

latency (optional)

  • time to wait, in milliseconds, before sending the response to the caller
  • good for testing timeouts, or slow connections
-  request:
      url: ^/hello/to/jupiter$
   response:
      latency: 800000
      body: Hello, World!

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Dynamic token replacement in stubbed response

During HTTP request verification, you can leverage regex capturing groups (Regex stubbing for dynamic matching) as token values for dynamic token replacement in stubbed response.

Click to expand

stubby supports dynamic token replacement on the following properties:

  • response body
  • response header name values (including location header value)
  • response file names & payloads.

Example

-  request:
      method: [GET]
      url: ^/regex-fileserver/([a-z]+).html$

   response:
      status: 200
      file: ../html/<% url.1 %>.html


-  request:
      method: [GET]
      url: ^/v\d/identity/authorize
      query:
         redirect_uri: "https://(.*)/app.*"

   response:
      headers:
         location: https://<% query.redirect_uri.1 %>/auth
      status: 302
  
            
-  request:
      method: [GET]
      url: ^/account/(\d{5})/category/([a-zA-Z]+)
      query:
         date: "([a-zA-Z]+)"
      headers:
         custom-header: "[0-9]+"

   response:
      status: 200
      body: Returned invoice number# <% url.1 %> in category '<% url.2 %>' on the date '<% query.date.1 %>', using header custom-header <% headers.custom-header.0 %>

Example explained

The url regex ^/account/(\d{5})/category/([a-zA-Z]+) has two defined capturing groups: (\d{5}) and ([a-zA-Z]+), query regex has one defined capturing group ([a-zA-Z]+). In other words, a manually defined capturing group has parenthesis around it.

Although, the headers regex does not have capturing groups defined explicitly (no regex sections within parenthesis), its matched value is still accessible in a template (keep on reading!).

Token structure

The tokens in response body follow the format of <% PROPERTY_NAME . CAPTURING_GROUP_ID %>. If it is a token that should correspond to headers or query regex match, then the token structure would be as follows: <% HEADERS_OR_QUERY . KEY_NAME . CAPTURING_GROUP_ID %>. Whitespace is allowed between the <% & %> and what's inside.

Numbering the tokens based on capturing groups without sub-groups

When giving tokens their ID based on the count of manually defined capturing groups within regex, you should start from 1, not zero (zero reserved for token that holds full regex match) from left to right. So the leftmost capturing group would be 1 and the next one to the right of it would be 2, etc.

In other words <% url.1 %> and <% url.2 %> tokens correspond to two capturing groups from the url regex (\d{5}) and ([a-zA-Z]+), while <% query.date.1 %> token corresponds to one capturing group ([a-zA-Z]+) from the query date property regex.

Numbering the tokens based on capturing groups with sub-groups

In regex world, capturing groups can contain capturing sub-groups, as an example consider proposed url regex: ^/resource/ ( ([a-z]{3}) - ([0-9]{3}) ) $. In the latter example, the regex has three groups - a parent group ([a-z]{3}-[0-9]{3}) and two sub-groups within: ([a-z]{3}) & ([0-9]{3}).

When giving tokens their ID based on the count of capturing groups, you should start from 1, not zero (zero reserved for token that holds full regex match) from left to right. If a group has sub-group within, you count the sub-group(s) first (also from left to right) before counting the next one to the right of the parent group.

In other words tokens <% url.1 %>, <% url.2 %> and <% url.3 %> correspond to the three capturing groups from the url regex (starting from left to right): ([a-z]{3}-[0-9]{3}), ([a-z]{3}) and ([0-9]{3}).

Tokens with ID zero

Tokens with ID zero can obtain full match value from the regex they reference. In other words, tokens with ID zero do not care whether regex has capturing groups defined or not. For example, token <% url.0 %> will be replaced with the url full regex match from ^/account/(\d{5})/category/([a-zA-Z]+). So if you want to access the url full regex match, respectively you would use token <% url.0 %> in your template.

Another example, would be the earlier case where headers custom-header property regex does not have capturing groups defined within. Which is fine, since the <% headers.custom-header.0 %> token corresponds to the full regex match in the header custom-header property regex: [0-9]+.

It is also worth to mention, that the full regex match value replacing token <% query.date.0 %>, would be equal to the regex capturing group value replacing <% query.date.1 %>. This is due to how the query date property regex is defined - the one and only capturing group in the query date regex, is also the full regex itself.

Where to specify the template

You can specify template with tokens in both body as a string or using file by specifying template as external local file. When template is specified as file, the contents of local file from file will be replaced.

Alternatively, you can also template the path to the file itself:

-  request:
      method: [GET]
      url: ^/regex-fileserver/([a-z]+).html$

   response:
      status: 200
      file: ../html/<% url.1 %>.html

When the request is recieved and the regex matches, the path to the file will get resolved and the file content will be served if it exists.

-  request:
      method: POST
      url: /post-body-as-json
      headers:
         content-type: application/json
      post: >
         {"userId":"19","requestId":"(.*)","transactionDate":"(.*)","transactionTime":"(.*)"}

   response:
      headers:
         content-type: application/json
      status: 200
      body: >
         {"requestId": "<%post.1%>", "transactionDate": "<%post.2%>", "transactionTime": "<%post.3%>"}

Another example demonstrating the usage of tokens from the matched regex groups

When token interpolation happens

After successful HTTP request verification, if your body or contents of local file from file contain tokens - the tokens will be replaced just before rendering HTTP response.

Troubleshooting

  • Make sure that the regex you used in your stubby4j configuration actually does what it suppose to do. Validate that it works before using it in stubby4j
  • Make sure that the regex has capturing groups for the parts of regex you want to capture as token values. In other words, make sure that you did not forget the parenthesis within your regex if your token IDs start from 1
  • Make sure that you are using token ID zero, when wanting to use full regex match as the token value
  • Make sure that the token names you used in your template are correct: check that property name is correct, capturing group IDs, token ID of the full match, the <% and %>

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Stubbing HTTP 30x redirects

In order to stub a 30x HTTP redirect, you need to stub the following:

  • the location header in headers section of the response
  • the status of the response must be one of the following HTTP codes: 301, 302, 303, 307 or 308.

Example

- request:
    method: GET
    headers:
      content-type: application/json
    url: /item/redirect/source

  response:
    status: 301
    headers:
      location: /item/redirect/destination


- request:
    method: GET
    headers:
      content-type: application/json
    url: /item/redirect/destination

  response:
    headers:
      content-type: application/json
    status: 200
    body: >
      {"response" : "content"}

Example explained

Upon successful HTTP request verification, the /item/redirect/destination value of the stubbed response header location will be set as the value of the location header of the Jetty HTTP response, which will cause the redirect to another stub with url value /item/redirect/destination

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Record and replay

If body of the stubbed response contains a URL starting with http(s), stubby knows that it should record an HTTP response from the provided URL (before rendering the stubbed response) and replay the recorded HTTP response on each subsequent call.

Example

-  request:
      method: [GET]
      url: /maps/api/geocode/json
      query:
         address: "1600%20Amphitheatre%20Parkway,%20Mountain%20View,%20CA"
         sensor: false

   response:
      status: 200
      headers:
         content-type: application/json
      body: http://maps.googleapis.com

Example explained

Upon successful HTTP request verification, properties of stubbed request (method, url, headers, post and query) are used to construct an HTTP request to the destination URL specified in body of the stubbed response.

In the above example, stubby will record HTTP response received after submitting an HTTP GET request to the url below: http://maps.googleapis.com/maps/api/geocode/json?sensor=false&address=1600+Amphitheatre+Parkway,+Mountain+View,+CA

Please note

  • Recorded HTTP response is not persistable, but kept in memory only. In other words, upon stubby shutdown the recording is lost
  • Make sure to specify in response body only the URL, without the path info. Path info should be specified in request url

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Supplying stubbed endpoints to stubby

There are two ways available (listed in no particular order):

  1. Submit POST requests to localhost:8889 at runtime (check the The admin portal)
  2. Load a YAML config data-file (using -d / --data flags) with the following structure for each stubbed endpoint:
  • description: optional description shown in logs
  • uuid: optional unique identifier
  • request: describes the client's call to the server
    • method: GET/POST/PUT/PATCH/DELETE/etc.
    • url: the URI regex string. GET parameters should also be included inline here
    • query: a key/value map of query string parameters included with the request. Query param value can be regex.
    • headers: a key/value map of headers the server should respond to. Header value can be regex.
    • post: a string matching the textual body of the response. Post value can be regex.
    • file: if specified, returns the contents of the given file as the request post. If the file cannot be found at request time, post is used instead
  • response: describes the server's response (or array of responses, refer to the earlier examples) to the client
    • headers: a key/value map of headers the server should use in it's response.
    • latency: the time in milliseconds the server should wait before responding. Useful for testing timeouts and latency
    • file: if specified, returns the contents of the given file as the response body. If the file cannot be found at request time, body is used instead
    • body: the textual body of the server's response to the client
    • status: the numerical HTTP status code (200 for OK, 404 for NOT FOUND, etc.)

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Splitting main YAML config

There are situations where your main YAML config file will grow and become bloated due to large number of stubs, e.g.: your application talks to many downstream services.

stubby4j supports splitting the main YAML config file into multiple sub-config YAML files, which allows for more logical & cleaner stub code organisation (kudos fly to https://github.com/harrysun2006).

Example

Main data.yaml:

includes:
   - service-1-stubs.yaml
   - service-2-stubs.yaml
   - ...
   - ...
   - service-N-stubs.yaml

Example explained

You define the stubbed endpoints for each service (or any other logical organisation of stubs that suits your needs) in their own some-name-that-suits-you-N.yaml sub-config files.

When stubby parses the main data.yaml provided using -d / --data flags, all included sub-configs will be loaded as if all the stubs were defined in one YAML.

Please note

You cannot mix in the same YAML config the includes with sub-configs & defining stubs using request/response, e.g.: stubby4j will fail to load the following YAML:

includes:
   - service-1-stubs.yaml
   - service-2-stubs.yaml
   - service-3-stubs.yaml
     
-  request:
      method:
         -  GET
         -  POST
         -  PUT
      url: ^/resources/asn/.*$

   response:
      status: 200
      body: >
         {"status": "ASN found!"}
      headers:
         content-type: application/json

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Performance optimization index

stubby4j uses a number of techniques to optimize evaluation of stubs

Regex pattern pre-compilation

During parsing of stubs config, the request.url, request.query, request.headers & request.post (or request.file) values are checked for presence of regex. If one of the aforementioned properties is a stubbed regex, then a regex pattern will be compiled & cached in memory. This way, the pattern(s) are compiled during config parsing, not stub evaluation.

Local caching of returning matched requests

On every incoming request, a local cache holding previously matched stubs is checked to see if there is a match for the incoming request hashCode. If the incoming request hashCode found in the cache, then the cached matched stub & the incoming request are compared to each other to determine a complete equality based on the stubbed request properties.

If a complete equality against the cached stub was not achieved, the incoming request is compared to all other stubs loaded in memory. If a full match was found, then that match will be cached using the incoming request hashCode as a key.

To disable stub caching pass --disable_stub_caching command-line arg to stubby4j jar upon start up (refer to Command-line switches sectio )

The admin portal

See ADMIN_PORTAL.md for details

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The stubs portal

Requests sent to any url at localhost:8882 (or wherever you told stubby to run) will search through the available endpoints and, if a match is found, respond with that endpoint's response data

How endpoints are matched

For a given endpoint, stubby only cares about matching the properties of the request that have been defined in the YAML. The exception to this rule is method; if it is omitted it is defaulted to GET.

For instance, the following will match any POST request to the root url:

-  request:
      url: /
      method: POST
   response: {}

The request could have any headers and any post body it wants. It will match the above.

Pseudocode (StubRepository#matchStub):

    if (<incoming request>.hashCode found in <local cache>) {
        get <cached stubbed endpoint> from <local cache> by <incoming request>.hashCode
        return <cached stubbed endpoint>
    } else {
        for each <stubbed endpoint> of stored endpoints {
            for each <property> of <stubbed endpoint> {
                if (<stubbed endpoint>.<property> != <incoming request>.<property>) {
                    next stubbed endpoint
                }
            }
            store in <local cache> the found <stubbed endpoint> by hashCode

            return <stubbed endpoint>
        }
    }

Change log

See CHANGELOG.md

Authors

See AUTHORS.md

Contributors

See CONTRIBUTORS.md

See also

Copyright

See COPYRIGHT.md for details

License

MIT. See LICENSE for details

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