Serverless OpenWhisk Plugin
This plugin enables support for the OpenWhisk platform within the Serverless Framework.
Getting Started
Register account with OpenWhisk
Before you can deploy your service to OpenWhisk, you need to have an account registered with the platform.
- Want to run the platform locally? Please read the project's Quick Start guide for deploying it locally.
- Want to use a hosted provider? Please sign up for an account with IBM Bluemix and then follow the instructions for getting access to OpenWhisk on Bluemix.
Set up account credentials
Account credentials for OpenWhisk can be provided through a configuration file or environment variables. This plugin requires the API endpoint, namespace and authentication credentials.
Do you want to use a configuration file for storing these values? Please follow the instructions for setting up the OpenWhisk command-line utility. This tool stores account credentials in the .wskprops
file in the user's home directory. The plugin automatically extracts credentials from this file at runtime. No further configuration is needed.
Do you want to use environment variables for credentials? Use the following environment variables to be pass in account credentials. These values override anything extracted from the configuration file.
- OW_APIHOST - Platform endpoint, e.g.
openwhisk.ng.bluemix.net
- OW_AUTH - Authentication key, e.g.
xxxxxx:yyyyy
- OW_APIGW_ACCESS_TOKEN - API gateway access token (optional)
Install Framework & Dependencies
Due to an outstanding issue with provider plugins, the OpenWhisk provider must be installed as a global module.
$ npm install --global serverless serverless-openwhisk
This framework plugin requires Node.js runtime version 6.0 or above.
Create Service From Template
Using the create
command, you can create an example service from the following template.
serverless create --template openwhisk-nodejs --path my_service
cd my_service
npm install
More service examples are available in the serverless-examples
repository.
Using a self-hosted version of the platform?
Ensure you set the ignore_certs
option in the serverless.yaml prior to deployment.
provider:
name: openwhisk
ignore_certs: true
Deploy Service
The sample service from the template can be deployed without modification.
serverless deploy
If the deployment succeeds, the following messages will be printed to the console.
$ serverless deploy
Serverless: Packaging service...
Serverless: Compiling Functions...
Serverless: Compiling API Gateway definitions...
Serverless: Compiling Rules...
Serverless: Compiling Triggers & Feeds...
Serverless: Deploying Functions...
Serverless: Deployment successful!
Service Information
platform: openwhisk.ng.bluemix.net
namespace: _
service: my_service
actions:
my_service-dev-hello
triggers:
**no triggers deployed***
rules:
**no rules deployed**
endpoints:
**no routes deployed**
web-actions:
**no web actions deployed**
Test Service
Use the invoke
command to test your newly deployed service.
$ serverless invoke --function hello
{
"payload": "Hello, World!"
}
$ serverless invoke --function hello --data '{"name": "OpenWhisk"}'
{
"payload": "Hello, OpenWhisk!"
}
Writing Functions - Node.js
Here's an index.js
file containing an example handler function.
function main(params) {
const name = params.name || 'World';
return {payload: 'Hello, ' + name + '!'};
};
exports.main = main;
Modules should return the function handler as a custom property on the global exports
object.
In the serverless.yaml
file, the handler
property is used to denote the source file and module property containing the serverless function.
functions:
my_function:
handler: index.main
Request Properties
OpenWhisk executes the handler function for each request. This function is called with a single argument, an object containing the request properties.
function main(params) {
const parameter = params.parameter_name;
...
};
Function Return Values
The handler must return an object from the function call. Returning undefined
or null
will result in an error. If the handler is carrying out an asynchronous task, it can return a Promise
.
// synchronous return
function main () {
return { payload: "..." }
}
// asychronous return
function main(args) {
return new Promise(function(resolve, reject) {
setTimeout(function() {
resolve({ done: true });
}, 2000);
})
}
If you want to return an error message, return an object with an error
property with the message. Promise values that are rejected will be interpreted as runtime errors.
// synchronous return
function main () {
return { error: "..." }
}
// asychronous return
function main(args) {
return new Promise(function(resolve, reject) {
setTimeout(function() {
reject("error message");
}, 2000);
})
}
Using NPM Modules
NPM modules must be installed locally in the node_modules
directory before deployment. This directory will be packaged up in the deployment artefact. Any dependencies included in node_modules
will be available through require()
in the runtime environment.
OpenWhisk provides a number of popular NPM modules in the runtime environment. Using these modules doesn't require them to be included in the deployment package. See this list for full details of which modules are available.
const leftPad = require("left-pad")
function pad_lines(args) {
const lines = args.lines || [];
return { padded: lines.map(l => leftPad(l, 30, ".")) }
};
exports.handler = pad_lines;
Writing Functions - PHP
Here's an index.php
file containing an example handler function.
<?php
function main(array $args) : array
{
$name = $args["name"] ?? "stranger";
$greeting = "Hello $name!";
echo $greeting;
return ["greeting" => $greeting];
}
In the serverless.yaml
file, the handler
property is used to denote the source file and function name of the serverless function.
functions:
my_function:
handler: index.main
runtime: php
Request Properties
OpenWhisk executes the handler function for each request. This function is called with a single argument, an associative array containing the request properties.
function main(array $args) : array
{
$name = $args["name"] ?? "stranger";
...
}
Function Return Values
The handler must return an associative array from the function call.
func main(args: [String:Any]) -> [String:Any] {
...
return ["foo" => $bar];
}
If you want to return an error message, return an object with an error
property with the message.
Writing Functions - Python
Here's an index.py
file containing an example handler function.
def endpoint(params):
name = params.get("name", "stranger")
greeting = "Hello " + name + "!"
print(greeting)
return {"greeting": greeting}
In the serverless.yaml
file, the handler
property is used to denote the source file and module property containing the serverless function.
functions:
my_function:
handler: index.endpoint
runtime: python
Request Properties
OpenWhisk executes the handler function for each request. This function is called with a single argument, a dictionary containing the request properties.
def endpoint(params):
name = params.get("name", "stranger")
...
Function Return Values
The handler must return a dictionary from the function call.
def endpoint(params):
...
return {"foo": "bar"}
If you want to return an error message, return an object with an error
property with the message.
Writing Functions - Swift
Here's an index.swift
file containing an example handler function.
func main(args: [String:Any]) -> [String:Any] {
if let name = args["name"] as? String {
return [ "greeting" : "Hello \(name)!" ]
} else {
return [ "greeting" : "Hello stranger!" ]
}
}
In the serverless.yaml
file, the handler
property is used to denote the source file and module property containing the serverless function.
functions:
my_function:
handler: index.main
runtime: swift
Request Properties
OpenWhisk executes the handler function for each request. This function is called with a single argument, a dictionary containing the request properties.
func main(args: [String:Any]) -> [String:Any] {
let prop = args["prop"] as? String
}
Function Return Values
The handler must return a dictionary from the function call.
func main(args: [String:Any]) -> [String:Any] {
...
return ["foo": "bar"]
}
If you want to return an error message, return an object with an error
property with the message.
Writing Functions - Pre-Compiled Swift Binaries
OpenWhisk supports creating Swift actions from a pre-compiled binary. This reduces startup time for Swift actions by removing the need for a dynamic compilation step.
In the serverless.yaml
file, the handler
property can refer to the compiled binary file produced by the build.
functions:
hello:
handler: .build/release/Hello
This configuration will generate the deployment package for that function containing only this binary file. It will not include other local files, e.g. Swift source files.
Pre-compiled Swift actions must be compatible with the platform runtime and architecture. There is an open-source Swift package (OpenWhiskAction
) that handles wrapping functions within a shim to support runtime execution.
import OpenWhiskAction
func hello(args: [String:Any]) -> [String:Any] {
if let name = args["name"] as? String {
return [ "greeting" : "Hello \(name)!" ]
} else {
return [ "greeting" : "Hello stranger!" ]
}
}
OpenWhiskAction(main: hello)
Binaries produced by the Swift build process must be generated for the correct platform architecture. This Docker command will compile Swift sources files using the relevant Swift environment.
docker run --rm -it -v $(pwd):/swift-package openwhisk/action-swift-v3.1.1 bash -e -c "cd /swift-package && swift build -v -c release"
Writing Functions - Java
Here's an src/main/java/HelloWorld.java
file containing an example handler function.
import com.google.gson.JsonObject;
public class HelloWorld {
public static JsonObject main(JsonObject args) throws Exception {
final String name = args.getAsJsonPrimitive("name").getAsString();
final JsonObject response = new JsonObject();
response.addProperty("greeting", "Hello " + name + "!");
return response;
}
}
Here is a simple pom.xml
file that will allow you to use Maven to build it. You will notice that gson
is excluded from the uberjar. That is because OpenWhisk already provides this dependency.
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>hello</groupId>
<artifactId>hello-world</artifactId>
<version>1.0</version>
<dependencies>
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.8.2</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>3.1.0</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<minimizeJar>true</minimizeJar>
<artifactSet>
<excludes>
<exclude>com.google.code.gson:gson</exclude>
</excludes>
</artifactSet>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
In the serverless.yaml
file (see below), the handler
property is the uberjar produced by calling mvn clean package
, a colon, and then the fully qualified class name of the class with the main function. If you do not provide a class name after the jar, it will look for a class in the default package called Main
.
service: my-java-service
provider:
name: openwhisk
runtime: java
functions:
hello:
handler: target/hello-world-1.0.jar:HelloWorld
plugins:
- serverless-openwhisk
Request Properties
OpenWhisk executes the handler function for each request. This function is called with a single argument, a com.google.gson.JsonObject
containing the request properties.
import com.google.gson.JsonObject;
public class MyActionClass {
public static JsonObject main(JsonObject args) throws Exception
{
final String name = args.getAsJsonPrimitive("name").getAsString();
...
}
}
Function Return Values
The handler must return an com.google.gson.JsonObject
from the function call.
import com.google.gson.JsonObject;
public class MyActionClass {
public static JsonObject main(JsonObject args) throws Exception
{
...
final JsonObject response = new JsonObject();
response.addProperty("greeting", "Hello " + name + "!");
return response;
}
}
If you want to return an error message, throw an exception.
Writing Functions - Binary
OpenWhisk supports executing a compiled binary for the function handler. Using a Python wrapper, the file will be invoked within the openwhisk/dockerskeleton
Docker container.
The binary must be compiled for the correct platform architecture and only link to shared libraries installed in the openwhisk/dockerskeleton
runtime.
In the serverless.yaml
file, the handler
property is used to denote the binary file to upload.
functions:
my_function:
handler: bin_file
runtime: binary
Request Properties
OpenWhisk executes the binary file for each request. Event parameters are streamed to stdio
as a JSON object string.
Function Return Values
The handler must write a JSON object string with the response parameters to stdout
before exiting.
If you want to return an error message, return an object with an error
property with the message.
Custom Runtime Images
OpenWhisk actions can use custom Docker images as the runtime environment. This allows extra packages, libraries or tools to be pre-installed in the runtime environment. Using a custom runtime image, with extra libraries and dependencies built-in, is useful for overcoming the maximum deployment size on actions.
Images must implement the API used by the platform to interact with runtime environments. Images must also be available on Docker Hub. OpenWhisk does not support private Docker registries.
OpenWhisk publishes the existing runtime images on Docker Hub. Using these images in the FROM
directive in the Dockerfile
is an easy way to create new images compatible with the platform.
In the serverless.yaml
file, the image
property is used to denote the custom runtime image.
functions:
my_function:
handler: source.js
runtime: nodejs
image: dockerhub_user/image_name
Node.js, Swift, Python and Binary runtimes support using a custom image property.
Writing Functions - Docker
OpenWhisk supports creating actions from public images on Docker Hub without handler files. These images are expected to support the platform API used to instantiate and invoke serverless functions.
All necessary files for execution must be provided within the image. Local source files will not be uploaded to the runtime environment.
In the serverless.yaml
file, the handler
property is used to denote the image label.
functions:
my_function:
handler: repo/image_name
runtime: docker
Working With Packages
OpenWhisk provides a concept called "packages" to manage related actions. Packages can contain multiple actions under a common identifier in a namespace. Configuration values needed by all actions in a package can be set as default properties on the package, rather than individually on each action.
Packages are identified using the following format: /namespaceName/packageName/actionName
.
Rules and triggers can not be created within packages.
Implicit Packages
Actions can be assigned to packages by setting the function name
with a package reference.
functions:
foo:
handler: handler.foo
name: "myPackage/foo"
bar:
handler: handler.bar
name: "myPackage/bar"
In this example, two new actions (foo
& bar
) will be created using the myPackage
package.
Packages which do not exist will be automatically created during deployments. When using the remove
command, any packages referenced in the serverless.yml
will be deleted.
Explicit Packages
Packages can also be defined explicitly to set shared configuration parameters. Default package parameters are merged into event parameters for each invocation.
functions:
foo:
handler: handler.foo
name: "myPackage/foo"
resources:
packages:
myPackage:
parameters:
hello: world
Explicit packages support the following properties: parameters
, annotations
and shared
.
Binding Packages
OpenWhisk also supports "binding" external packages into your workspace. Bound packages can have default parameters set for shared actions.
For example, binding the /whisk.system/cloudant
package into a new package allows you to set default values for the username
, password
and dbname
properties. Actions from this package can then be invoked with having to pass these parameters in.
Define packages explicitly with a binding
parameter to use this behaviour.
resources:
packages:
mySamples:
binding: /whisk.system/cloudant
parameters:
username: bernie
password: sanders
dbname: vermont
For more details on package binding, please see the documentation here.
Runtime Configuration Properties
The following OpenWhisk configuration properties are supported for functions defined in
the serverless.yaml
file.
functions:
my_function:
handler: file_name.handler_func
name: "custom_function_name"
runtime: 'runtime_label' // defaults to nodejs:default
namespace: "..." // defaults to user-provided credentials
memory: 256 // 128 to 512 (MB).
timeout: 60 // 0.1 to 600 (seconds)
parameters:
foo: bar // default parameters
annotations:
foo: bar // action annotations
Writing Sequences
OpenWhisk supports a special type of serverless function called sequences.
These functions are defined from a list of other serverless functions. Upon invocation, the platform executes each function in series. Request parameters are passed into the first function in the list. Each subsequent function call is passed the output from the previous step as input parameters. The last function's return value is returned as the response result.
Here's an example of the configuration to define a sequence function, composed of three other functions.
functions:
my_function:
sequence:
- parse_input
- do_some_algorithm
- construct_output
Sequence functions do not have a handler file defined. If you want to refer to functions not defined in the serverless project, use the fully qualified identifier e.g. /namespace/package/action_name
Connecting HTTP Endpoints
Functions can be bound to public URL endpoints using the API Gateway service. HTTP requests to configured endpoints will invoke functions on-demand. Requests parameters are passed as function arguments. Function return values are serialised as the JSON response body.
HTTP endpoints for functions can be configured through the serverless.yaml
file.
functions:
my_function:
handler: index.main
events:
- http: GET /api/greeting
HTTP event configuration also supports using explicit parameters.
method
- HTTP method (mandatory).path
- URI path for API gateway (mandatory).resp
- controls web action content type, values include:json
,html
,http
,svg
ortext
(optional, defaults tojson
).
functions:
my_function:
handler: index.main
events:
- http:
method: GET
path: /api/http
resp: http
API Gateway hosts serving the API endpoints will be shown during deployment.
$ serverless deploy
...
endpoints:
GET https://xxx-gws.api-gw.mybluemix.net/service_name/api/path --> service_name-dev-my_function
Calling the configured API endpoints will execute the deployed functions.
$ http get https://xxx-gws.api-gw.mybluemix.net/api/greeting?user="James Thomas"
HTTP/1.1 200 OK
Content-Type: application/json; charset=UTF-8
Date: Mon, 19 Dec 2016 15:47:53 GMT
{
"message": "Hello James Thomas!"
}
Exporting Web Actions
Functions can be turned into "web actions" which return HTTP content without use of an API Gateway. This feature is enabled by setting an annotation (web-export
) in the configuration file.
functions:
my_function:
handler: index.main
annotations:
web-export: true
Functions with this annotation can be invoked through a URL template with the following parameters.
https://{APIHOST}/api/v1/web/{USER_NAMESPACE}/{PACKAGE}/{ACTION_NAME}.{TYPE}
- APIHOST - platform endpoint e.g. openwhisk.ng.bluemix.net.
- USER_NAMESPACE - this must be an explicit namespace and cannot use the default namespace (_).
- PACKAGE - action package or
default
. - ACTION_NAME - default form
${servicename}-${space}-${name}
. - TYPE -
.json
,.html
,.text
or.http
.
Return values from the function are used to construct the HTTP response. The following parameters are supported.
headers
: a JSON object where the keys are header-names and the values are string values for those headers (default is no headers).code
: a valid HTTP status code (default is 200 OK).body
: a string which is either plain text or a base64 encoded string (for binary data).
Here is an example of returning HTML content:
function main(args) {
var msg = "you didn't tell me who you are."
if (args.name) {
msg = `hello ${args.name}!`
}
return {body:
`<html><body><h3><center>${msg}</center></h3></body></html>`}
}
Here is an example of returning binary data:
function main() {
let png = <base 64 encoded string>
return {
headers: { "Content-Type": "image/png" },
body: png };
}
Functions can access request parameters using the following environment variables.
__ow_method
- HTTP method of the request.__ow_headers
- HTTP request headers.__ow_path
- Unmatched URL path of the request.__ow_body
- Body entity from request.__ow_query
- Query parameters from the request.
Full details on this feature are available in this here.
Scheduled Invocations
Functions can be set up to fire automatically using the alarm package. This allows you to invoke functions with preset parameters at specific times (12:00 each day) or according to a schedule (every ten minutes).
Scheduled invocation for functions can be configured through the serverless.yaml
file.
The schedule
event configuration is controlled by a string, based on the UNIX crontab syntax, in the format cron(X X X X X)
. This can either be passed in as a native string or through the rate
parameter.
functions:
my_function:
handler: index.main
events:
- schedule: cron(* * * * *) // fires each minute.
This above example generates a new trigger (${service}_crawl_schedule_trigger
) and rule (${service}_crawl_schedule_rule
) during deployment.
Other schedule
event parameters can be manually configured, e.g trigger or rule names.
functions:
aggregate:
handler: statistics.handler
events:
- schedule:
rate: cron(0 * * * *) // call once an hour
trigger: triggerName
rule: ruleName
max: 10000 // max invocations, default: 1000, max: 10000
params: // event params for invocation
hello: world
IBM Message Hub Events
IBM Bluemix provides an "Apache Kafka"-as-a-Service called IBM Message Hub. Functions can be connected to fire when messages arrive on Kafka topics.
IBM Message Hub instances can be provisioned through the IBM Bluemix platform. OpenWhisk on Bluemix will export Message Hub service credentials bound to a package with the following name:
/${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1
Rather than having to manually define all the properties needed by the Message Hub trigger feed, you can reference a package to use instead. Credentials from the referenced package will be used when executing the trigger feed.
Developers only need to add the topic to listen to for each trigger.
# serverless.yaml
functions:
index:
handler: users.main
events:
- message_hub:
package: /${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1
topic: my_kafka_topic
The plugin will create a trigger called ${serviceName}_${fnName}_messagehub_${topic}
and a rule called ${serviceName}_${fnName}_messagehub_${topic}_rule
to bind the function to the message hub events.
The trigger and rule names created can be set explicitly using the trigger
andrule
parameters.
Other functions can bind to the same trigger using the inline trigger
event referencing this trigger name.
# serverless.yaml
functions:
index:
handler: users.main
events:
- message_hub:
package: /${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1
topic: my_kafka_topic
trigger: log_events
rule: connect_index_to_kafka
another:
handler: users.another
events:
- trigger: log_events
Using Manual Parameters
Parameters for the Message Hub event source can be defined explicitly, rather than using pulling credentials from a package.
# serverless.yaml
functions:
index:
handler: users.main
events:
- message_hub:
topic: my_kafka_topic
brokers: afka01-prod01.messagehub.services.us-south.bluemix.net:9093
user: USERNAME
password: PASSWORD
admin_url: https://kafka-admin-prod01.messagehub.services.us-south.bluemix.net:443
json: true
binary_key: true
binary_value: true
topic
, brokers
, user
, password
and admin_url
are mandatory parameters.
Cloudant DB Events
IBM Cloudant provides a hosted NoSQL database, based upon CouchDB, running on IBM Bluemix. Functions can be connected to events fired when the database is updated. These events use the CouchDB changes feed to follow database modifications.
IBM Cloudant instances can be provisioned through the IBM Bluemix platform. OpenWhisk on Bluemix will export Cloudant service credentials bound to a package with the following name:
/${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1
Rather than having to manually define all the properties needed by the Cloudant trigger feed, you can reference a package to use instead. Credentials from the referenced package will be used when executing the trigger feed.
Developers only need to add the database name to follow for modifications.
# serverless.yaml
functions:
index:
handler: users.main
events:
- cloudant:
package: /${BLUEMIX_ORG}_${BLUEMIX_SPACE}/Bluemix_${SERVICE_NAME}_Credentials-1
db: my_db_name
The plugin will create a trigger called ${serviceName}_${fnName}_cloudant_${topic}
and a rule called ${serviceName}_${fnName}_cloudant_${topic}_rule
to bind the function to the Cloudant update events.
The trigger and rule names created can be set explicitly using the trigger
andrule
parameters.
Other functions can bind to the same trigger using the inline trigger
event referencing this trigger name.
Using Manual Parameters
Parameters for the Cloudant event source can be defined explicitly, rather than using pulling credentials from a package.
# serverless.yaml
functions:
index:
handler: users.main
events:
- cloudant:
host: xxx-yyy-zzz-bluemix.cloudant.com
username: USERNAME
password: PASSWORD
db: db_name
Adding Optional Parameters
The following optional feed parameters are also supported:
max
- Maximum number of triggers to fire. Defaults to infinite.filter
- Filter function defined on a design document.query
- Optional query parameters for the filter function.
# serverless.yaml
functions:
index:
handler: users.main
events:
- cloudant:
...
max: 10000
query:
status: new
filter: mailbox/by_status
Custom Event Triggers
Functions are connected to event sources in OpenWhisk using triggers and rules. Triggers create a named event stream within the system. Triggers can be fired manually or connected to external data sources, like databases or message queues.
Rules set up a binding between triggers and serverless functions. With an active rule, each time a trigger is fired, the function will be executed with the trigger payload.
Event binding for functions can be configured through the serverless.yaml
file.
functions:
my_function:
handler: index.main
events:
- trigger: my_trigger
This configuration will create a trigger called servicename-my_trigger
with an active rule binding my_function
to this event stream.
Customising Rules
Rule names default to the following format servicename-trigger-to-action
. These names be explicitly set through configuration.
functions:
my_function:
handler: index.main
events:
- trigger:
name: "my_trigger"
rule: "rule_name"
Customing Triggers
Triggers can be defined as separate resources in the serverless.yaml
file. This allows you to set up trigger properties like default parameters.
functions:
my_function:
handler: index.main
events:
- trigger: my_trigger
resources:
triggers:
my_trigger:
parameters:
hello: world
Trigger Feeds
Triggers can be bound to external event sources using the feed
property. OpenWhisk provides a catalogue of third-party event sources bundled as packages.
This example demonstrates setting up a trigger which uses the /whisk.system/alarms/alarm
feed. The alarm
feed will fire a trigger according to a user-supplied cron schedule.
resources:
triggers:
alarm_trigger:
parameters:
hello: world
feed: /whisk.system/alarms/alarm
feed_parameters:
cron: '*/8 * * * * *'
Commands
The following serverless commands are currently implemented for the OpenWhisk provider.
deploy
- Deploy functions, triggers and rules for service.invoke
- Invoke deployed serverless function and show result.invokeLocal
- Invoke serverless functions locally and show result.remove
- Remove functions, triggers and rules for service.logs
- Display activation logs for deployed function.info
- Display details on deployed functions, triggers and rules.