/proxy-image

Image proxy server based on spring cloud gateway filters

Primary LanguageKotlin

Description

Image proxy server based on spring cloud gateway filters provides opportunity to modify images on fly.
There are two ways to customize response image:

  • By passing additional query parameter at the request, see tables below
  • By setting up default filters parameters at the spring application properties

It is available to use several filters for a specific url and enable an image filter by customizing settings of proxied server response (see io.github.aptushkin.proxy.image.modify.predicate.ImageModifierPredicate and responseHeaderName property).


Usage:

  1. As standalone http (https in todo list) proxy server to modify image responses from proxied servers
  2. As dependency, it is possible to fetch proxy-image-starter to get image modifications filters for your custom spring cloud gateway server
  3. TODO: As part of spring cloud microservices infrastructure (eureka, config server)
  4. TODO: As part of your Spring REST API server by fetching a starter

How to use inside your spring-cloud-gateway server

Fetch dependency from https://repo1.maven.org/maven2:
Maven:

<dependency>
    <groupId>io.github.artemptushkin.proxy.image</groupId>
    <artifactId>proxy-image-starter</artifactId>
    <version>1.0.3</version>
</dependency>

Gradle:

compile group: 'io.github.aptushkin.proxy.image', name: 'proxy-image-starter', version: '0.0.1-SNAPSHOT'

Use spring properties to activate custom image filters:

proxy.image:
    enalbed: true

Customization of gateway filters properties

  1. Enable default filter to proxy every request to the target destination

    spring:
  cloud:
    gateway:
      default-filters:
        - ProxyForward

  2. Customize routing properties to specify image modification filters

     spring.cloud.gateway.routes:
   - id: modify_image_router
   uri: no://op
    predicates:
     - Path=/**

  3. Specify required filters

    spring.cloud.gateway:
 filters:
   name: ModifyImageSize
   args:
     responseHeaderName: Content-Type
     regexp: image/.*

Available image filters

Resize filter

Spring properties name: ResizeImage

Default properties:

Property Required Description
defaultWidth N Default width value of resize method
defaultHeight N Default height value of resize method
defaultMode N Default mode value of resize method; See http://javadox.com/org.imgscalr/imgscalr-lib/4.2/org/imgscalr/Scalr.Mode.html
defaultMethod N Default method value of resize method; http://javadox.com/org.imgscalr/imgscalr-lib/4.2/org/imgscalr/Scalr.Method.html
responseHeaderName Y The header name of proxied server response
regexp Y Regex to verify response header value. If matched then current filter should be applied
onNotExistedHeader N If true, current filter will be applied; otherwise not
defaultFormat N default file format for image modification

Query parameters:

Property Description
width Width value of target image
height Height value of target image
format File format for image modification
mode Mode value of resize method; See http://javadox.com/org.imgscalr/imgscalr-lib/4.2/org/imgscalr/Scalr.Mode.html
method Method value of resize method; See http://javadox.com/org.imgscalr/imgscalr-lib/4.2/org/imgscalr/Scalr.Mode.html

Curl example:

curl --location --request GET 'http://github.githubassets.com/images/modules/open_graph/github-octocat.png?width=100&height=300&format=jpg'

Crop filter

Spring properties name: CropImage

Default properties:

Property Required Description
defaultWidth N Default width value of crop method
defaultHeight N Default height value of crop method
defaultX N Default X value of crop method; Used to crop the proxy image from the top-left corner
defaultY N Default Y value of crop method; Used to crop the proxy image from the top-left corner
responseHeaderName Y The header name of proxied server response
regexp Y Regex to verify response header value. If matched then current filter should be applied
onNotExistedHeader N If true, current filter will be applied; otherwise not
defaultFormat N default file format for image modification

Query parameters:

Property Description
width Width value of target image
height Height value of target image
format File format for image modification
x X value of crop method; Used to crop the proxy image from the top-left corner
y Y value of crop method; Used to crop the proxy image from the top-left corner

Curl example:

curl --location --request GET 'http://github.githubassets.com/images/modules/open_graph/github-octocat.png?width=600&height=500&x=400&y=100&format=jpg'

Rotate filter

Spring properties name: RotateImage

Default properties:

Property Required Description
rotation N Default rotation value for rotation method; See http://javadox.com/org.imgscalr/imgscalr-lib/4.2/org/imgscalr/Scalr.Rotation.html
responseHeaderName Y The header name of proxied server response
regexp Y Regex to verify response header value. If matched then current filter should be applied
onNotExistedHeader N If true, current filter will be applied; otherwise not
defaultFormat N default file format for image modification

Query parameters:

Property Description
rotation Rotation value for rotation method; See http://javadox.com/org.imgscalr/imgscalr-lib/4.2/org/imgscalr/Scalr.Rotation.html
format File format for image modification

Curl example:

curl --location --request GET 'http://github.githubassets.com/images/modules/open_graph/github-octocat.png?rotation=CW_180'

Development

How to build

mvn clean install

How to run

Run proxy server with classpath config file

java -jar ./proxy-image-server/target/proxy-image-server-0.0.1-SNAPSHOT.jar

How deploy current build to sonartype nexus

mvn clean deploy

How to release deploy to sonartype nexus

mvn clean release:prepare release:perform -Prelease

TODO

  1. Enabled HTTPS proxy requests for image-server
  2. Make starter for common web applications to use it with internal response filters for a specific url
  3. To add dependencies of spring cloud infrastructure: eureka-client, config-client