README

Example: Jib Sync

Jib is one of the supported builders in Skaffold. Jib has special sync support using the auto configuration.

Running the example

Run the maven or gradle version of the example.

Gradle

$ skaffold dev -f skaffold-gradle.yaml

Maven

$ skaffold dev -f skaffold-maven.yaml

You can now see sync in action:

1. See the original response from the HelloController in the spring application

$ curl localhost:8080
text-to-replace

1. Edit the hello controller src/main/java/hello/HelloController.java

+       return "some-new-text\n";
-       return "text-to-replace\n";

1. Give skaffold a few seconds to synchronize the file to the container, and give Spring Boot Developer Tools a chance to reload your application.
2. See the updated response from the HelloController

$ curl localhost:8080
some-new-text

1. You've now seen auto sync in action!

How it works

This example contains both maven and gradle build configs and separate skaffold.yamls.

• gradle: skaffold-gradle.yaml
• maven: skaffold-maven.yaml

use the -f flag to specify the correct buildfile when running (or rename your preferred option to skaffold.yaml)

$ skaffold -f skaffold-gradle.yaml ...

We configure it in skaffold.yaml, by enabling sync on the jib artifact.

build:
  artifacts:
  - image: skaffold-example
    context: .
    jib: {}
    sync: 
      auto: true

This example is designed around the functionality available in Spring Boot Developer Tools for developing against running applications.

Some additional steps are required for this to work:

• Sync requires tar on the running container to copy files over. The default base image that Jib uses gcr.io/distroless/java does not include tar or any utilities. During development, you must use a base image that includes tar, in this example we use the debug flavor of distroless: gcr.io/distroless/java:debug

This can be done directly in the artifact configuration by overriding the fromImage property.

build:
  artifacts:
  - image: skaffold-example
    context: .
    jib: 
      fromImage: gcr.io/distroless/java:debug
    sync: 
      auto: true

• You must include the spring-boot-devtools dependency at the compile/implementation scope, which is contrary to the configuration outlined in the official docs. Because jib is unaware of any special spring only configuration in your builds, we recommend using profiles to turn on or off devtools support in your jib container builds.

maven

<profiles>
  <profile>
    <id>sync</id>
    <dependencies>
      <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <!-- <optional>true</optional> not required -->
      </dependency>
    </dependencies>
  </profile>
</profiles>

gradle

dependencies {
  ...
  if (project.hasProperty('sync')) {
    implementation "org.springframework.boot:spring-boot-devtools"
    // do not use developmentOnly
  }
}

To activate these profiles, we add -Psync to the maven/gradle build command. This can be done directly in the artifact configuration

skaffold.yaml

build:
  artifacts:
  - image: skaffold-example
    context: .
    jib: 
      args: 
      - -Psync
    sync: 
      auto: true

You can also take advantage of skaffold profiles to control when to activate sync on your project.

skaffold.yaml

build:
  artifacts:
  - image: test-file-sync
    jib: {}

profiles:
- name: sync
  patches:
    # assuming jib is the first artifact (index 0) in your build.artifacts list
  - op: add
    # we want to activate sync on our skaffold artifact
    path: /build/artifacts/0/sync
    value:
      - auto: true
  - op: add
    # we activate the sync profile in our java builds
    path: /build/artifacts/0/jib/args
    value:
    - -Psync

skaffold profiles can be activated using the the -p flag when running

$ skaffold -p sync ...