chore: allow to build and publish experimental Linux images

[lemeurherve]

This change allow to build and publish experimental inbound agent image using jlink.

By default using a Debian JDK25 image as base, it cCan be extended to other distributions and experiments if needed.

If PUBLISH_EXPERIMENTAL is set to true, the experimental image would be published with a unique tag like 3355.v388858a_47b_33-1-debian_jdk25-experimental-jlink-not-prod-ready.

Extracted from:

• feat: publish inbound-agent_debian_jdk25_experimental-jlink image #1128

Refs:

• Don't use jlink in newer JDKs images until properly tested #1124 (comment)
• Publish experimental jlink image for newer JDK(s) #1131

Testing done

$ make test
$ make test-experimental

$  make list
agent_alpine_jdk21
agent_alpine_jdk25
agent_debian_jdk17
agent_debian_jdk21
agent_debian_jdk25
agent_rhel_ubi9_jdk17
agent_rhel_ubi9_jdk21
agent_rhel_ubi9_jdk25
inbound-agent_alpine_jdk21
inbound-agent_alpine_jdk25
inbound-agent_debian_jdk17
inbound-agent_debian_jdk21
inbound-agent_debian_jdk25
inbound-agent_debian_jdk25_experimental-jlink
inbound-agent_rhel_ubi9_jdk17
inbound-agent_rhel_ubi9_jdk21
inbound-agent_rhel_ubi9_jdk25

$ make show-experimental
{
  "group": {
    "default": {
      "targets": [
        "experimental"
      ]
    },
    "experimental": {
      "targets": [
        "experimental_jlink"
      ]
    },
    "experimental_jlink": {
      "targets": [
        "inbound-agent_debian_jdk25_experimental-jlink"
      ]
    }
  },
  "target": {
    "inbound-agent_debian_jdk25_experimental-jlink": {
      "context": ".",
      "dockerfile": "debian/Dockerfile",
      "args": {
        "DEBIAN_RELEASE": "trixie-20260112",
        "EXPERIMENTAL_JLINK": "true",
        "JAVA_VERSION": "25.0.1+8",
        "VERSION": "3355.v388858a_47b_33"
      },
      "labels": {
        "org.opencontainers.image.title": "Jenkins experimental debian_jdk25 image using jlink"
      },
      "tags": [
        "docker.io/jenkins/inbound-agent:3355.v388858a_47b_33-1-debian_jdk25-experimental-jlink-not-prod-ready"
      ],
      "target": "inbound-agent",
      "platforms": [
        "linux/amd64",
        "linux/arm64",
        "linux/ppc64le",
        "linux/s390x"
      ],
      "output": [
        {
          "type": "cacheonly"
        }
      ]
    }
  }
}

# Check that no experimental image is pushed on publication by default if PUBLISH_EXPERIMENTAL is not set
$ export DOCKERHUB_ORGANISATION=hlemeur
$ ./build.sh publish
$ curl -s "https://registry.hub.docker.com/v2/repositories/${DOCKERHUB_ORGANISATION}/inbound-agent/tags?page_size=100" \
   | jq -r '.results[].name' | sort
3192.v713e3b_039fb_e-1-jdk21
3355.v388858a_47b_33-1
3355.v388858a_47b_33-1-alpine
3355.v388858a_47b_33-1-alpine-jdk17
3355.v388858a_47b_33-1-alpine-jdk21
3355.v388858a_47b_33-1-alpine-jdk25
3355.v388858a_47b_33-1-alpine3.23
3355.v388858a_47b_33-1-alpine3.23-jdk17
3355.v388858a_47b_33-1-alpine3.23-jdk21
3355.v388858a_47b_33-1-alpine3.23-jdk25
3355.v388858a_47b_33-1-inbound-agent_debian_jdk25-experimental-jlink-not-prod-ready
3355.v388858a_47b_33-1-jdk17
3355.v388858a_47b_33-1-jdk21
3355.v388858a_47b_33-1-jdk25
3355.v388858a_47b_33-1-rhel-ubi9
3355.v388858a_47b_33-1-rhel-ubi9-jdk17
3355.v388858a_47b_33-1-rhel-ubi9-jdk21
3355.v388858a_47b_33-1-rhel-ubi9-jdk25
alpine
alpine-jdk17
alpine-jdk21
alpine-jdk25
alpine3.23
alpine3.23-jdk17
alpine3.23-jdk21
alpine3.23-jdk25
bookworm-jdk21
jdk17
jdk21
jdk25
latest
latest-alpine
latest-alpine-jdk17
latest-alpine-jdk21
latest-alpine-jdk25
latest-alpine3.23
latest-alpine3.23-jdk17
latest-alpine3.23-jdk21
latest-alpine3.23-jdk25
latest-bookworm-jdk21
latest-jdk17
latest-jdk21
latest-jdk25
latest-rhel-ubi9
latest-rhel-ubi9-jdk17
latest-rhel-ubi9-jdk21
latest-rhel-ubi9-jdk25
latest-trixie
latest-trixie-jdk17
latest-trixie-jdk21
latest-trixie-jdk25
rhel-ubi9
rhel-ubi9-jdk17
rhel-ubi9-jdk21
rhel-ubi9-jdk25
trixie
trixie-jdk17
trixie-jdk21
trixie-jdk25

# Check that experimental image is pushed on publication if PUBLISH_EXPERIMENTAL is set to true
$ export PUBLISH_EXPERIMENTAL=true

$ make show-experimental
{
  "group": {
    "default": {
      "targets": [
        "experimental"
      ]
    },
    "experimental": {
      "targets": [
        "experimental_jlink"
      ]
    },
    "experimental_jlink": {
      "targets": [
        "inbound-agent_debian_jdk25_experimental-jlink"
      ]
    }
  },
  "target": {
    "inbound-agent_debian_jdk25_experimental-jlink": {
      "context": ".",
      "dockerfile": "debian/Dockerfile",
      "args": {
        "DEBIAN_RELEASE": "trixie-20260112",
        "EXPERIMENTAL_JLINK": "true",
        "JAVA_VERSION": "25.0.1+8",
        "VERSION": "3355.v388858a_47b_33"
      },
      "labels": {
        "org.opencontainers.image.title": "Jenkins experimental debian_jdk25 image using jlink"
      },
      "tags": [
        "docker.io/jenkins/inbound-agent:3355.v388858a_47b_33-1-debian_jdk25-experimental-jlink-not-prod-ready"
      ],
      "target": "inbound-agent",
      "platforms": [
        "linux/amd64",
        "linux/arm64",
        "linux/ppc64le",
        "linux/s390x"
      ],
      "output": [
        {
          "type": "image"
        },
        {
          "type": "docker"
        }
      ]
    }
  }
}

$ ./build.sh publish
$ curl -s "https://registry.hub.docker.com/v2/repositories/${DOCKERHUB_ORGANISATION}/inbound-agent/tags?page_size=100" \
   | jq -r '.results[].name' | sort | grep experimental
3355.v388858a_47b_33-1-debian_jdk25-experimental-jlink-not-prod-ready

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed

[dduportal]

#1131 (comment)

I think this is a bad idea to have experimental images in the normal DockerHub namespace. It will have consequences in term of usage and trust.

I think, though, that building a proper "incremental" (or "experimental", 2 words, same concept) system to provide early testers an image can be discussed and implemented. But not coupled with a specifc case such as jlink here: it is a "scope creep" approach which will only results in discussions and frictions by trying to kill 2 birds with one little stone