fix(alpine) The Alpine Dockerfile does not use the ALPINE_TAG arg

[gounthar]

@MarkEWaite detected in #415 that there was a mismatch in the naming of our Alpine Docker image, and solved it in #416.
@dduportal took some time to guide me in figuring out the problem may need a more permanent fix.

We are getting the Alpine version shipped with Eclipse Temurin. We don't take into account the ALPINE_TAG set in the docker-bake.hcl file. Damien's proposal was to do as we do with Debian, proceed with two stages.
One stage to get the Temurin build, and one to get the correct (i.e. defined in the docker-bake) Alpine version.
The (optional?) next step would be to use jlink as we do in the Debian image.

Testing done

The only testing I have done is run locally after building the image:

docker run --rm jenkins/agent:alpine-jdk17 cat /etc/os-release
NAME="Alpine Linux"
ID=alpine
VERSION_ID=3.17.3
PRETTY_NAME="Alpine Linux v3.17"
HOME_URL="https://alpinelinux.org/"
BUG_REPORT_URL="https://gitlab.alpinelinux.org/alpine/aports/-/issues"

and

docker run --rm jenkins/agent:alpine-jdk17 java --version
openjdk 17.0.7 2023-04-18
OpenJDK Runtime Environment Temurin-17.0.7+7 (build 17.0.7+7)
OpenJDK 64-Bit Server VM Temurin-17.0.7+7 (build 17.0.7+7, mixed mode, sharing)

Submitter checklist

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• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[dduportal]

Nice job buddy! It looks like it's working.

I'ts almost ready to merge!

I see two last steps (which we did not discuss before):

• Required for this PR to land: Could you set the ARG ALPINE_TAG value to the same exact value as the variable ALPINE_FULL_TAG in the bake file please? (ref.

  docker-agent/docker-bake.hcl

  Line 65 in e4c81a8

  default = "3.17.3"

  ). The reason is to avoid any risk of configuration shift and for the sake of homogeneity (please note that Code simplification: removal of default build ARG values when factorized #418 should solve this problem)

• Nice to have (can be in this PR or a subsequent one): track the Alpine (full) version by adding a new updatecli manifest.

  • You may start by duplicating https://github.com/jenkinsci/docker-agent/blob/master/updatecli/updatecli.d/jdk17.yaml which should give you an idea of the process
  • The "source" of available versions for Alpine, you can inspire yourself from this updatecli manifest I wrote for the Asciidoctor Docker image: https://github.com/asciidoctor/docker-asciidoctor/blob/941226d8ff0e654c3a32b4e0d0b940eddc917670/updatecli/updatecli.d/alpine-linux.yml#L16-L29 (warning: you may want to remove the pattern: "~3.17" to avoid locking to 3.17.x version
  • The "condition" should be set verifying that a Docker image alpine:<found version> is available (as it is introduced by your PR here)

[dduportal]

Suggested change

ARG ALPINE_TAG=3.17.3

As the ALPINE_TAG build argument is only consumed by the FROM alpine ... AS build instruction, it's only needed once, before any FROM instruction as per the Dockerfile ARG scope documentation.

Yeah I know it's a bit weird, and this change is not blocking.

[gounthar]

The thing is I have an error when removing the first ARG.

docker buildx bake alpine_jdk17 --load
[+] Building 0.2s (3/3) FINISHED
 => [internal] load .dockerignore                                                                                                                                             0.1s
 => => transferring context: 2B                                                                                                                                               0.1s
 => [internal] load build definition from Dockerfile                                                                                                                          0.0s
 => => transferring dockerfile: 3.81kB                                                                                                                                        0.0s
 => CANCELED [internal] load metadata for docker.io/library/eclipse-temurin:17.0.7_7-jdk-alpine                                                                               0.0s
Dockerfile:43
--------------------
  41 |
  42 |     ARG ALPINE_TAG=3.17.3
  43 | >>> FROM alpine:"${ALPINE_TAG}" AS build
  44 |
  45 |     ARG user=jenkins
--------------------
ERROR: failed to solve: failed to parse stage name "alpine:": invalid reference format

[dduportal]

LGTM thanks!

I've added a non blocking comment: we can merge now or add my suggestion (and fix the comment later): your call :)

[gounthar]

LGTM thanks!

I've added a non blocking comment: we can merge now or add my suggestion (and fix the comment later): your call :)

Sorry, I did not react fast enough.
I'll add it to the next PR if you don't mind.

[dduportal]

LGTM thanks!
I've added a non blocking comment: we can merge now or add my suggestion (and fix the comment later): your call :)

Sorry, I did not react fast enough. I'll add it to the next PR if you don't mind.

No problem buddy, it's full async and my comment was not blocking. I prefer shipping "fast" (but without rush from the author :) ) tiny PRs and release often