I am trying to build CI pipeline which does build for particular image. In the CI file however, I could not find a way to specify image platform.
stages:
- build
- deploy
build_j:
image: customServer/debian/jessy
I checked Docker Images doc and this but could not find any example. Alternative way perhaps is to pull image explicitly and run commands using script.
docker pull debian:jessy -platform i386
Since multi architecture/platform tags of a Docker image have different digests, You can pull a Docker image using its digest (instead of using tags) to pull the desired architecture/platform.
Here is an example of multi architecture/platform tag of a Docker image (Ubuntu) in Docker Hub:
As you can see, 20.04 is a multi architecture tag and there are different digests for each of architectures in the tag.
If you run command docker pull ubuntu:20.04
it will pull all architectures.
But command
docker pull ubuntu@sha256:55e5613c8c7bcd8044aaf09d64d20518964a0d7a6e41af129f95b731301c2659
will pull just linux/arm/v7.
As I tried, it is possible to use digest in .gitlab-ci.yml:
job_1:
image: ubuntu@sha256:55e5613c8c7bcd8044aaf09d64d20518964a0d7a6e41af129f95b731301c2659
script:
- ...
job_2:
image: alpine@sha256:71465c7d45a086a2181ce33bb47f7eaef5c233eace65704da0c5e5454a79cee5
script:
- ...
Speaking of image digest, GitLab 13.5 (October 2020) proposes:
Create release with image digest on new tag
Docker supports immutable image identifiers and we have adopted this best practice to update our cloud-deploy images.
When a new image is tagged, we also programmatically retrieve the image digest upon its build, and create a release note to effectively communicate this digest to users.
This guarantees that every instance of the service runs exactly the same code.
You can roll back to an earlier version of the image, even if that version wasn’t tagged (or is no longer tagged). This can even prevent race conditions if a new image is pushed while a deploy is in progress.
See Documentation and Issue.
