melopt/ci-runner-default-image repository overview

⁠Docker build image

This image install some useful commands to the Ubuntu official image⁠, that make it easier to use as base image for Gitlab CI/CD runners.

The following packages are installed:

• git;
• curl;
• jq;
• nodejs and npm;
• perl;
• docker;
• docker-compose;
• redis client;
• mysql client.

The following npm modules are installed, globally:

• uglifyjs: JS minifier;
• csso: a semantic CSS minifier.

The following Perl modules are installed, globally:

• App::cpanminus;
• Carton.

⁠Helper commands

We also include some helpers for common CI tasks.

⁠cmd-retry

The cmd-retry helper will repeat the execution of the command given as parameter while a specific string shows up in the output. For example:

cmd-retry "502 Bad Gateway" docker login -u gitlab-ci-token -p $CI_BUILD_TOKEN $CI_REGISTRY

This will retry the docker login command while the 502 Bad gateway shows in the command output. The command will pause 5 seconds between retries and will retry at most 60 seconds.

⁠ci-bootstrap

This command, usually used on before_script blocks, will output several pieces of information that might be useful to diagnose issues with your jobs.

It will also login into the Gitlab Registry using the environment variable CI_BUILD_TOKEN.

In particular:

• Gitlab Registry information;
• Dump of all environment variables that end in _IMAGE: we tipically use a variables block with BUILD_IMAGE and RELEASE_IMAGE entries to be reused on multiple jobs;
• The version of some utilities: git, docker, and docker-compose;
• If a Perl project is detected, we will also output the perl version and list the cpanfile* files.

⁠docker-pull-build

This wrapper around docker build will read the Dockerfile file and use docker pull on all images used as FROM.

If the -t or --tag options is present, we will also use pull it to prime the Docker build cache. See docker-prime-cache for a standalone version of this process.

This is a workaround for a Docker bug that fails to pull images mentioned in a FROM if the registry is private and requires authentication.

⁠docker-prime-cache

This script accetps a list of docker images and tries to pull them. If the pull fails, the error is ignored.

It will always exit 0.

This is useful to prime the Docker build cache. If you are building a image named x:latest, you can pull x:latest before starting the build try and reuse as much layers as possible, because usually pulling a image is faster than building the same image.

⁠docker-push-retry

This is just a small wrapper script that will accept all of docker push arguments and wrap it with a cmd-retr '502 Bad Gateway' to work around some unstable Docker Registries.