This in-depth explanation is presented per the order of jobs in the ‘stages’ section of the .gitlab-ci.yml file.

Jobs Overview

The pipeline consists of the following stages:

• Quality: Evaluates the quality of the image.
• Get-version: Gets the latest version of Squid.
• Docker-hub-build: Builds Docker images for both ARM and AMD64 architectures.
• Docker-hub-test: Tests the built Docker images.
• Docker-hub-pushtag: Pushes the Docker images to Docker hub.
• Docs: Generates documentation and analysis.

Quality stage: hadolint

The hadolint job checks the Dockerfile syntax using a Docker linter named hadolint.

The image used in this stage is hadolint/hadolint:latest-debian.

hadolint:
 image: hadolint/hadolint:latest-debian
 stage: Quality
 before_script:
 - cd $CI_PROJECT_DIR 
 script:
 - hadolint --ignore DL3008 Dockerfile 

• script section:
• hadolint --ignore DL3008 Dockerfile: Lints the Dockerfile, ignoring rule DL3008.

Get-version stage: getsquid_vars

The getsquid_vars job fetches the latest version of Squid and creates variables.env which is used by subsequent jobs.

The image used for this stage is defined by $CONTAINER_CLIENT_IMAGE.

Code

getsquid_vars:
 stage: Get-version
 image: 
 name: $CONTAINER_CLIENT_IMAGE
 artifacts:
 expire_in: 1 hour
 paths:
 - variables.env
 script:
 - apt update && apt install git curl ca-certificates -y --no-upgrade --no-install-recommends --no-install-suggests
 - export SQUID_VERSION=$(curl -LsXGET https://github.com/squid-cache/squid/releases/latest | grep -m 1 "Release" | cut -d " " -f4 |tr -d 'v')
 - echo "SQUID_VERSION=$SQUID_VERSION" > variables.env
 ...

Commands explanation

• apt update && apt install git curl ca-certificates -y --no-upgrade --no-install-recommends --no-install-suggests: Updates package index and installs necessary packages.
• export SQUID_VERSION=$(curl -LsXGET https://github.com/squid-cache/squid/releases/latest | grep -m 1 "Release" | cut -d " " -f4 |tr -d 'v'): Fetches the latest release version of Squid and assigns it as the value of the SQUID_VERSION environment variable.
• echo "SQUID_VERSION=$SQUID_VERSION" > variables.env: Writes the SQUID_VERSION variable to variables.env.

Docker-hub-build stage: docker-hub-build, docker-hub-build-arm

The docker-hub-build and docker-hub-build-arm jobs build the Docker images for AMD64 and ARM architectures, respectively, and push the images to Docker Hub.

The image used for both jobs is docker:dind, which provides Docker in Docker capabilities, necessary for building Docker images within a CI environment.

docker-hub-build:
 image: docker:dind
 ....

docker-hub-build-arm:
 image: docker:dind
 ...

Both jobs contains a similar set of steps listed below:

• Log in to Docker Hub: docker login -u "$DOCKER_HUB_USER" -p "$DOCKER_HUB_TOKEN" $DOCKER_HUB_REGISTRY
• Build the Docker image with the latest fetched Squid version: docker build --build-arg SQUID_VERSION=$SQUID_VERSION --pull -t $CONTAINER_BUILD_NOPROD_NAME .
• Here, --build-arg SQUID_VERSION=$SQUID_VERSION passes the SQUID_VERSION variable as a build argument.
• Push the built image to Docker Hub: docker push $CONTAINER_BUILD_NOPROD_NAME

Docker-hub-test stage: docker-hub-test, docker-hub-test-arm

The docker-hub-test and docker-hub-test-arm jobs test the previously built Docker images by starting a container with the image and testing if Squid is running and available.

The image used in these jobs is defined by $CONTAINER_CLIENT_IMAGE.

Commands include:

• apt update && apt install -y curl --no-upgrade --no-install-recommends --no-install-suggests: Installs necessary packages
• export https_proxy=http://$CONTAINER_TEST_NAME:3128 && curl -k https://www.google.fr: Sets https_proxy to use the Squid proxy server and tries to reach google.fr.

Docker-hub-pushtag stage : push-docker-hub and push-docker-hub-arm

These jobs push the Docker images to Docker Hub with appropriate tags.

The image used in both jobs is docker:dind, which provides Docker in Docker capabilities, necessary for building Docker images within a CI environment.

Steps include:

• Log in to Docker Hub.
• Pull the Docker image: docker pull $CONTAINER_BUILD_NOPROD_NAME.
• Tag and push the Docker image with Squid version tag:
• docker tag $CONTAINER_BUILD_NOPROD_NAME $HUB_REGISTRY_IMAGE:$SQUID_VERSION
• docker push $HUB_REGISTRY_IMAGE:$SQUID_VERSION
• Tag and push the Docker image with the latest tag:
• docker tag $CONTAINER_BUILD_NOPROD_NAME $HUB_REGISTRY_IMAGE:latest
• docker push $HUB_REGISTRY_IMAGE:latest

Docs stage: chatgpt_analysis, update_dockerhub_readme

The chatgpt_analysis job initiates a ChatGPT task, providing extensive command explanations based on the current pipeline configuration. GPT-4 prompts include listing, explaining jobs, covering parameters, its dependencies, outcomes, and the latest commit.

The update_dockerhub_readme job updates Docker Hub container description with the contents of the README.md.

Last commit

The last commit was titled README Auto update and update last_squid_version [skip ci]. It is an automatic update of the README and Squid’s version without triggering a new CI run, by using [skip ci]. The last known Squid version is saved in ci/last_squid_version.txt and versions are checked in the getsquid_vars job to determine if an update occurred.