Pipeline Configuration & Resources

Config File: The pipeline is defined in gitlab-ci.yml.

A pipeline can run automatically when pushing to a branch, creating MR or on a schedule. It can also be run manually.

Pipeline Flow

The repository is cloned into /builds/gitlab-username/my-repo and is set as the working directory and the image file structure remains as it is.
The CMD command of the image is overriden by before_script and script

In case the image’s ENTRYPOINT command causes an issue, it has to be overriden in the pipeline

image:
  name: custom-image:latest
  entrypoint: [""] # Explicitly overrides the ENTRYPOINT

If the image used by the job is on a private registry, gitlab has to be given the docker credentials through the DOCKER_AUTH_CONFIG variable or on the gitlab runner server in the config.toml file.
A typical pipeline flow involves: Run Tests $\rightarrow$ Build Docker Image $\rightarrow$ Push to Registry $\rightarrow$ Deploy to Server (Optionally perform security scans).

Key Resources

1. Job

The smallest unit of work. It runs in its own environment with its own script of commands inside a stage.

All jobs in a stage run parallelly.
Default image used in a Gitlab job is Ruby

2. Stage

A group of jobs that run in parallel.
Sequential: Stages themselves run sequentially (jobs run in parallel by default).
Stages are necessary to provide sequence.

3. Variables

Store values you can reuse anywhere in the pipeline.
Can be defined inside a job, pipeline, or CI/CD settings.
Variables are also passed to the containers running the job scripts.

A file added in variables will give permissions to everyone to read and write.

Priority: Variables defined by us have higher priority than pre-defined variables.

4. Default

Keyword used to set default configuration for all other jobs in the pipeline.

5. Inherit

Inheritance of default keywords and variables can be controlled using the inherit keyword in a job.

6. Groups

Jobs can be automatically grouped for concise pipeline building.
Syntax: Separate each job name with a number and a slash, colon, or space (e.g., 1/3, 1:3, 1 3).