CI/CD component examples

Test a component

Depending on a component's functionality, testing the component might require additional files in the repository. For example, a component which lints, builds, and tests software in a specific programming language requires actual source code samples. You can have source code examples, configuration files, and similar in the same repository.

For example, the Code Quality CI/CD component's has several code samples for testing.

Example: Test a Rust language CI/CD component

Depending on a component's functionality, testing the component might require additional files in the repository.

The following "hello world" example for the Rust programming language uses the cargo tool chain for simplicity:

Go to the CI/CD component root directory.
Initialize a new Rust project by using the cargo init command.
```
cargo init
```
The command creates all required project files, including a src/main.rs "hello world" example. This step is sufficient to build the Rust source code in a component job with cargo build.
```
tree
.
├── Cargo.toml
├── LICENSE.md
├── README.md
├── src
│   └── main.rs
└── templates
    └── build.yml
```

Ensure that the component has a job to build the Rust source code, for example, in templates/build.yml:

spec:
  inputs:
    stage:
      default: build
      description: 'Defines the build stage'
    rust_version:
      default: latest
      description: 'Specify the Rust version, use values from https://hub.docker.com/_/rust/tags Defaults to latest'
---

"build-$[[ inputs.rust_version ]]":
  stage: $[[ inputs.stage ]]
  image: rust:$[[ inputs.rust_version ]]
  script:
    - cargo build --verbose

In this example:

The stage and rust_version inputs can be modified from their default values. The CI/CD job starts with a build- prefix and dynamically creates the name based on the rust_version input. The command cargo build --verbose compiles the Rust source code.

Test the component's build template in the project's .gitlab-ci.yml configuration file:

include:
  # include the component located in the current project from the current SHA
  - component: $CI_SERVER_FQDN/$CI_PROJECT_PATH/build@$CI_COMMIT_SHA
    inputs:
      stage: build

stages: [build, test, release]

For running tests and more, add additional functions and tests into the Rust code, and add a component template and job running cargo test in templates/test.yml.

spec:
  inputs:
    stage:
      default: test
      description: 'Defines the test stage'
    rust_version:
      default: latest
      description: 'Specify the Rust version, use values from https://hub.docker.com/_/rust/tags Defaults to latest'
---

"test-$[[ inputs.rust_version ]]":
  stage: $[[ inputs.stage ]]
  image: rust:$[[ inputs.rust_version ]]
  script:
    - cargo test --verbose

Test the additional job in the pipeline by including the test component template:

include:
  # include the component located in the current project from the current SHA
  - component: $CI_SERVER_FQDN/$CI_PROJECT_PATH/build@$CI_COMMIT_SHA
    inputs:
      stage: build
  - component: $CI_SERVER_FQDN/$CI_PROJECT_PATH/test@$CI_COMMIT_SHA
    inputs:
      stage: test

stages: [build, test, release]

CI/CD component migration examples

This section shows practical examples of migrating CI/CD templates and pipeline configuration into reusable CI/CD components.

CI/CD component migration example: Go

A complete pipeline for the software development lifecycle can be composed with multiple jobs and stages. CI/CD templates for programming languages may provide multiple jobs in a single template file. As a practice, the following Go CI/CD template should be migrated.

image: golang:latest

stages:
  - test
  - build
  - deploy

format:
  stage: test
  script:
    - go fmt $(go list ./... | grep -v /vendor/)
    - go vet $(go list ./... | grep -v /vendor/)
    - go test -race $(go list ./... | grep -v /vendor/)

compile:
  stage: build
  script:
    - mkdir -p mybinaries
    - go build -o mybinaries ./...
  artifacts:
    paths:
      - mybinaries

NOTE: You can also start with migrating one job, instead of all jobs. Follow the instructions below, and only migrate the build CI/CD job in the first iteration.

The CI/CD template migration involves the following steps:

Analyze the CI/CD jobs and dependencies, and define migration actions:
- The image configuration is global, needs to be moved into the job definitions.
- The format job runs multiple go commands in one job. The go test command should be moved into a separate job to increase pipeline efficiency.
- The compile job runs go build and should be renamed to build.
Define optimization strategies for better pipeline efficiency.
- The stage job attribute should be configurable to allow different CI/CD pipeline consumers.
- The image key uses a hardcoded image tag latest. Add golang_version as input with latest as default value for more flexible and reusable pipelines. The input must match the Docker Hub image tag values.
- The compile job builds the binaries into a hard-coded target directory mybinaries, which can be enhanced with a dynamic input and default value mybinaries.
Create a template directory structure for the new component, based on one template for each job.
- The name of the template should follow the go command, for example format.yml, build.yml, and test.yml.
- Create a new project, initialize a Git repository, add/commit all changes, set a remote origin and push. Modify the URL for your CI/CD component project path.
- Create additional files as outlined in the guidance to write a component: README.md, LICENSE.md, .gitlab-ci.yml, .gitignore. The following shell commands initialize the Go component structure:
```
git init

mkdir templates
touch templates/{format,build,test}.yml

touch README.md LICENSE.md .gitlab-ci.yml .gitignore

git add -A
git commit -avm "Initial component structure"

git remote add origin https://gitlab.example.com/components/golang.git

git push
```

Create the CI/CD jobs as template. Start with the build job.

Define the following inputs in the spec section: stage, golang_version and binary_directory.
Add a dynamic job name definition, accessing inputs.golang_version.
Use the similar pattern for dynamic Go image versions, accessing inputs.golang_version.
Assign the stage to the inputs.stage value.
Create the binary director from inputs.binary_directory and add it as parameter to go build.

Define the artifacts path to inputs.binary_directory.

spec:
  inputs:
    stage:
      default: 'build'
      description: 'Defines the build stage'
    golang_version:
      default: 'latest'
      description: 'Go image version tag'
    binary_directory:
      default: 'mybinaries'
      description: 'Output directory for created binary artifacts'
---

"build-$[[ inputs.golang_version ]]":
  image: golang:$[[ inputs.golang_version ]]
  stage: $[[ inputs.stage ]]
  script:
    - mkdir -p $[[ inputs.binary_directory ]]
    - go build -o $[[ inputs.binary_directory ]] ./...
  artifacts:
    paths:
      - $[[ inputs.binary_directory ]]

The format job template follows the same patterns, but only requires the stage and golang_version inputs.

spec:
  inputs:
    stage:
      default: 'format'
      description: 'Defines the format stage'
    golang_version:
      default: 'latest'
      description: 'Golang image version tag'
---

"format-$[[ inputs.golang_version ]]":
  image: golang:$[[ inputs.golang_version ]]
  stage: $[[ inputs.stage ]]
  script:
    - go fmt $(go list ./... | grep -v /vendor/)
    - go vet $(go list ./... | grep -v /vendor/)

The test job template follows the same patterns, but only requires the stage and golang_version inputs.

spec:
  inputs:
    stage:
      default: 'test'
      description: 'Defines the format stage'
    golang_version:
      default: 'latest'
      description: 'Golang image version tag'
---

"test-$[[ inputs.golang_version ]]":
  image: golang:$[[ inputs.golang_version ]]
  stage: $[[ inputs.stage ]]
  script:
    - go test -race $(go list ./... | grep -v /vendor/)

In order to test the component, modify the .gitlab-ci.yml configuration file, and add tests.

Specify a different value for golang_version as input for the build job.

Modify the URL for your CI/CD component path.

stages: [format, build, test]

include:
  - component: $CI_SERVER_FQDN/$CI_PROJECT_PATH/format@$CI_COMMIT_SHA
  - component: $CI_SERVER_FQDN/$CI_PROJECT_PATH/build@$CI_COMMIT_SHA
  - component: $CI_SERVER_FQDN/$CI_PROJECT_PATH/build@$CI_COMMIT_SHA
    inputs:
      golang_version: "1.21"
  - component: $CI_SERVER_FQDN/$CI_PROJECT_PATH/test@$CI_COMMIT_SHA
    inputs:
      golang_version: latest

Add Go source code to test the CI/CD component. The go commands expect a Go project with go.mod and main.go in the root directory.

Initialize the Go modules. Modify the URL for your CI/CD component path.
```
go mod init example.gitlab.com/components/golang
```

Create a main.go file with a main function, printing Hello, CI/CD component for example. Tip: Use code comments to generate Go code using GitLab Duo Code Suggestions.

// Specify the package, import required packages
// Create a main function
// Inside the main function, print "Hello, CI/CD Component"

package main

import "fmt"

func main() {
  fmt.Println("Hello, CI/CD Component")
}

The directory tree should look as follows:

tree
.
├── LICENSE.md
├── README.md
├── go.mod
├── main.go
└── templates
    ├── build.yml
    ├── format.yml
    └── test.yml

Follow the remaining steps in the converting a CI/CD template into a component section to complete the migration:

Commit and push the changes, and verify the CI/CD pipeline results.
Follow the guidance on writing a component to update the README.md and LICENSE.md files.
Release the component and verify it in the CI/CD catalog.
Add the CI/CD component into your staging/production environment.

The GitLab-maintained Go component provides an example for a successful migration from a Go CI/CD template, enhanced with inputs and component best practices. You can inspect the Git history to learn more.