jrpespinas / intro-to-cicd

Publish a simple FastAPI endpoint to Docker Hub using basic CI/CD workflow

Introduction to CI/CD

Publish a simple FastAPI endpoint to Docker Hub using basic CI/CD workflow

Testing & Linting

Inspect the pre-build.yaml which contains the jobs for testing the API and checking the source code formatting.

This workflow triggers whenever we make a pull request to the main branch.

The workflow_dispatch is included as an option to manually trigger the workflow in Github using the browser.

The workflow has two jobs: testing and linting

Testing

Under testing, we defined an optional name property to make it more readable when inspecting the job in the browser. This job must specify an operating system to execute on the runner using the runs-on property. The steps property define the steps of the job.

Steps:

1. checkout repository onto the runner - It uses the uses property to utilize a github action named actions/checkout@v3
   
   Note: you may find more actions using the github marketplace
2. setup python environment - uses the actions/setup-python@v4 to set the python version of the runner
3. install dependencies - it uses the run property to run the command make pip-init and make build which is found in our makefile in the repository.
4. pytest - runs the make test to trigger the unit test

Once done, the runner will clean up the resources used and it will proceed to the next job.

Linting

Similar to testing, we defined an operating system for it to run-on and the steps to perform this job.

However, we only want this job to run after testing is successful, therefore we define a needs property and specify testing as the job we wait for to finish.

Steps:

1. checkout repository onto the runner - It uses the same action actions/checkout@v3
   
   Note: you have to checkout the repository as this job runs on a different runner instance.

2. setup python environment

3. flake8 int - we use an action from github marketplace to run a linting action in our runner to check for source code formatting

Publishing

Inspect publish.yaml which contains the publishing job.

This job only triggers whenever we push something to the main branch. This could be a commit or a merge.

Similar to Testing & Linting, we defined an operating system for the runner and the steps.

Notice that there is also a property called env that defines any variables that is repeatedly used through out the job. The env can be defined in the workflow level, job level, or step level.

Steps

1. checkout repository onto the runner
2. Login to Docker Hub - uses the docker/login-action@v2 (again, found in the github marketplace) action to login to your docker hub. It is best practice to hide your credentials so we used Github Action Secrets to store sensitive information
3. Build and push - push the docker image to docker hub. We use a combination of secrets variable and the env variable to name our docker image