Integration of Continuous Integration (CI) Workflows via Branch Protection

Question

Pulumi · Accepted Answer

In the context of software development, Continuous Integration (CI) is a practice where developers frequently merge their code changes into a central repository, where automated builds and tests run. A CI workflow typically includes steps for compiling code, running tests, and potentially even automatically deploying to a development environment. To safeguard the source code, especially the main branches like `master` or `main`, branch protection rules can be established, ensuring that specific criteria are met before code is merged.

When we talk about branch protection in the realm of cloud development with Pulumi, it often means setting up rules in version control systems such as GitHub or GitLab that protect branches by preventing direct pushes, requiring pull request reviews, status checks, etc.

Using the Pulumi GitHub provider as an example, you can define branch protection on your GitHub repository, specifying rules that enforce different CI requirements. Below is a Pulumi program that demonstrates how to set up branch protection rules for a GitHub repository.

This program does the following:

1. Imports the needed Pulumi packages.
2. Sets up a new GitHub branch protection rule for a specified branch.
3. Defines which checks need to pass before a pull request can be merged.
4. Specifies how many reviews are needed and whether administrators are enforced to follow the same rules.

Please replace `'replace-with-repository-id'` and `'replace-with-branch-name'` with your actual GitHub repository ID and the branch name you want to protect.

```python
import pulumi
import pulumi_github as github

# Replace 'replace-with-repository-id' with your actual GitHub repository ID.
repository_id = 'replace-with-repository-id'
# Replace 'replace-with-branch-name' with the branch name you want to protect.
branch_to_protect = 'replace-with-branch-name'

# Create a new GitHub branch protection rule.
branch_protection = github.BranchProtection("branchProtection",
    # The repository to which this branch protection will apply.
    repository_id=repository_id,
    # The pattern of the branch to protect. Often this is "main" or "master".
    pattern=branch_to_protect,
    # Whether the branch protection rule enforces required status checks.
    required_status_checks=github.BranchProtectionRequiredStatusChecksArgs(
        # List of status checks that must pass before merging.
        # For example: ['build', 'test']
        # You would replace these with the checks your CI runs.
        contexts=['build', 'test'],
        # Requires the branch to be up to date before merging.
        strict=True,
    ),
    # Controls whether GitHub administrators are subject to the branch protection rules.
    enforce_admins=True,
    # Requires that pull requests have at least one approved review before merging.
    required_pull_request_reviews=github.BranchProtectionRequiredPullRequestReviewsArgs(
        # How many reviewers are required to approve. The default is 1.
        required_approving_review_count=1,
    ),
    # Prevents the branch from being deleted.
    # This is particularly useful for core branches like "main" or "master".
    allows_deletions=False,
)

# Export the branch protection rule ID 
pulumi.export('branch_protection_id', branch_protection.id)
```

Remember, to use this program, you'll need to install Pulumi and the Pulumi GitHub provider. You will also need to have a GitHub token set up and configured so that Pulumi can authenticate with your GitHub account to set up the branch protection rules.

By enabling branch protection through Pulumi, you incorporate a crucial aspect of a CI workflow into your infrastructure as code, ensuring consistency and reliability in your development process.