3.12 Advanced Bitbucket Pipelines: Caching, Conditional Steps, and Parallel Builds

Level Up Your Bitbucket Pipelines: Caching, Conditional Steps, and Parallel Builds

So, you’re comfortable with the basics of Bitbucket Pipelines – congratulations! You’ve automated your builds and deployments, and you’re saving time and headaches. But did you know you can take your pipelines to the next level and make them even more efficient and powerful?

In this post, we’ll explore three advanced features that can significantly improve your Bitbucket Pipelines:

• Caching: Speed up your builds by reusing downloaded dependencies.
• Conditional Steps: Run steps only when specific conditions are met.
• Parallel Builds: Run multiple steps concurrently to reduce overall execution time.

Let’s dive in!

1. Caching: Turbocharge Your Builds

Imagine having to download the same libraries and dependencies every single time you run a build. That’s a lot of wasted time! Caching allows you to store these downloaded files and reuse them in subsequent builds. This dramatically reduces build times, especially for projects with many dependencies.

How it works:

Bitbucket Pipelines stores cached files in a storage location. When a new build runs, it checks if the required files are already in the cache. If they are, it reuses them instead of downloading them again.

Example (using Node.js and npm):

pipelines:
  default:
    - step:
        caches:
          - node
        script:
          - npm install
          - npm run build
definitions:
  caches:
    node: ~/.npm

Explanation:

• caches: defines a cache named node.
• ~/.npm specifies the directory where npm stores downloaded packages. This is where npm keeps all of your project’s dependencies.
• The npm install command downloads and installs the dependencies. On the first run, this takes a while. Subsequent runs using the cache will be much faster because npm can pull the dependencies from the cache instead of downloading them.

Key Takeaways for Caching:

• Identify commonly used dependencies: Figure out which files and folders are frequently downloaded or generated during your builds.
• Use descriptive cache names: Make it easy to understand what each cache contains.
• Cache only what’s necessary: Don’t cache everything, as it can slow down the process. Focus on dependencies and generated files that are slow to recreate.

2. Conditional Steps: Tailoring Your Workflow

Sometimes, you only want to run certain steps under specific circumstances. Maybe you want to deploy only to production when a tag is pushed, or run a different set of tests based on the branch. Conditional steps allow you to achieve this level of customization.

How it works:

You use the condition: keyword to specify a boolean expression that determines whether a step will run.

Example (deploying to production on tagged commits):

pipelines:
  tags:
    '*': # For all tags
      - step:
          name: Deploy to Production
          condition: $BITBUCKET_TAG != null  # Simplified condition for clarity
          script:
            - echo "Deploying to Production for tag: $BITBUCKET_TAG"
            - # Your deployment commands here

Explanation:

• tags: '*' defines a pipeline that runs for all tags.
• condition: $BITBUCKET_TAG != null means this step will only execute if the $BITBUCKET_TAG environment variable is set. This variable is automatically set by Bitbucket Pipelines when a tag is triggered.
• Inside the script, you’d include the commands to deploy your application to your production environment.

Other useful environment variables for conditions:

• $BITBUCKET_BRANCH: The name of the branch being built.
• $BITBUCKET_COMMIT: The commit SHA being built.
• $BITBUCKET_PR_ID: The ID of the pull request being built (if applicable).

Key Takeaways for Conditional Steps:

• Use environment variables: Leverage Bitbucket Pipelines’ built-in environment variables to create dynamic conditions.
• Keep conditions simple: Avoid complex conditions that are difficult to understand and maintain.
• Test your conditions thoroughly: Ensure your steps run as expected under different scenarios.

3. Parallel Builds: Speeding Up Execution with Concurrency

If your pipeline includes several independent steps, you can dramatically reduce the overall build time by running them concurrently. This is where parallel builds come in handy.

How it works:

You define a list of steps under the parallel: keyword. Bitbucket Pipelines will execute these steps simultaneously, using multiple runners.

Example (running tests and linting in parallel):

pipelines:
  default:
    - parallel:
        - step:
            name: Run Unit Tests
            script:
              - npm run test:unit
        - step:
            name: Run Linting
            script:
              - npm run lint
    - step: #This step will only run AFTER both parallel steps complete
        name: Report Results
        script:
          - echo "All tests and linting completed."

Explanation:

• parallel: indicates that the following steps should be executed concurrently.
• The Run Unit Tests and Run Linting steps will run at the same time.
• The Report Results step will only run after both parallel steps have finished successfully.

Important Considerations for Parallel Builds:

• Dependencies: Ensure that parallel steps do not have conflicting dependencies.
• Resource limitations: Be mindful of the resources available to your runners. Running too many parallel steps can lead to performance degradation.
• Sequential Steps: If a step relies on the output of a parallel step, it must come after the parallel block. Bitbucket Pipelines guarantees execution order: it will wait for all steps within a parallel block to complete before moving on to the next step in the main pipeline.

Key Takeaways for Parallel Builds:

• Identify independent steps: Look for steps that don’t depend on each other’s output.
• Monitor resource usage: Ensure that your runners have sufficient resources to handle parallel execution.
• Test thoroughly: Test your pipeline with parallel builds to ensure that everything works as expected.

Conclusion

By mastering caching, conditional steps, and parallel builds, you can transform your Bitbucket Pipelines into highly efficient and customized workflows. These advanced features will not only save you time but also improve the overall reliability and maintainability of your build and deployment processes. So, go ahead, experiment, and take your Bitbucket Pipelines to the next level! Happy building!