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CONTRIBUTING.md

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Contribution Guidelines

Contributions to this repo are very welcome! We follow a fairly standard pull request process for contributions, subject to the following guidelines:

  1. Types of contributions
  2. File a GitHub issue
  3. Update the documentation
  4. Update the tests
  5. Update the code
  6. Create a pull request
  7. Merge and release

Types of contributions

Broadly speaking, Terratest contains two types of helper functions:

  1. Integrations with external tools
  2. Infrastructure and validation helpers

We accept different types of contributions for each of these two types of helper functions, as described next.

Integrations with external tools

These are helper functions that integrate with various DevOps tools—e.g., Terraform, Docker, Packer, and Kubernetes—that you can use to deploy infrastructure in your automated tests. Examples:

  • terraform.InitAndApply: run terraform init and terraform apply.
  • packer.BuildArtifacts: run packer build.
  • shell.RunCommandAndGetOutput: run an arbitrary shell command and return stdout and stderr as a string.

Here are the guidelines for contributions with external tools:

  1. Fixes and improvements to existing integrations: All bug fixes and new features for existing tool integrations are very welcome!

  2. New integrations: Before contributing an integration with a totally new tool, please file a GitHub issue to discuss with us if it's something we are interested in supporting and maintaining. For example, we may be open to new integrations with Docker and Kubernetes tools, but we may not be open to integrations with Chef or Puppet, as there are already testing tools available for them.

Infrastructure and validation helpers

These are helper functions for creating, destroying, and validating infrastructure directly via API calls or SDKs. Examples:

  • http_helper.HttpGetWithRetry: make an HTTP request, retrying until you get a certain expected response.
  • ssh.CheckSshCommand: SSH to a server and execute a command.
  • aws.CreateS3Bucket: create an S3 bucket.
  • aws.GetPrivateIpsOfEc2Instances: use the AWS APIs to fetch IPs of some EC2 instances.

The number of possible such helpers is nearly infinite, so to avoid Terratest becoming a gigantic, sprawling library we ask that contributions for new infrastructure helpers are limited to:

  1. Platforms: we currently only support three major public clouds (AWS, GCP, Azure) and Kubernetes. There is some code contributed earlier for other platforms (e.g., OCI), but until we have the time/resources to support those platforms fully, we will only accept contributions for the major public clouds and Kubernetes.

  2. Complexity: we ask that you only contribute infrastructure and validation helpers for code that is relatively complex to do from scratch. For example, a helper that merely wraps an existing function in the AWS or GCP SDK is not a great choice, as the wrapper isn't contributing much value, but is bloating the Terratest API. On the other hand, helpers that expose simple APIs for complex logic are great contributions: ssh.CheckSshCommand is a great example of this, as it provides a simple one-line interface for dozens of lines of complicated SSH logic.

  3. Popularity: Terratest should only contain helpers for common use cases that come up again and again in the course of testing. We don't want to bloat the library with lots of esoteric helpers for rarely used tools, so here's a quick litmus test: (a) Is this helper something you've used once or twice in your own tests, or is it something you're using over and over again? (b) Does this helper only apply to some use case specific to your company or is it likely that many other Terratest users are hitting this use case over and over again too?

  4. Creating infrastructure: we try to keep helper functions that create infrastructure (e.g., use the AWS SDK to create an S3 bucket or EC2 instance) to a minimum, as those functions typically require maintaining state (so that they are idempotent and can clean up that infrastructure at the end of the test) and dealing with asynchronous and eventually consistent cloud APIs. This can be surprisingly complicated, so we typically recommend using a tool like Terraform, which already handles all that complexity, to create any infrastructure you need at test time, and running Terratest's built-in terraform helpers as necessary. If you're considering contributing a function that creates infrastructure directly (e.g., using a cloud provider's APIs), please file a GitHub issue to explain why such a function would be a better choice than using a tool like Terraform.

File a GitHub issue

Before starting any work, we recommend filing a GitHub issue in this repo. This is your chance to ask questions and get feedback from the maintainers and the community before you sink a lot of time into writing (possibly the wrong) code. If there is anything you're unsure about, just ask!

Update the documentation

We recommend updating the documentation before updating any code (see Readme Driven Development). This ensures the documentation stays up to date and allows you to think through the problem at a high level before you get lost in the weeds of coding.

Update the tests

We also recommend updating the automated tests before updating any code (see Test Driven Development). That means you add or update a test case, verify that it's failing with a clear error message, and then make the code changes to get that test to pass. This ensures the tests stay up to date and verify all the functionality in this Module, including whatever new functionality you're adding in your contribution. Check out the test folder for instructions on running the automated tests.

Update the code

At this point, make your code changes and use your new test case to verify that everything is working. As you work, please make every effort to avoid unnecessary backwards incompatible changes. This generally means that you should not delete or rename anything in a public API.

If a backwards incompatible change cannot be avoided, please make sure to call that out when you submit a pull request, explaining why the change is absolutely necessary.

Note that we use pre-commit hooks with this project. To ensure they run:

  1. Install pre-commit.
  2. Run pre-commit install.

One of the pre-commit hooks we run is goimports. To prevent the hook from failing, make sure to :

  1. Install goimports
  2. Run goimports -w ..

Create a pull request

Create a pull request with your changes. Please make sure to include the following:

  1. A description of the change, including a link to your GitHub issue.
  2. The output of your automated test run, preferably in a GitHub Gist. We cannot run automated tests for pull requests automatically due to security concerns, so we need you to manually provide this test output so we can verify that everything is working.
  3. Any notes on backwards incompatibility or downtime.

Merge and release

The maintainers for this repo will review your code and provide feedback. If everything looks good, they will merge the code and release a new version, which you'll be able to find in the releases page.