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Developing terraform-provider-cockroach

Installation

  1. In a terminal clone the terraform-provider-cockroach repository:

    git clone https://github.com/cockroachdb/terraform-provider-cockroach.git

  2. Navigate to the terraform-provider-cockroach directory.

    cd terraform-provider-cockroach

  3. Build the binary and copy it to your path.

    make install

Environment Variables

To override the hostname of the cockroach cloud api server used by the terraform provider

# no trailing slash!
export COCKROACH_SERVER=https://apiserver.com

Regenerating Docs

Documentation is generated based on the Description and MarkdownDescription fields in the schemas.

make generate

Contributor Guide

Suggested Reading

Provider Philosophy

In a nutshell, a Terraform provider tells Terraform how to manage external resources and read from data sources. Terraform users specify their desired state of the world in one or more config files. Terraform then uses the appropriate providers to read the actual state of the world and attempts to use CRUD operations to make the state match the plan.

Editor Support

VSCode has a Terraform extension written by Hashicorp which I recommend.

Goland appears to also have an extension although it has poor reviews.

Debugging (VSCode)

Using a debugger to run the provider is fairly straightforward. You can set up a launch configuration like so:

{
    "name": "Debug Terraform Provider",
    "type": "go",
    "request": "launch",
    "mode": "debug",
    "program": "${workspaceFolder}",
    "env": {
        "COCKROACH_SERVER": "https://apiserver.com",
        "TF_LOG_PROVIDER": "DEBUG",
    },
    "args": [
        "-debug",
    ]
}

One caveat to be aware of while running the provider in a debugger is that the provider needs to have access to the required environment variables. They are not passed through the cli. Note the setting of the COCKROACH_SERVER var above.

You can additionally set the apikey within the provider block of the hcl that's being executed. For example:

provider "cockroach" {
    apikey="myabikey123123123"
}

After starting the provider debug process, a TF_REATTACH_PROVIDERS env var execution line will be printed to the DEBUG CONSOLE tab. Export that variable in your shell. For example:

export TF_REATTACH_PROVIDERS='{"registry.terraform.io/cockroachdb/cockroach":{"Protocol":"grpc","ProtocolVersion":6,"Pid":33120,"Test":true,"Addr":{"Network":"unix","String":"/var/folders/vy/ydj1pzwj42bg32lxy4dd49lh0000gq/T/plugin3119263782"}}}'

At this point you should be able to use the terraform CLI as normal.

Asynchronous Operations

Terraform operations need to be fully blocking. We can't spin up a dedicated cluster and immediately declare the resource as created, because that would signal to Terraform that it's ok to start creating dependent resources. Usually, this means API polling. There are some good examples of how to do this in the cluster and CMEK resources.

Testing

We have two types of required tests for each resource and data source: Integration tests and acceptance tests. Both typically call into a shared test method where we specify a series of configs and checks for each step, then run them with the Terraform acceptance testing framework. The difference is that the integration tests use a mocked API client library, while the acceptance tests are live and create real resources. The integration test wrapper needs to set expected mock calls before calling that common method.

Integration and unit tests are run on every commit, while acceptance tests are only automatically run during the release process. Unit tests are great, but rare since TF provider methods don't usually contain complex business logic.

It's generally a good idea to run acceptance tests affected by your change manually before submitting a PR. If you're using GoLand, you can run them individually, setting TF_ACC=1 and setting COCKROACH_SERVER and COCKROACH_API_KEY to appropriate values.

Getting the mock calls right for integration tests can be challenging. You may be surprised at how many read calls are issued at each stage. A technique that I've found works well is using .AnyTimes() and setting break points in the mock controller's method implementations, then setting .Times(n) to the actual number of calls at each stage.

Tests should generally cover all of a resource's CRUD operations, plus import. That generally means at least three test steps. Data sources can either have their own simple test method or, if convenient, be dropped into an existing resource test.

There are currently no permanent fixtures for acceptance tests to use. Each test needs to create the resources it depends on. Prefer using serverless clusters in tests when possible, since they're way quicker to create.

Releasing

There's currently no set release cadence. Whenever a couple features and/or bug fixes are ready, we kick off a release.

Before starting a new release, first make sure CHANGELOG.md is up-to-date. Then it's recommended that you run COCKROACH_SERVER=<non-production QA server> COCKROACH_API_KEY=<API key for that server> make testacc.

To start the release process, simply push a new tag. Tags should follow semver semantics with a 'v' prefix, e.g. "v1.0.0". From there, it's all GitHub workflow magic. It'll run all tests (including acceptance) and, if they pass, generate and publish platform-specific binaries. The new version should show up on the Terraform provider registry shortly after. Sometimes it can take up to a day or so, but usually it's much quicker.

FAQs

Q: What's the difference between the plan and the config in create/update requests?

A: The config is the raw set of attributes that are explicitly set in the user's config file(s). Terraform takes this config and uses it to generate a plan, sometimes using something called a plan modifier. It's technically more correct to use the plan in most cases, but as of this writing, we make fairly light and simple use of plan modifiers, and the config is generally easier to work with since you only need to check for Null, not Unknown.

Q: When and why do we need both a TF resource and data source for the same CC resource?

A: Sometimes a preexisting CC resource is valuable as a source of data that other resources rely on, but users might not want to use Terraform to manage it. An obvious example would be a single production cluster environment. Users may want to manage users and network configuration in Terraform, and simply read the cluster's ID or AWS account ID without importing it as a resource.

Questions?

If you're a CRL employee, feel free to reach out to the Console team or hop into #_cc-terraform.

If you're an external contributor, first of all, thank you! The best way to contact us is with a GitHub issue. Any and all feedback is welcome.