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Contributing to Databricks Terraform Provider

We happily welcome contributions to databricks-terraform. We use GitHub Issues to track community reported issues and GitHub Pull Requests for accepting changes.

Installing for Terraform 0.12

If you use Terraform 0.12, please execute the following curl command in your shell:

curl https://raw.githubusercontent.com/databrickslabs/databricks-terraform/master/godownloader-databricks-provider.sh | bash -s -- -b $HOME/.terraform.d/plugins

Installing from source

On MacOS X, you can install GoLang through brew install go, on Debian-based Linux, you can install it by sudo apt-get install golang -y.

git clone https://github.com/databrickslabs/terraform-provider-databricks.git
cd terraform-provider-databricks
make install

Most likely, terraform init -upgrade -verify-plugins=false -lock=false would be a very great command to use.

Contributing documentation

All documentation contributions should be as detailed as possible and follow the required format. The following additional checks must also be valid:

  • make fmt-docs to make sure code examples are consistent
  • Correct rendering with Terraform Registry Doc Preview Tool - https://registry.terraform.io/tools/doc-preview
  • Cross-linking integrity between markdown files. Pay special attention, when resource doc refers to data doc or guide.

Developing provider

In order to simplify development workflow, you should use dev_overrides section in your ~/.terraformrc file. Please run make build and replace "provider-binary" with the path to terraform-provider-databricks executable in your current working directory:

$ cat ~/.terraformrc
provider_installation {
   dev_overrides {
     "databrickslabs/databricks" = "provider-binary"
   }
   direct {}
}

After installing necessary software for building provider from sources, you should install staticcheck and gotestsum in order to run make test.

Make sure you have $GOPATH/bin in your $PATH:

echo "export PATH=\$PATH:$(go env GOPATH)/bin" >> ~/.bash_profile

Installing staticcheck:

go install honnef.co/go/tools/cmd/staticcheck

Installing gotestsum:

go get gotest.tools/gotestsum

Installing goimports:

go get golang.org/x/tools/cmd/goimports

After this, you should be able to run make coverage to run the tests and see the coverage.

Debugging

TF_LOG_PROVIDER=DEBUG terraform apply allows you to see the internal logs from terraform apply.

You can run provider in a debug mode from VScode IDE by launching Debug Provider run configuration and invoking terraform apply with TF_REATTACH_PROVIDERS environment variable.

Adding a new resource

The general process for adding a new resource is:

Define the resource models. The models for a resource are structs defining the schemas of the objects in the Databricks REST API. Define structures used for multiple resources in a common models.go file; otherwise, you can define these directly in your resource file. An example model:

type Field struct {
 A string `json:"a,omitempty"`
 AMoreComplicatedName int `json:"a_more_complicated_name,omitempty"`
}

type Example struct {
 ID string `json:"id"`
 TheField *Field `json:"the_field"`
 AnotherField bool `json:"another_field"`
 Filters []string `json:"filters" tf:"optional"`
}

Some interesting points to note here:

  • Use the json tag to determine the serde properties of the field. The allowed tags are defined here: https://go.googlesource.com/go/+/go1.16/src/encoding/json/encode.go#158
  • Use the custom tf tag indicates properties to be annotated on the Terraform schema for this struct. Supported values are:
    • optional for optional fields
    • computed for computed fields
    • alias:X to use a custom name in HCL for a field
    • default:X to set a default value for a field
    • max_items:N to set the maximum number of items for a multi-valued parameter
    • slice_set to indicate that a the parameter should accept a set instead of a list
  • Do not use bare references to structs in the model; rather, use pointers to structs. Maps and slices are permitted, as well as the following primitive types: int, int32, int64, float64, bool, string. See typeToSchema in common/reflect_resource.go for the up-to-date list of all supported field types and values for the tf tag.

Define the Terraform schema. This is made easy for you by the StructToSchema method in the common package, which converts your struct automatically to a Terraform schema, accepting also a function allowing the user to post-process the automatically generated schema, if needed.

var exampleSchema = common.StructToSchema(Example{}, func(m map[string]*schema.Schema) map[string]*schema.Schema { return m })

Define the API client for the resource. You will need to implement create, read, update, and delete functions.

type ExampleApi struct {
	client *common.DatabricksClient
	ctx    context.Context
}

func NewExampleApi(ctx context.Context, m interface{}) ExampleApi {
	return ExampleApi{m.(*common.DatabricksClient), ctx}
}

func (a ExampleApi) Create(e Example) (string, error) {
	var id string
	err := a.client.Post(a.ctx, "/example", e, &id)
	return id, err
}

func (a ExampleApi) Read(id string) (e Example, err error) {
	err = a.client.Get(a.ctx, "/example/"+id, nil, &e)
	return
}

func (a ExampleApi) Update(id string, e Example) error {
	return a.client.Put(a.ctx, "/example/"+string(id), e)
}

func (a ExampleApi) Delete(id string) error {
	return a.client.Delete(a.ctx, "/pipelines/"+id, nil)
}

Define the Resource object itself. This is made quite simple by using the toResource function defined on the Resource type in the common package. A simple example:

func ResourceExample() *schema.Resource {
	return common.Resource{
		Schema: exampleSchema,
		Create: func(ctx context.Context, d *schema.ResourceData, c *common.DatabricksClient) error {
			var e Example
			common.DataToStructPointer(d, exampleSchema, &e)
			id, err := NewExampleApi(ctx, c).Create(e)
			if err != nil {
				return err
			}
			d.SetId(string(id))
			return nil
		},
		Read: func(ctx context.Context, d *schema.ResourceData, c *common.DatabricksClient) error {
			i, err := NewExampleApi(ctx, c).Read(d.Id())
			if err != nil {
				return err
			}
			return common.StructToData(i.Spec, exampleSchema, d)
		},
		Update: func(ctx context.Context, d *schema.ResourceData, c *common.DatabricksClient) error {
			var e Example
			common.DataToStructPointer(d, exampleSchema, &e)
			return NewExampleApi(ctx, c).Update(d.Id(), e)
		},
		Delete: func(ctx context.Context, d *schema.ResourceData, c *common.DatabricksClient) error {
			return NewExampleApi(ctx, c).Delete(d.Id())
		},
	}.ToResource()
}

Add the resource to the top-level provider. Simply add the resource to the provider definition in provider/provider.go.

Write unit tests for your resource. To write your unit tests, you can make use of ResourceFixture and HTTPFixture structs defined in the qa package. This starts a fake HTTP server, asserting that your resource provdier generates the correct request for a given HCL template body for your resource. Update tests should have InstanceState field in order to test various corner-cases, like ForceNew schemas. It's possible to expect fixture to require new resource by specifying RequiresNew field. With the help of qa.ResourceCornerCases and qa.ResourceFixture one can achieve 100% code coverage for all of the new code.

A simple example:

func TestExampleCornerCases(t *testing.T) {
	qa.ResourceCornerCases(t, ResourceExample())
}

func TestExampleResourceCreate(t *testing.T) {
	qa.ResourceFixture{
		Fixtures: []qa.HTTPFixture{
			{
				Method:          "POST",
				Resource:        "/api/2.0/example",
				ExpectedRequest: Example{
					TheField: Field{
						A: "test",
					},
				},
				Response: map[string]interface{} {
					"id": "abcd",
					"the_field": map[string]interface{} {
						"a": "test",
					},
				},
			},
			{
				Method:   "GET",
				Resource: "/api/2.0/example/abcd",
				Response: map[string]interface{}{
					"id":    "abcd",
					"the_field": map[string]interface{} {
						"a": "test",
					},
				},
			},
		},
		Create:   true,
		Resource: ResourceExample(),
		HCL: `the_field {
			a = "test"
		}`,
	}.ApplyNoError(t)
}

Write acceptance tests. These are E2E tests which run terraform against the live cloud and Databricks APIs. For these, you can use the Test and Step structs defined in the acceptance package. An example:

func TestPreviewAccPipelineResource_CreatePipeline(t *testing.T) {
	acceptance.Test(t, []acceptance.Step{
		{
			Template: `
			resource "databricks_example" "this" {
				the_field {
					a = "test"
					a_more_complicated_name = 3
				}
				another_field = true
				filters = [
					"a",
					"b"
				]
			}
			`,
		},
	})
}

Testing

  • Integration tests should be run at a client level against both azure and aws to maintain sdk parity against both apis.
  • Terraform acceptance tests should be run against both aws and azure to maintain parity of provider between both cloud services
  • Consider test functions as scenarios, that you are debugging from IDE when specific issues arise. Test tables are discouraged. Single-use functions in tests are discouraged, unless resource definitions they make are longer than 80 lines.
  • All tests should be capable of repeatedly running on "dirty" environment, which means not requiring a new clean environment every time the test runs.
  • All tests should re-use compute resources whenever possible.
  • Prefer require.NoError (stops the test on error) to assert.NoError (continues the test on error) when checking the results.

Code conventions

  • Files should not be larger than 600 lines
  • Single function should fit to be seen on 13" screen: no more than 40 lines of code. Only exception to this rule is *_test.go files.
  • There should be no unnecessary package exports: no structs & types with leading capital letter, unless they are of value outside of the package.
  • fmt.Sprintf with more than 4 placeholders is considered too complex to maintain. Should be avoided at all cost. Use qa.EnvironmentTemplate(t, "This is {env.DATABRICKS_HOST} with {var.RANDOM} name.") instead
  • Import statements should all be first ordered by "GoLang internal", "Vendor packages" and then "current provider packages". Within those sections imports must follow alphabetical order.

Linting

Please use makefile for linting. If you run staticcheck by itself it will fail due to different tags containing same functions. So please run make lint instead.

Developing with Visual Studio Code Devcontainers

This project has configuration for working with Visual Studio Code Devcontainers - this allows you to containerise your development prerequisites (e.g. golang, terraform). To use this you will need Visual Studio Code and Docker.

To get started, clone this repo and open the folder with Visual Studio Code. If you don't have the Remote Development extension then you should be prompted to install it.

Once the folder is loaded and the extension is installed you should be prompted to re-open the folder in a devcontainer. This will built and run the container image with the correct tools (and versions) ready to start working on and building the code. The in-built terminal will launch a shell inside the container for running make commands etc.

See the docs for more details on working with devcontainers.