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Developing with a Terraform Bridge Provider

This document describes the procedures for developing and maintaining a Pulumi provider based on the Pulumi Terraform Bridge.

Creating a Pulumi Terraform Bridge Provider

The following instructions cover:

  • providers maintained by Pulumi (denoted with a "Pulumi Official" checkmark on the Pulumi registry)
  • providers published and maintained by the Pulumi community, referred to as "third-party" providers

We showcase a Pulumi-owned provider based on an upstream provider named terraform-provider-mssql. Substitute appropriate values below for your use case.

Note: If the name of the desired Pulumi provider differs from the name of the Terraform provider, you will need to carefully distinguish between the references - see https://github.com/pulumi/pulumi-azure for an example.

Prerequisites

Ensure the following tools are installed and present in your $PATH:

Composing the Provider Code - Prerequisites

Pulumi provider repositories have the following general structure:

  • examples/ contains sample code which may optionally be included as integration tests to be run as part of a CI/CD pipeline.
  • provider/ contains the Go code used to create the provider as well as generate the SDKs in the various languages that Pulumi supports.
    • provider/cmd/pulumi-tfgen-mssql generates the Pulumi resource schema (schema.json), based on the Terraform provider's resources.
    • provider/cmd/pulumi-resource-mssql generates the SDKs in all supported languages from the schema, placing them in the sdk/ folder.
    • provider/pkg/resources.go is the location where we will define the Terraform-to-Pulumi mappings for resources.
  • sdk/ contains the generated SDK code for each of the language platforms that Pulumi supports, with each supported platform in a separate subfolder.

  1. In provider/go.mod, add a reference to the upstream Terraform provider in the require section, e.g.

    github.com/foo/terraform-provider-mssql v0.4.0

  2. In provider/resources.go, ensure the reference in the import section uses the correct Go module path, e.g.:

    github.com/foo/terraform-provider-mssql/mssql

  3. Download the dependencies:

    cd provider && go mod tidy && cd -

  4. Create the schema by running the following command:

    make tfgen

    Note warnings about unmapped resources and data sources in the command's output. We map these in the next section, e.g.:

    warning: resource mssql_something not found in provider map; skipping
warning: resource mssql_something_else not found in provider map; skipping
warning: data source mssql_something not found in provider map; skipping
warning: data source mssql_something_else not found in provider map; skipping

Adding Mappings, Building the Provider and SDKs

In this section we will add the mappings that allow the interoperation between the Pulumi provider and the Terraform provider. Terraform resources map to an identically named concept in Pulumi. Terraform data sources map to plain old functions in your supported programming language of choice. Pulumi also allows provider functions and resources to be grouped into namespaces to improve the cohesion of a provider's code, thereby making it easier for developers to use. If your provider has a large number of resources, consider using namespaces to improve usability.

The following instructions all pertain to provider/resources.go, in the section of the code where we construct a tfbridge.ProviderInfo object:

  1. Add resource mappings: For each resource in the provider, add an entry in the Resources property of the tfbridge.ProviderInfo, e.g.:

    // Most providers will have all resources (and data sources) in the main module.
// Note the mapping from snake_case HCL naming conventions to UpperCamelCase Pulumi SDK naming conventions.
// The name of the provider is omitted from the mapped name due to the presence of namespaces in all supported Pulumi languages.
"mssql_something":      {Tok: tfbridge.MakeResource(mainPkg, mainMod, "Something")},
"mssql_something_else": {Tok: tfbridge.MakeResource(mainPkg, mainMod, "SomethingElse")},

  2. Add CSharpName (if necessary): Dotnet does not allow for fields named the same as the enclosing type, which sometimes results in errors during the dotnet SDK build. If you see something like

    error CS0542: 'ApiKey': member names cannot be the same as their enclosing type [/Users/guin/go/src/github.com/pulumi/pulumi-artifactory/sdk/dotnet/Pulumi.Artifactory.csproj]

    you'll want to give your Resource a CSharpName, which can have any value that makes sense:

    "mssql_something_dotnet": {
    Tok: tfbridge.MakeResource(mainPkg, mainMod, "SomethingDotnet"),
    Fields: map[string]*tfbridge.SchemaInfo{
        "something_dotnet": {
            CSharpName: "SpecialName",
        },
    },
},

    See the underlying terraform-bridge code here.

  3. Add data source mappings: For each data source in the provider, add an entry in the DataSources property of the tfbridge.ProviderInfo, e.g.:

    // Note the 'get' prefix for data sources
"mssql_something":      {Tok: tfbridge.MakeDataSource(mainPkg, mainMod, "getSomething")},
"mssql_something_else": {Tok: tfbridge.MakeDataSource(mainPkg, mainMod, "getSomethingElse")},

  4. Add documentation mapping (sometimes needed): If the upstream provider's repo is not a part of the terraform-providers GitHub organization, specify the GitHubOrg property of tfbridge.ProviderInfo to ensure that documentation is picked up by the codegen process, and that attribution for the upstream provider is correct, e.g.:

    GitHubOrg: "pulumiverse",

  5. Add provider configuration overrides (not typically needed): Pulumi's Terraform bridge automatically detects configuration options for the upstream provider. However, in rare cases these settings may need to be overridden, e.g. if we want to change an environment variable default from API_KEY to mssql_API_KEY. Examples of common uses cases:

    "additional_required_parameter": {},
"additional_optional_string_parameter": {
    Default: &tfbridge.DefaultInfo{
        Value: "default_value",
    },
"additional_optional_boolean_parameter": {
    Default: &tfbridge.DefaultInfo{
        Value: true,
    },
// Renamed environment variables can be accounted for like so:
"apikey": {
    Default: &tfbridge.DefaultInfo{
        EnvVars: []string{"mssql_API_KEY"},
    },

  6. Build the provider binary and ensure there are no warnings about unmapped resources and no warnings about unmapped data sources:

    make provider

    You may see warnings about documentation and examples, including "unexpected code snippets". These can be safely ignored for now. Pulumi will add additional documentation on mapping docs in a future revision of this guide.

  7. Build the SDKs in the various languages Pulumi supports:

    make build_sdks

  8. Ensure the Golang SDK is a proper go module:

    cd sdk && go mod tidy && cd -

    This will pull in the correct dependencies in sdk/go.mod as well as setting the dependency tree in sdk/go.sum.

  9. Finally, ensure the provider code conforms to Go standards:

    make lint_provider

    Fix any issues found by the linter.

Note: If you make revisions to code in resources.go, you must re-run the make tfgen target to regenerate the schema. The make tfgen target will take the file schema.json and serialize it to a byte array so that it can be included in the build output. (This is a holdover from Go 1.16, which does not have the ability to directly embed text files. We are working on removing the need for this step.)

Sample Program

In this section, we will create a Pulumi program in TypeScript that utilizes the provider we created to ensure everything is working properly.

  1. Create an account with the provider's service and generate any necessary credentials, e.g. API keys.

    • Email: bot@pulumi.com
    • Password: (Create a random password in 1Password with the maximum length and complexity allowed by the provider.)
    • Ensure all secrets (passwords, generated API keys) are stored in Pulumi's 1Password vault.

  2. Copy the pulumi-resource-mssql binary generated by make provider and place it in your $PATH ($GOPATH/bin is a convenient choice), e.g.:

    cp bin/pulumi-resource-mssql $GOPATH/bin

  3. Tell Yarn to use your local copy of the SDK:

    make install_nodejs_sdk

  4. Create a new Pulumi program in the examples/ directory, e.g.:

    mkdir examples/my-example/ts # Change "my-example" to something more meaningful.
cd examples/my-example/ts
pulumi new typescript
# (Go through the prompts with the default values)
npm install
yarn link @pulumiverse/mssql

  5. Create a minimal program for the provider, i.e. one that creates the smallest-footprint resource. Place this code in index.ts.

  6. Configure any necessary environment variables for authentication, e.g $FOO_USERNAME, $FOO_TOKEN, in your local environment.

  7. Ensure the program runs successfully via pulumi up.

  8. Once the program completes successfully, verify the resource was created in the provider's UI.

  9. Destroy any resources created by the program via pulumi destroy.

Optionally, you may create additional examples for SDKs in other languages supported by Pulumi:

  1. Python:

    mkdir examples/my-example/py
cd examples/my-example/py
pulumi new python
# (Go through the prompts with the default values)
source venv/bin/activate # use the virtual Python env that Pulumi sets up for you
pip install pulumi_mssql

  2. Follow the steps above to verify the program runs successfully.

Add End-to-end Testing

We can run integration tests on our examples using the *_test.go files in the examples/ folder.

  1. Add code to examples_nodejs_test.go to call the example you created, e.g.:

    // Swap out MyExample and "my-example" below with the name of your integration test.
func TestAccMyExampleTs(t *testing.T) {
    test := getJSBaseOptions(t).
        With(integration.ProgramTestOptions{
            Dir: filepath.Join(getCwd(t), "my-example", "ts"),
        })
    integration.ProgramTest(t, &test)
}

  2. Add a similar function for each example that you want to run in an integration test. For examples written in other languages, create similar files for examples_${LANGUAGE}_test.go.

  3. You can run these tests locally via Make:

    make test

    You can also run each test file separately via test tags:

    cd examples && go test -v -tags=nodejs

Configuring CI with GitHub Actions

Third-party providers

  1. Follow the instructions laid out in the deployment templates.

Pulumi Internal

In this section, we'll add the necessary configuration to work with GitHub Actions for Pulumi's standard CI/CD workflows for providers.

  1. Generate GitHub workflows per the instructions in the ci-mgmt repository and copy to .github/ in this repository.

  2. Ensure that any required secrets are present as repository-level secrets in GitHub. These will be used by the integration tests during the CI/CD process.

  3. Repository settings: Toggle Allow auto-merge on in your provider repo to automate GitHub Actions workflow updates.

Final Steps

  1. Ensure all required configurations (API keys, etc.) are documented in README-PROVIDER.md.

  2. Replace this file with the README for the provider and push your changes:

    mv README-PROVIDER.md README.md

  3. If publishing the npm package fails during the "Publish SDKs" Action, perform the following steps:

    1. Go to NPM Packages and sign in as pulumi-bot.
    2. Click on the bot's profile pic and navigate to "Packages".
    3. On the left, under "Organizations, click on the Pulumi organization.
    4. On the last page of the listed packages, you should see the new package.
    5. Under "Settings", set the Package Status to "public".

Now you are ready to use the provider, cut releases, and have some well-deserved 🍨!