feat(pipeline): allow the build step to have its own runner configura…

…tion (#10)

This change allows the `build` (synth) step to have its own Github
Runner configuration that is separate from the deployment steps. This
allows the build step to have faster/larger hardware without impacting
the cost of the other steps. I've also added in the ability to pass in
runner groups.

src/pipeline.ts

@@ -83,6 +83,13 @@ export interface GitHubWorkflowProps extends PipelineBaseProps {
    */
   readonly buildContainer?: github.ContainerOptions;
 
+  /**
+   * The type of Github Runner that the build workflow runs on.
+   *
+   * @default Runner.UBUNTU_LATEST
+   */
+  readonly buildRunner?: github.Runner;
+
   /**
    * GitHub workflow steps to execute before build.
    *
@@ -104,8 +111,8 @@ export interface GitHubWorkflowProps extends PipelineBaseProps {
   readonly diffFirst?: boolean;
 
   /**
-   * The type of runner to run the job on. The runner can be either a
-   * GitHub-hosted runner or a self-hosted runner.
+   * The type of runner that the entire workflow runs on. You can also set the
+   * runner specifically for the `build` (synth) step separately.
    *
    * @default Runner.UBUNTU_LATEST
    */
@@ -132,6 +139,7 @@ export class GitHubWorkflow extends PipelineBase {
   private readonly awsCredentials: AwsCredentialsProvider;
   private readonly workflowTriggers: github.WorkflowTriggers;
   private readonly buildContainer?: github.ContainerOptions;
+  private readonly buildRunner: github.Runner;
   private readonly preBuildSteps: github.JobStep[];
   private readonly postBuildSteps: github.JobStep[];
   private readonly diffFirst: boolean;
@@ -176,6 +184,7 @@ export class GitHubWorkflow extends PipelineBase {
     };
 
     this.runner = props.runner ?? github.Runner.UBUNTU_LATEST;
+    this.buildRunner = props.buildRunner ?? this.runner;
   }
 
   /**
@@ -484,7 +493,7 @@ export class GitHubWorkflow extends PipelineBase {
           // that it is being used in the preBuildSteps.
           idToken: this.awsCredentials.jobPermission(),
         },
-        runsOn: this.runner.runsOn,
+        runsOn: this.buildRunner.runsOn,
         needs: this.renderDependencies(node),
         env: step.env,
         container: this.buildContainer,

src/workflows-model.ts

@@ -12,7 +12,7 @@ export interface Job {
    *
    * @example ["ubuntu-latest"]
    */
-  readonly runsOn: string[] | string;
+  readonly runsOn: string[] | string | Record<string, string | string[]>;
 
   /**
    * A job contains a sequence of tasks called steps. Steps can run commands,
@@ -225,15 +225,39 @@ export class Runner {
     }
   }
 
-  public get runsOn(): string[] | string {
+  /**
+   * Creates a runner that sets runsOn to a Github-hosted runner Group.
+   */
+  public static onGroup(name: string, labels?: string[]) {
+    return new Runner(labels ?? [], name);
+  }
+
+  public get runsOn(): string[] | string | Record<string, string | string[]> {
+    /**
+     * If the group was set - then we return in this format:
+     *
+     * https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#example-combining-groups-and-labels
+     */
+    if (this.group) {
+      return {
+        group: this.group,
+        labels: this.labels,
+      };
+    }
+
+    /** Otherwise, return in string format... */
     if (this.labels[0] === 'self-hosted') {
+      /** https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#choosing-self-hosted-runners */
       return this.labels;
     } else {
       return this.labels[0];
     }
   }
 
-  private constructor(private readonly labels: string[]) {}
+  private constructor(
+    private readonly labels: string[],
+    private readonly group?: string,
+  ) {}
 }
 
 /**

test/github.test.ts

@@ -40,6 +40,42 @@ test('pipeline with only a synth step', () => {
   });
 });
 
+test('pipeline with a dedicated buildRunner setting', () => {
+  withTemporaryDirectory((dir) => {
+    const github = new GitHubWorkflow(app, 'Pipeline', {
+      workflowPath: `${dir}/.github/workflows/deploy.yml`,
+      awsCreds: AwsCredentials.runnerHasPreconfiguredCreds(),
+      buildRunner: Runner.onGroup('test-group'),
+      synth: new ShellStep('Build', {
+        installCommands: ['yarn'],
+        commands: ['yarn build'],
+      }),
+    });
+
+    app.synth();
+
+    expect(readFileSync(github.workflowPath, 'utf-8')).toMatchSnapshot();
+  });
+});
+
+test('pipeline with a dedicated buildRunner setting and labels', () => {
+  withTemporaryDirectory((dir) => {
+    const github = new GitHubWorkflow(app, 'Pipeline', {
+      workflowPath: `${dir}/.github/workflows/deploy.yml`,
+      awsCreds: AwsCredentials.runnerHasPreconfiguredCreds(),
+      buildRunner: Runner.onGroup('test-group', ['withLabel']),
+      synth: new ShellStep('Build', {
+        installCommands: ['yarn'],
+        commands: ['yarn build'],
+      }),
+    });
+
+    app.synth();
+
+    expect(readFileSync(github.workflowPath, 'utf-8')).toMatchSnapshot();
+  });
+});
+
 test('pipeline with aws credentials using awsCreds', () => {
   withTemporaryDirectory((dir) => {
     const github = new GitHubWorkflow(app, 'Pipeline', {