feat: build workflow for sub-projects (#3317)

Creates a working `build` workflow specific to a sub-project when that project has `buildWorkflow` set to `true`.

Based on #3208. So most of the same decisions were made. The `install` command is always run in the root directory same as the `release` workflow. But based on discussion in #3304, we may want to make that configurable. I could make that change in this PR for `build`. Or just address it in a followup PR for both `build` and `release`.
I added a `buildWorkflowName` option to `NodeProject` to support customizing each build workflow name; but it still defaults to `build` or `build_{package-name}` for sub-projects.

I've successfully tested this with my own monorepo and added a few tests.

---
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

docs/api/build.md

@@ -249,6 +249,7 @@ Test whether the given construct is a component.
 | <code><a href="#projen.build.BuildWorkflow.property.node">node</a></code> | <code>constructs.Node</code> | The tree node. |
 | <code><a href="#projen.build.BuildWorkflow.property.project">project</a></code> | <code>projen.Project</code> | *No description.* |
 | <code><a href="#projen.build.BuildWorkflow.property.buildJobIds">buildJobIds</a></code> | <code>string[]</code> | Returns a list of job IDs that are part of the build. |
+| <code><a href="#projen.build.BuildWorkflow.property.name">name</a></code> | <code>string</code> | Name of generated github workflow. |
 
 ---
 
@@ -286,6 +287,18 @@ Returns a list of job IDs that are part of the build.
 
 ---
 
+##### `name`<sup>Required</sup> <a name="name" id="projen.build.BuildWorkflow.property.name"></a>
+
+```typescript
+public readonly name: string;
+```
+
+- *Type:* string
+
+Name of generated github workflow.
+
+---
+
 
 ## Structs <a name="Structs" id="Structs"></a>
 

src/build/build-workflow.ts

@@ -1,6 +1,13 @@
+import * as path from "path";
 import { Task } from "..";
 import { Component } from "../component";
-import { GitHub, GithubWorkflow, GitIdentity, WorkflowSteps } from "../github";
+import {
+  GitHub,
+  GithubWorkflow,
+  GitIdentity,
+  workflows,
+  WorkflowSteps,
+} from "../github";
 import {
   BUILD_ARTIFACT_NAME,
   DEFAULT_GITHUB_ACTIONS_USER,
@@ -18,6 +25,8 @@ import {
 import { NodeProject } from "../javascript";
 import { Project } from "../project";
 import { GroupRunnerOptions, filteredRunsOnOptions } from "../runner-options";
+import { workflowNameForProject } from "../util/name";
+import { ensureRelativePathStartsWithDot } from "../util/path";
 
 const PULL_REQUEST_REF = "${{ github.event.pull_request.head.ref }}";
 const PULL_REQUEST_REPOSITORY =
@@ -123,21 +132,25 @@ export interface BuildWorkflowOptions {
 }
 
 export class BuildWorkflow extends Component {
+  /**
+   * Name of generated github workflow
+   */
+  public readonly name: string;
+
   private readonly postBuildSteps: JobStep[];
   private readonly preBuildSteps: JobStep[];
   private readonly gitIdentity: GitIdentity;
   private readonly buildTask: Task;
   private readonly github: GitHub;
   private readonly workflow: GithubWorkflow;
   private readonly artifactsDirectory: string;
-  private readonly name: string;
 
   private readonly _postBuildJobs: string[] = [];
 
   constructor(project: Project, options: BuildWorkflowOptions) {
     super(project);
 
-    const github = GitHub.of(project);
+    const github = GitHub.of(this.project.root);
     if (!github) {
       throw new Error(
         "BuildWorkflow is currently only supported for GitHub projects"
@@ -150,7 +163,7 @@ export class BuildWorkflow extends Component {
     this.gitIdentity = options.gitIdentity ?? DEFAULT_GITHUB_ACTIONS_USER;
     this.buildTask = options.buildTask;
     this.artifactsDirectory = options.artifactsDirectory;
-    this.name = options.name ?? "build";
+    this.name = options.name ?? workflowNameForProject("build", this.project);
     const mutableBuilds = options.mutableBuild ?? true;
 
     this.workflow = new GithubWorkflow(github, this.name);
@@ -173,7 +186,11 @@ export class BuildWorkflow extends Component {
   }
 
   private addBuildJob(options: BuildWorkflowOptions) {
-    const jobConfig = {
+    const projectPathRelativeToRoot = path.relative(
+      this.project.root.outdir,
+      this.project.outdir
+    );
+    const jobConfig: workflows.Job = {
       ...filteredRunsOnOptions(options.runsOn, options.runsOnGroup),
       container: options.containerImage
         ? { image: options.containerImage }
@@ -186,7 +203,16 @@ export class BuildWorkflow extends Component {
         contents: JobPermission.WRITE,
         ...options.permissions,
       },
-      steps: (() => this.renderBuildSteps()) as any,
+      defaults: this.project.parent // is subproject,
+        ? {
+            run: {
+              workingDirectory: ensureRelativePathStartsWithDot(
+                projectPathRelativeToRoot
+              ),
+            },
+          }
+        : undefined,
+      steps: (() => this.renderBuildSteps(projectPathRelativeToRoot)) as any,
       outputs: {
         [SELF_MUTATION_HAPPENED_OUTPUT]: {
           stepId: SELF_MUTATION_STEP,
@@ -378,7 +404,7 @@ export class BuildWorkflow extends Component {
   /**
    * Called (lazily) during synth to render the build job steps.
    */
-  private renderBuildSteps(): JobStep[] {
+  private renderBuildSteps(projectPathRelativeToRoot: string): JobStep[] {
     return [
       WorkflowSteps.checkout({
         with: {
@@ -417,7 +443,9 @@ export class BuildWorkflow extends Component {
             WorkflowSteps.uploadArtifact({
               with: {
                 name: BUILD_ARTIFACT_NAME,
-                path: this.artifactsDirectory,
+                path: this.project.parent
+                  ? `${projectPathRelativeToRoot}/${this.artifactsDirectory}`
+                  : this.artifactsDirectory,
               },
             }),
           ]),

src/github/workflow-actions.ts

@@ -39,11 +39,17 @@ export class WorkflowActions {
           "git add .",
           `git diff --staged --patch --exit-code > ${GIT_PATCH_FILE} || echo "${options.outputName}=true" >> $GITHUB_OUTPUT`,
         ].join("\n"),
+        // always run from root of repository
+        // overrides default working directory which is set by some workflows using this function
+        workingDirectory: "./",
       },
       WorkflowSteps.uploadArtifact({
         if: MUTATIONS_FOUND,
         name: "Upload patch",
-        with: { name: GIT_PATCH_FILE, path: GIT_PATCH_FILE },
+        with: {
+          name: GIT_PATCH_FILE,
+          path: GIT_PATCH_FILE,
+        },
       }),
     ];
 

src/javascript/node-project.ts

@@ -15,6 +15,7 @@ import { PROJEN_DIR } from "../common";
 import {
   AutoMerge,
   DependabotOptions,
+  GitHub,
   GitHubProject,
   GitHubProjectOptions,
   GitIdentity,
@@ -92,7 +93,6 @@ export interface NodeProjectOptions
    * @default - true if not a subproject
    */
   readonly buildWorkflow?: boolean;
-
   /**
    * Automatically update files modified during builds to pull-request branches. This means
    * that any files synthesized by projen or e.g. test snapshots will always be up-to-date
@@ -593,14 +593,17 @@ export class NodeProject extends GitHubProject {
       idToken: requiresIdTokenPermission ? JobPermission.WRITE : undefined,
     };
 
-    if (buildEnabled && this.github) {
+    if (buildEnabled && (this.github || GitHub.of(this.root))) {
       this.buildWorkflow = new BuildWorkflow(this, {
         buildTask: this.buildTask,
         artifactsDirectory: this.artifactsDirectory,
         containerImage: options.workflowContainerImage,
         gitIdentity: this.workflowGitIdentity,
         mutableBuild: options.mutableBuild,
         preBuildSteps: this.renderWorkflowSetup({
+          installStepConfiguration: {
+            workingDirectory: this.determineInstallWorkingDirectory(),
+          },
           mutable: options.mutableBuild ?? true,
         }),
         postBuildSteps: options.postBuildSteps,

src/release/release.ts

@@ -26,6 +26,7 @@ import {
   filteredWorkflowRunsOnOptions,
 } from "../runner-options";
 import { Task } from "../task";
+import { workflowNameForProject } from "../util/name";
 import { ensureRelativePathStartsWithDot } from "../util/path";
 import { ReleasableCommits, Version } from "../version";
 
@@ -760,20 +761,6 @@ export class Release extends Component {
   }
 }
 
-function workflowNameForProject(base: string, project: Project): string {
-  // Subprojects
-  if (project.parent) {
-    return `${base}_${fileSafeName(project.name)}`;
-  }
-
-  // root project doesn't get a suffix
-  return base;
-}
-
-function fileSafeName(name: string): string {
-  return name.replace("@", "").replace(/\//g, "-");
-}
-
 /**
  * Options for a release branch.
  */

src/util/name.ts

@@ -0,0 +1,20 @@
+import { Project } from "../project";
+
+/**
+ * Generate workflow name with suffix based on if project is subproject or not
+ * @param base name prefix
+ * @param project to which the workflow belongs
+ */
+export function workflowNameForProject(base: string, project: Project): string {
+  // Subprojects
+  if (project.parent) {
+    return `${base}_${fileSafeName(project.name)}`;
+  }
+
+  // root project doesn't get a suffix
+  return base;
+}
+
+function fileSafeName(name: string): string {
+  return name.replace("@", "").replace(/\//g, "-");
+}