ci: always use version named branches (backport #752) (#754)

This is an automatic backport of pull request #752 done by [Mergify](https://mergify.com).

---


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.projenrc.ts

@@ -5,17 +5,23 @@ import { IntegrationTests } from './projenrc/IntegrationTests';
 import { Esbuild } from './src/private/esbuild-source';
 
 const releaseBranches: StableReleaseBranches = {
-  main: {
+  v4: {
+    isCurrent: true,
     majorVersion: 4,
     cdkVersion: '2.12.0',
     minNodeVersion: '16.x', // should be 14.x but that version doesn't build anymore
     releaseSchedule: '0 5 15 * *',
+    jsiiVersion: '1.x',
+    typescriptVersion: '4.9.x',
   },
   v3: {
     majorVersion: 3,
     cdkVersion: '2.0.0',
+    syntheticsVersion: '2.0.0-alpha.11',
     minNodeVersion: '16.x', // should be 14.x but that version doesn't build anymore
     releaseSchedule: '0 5 15 * *',
+    jsiiVersion: '1.x',
+    typescriptVersion: '4.9.x',
   },
 };
 
@@ -95,9 +101,7 @@ const project = new awscdk.AwsCdkConstructLibrary({
   },
 
   // Dependencies
-  cdkVersion: releaseBranches.main.cdkVersion,
   devDeps: [
-    `@aws-cdk/aws-synthetics-alpha@${releaseBranches.main.cdkVersion}-alpha.0`,
     '@types/eslint',
     Esbuild.spec,
     'jest-mock',

projenrc/ReleaseBranches.ts

@@ -1,10 +1,14 @@
 import { Component, JsonPatch, release, typescript } from 'projen';
 
 export interface StableReleaseBranchOptions extends Omit<release.BranchOptions, 'npmDistTag'> {
+  isCurrent?: boolean;
   minNodeVersion: string;
   releaseSchedule: string;
   npmDistTags?: string[];
   cdkVersion: string;
+  jsiiVersion: string;
+  typescriptVersion: string;
+  syntheticsVersion?: string;
 }
 
 export interface StableReleaseBranches {
@@ -14,15 +18,20 @@ export interface StableReleaseBranches {
 export class StableReleases extends Component {
   public project: typescript.TypeScriptProject;
 
-  public constructor(project: typescript.TypeScriptProject, options: StableReleaseBranches) {
+  public constructor(project: typescript.TypeScriptProject, public readonly branches: StableReleaseBranches) {
     super(project);
     this.project = project;
 
     for (const branch of project.release?.branches ?? []) {
-      const opts = options[branch];
-      const isDefaultBranch = this.isDefaultBranch(branch);
+      const opts = branches[branch];
+      const isCurrentBranch = this.isCurrentBranch(branch);
       const releaseWorkflow = this.getReleaseWorkflow(branch);
 
+      // Features only for current branch
+      if (isCurrentBranch) {
+        project.addDevDeps( `@aws-cdk/aws-synthetics-alpha@${opts.syntheticsVersion ?? opts.cdkVersion + '-alpha.0'}`);
+      }
+
       // Release schedule
       releaseWorkflow?.patch(JsonPatch.replace('/on/schedule', [{ cron: opts.releaseSchedule }]));
 
@@ -38,7 +47,7 @@ export class StableReleases extends Component {
         gitBranch: branch,
       });
       const publishChangelogTask = ['publish', 'git'];
-      if (!isDefaultBranch) {
+      if (!isCurrentBranch) {
         publishChangelogTask.push(branch);
       }
       releaseWorkflow?.patch(JsonPatch.add('/jobs/release/steps/-', {
@@ -62,12 +71,13 @@ export class StableReleases extends Component {
     }
   }
 
-  private isDefaultBranch(branch: string): boolean {
-    return branch === 'main';
+  private isCurrentBranch(branch: string): boolean {
+    const [currentBranch] = Object.entries(this.branches).find(([_, options]) => options.isCurrent) || [];
+    return branch === currentBranch;
   }
 
   private getReleaseWorkflow(branch: string) {
-    if (this.isDefaultBranch(branch)) {
+    if (this.isCurrentBranch(branch)) {
       return this.project.tryFindObjectFile('.github/workflows/release.yml');
     }
 
@@ -90,20 +100,32 @@ export class StableReleases extends Component {
 
 }
 
-export function releaseOptions(branches: StableReleaseBranches, currentBranch = 'main'): {
+export function releaseOptions(branches: StableReleaseBranches): {
   npmDistTag: string;
   defaultReleaseBranch: string;
   majorVersion: number;
+  prerelease?: string;
   releaseBranches: StableReleaseBranches;
   workflowNodeVersion: string;
   releaseTrigger: release.ReleaseTrigger;
+  cdkVersion: string;
+  jsiiVersion: string;
+  typescriptVersion: string;
 } {
-  const current = branches[currentBranch];
+  const [currentBranch, current] = Object.entries(branches).find(([_, options]) => options.isCurrent) || [];
+  if (!currentBranch || !current) {
+    throw Error('Exactly one branch must be the current version');
+  }
+
   return {
     npmDistTag: 'latest',
     defaultReleaseBranch: currentBranch,
     majorVersion: current.majorVersion,
     workflowNodeVersion: current.minNodeVersion,
+    prerelease: current.prerelease,
+    cdkVersion: current.cdkVersion,
+    jsiiVersion: current.jsiiVersion,
+    typescriptVersion: current.typescriptVersion,
     releaseBranches: Object.fromEntries(
       Object.entries(branches)
         .filter(([b]) => b !== currentBranch)