build: update projen version as part of upgrade workflow (#695)

Adds a task to run as part of the upgrade-mainline workflow which updates the projen version such that PDK and its vended projects all depend on the same projen version.

.github/workflows/upgrade-mainline.yml

@@ -20,6 +20,8 @@ jobs:
           ref: mainline
       - name: PDK Init
         uses: ./.github/actions/pdk-init
+      - name: Upgrade projen
+        run: pnpm nx run @aws/monorepo:upgrade-projen
       - name: Upgrade dependencies
         run: pnpm projen upgrade-deps
       - name: Build

packages/monorepo/scripts/upgrade-projen.ts

@@ -0,0 +1,15 @@
+import * as ncu from "npm-check-updates";
+import * as fs from "fs";
+import * as path from "path";
+
+(async () => {
+  // Get the latest minor version update of projen
+  const { projen } = await ncu.run({
+    jsonUpgraded: true,
+    target: "minor",
+    filter: "projen",
+  }) as any;
+
+  // Write the projen version to projen-version.ts
+  fs.writeFileSync(path.resolve(__dirname, "../src/components/projen-version.ts"), `export default "^${projen}";`);
+})();

projenrc/projects/monorepo-project.ts

@@ -51,6 +51,9 @@ export class MonorepoProject extends PDKProject {
     // Don't check for a license header etc for projen-version.ts so this can be written via automation
     this.eslint?.addIgnorePattern("src/components/projen-version.ts");
 
+    // Add a task to upgrade the projen version. Ideally run before upgrade-deps in the root.
+    this.addTask("upgrade-projen").exec("ts-node ./scripts/upgrade-projen.ts")
+
     this.generateInterfaces();
   }