Use cookie cutter installed on host

plugins/scaffolder-backend/package.json

@@ -27,6 +27,7 @@
     "@octokit/rest": "^18.0.0",
     "@types/dockerode": "^2.5.32",
     "@types/express": "^4.17.6",
+    "command-exists-promise": "^2.0.2",
     "compression": "^1.7.4",
     "cors": "^2.8.5",
     "dockerode": "^3.2.0",

plugins/scaffolder-backend/src/scaffolder/stages/templater/cookiecutter.ts

@@ -15,11 +15,13 @@
  */
 import fs from 'fs-extra';
 import { JsonValue } from '@backstage/config';
-import { runDockerContainer } from './helpers';
+import { runDockerContainer, runCommand } from './helpers';
 import { TemplaterBase, TemplaterRunOptions } from '.';
 import path from 'path';
 import { TemplaterRunResult } from './types';
 
+const commandExists = require('command-exists-promise');
+
 export class CookieCutter implements TemplaterBase {
   private async fetchTemplateCookieCutter(
     directory: string,
@@ -51,21 +53,30 @@ export class CookieCutter implements TemplaterBase {
     const templateDir = options.directory;
     const resultDir = await fs.promises.mkdtemp(`${options.directory}-result`);
 
-    await runDockerContainer({
-      imageName: 'spotify/backstage-cookiecutter',
-      args: [
-        'cookiecutter',
-        '--no-input',
-        '-o',
-        '/result',
-        '/template',
-        '--verbose',
-      ],
-      templateDir,
-      resultDir,
-      logStream: options.logStream,
-      dockerClient: options.dockerClient,
-    });
+    const cookieCutterInstalled = await commandExists('cookiecutter');
+    if (cookieCutterInstalled) {
+      await runCommand({
+        command: 'cookiecutter',
+        args: ['--no-input', '-o', resultDir, templateDir, '--verbose'],
+        logStream: options.logStream,
+      });
+    } else {
+      await runDockerContainer({
+        imageName: 'spotify/backstage-cookiecutter',
+        args: [
+          'cookiecutter',
+          '--no-input',
+          '-o',
+          '/result',
+          '/template',
+          '--verbose',
+        ],
+        templateDir,
+        resultDir,
+        logStream: options.logStream,
+        dockerClient: options.dockerClient,
+      });
+    }
 
     return {
       resultDir: path.resolve(resultDir, options.values.component_id as string),

plugins/scaffolder-backend/src/scaffolder/stages/templater/helpers.ts

@@ -18,6 +18,7 @@ import Docker from 'dockerode';
 import fs from 'fs';
 import { TemplateEntityV1alpha1 } from '@backstage/catalog-model';
 import { InputError } from '@backstage/backend-common';
+import { spawn } from 'child_process';
 
 export type RunDockerContainerOptions = {
   imageName: string;
@@ -29,6 +30,12 @@ export type RunDockerContainerOptions = {
   createOptions?: Docker.ContainerCreateOptions;
 };
 
+export type RunCommandOptions = {
+  command: string;
+  args: string[];
+  logStream?: Writable;
+};
+
 /**
  * Gets the templater key to use for templating from the entity
  * @param entity Template entity
@@ -43,6 +50,42 @@ export const getTemplaterKey = (entity: TemplateEntityV1alpha1): string => {
   return templater;
 };
 
+/**
+ *
+ * @param options the options object
+ * @param options.command the command to run
+ * @param options.args the arguments to pass the command
+ * @param options.logStream the log streamer to capture log messages
+ */
+export const runCommand = async ({
+  command,
+  args,
+  logStream = new PassThrough(),
+}: RunCommandOptions) => {
+  await new Promise((resolve, reject) => {
+    const process = spawn(command, args);
+
+    process.stdout.on('data', stream => {
+      logStream.write(stream);
+    });
+
+    process.stderr.on('data', stream => {
+      logStream.write(stream);
+    });
+
+    process.on('error', error => {
+      return reject(error);
+    });
+
+    process.on('close', code => {
+      if (code !== 0) {
+        return reject(`Command ${command} failed, exit code: ${code}`);
+      }
+      return resolve();
+    });
+  });
+};
+
 /**
  *
  * @param options the options object