TechDocs: Pass user and group ID when invoking docker container

Without this, files generated by Docker container will be restricted to the root  user

packages/techdocs-common/src/stages/generate/helpers.test.ts

@@ -30,6 +30,7 @@ import {
   patchMkdocsYmlPreBuild,
   runDockerContainer,
   storeEtagMetadata,
+  UserOptions,
 } from './helpers';
 
 const mockEntity = {
@@ -114,7 +115,7 @@ describe('helpers', () => {
         imageName,
         args,
         expect.any(Stream),
-        {
+        expect.objectContaining({
           Volumes: {
             '/content': {},
             '/result': {},
@@ -123,7 +124,7 @@ describe('helpers', () => {
           HostConfig: {
             Binds: [`${docsDir}:/content`, `${outputDir}:/result`],
           },
-        },
+        }),
       );
     });
 
@@ -139,6 +140,30 @@ describe('helpers', () => {
       expect(mockDocker.ping).toHaveBeenCalled();
     });
 
+    it('should pass through the user and group id from the host machine and set the home dir', async () => {
+      await runDockerContainer({
+        imageName,
+        args,
+        docsDir,
+        outputDir,
+        dockerClient: mockDocker,
+      });
+
+      const userOptions: UserOptions = {};
+      if (process.getuid && process.getgid) {
+        userOptions.User = `${process.getuid()}:${process.getgid()}`;
+      }
+
+      expect(mockDocker.run).toHaveBeenCalledWith(
+        imageName,
+        args,
+        expect.any(Stream),
+        expect.objectContaining({
+          ...userOptions,
+        }),
+      );
+    });
+
     describe('where docker is unavailable', () => {
       const dockerError = 'a docker error';
 

packages/techdocs-common/src/stages/generate/helpers.ts

@@ -51,6 +51,12 @@ export type RunCommandOptions = {
   logStream?: Writable;
 };
 
+export type UserOptions = {
+  User?: string;
+};
+
+// To be replaced by a runDockerContainer from backend-common
+// shared between Scaffolder and TechDocs and any other plugin.
 export async function runDockerContainer({
   imageName,
   args,
@@ -78,6 +84,17 @@ export async function runDockerContainer({
     });
   });
 
+  const userOptions: UserOptions = {};
+  // @ts-ignore
+  if (process.getuid && process.getgid) {
+    // Files that are created inside the Docker container will be owned by
+    // root on the host system on non Mac systems, because of reasons. Mainly the fact that
+    // volume sharing is done using NFS on Mac and actual mounts in Linux world.
+    // So we set the user in the container as the same user and group id as the host.
+    // On Windows we don't have process.getuid nor process.getgid
+    userOptions.User = `${process.getuid()}:${process.getgid()}`;
+  }
+
   const [{ Error: error, StatusCode: statusCode }] = await dockerClient.run(
     imageName,
     args,
@@ -91,6 +108,7 @@ export async function runDockerContainer({
       HostConfig: {
         Binds: [`${docsDir}:/content`, `${outputDir}:/result`],
       },
+      ...userOptions,
       ...createOptions,
     },
   );