feat: support self-hosted runners

similar to game-ci/unity-builder#355

* Use $RUNNER_TEMP variable instead of hardcoded path for _github_home and _github_workflow
* create the folders if they don't exist
* mount volumes with :z for compatibility with SELinux

Author: paulpach

src/index.ts

@@ -20,6 +20,7 @@ async function run() {
       checkName,
     } = Input.getFromUser();
     const baseImage = new ImageTag({ version: unityVersion, customImage });
+    const runnerTempPath = process.env.RUNNER_TEMP;
 
     try {
       // Build docker image
@@ -37,6 +38,7 @@ async function run() {
         sshAgent,
         gitPrivateToken,
         githubToken,
+        runnerTempPath,
       });
     } finally {
       // Set output

src/model/docker.ts

@@ -1,13 +1,15 @@
+import { existsSync, mkdirSync } from 'fs';
 import ImageTag from './image-tag';
 import { exec } from '@actions/exec';
+import path from 'path';
 
 const Docker = {
   async build(buildParameters, silent = false) {
-    const { path, dockerfile, baseImage } = buildParameters;
+    const { path: buildPath, dockerfile, baseImage } = buildParameters;
     const { version } = baseImage;
 
     const tag = new ImageTag({ version });
-    const command = `docker build ${path} \
+    const command = `docker build ${buildPath} \
       --file ${dockerfile} \
       --build-arg IMAGE=${baseImage} \
       --tag ${tag}`;
@@ -29,8 +31,14 @@ const Docker = {
       sshAgent,
       gitPrivateToken,
       githubToken,
+      runnerTempPath,
     } = parameters;
 
+    const githubHome = path.join(runnerTempPath, '_github_home');
+    if (!existsSync(githubHome)) mkdirSync(githubHome);
+    const githubWorkflow = path.join(runnerTempPath, '_github_workflow');
+    if (!existsSync(githubWorkflow)) mkdirSync(githubWorkflow);
+
     const command = `docker run \
         --workdir /github/workspace \
         --rm \
@@ -62,9 +70,9 @@ const Docker = {
         --env GIT_PRIVATE_TOKEN="${gitPrivateToken}" \
         ${sshAgent ? '--env SSH_AUTH_SOCK=/ssh-agent' : ''} \
         --volume "/var/run/docker.sock":"/var/run/docker.sock" \
-        --volume "/home/runner/work/_temp/_github_home":"/root" \
-        --volume "/home/runner/work/_temp/_github_workflow":"/github/workflow" \
-        --volume "${workspace}":"/github/workspace" \
+        --volume "${githubHome}":"/root:z" \
+        --volume "${githubWorkflow}":"/github/workflow:z" \
+        --volume "${workspace}":"/github/workspace:z" \
         ${sshAgent ? `--volume ${sshAgent}:/ssh-agent` : ''} \
         ${sshAgent ? '--volume /home/runner/.ssh/known_hosts:/root/.ssh/known_hosts:ro' : ''} \
         ${useHostNetwork ? '--net=host' : ''} \