Integrate remote cache server for Bazel

config.js

@@ -151,4 +151,9 @@ module.exports = {
     name: 'repository',
     paths: [bazelRepository]
   },
+  remoteCacheServer: {
+    enabled: true,
+    url: 'http://localhost:8080/cache',
+    logPath: `${os.tmpdir()}/remote-cache-server.log`,
+  }
 }

index.js

@@ -6,6 +6,8 @@ const github = require('@actions/github')
 const glob = require('@actions/glob')
 const tc = require('@actions/tool-cache')
 const config = require('./config')
+const { fork } = require('child_process')
+const path = require('path')
 
 async function run() {
   try {
@@ -28,6 +30,7 @@ async function setupBazel() {
   await restoreCache(config.diskCache)
   await restoreCache(config.repositoryCache)
   await restoreExternalCaches(config.externalCache)
+  await startRemoteCacheServer()
 }
 
 async function setupBazelisk() {
@@ -92,8 +95,8 @@ async function downloadBazelisk() {
   core.debug(`Downloading from ${url}`)
   const downloadPath = await tc.downloadTool(url, undefined, `token ${token}`)
 
-  core.debug('Adding to the cache...');
-  fs.chmodSync(downloadPath, '755');
+  core.debug('Adding to the cache...')
+  fs.chmodSync(downloadPath, '755')
   const cachePath = await tc.cacheFile(downloadPath, 'bazel', 'bazelisk', version)
   core.debug(`Successfully cached bazelisk to ${cachePath}`)
 
@@ -107,6 +110,7 @@ async function setupBazelrc() {
       `startup --output_base=${config.paths.bazelOutputBase}\n`
     )
     fs.appendFileSync(bazelrcPath, config.bazelrc.join("\n"))
+    fs.appendFileSync(bazelrcPath, `build --remote_cache=${config.remoteCacheServer.url}\n`)
   }
 }
 
@@ -174,4 +178,13 @@ async function restoreCache(cacheConfig) {
   }())
 }
 
-run()
+async function startRemoteCacheServer() {
+  const log = fs.openSync(config.remoteCacheServer.logPath, 'a')
+  const serverProcess = fork(path.join(__dirname, 'dist', 'remote-cache-server', 'index.js'), [], {
+    detached: true,
+    stdio: ['ignore', log, log, 'ipc']
+  })
+  serverProcess.unref()
+  
+  core.saveState('remote-cache-server-pid', serverProcess.pid.toString())
+}

package.json

@@ -7,7 +7,7 @@
     "node": "20.x"
   },
   "scripts": {
-    "build": "ncc build index.js -s -o dist/main && ncc build post.js -s -o dist/post",
+    "build": "ncc build index.js -s -o dist/main && ncc build post.js -s -o dist/post && ncc build remote-cache-server.js -s -o dist/remote-cache-server",
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "author": "Alex Rodionov <p0deje@gmail.com>",

post.js

@@ -5,11 +5,31 @@ const core = require('@actions/core')
 const glob = require('@actions/glob')
 const config = require('./config')
 const { getFolderSize } = require('./util')
+const { execSync } = require('child_process')
 
 async function run() {
+  await stopRemoteCacheServer()
   await saveCaches()
 }
 
+async function stopRemoteCacheServer() {
+  const pid = core.getState('remote-cache-server-pid')
+  if (pid) {
+    try {
+      process.kill(pid, 'SIGTERM')
+      core.debug(`Stopped remote cache server with PID: ${pid}`)
+    } catch (error) {
+      core.error(`Failed to stop remote cache server with PID: ${pid}. Error: ${error}`)
+    }
+  }
+
+  const logPath = config.remoteCacheServer.logPath
+  if (fs.existsSync(logPath)) {
+    const logContent = fs.readFileSync(logPath, 'utf8')
+    core.debug(`Remote cache server log:\n${logContent}`)
+  }
+}
+
 async function saveCaches() {
   await saveCache(config.bazeliskCache)
   await saveCache(config.diskCache)

remote-cache-server.js

@@ -0,0 +1,50 @@
+const http = require('http')
+const cache = require('@actions/cache')
+const fs = require('fs')
+
+// https://bazel.build/remote/caching#http-caching
+const server = http.createServer(async (req, res) => {
+  const { method, url } = req
+  const [, , cacheType, sha] = url.split('/')
+  const filePath = `/tmp/cache-${cacheType}-${sha}`
+
+  if (method === 'GET') {
+    try {
+      const cacheId = await cache.restoreCache([filePath], sha)
+      if (!cacheId) {
+        console.log(`Cache miss for ${sha}`)
+        res.writeHead(404)
+        return res.end('Cache miss')
+      }
+      const data = fs.readFileSync(filePath)
+      res.writeHead(200, { 'Content-Type': 'application/octet-stream' })
+      res.end(data)
+    } catch (error) {
+      console.error(`Error retrieving cache for ${sha}: ${error}`)
+      res.writeHead(500)
+      res.end('Internal Server Error')
+    }
+  } else if (method === 'PUT') {
+    const data = []
+    req.on('data', chunk => data.push(chunk))
+    req.on('end', async () => {
+      try {
+        fs.writeFileSync(filePath, Buffer.concat(data))
+        await cache.saveCache([filePath], sha)
+        console.log(`Cache saved for ${sha}`)
+        res.writeHead(201)
+        res.end('Cache saved')
+      } catch (error) {
+        console.error(`Error saving cache for ${sha}: ${error}`)
+        res.writeHead(500)
+        res.end('Internal Server Error')
+      }
+    })
+  } else {
+    res.writeHead(405)
+    res.end('Method Not Allowed')
+  }
+})
+
+const PORT = process.env.PORT || 8080
+server.listen(PORT, () => console.log(`Server listening on port ${PORT}`))