Fix #13 Task output buffer unconstrained

lib/tasks/exec.js

@@ -28,7 +28,7 @@ class ExecTask {
       };
 
       const exec = await container.exec(opt);
-      const bufferStream = util.buildBufferStream();
+      const bufferStream = util.buildOutputBufferStream();
       const outputStream = await exec.start();
 
       await new Promise((res, rej) => {

lib/tasks/run.js

@@ -46,7 +46,6 @@ class RunTask {
     log.info('Started task');
     try {
 
-      const bufferStream = util.buildBufferStream();
       await this.checkOrPull(this.image, log);
       const opt = {
         User: this.user,
@@ -59,6 +58,7 @@ class RunTask {
       if (this.environment) opt.Env = this.environment;
       if (this.volumes) opt.HostConfig.Binds = this.volumes;
 
+      const bufferStream = util.buildOutputBufferStream();
       const [res, container] = await this.docker.run(this.image, this.command, bufferStream.stream, opt);
 
       const { Error: error, StatusCode: exitCode } = res;

lib/util.js

@@ -3,6 +3,8 @@ const dockerUtil = require('dockerode/lib/util');
 const { Writable } = require('stream');
 const { StringDecoder } = require('string_decoder');
 
+const MAX_OUTPUT_BUFFER_SIZE = 200000; // 200KB
+
 class Util {
 
   static parseRepositoryTag(image) {
@@ -21,12 +23,16 @@ class Util {
     return Object.entries(env).map(([k, v]) => `${k}${v ? `=${v}` : ''}`);
   }
 
-  static buildBufferStream() {
+  static buildOutputBufferStream() {
     const decoder = new StringDecoder('utf8');
     const res = { buffer: '' };
     res.stream = new Writable({
       write(chunk, encoding, callback) {
         res.buffer += decoder.write(chunk);
+        if (res.buffer.length > Util.MAX_OUTPUT_BUFFER_SIZE) {
+          const start = res.buffer.length - Util.MAX_OUTPUT_BUFFER_SIZE;
+          res.buffer = res.buffer.substring(start);
+        }
         callback();
       }
     });
@@ -47,4 +53,6 @@ class Util {
 
 }
 
+Util.MAX_OUTPUT_BUFFER_SIZE = MAX_OUTPUT_BUFFER_SIZE;
+
 module.exports = Util;

package.json

@@ -10,7 +10,7 @@
   },
   "scripts": {
     "start": "node ./bin/cli.js",
-    "test": "ava",
+    "test": "ava -T 1m --verbose",
     "lint": "eslint ."
   },
   "author": "Nicolas Martinez",

test/tasks/run.js

@@ -2,6 +2,7 @@ const path = require('path');
 const test = require('ava');
 const dockerUtil = require('../util/docker');
 const MockLog = require('../mock/log');
+const util = require('../../lib/util');
 const RunTask = require('../../lib/tasks/run');
 
 const log = new MockLog();
@@ -202,3 +203,15 @@ test('run: custom workingdir', async (t) => {
   t.is(exitCode, 0);
   t.is(output, '/tmp');
 });
+
+test('run: very long output', async (t) => {
+  const task = new RunTask('test', {
+    image: 'busybox',
+    command: 'sh -c "yes 0123456789 | head -1000000"'
+  });
+
+  const { exitCode, output } = await task.execute(log);
+  t.is(task.name, 'test');
+  t.is(exitCode, 0);
+  t.true(output.length <= util.MAX_OUTPUT_BUFFER_SIZE);
+});