[optimize] inject publicPath at request time (#14007)

* [optimize] inject publicPath at request time

* [optimize/getFileHash] finish doc block

* [optimize/bundlesRoute] correct return value doc type

* [optimize/bundleRoute] use more descriptive name for file hash cache

* [optimize/dynamicAssetResponse] add more details to doc

* [utils/createReplaceStream] trim the buffer based on the length of toReplace, not replacement

* [utils/createReplaceStream] add inline docs

* [utils/createReplaceStream] write unit tests

* [optimize/bundleRoute] expect supports buffers

* [optimize/bundleRoute/basePublicPath/tests] add happy path

* [optimize/bundlesRoute/tests] verify content-type header

* [optimize/bundlesRoute] use '

(cherry picked from commit 1ea82fa869)

package.json

@@ -148,6 +148,7 @@
     "less": "2.7.1",
     "less-loader": "2.2.3",
     "lodash": "3.10.1",
+    "lru-cache": "4.1.1",
     "markdown-it": "8.3.2",
     "minimatch": "2.0.10",
     "mkdirp": "0.5.1",
@@ -190,6 +191,7 @@
     "rimraf": "2.4.3",
     "rison-node": "1.0.0",
     "rjs-repack-loader": "1.0.6",
+    "rxjs": "5.4.3",
     "script-loader": "0.6.1",
     "semver": "5.1.0",
     "style-loader": "0.12.3",

src/optimize/base_optimizer.js

@@ -11,6 +11,8 @@ import { defaults, transform } from 'lodash';
 
 import { fromRoot } from '../utils';
 import pkg from '../../package.json';
+
+import { PUBLIC_PATH_PLACEHOLDER } from './public_path_placeholder';
 import { setLoaderQueryParam, makeLoaderString } from './loaders';
 
 const babelExclude = [/[\/\\](webpackShims|node_modules|bower_components)[\/\\]/];
@@ -18,7 +20,6 @@ const babelExclude = [/[\/\\](webpackShims|node_modules|bower_components)[\/\\]/
 export default class BaseOptimizer {
   constructor(opts) {
     this.env = opts.env;
-    this.urlBasePath = opts.urlBasePath;
     this.bundles = opts.bundles;
     this.profile = opts.profile || false;
 
@@ -100,7 +101,7 @@ export default class BaseOptimizer {
         path: this.env.workingDir,
         filename: '[name].bundle.js',
         sourceMapFilename: '[file].map',
-        publicPath: `${this.urlBasePath || ''}/bundles/`,
+        publicPath: PUBLIC_PATH_PLACEHOLDER,
         devtoolModuleFilenameTemplate: '[absolute-resource-path]'
       },
 

src/optimize/bundles_route/__tests__/bundles_route.js

@@ -0,0 +1,321 @@
+import { resolve } from 'path';
+import { readFileSync } from 'fs';
+import crypto from 'crypto';
+
+import Chance from 'chance';
+import expect from 'expect.js';
+import Hapi from 'hapi';
+import Inert from 'inert';
+import sinon from 'sinon';
+
+import { createBundlesRoute } from '../bundles_route';
+import { PUBLIC_PATH_PLACEHOLDER } from '../../public_path_placeholder';
+
+const chance = new Chance();
+const outputFixture = resolve(__dirname, './fixtures/output');
+
+function replaceAll(source, replace, replaceWith) {
+  return source.split(replace).join(replaceWith);
+}
+
+describe('optimizer/bundle route', () => {
+  const sandbox = sinon.sandbox.create();
+
+  function createServer(options = {}) {
+    const {
+      bundlesPath = outputFixture,
+      basePublicPath = ''
+    } = options;
+
+    const server = new Hapi.Server();
+    server.connection({ port: 0 });
+    server.register([Inert]);
+
+    server.route(createBundlesRoute({
+      bundlesPath,
+      basePublicPath,
+    }));
+
+    return server;
+  }
+
+  afterEach(() => sandbox.restore());
+
+  describe('validation', () => {
+    it('validates that bundlesPath is an absolute path', () => {
+      expect(() => {
+        createBundlesRoute({
+          bundlesPath: null,
+          basePublicPath: ''
+        });
+      }).to.throwError(/absolute path/);
+      expect(() => {
+        createBundlesRoute({
+          bundlesPath: './relative',
+          basePublicPath: ''
+        });
+      }).to.throwError(/absolute path/);
+      expect(() => {
+        createBundlesRoute({
+          bundlesPath: 1234,
+          basePublicPath: ''
+        });
+      }).to.throwError(/absolute path/);
+      expect(() => {
+        createBundlesRoute({
+          bundlesPath: '/absolute/path',
+          basePublicPath: ''
+        });
+      }).to.not.throwError();
+    });
+    it('validates that basePublicPath is valid', () => {
+      expect(() => {
+        createBundlesRoute({
+          bundlesPath: '/bundles',
+          basePublicPath: 123
+        });
+      }).to.throwError(/string/);
+      expect(() => {
+        createBundlesRoute({
+          bundlesPath: '/bundles',
+          basePublicPath: {}
+        });
+      }).to.throwError(/string/);
+      expect(() => {
+        createBundlesRoute({
+          bundlesPath: '/bundles',
+          basePublicPath: '/a/'
+        });
+      }).to.throwError(/start and not end with a \//);
+      expect(() => {
+        createBundlesRoute({
+          bundlesPath: '/bundles',
+          basePublicPath: 'a/'
+        });
+      }).to.throwError(/start and not end with a \//);
+      expect(() => {
+        createBundlesRoute({
+          bundlesPath: '/bundles',
+          basePublicPath: '/a'
+        });
+      }).to.not.throwError();
+      expect(() => {
+        createBundlesRoute({
+          bundlesPath: '/bundles',
+          basePublicPath: ''
+        });
+      }).to.not.throwError();
+    });
+  });
+
+  describe('image', () => {
+    it('responds with exact file data', async () => {
+      const server = createServer();
+      const response = await server.inject({
+        url: '/bundles/image.png'
+      });
+
+      expect(response.statusCode).to.be(200);
+      const image = readFileSync(resolve(outputFixture, 'image.png'));
+      expect(response.headers).to.have.property('content-length', image.length);
+      expect(response.headers).to.have.property('content-type', 'image/png');
+      expect(image).to.eql(response.rawPayload);
+    });
+  });
+
+  describe('js file without placeholder', () => {
+    it('responds with no content-length and exact file data', async () => {
+      const server = createServer();
+      const response = await server.inject({
+        url: '/bundles/no_placeholder.js'
+      });
+
+      expect(response.statusCode).to.be(200);
+      expect(response.headers).to.not.have.property('content-length');
+      expect(response.headers).to.have.property('content-type', 'application/javascript; charset=utf-8');
+      expect(readFileSync(resolve(outputFixture, 'no_placeholder.js')))
+        .to.eql(response.rawPayload);
+    });
+  });
+
+  describe('js file with placeholder', () => {
+    it('responds with no content-length and modified file data', async () => {
+      const basePublicPath = `/${chance.word()}`;
+      const server = createServer({ basePublicPath });
+
+      const response = await server.inject({
+        url: '/bundles/with_placeholder.js'
+      });
+
+      expect(response.statusCode).to.be(200);
+      const source = readFileSync(resolve(outputFixture, 'with_placeholder.js'), 'utf8');
+      expect(response.headers).to.not.have.property('content-length');
+      expect(response.headers).to.have.property('content-type', 'application/javascript; charset=utf-8');
+      expect(response.result.indexOf(source)).to.be(-1);
+      expect(response.result).to.be(replaceAll(
+        source,
+        PUBLIC_PATH_PLACEHOLDER,
+        `${basePublicPath}/bundles/`
+      ));
+    });
+  });
+
+  describe('css file without placeholder', () => {
+    it('responds with no content-length and exact file data', async () => {
+      const server = createServer();
+      const response = await server.inject({
+        url: '/bundles/no_placeholder.css'
+      });
+
+      expect(response.statusCode).to.be(200);
+      expect(response.headers).to.not.have.property('content-length');
+      expect(response.headers).to.have.property('content-type', 'text/css; charset=utf-8');
+      expect(readFileSync(resolve(outputFixture, 'no_placeholder.css')))
+        .to.eql(response.rawPayload);
+    });
+  });
+
+  describe('css file with placeholder', () => {
+    it('responds with no content-length and modified file data', async () => {
+      const basePublicPath = `/${chance.word()}`;
+      const server = createServer({ basePublicPath });
+
+      const response = await server.inject({
+        url: '/bundles/with_placeholder.css'
+      });
+
+      expect(response.statusCode).to.be(200);
+      const source = readFileSync(resolve(outputFixture, 'with_placeholder.css'), 'utf8');
+      expect(response.headers).to.not.have.property('content-length');
+      expect(response.headers).to.have.property('content-type', 'text/css; charset=utf-8');
+      expect(response.result.indexOf(source)).to.be(-1);
+      expect(response.result).to.be(replaceAll(
+        source,
+        PUBLIC_PATH_PLACEHOLDER,
+        `${basePublicPath}/bundles/`
+      ));
+    });
+  });
+
+  describe('js file outside bundlesPath', () => {
+    it('responds with a 403', async () => {
+      const server = createServer();
+
+      const response = await server.inject({
+        url: '/bundles/../outside_output.js'
+      });
+
+      expect(response.statusCode).to.be(403);
+      expect(response.result).to.eql({
+        error: 'Forbidden',
+        message: 'Forbidden',
+        statusCode: 403
+      });
+    });
+  });
+
+  describe('missing js file', () => {
+    it('responds with 404', async () => {
+      const server = createServer();
+
+      const response = await server.inject({
+        url: '/bundles/non_existant.js'
+      });
+
+      expect(response.statusCode).to.be(404);
+      expect(response.result).to.eql({
+        error: 'Not Found',
+        message: 'Not Found',
+        statusCode: 404
+      });
+    });
+  });
+
+  describe('missing bundlesPath', () => {
+    it('responds with 404', async () => {
+      const server = createServer({
+        bundlesPath: resolve(__dirname, 'fixtures/not_really_output')
+      });
+
+      const response = await server.inject({
+        url: '/bundles/with_placeholder.js'
+      });
+
+      expect(response.statusCode).to.be(404);
+      expect(response.result).to.eql({
+        error: 'Not Found',
+        message: 'Not Found',
+        statusCode: 404
+      });
+    });
+  });
+
+  describe('etag', () => {
+    it('only calculates hash of file on first request', async () => {
+      const createHash = sandbox.spy(crypto, 'createHash');
+
+      const server = createServer();
+
+      sinon.assert.notCalled(createHash);
+      const resp1 = await server.inject({
+        url: '/bundles/no_placeholder.js'
+      });
+
+      sinon.assert.calledOnce(createHash);
+      createHash.reset();
+      expect(resp1.statusCode).to.be(200);
+
+      const resp2 = await server.inject({
+        url: '/bundles/no_placeholder.js'
+      });
+
+      sinon.assert.notCalled(createHash);
+      expect(resp2.statusCode).to.be(200);
+    });
+
+    it('is unique per basePublicPath although content is the same', async () => {
+      const basePublicPath1 = `/${chance.word()}`;
+      const basePublicPath2 = `/${chance.word()}`;
+
+      const [resp1, resp2] = await Promise.all([
+        createServer({ basePublicPath: basePublicPath1 }).inject({
+          url: '/bundles/no_placeholder.js'
+        }),
+        createServer({ basePublicPath: basePublicPath2 }).inject({
+          url: '/bundles/no_placeholder.js'
+        }),
+      ]);
+
+      expect(resp1.statusCode).to.be(200);
+      expect(resp2.statusCode).to.be(200);
+
+      expect(resp1.rawPayload).to.eql(resp2.rawPayload);
+
+      expect(resp1.headers.etag).to.be.a('string');
+      expect(resp2.headers.etag).to.be.a('string');
+      expect(resp1.headers.etag).to.not.eql(resp2.headers.etag);
+    });
+  });
+
+  describe('cache control', () => {
+    it('responds with 304 when etag and last modified are sent back', async () => {
+      const server = createServer();
+      const resp = await server.inject({
+        url: '/bundles/with_placeholder.js'
+      });
+
+      expect(resp.statusCode).to.be(200);
+
+      const resp2 = await server.inject({
+        url: '/bundles/with_placeholder.js',
+        headers: {
+          'if-modified-since': resp.headers['last-modified'],
+          'if-none-match': resp.headers.etag
+        }
+      });
+
+      expect(resp2.statusCode).to.be(304);
+      expect(resp2.result).to.have.length(0);
+    });
+  });
+});

src/optimize/bundles_route/__tests__/fixtures/output/no_placeholder.css

@@ -0,0 +1,3 @@
+body {
+  background-color: goldenrod;
+}

src/optimize/bundles_route/__tests__/fixtures/output/no_placeholder.js

@@ -0,0 +1 @@
+console.log('chunk2');

src/optimize/bundles_route/__tests__/fixtures/output/with_placeholder.css

@@ -0,0 +1,3 @@
+body {
+  background-image: url(__REPLACE_WITH_PUBLIC_PATH__/image.png);
+}

src/optimize/bundles_route/__tests__/fixtures/output/with_placeholder.js

@@ -0,0 +1 @@
+console.log('__REPLACE_WITH_PUBLIC_PATH__');

src/optimize/bundles_route/__tests__/fixtures/outside_output.js

@@ -0,0 +1 @@
+console.log('outside output');

src/optimize/bundles_route/bundles_route.js

@@ -0,0 +1,66 @@
+import { isAbsolute, extname } from 'path';
+
+import LruCache from 'lru-cache';
+
+import { createDynamicAssetResponse } from './dynamic_asset_response';
+
+/**
+ *  Creates a route that serves files from `bundlesPath`. If the
+ *  file is js or css then it is searched for instances of
+ *  PUBLIC_PATH_PLACEHOLDER and replaces them with `publicPath`.
+ *  @param {Object} options
+ *  @property {string} options.bundlesPath
+ *  @property {string} options.basePublicPath
+ *  @return {Hapi.RouteConfig}
+ */
+export function createBundlesRoute({ bundlesPath, basePublicPath }) {
+
+  // rather than calculate the fileHash on every request, we
+  // provide a cache object to `createDynamicAssetResponse()` that
+  // will store the 100 most recently used hashes.
+  const fileHashCache = new LruCache(100);
+
+  if (typeof bundlesPath !== 'string' || !isAbsolute(bundlesPath)) {
+    throw new TypeError('bundlesPath must be an absolute path to the directory containing the bundles');
+  }
+
+  if (typeof basePublicPath !== 'string') {
+    throw new TypeError('basePublicPath must be a string');
+  }
+
+  if (!basePublicPath.match(/(^$|^\/.*[^\/]$)/)) {
+    throw new TypeError('basePublicPath must be empty OR start and not end with a /');
+  }
+
+  return {
+    method: 'GET',
+    path: '/bundles/{path*}',
+    config: {
+      auth: false,
+      ext: {
+        onPreHandler: {
+          method(request, reply) {
+            const ext = extname(request.params.path);
+            if (ext !== '.js' && ext !== '.css') {
+              return reply.continue();
+            }
+
+            reply(createDynamicAssetResponse({
+              request,
+              bundlesPath,
+              fileHashCache,
+              publicPath: `${basePublicPath}/bundles/`
+            }));
+          }
+        }
+      },
+    },
+    handler: {
+      directory: {
+        path: bundlesPath,
+        listing: false,
+        lookupCompressed: true,
+      }
+    }
+  };
+}

src/optimize/bundles_route/dynamic_asset_response.js

@@ -0,0 +1,90 @@
+import { resolve } from 'path';
+import { open, fstat, createReadStream, close } from 'fs';
+
+import Boom from 'boom';
+import { fromNode as fcb } from 'bluebird';
+
+import { getFileHash } from './file_hash';
+import { replacePlaceholder } from '../public_path_placeholder';
+
+/**
+ *  Create a Hapi response for the requested path. This is designed
+ *  to replicate a subset of the features provided by Hapi's Inert
+ *  plugin including:
+ *   - ensure path is not traversing out of the bundle directory
+ *   - manage use file descriptors for file access to efficiently
+ *     interact with the file multiple times in each request
+ *   - generate and cache etag for the file
+ *   - write correct headers to response for client-side caching
+ *     and invalidation
+ *   - stream file to response
+ *
+ *  It differs from Inert in some important ways:
+ *   - the PUBLIC_PATH_PLACEHOLDER is replaced with the correct
+ *     public path as the response is streamed
+ *   - cached hash/etag is based on the file on disk, but modified
+ *     by the public path so that individual public paths have
+ *     different etags, but can share a cache
+ *
+ *  @param {Object} options
+ *  @property {Hapi.Request} options.request
+ *  @property {string} options.bundlesPath
+ *  @property {string} options.publicPath
+ *  @property {LruCache} options.fileHashCache
+ */
+export async function createDynamicAssetResponse(options) {
+  const {
+    request,
+    bundlesPath,
+    publicPath,
+    fileHashCache,
+  } = options;
+
+  let fd;
+  try {
+    const path = resolve(bundlesPath, request.params.path);
+
+    // prevent path traversal, only process paths that resolve within bundlesPath
+    if (!path.startsWith(bundlesPath)) {
+      return Boom.forbidden(null, 'EACCES');
+    }
+
+    // we use and manage a file descriptor mostly because
+    // that's what Inert does, and since we are accessing
+    // the file 2 or 3 times per request it seems logical
+    fd = await fcb(cb => open(path, 'r', cb));
+
+    const stat = await fcb(cb => fstat(fd, cb));
+    const hash = await getFileHash(fileHashCache, path, stat, fd);
+
+    const read = createReadStream(null, {
+      fd,
+      start: 0,
+      autoClose: true
+    });
+    fd = null; // read stream is now responsible for fd
+
+    const response = request.generateResponse(replacePlaceholder(read, publicPath));
+    response.code(200);
+    response.etag(`${hash}-${publicPath}`);
+    response.header('last-modified', stat.mtime.toUTCString());
+    response.type(request.server.mime.path(path).type);
+    return response;
+
+  } catch (error) {
+    if (fd) {
+      try {
+        await fcb(cb => close(fd, cb));
+      } catch (error) {
+        // ignore errors from close, we already have one to report
+        // and it's very likely they are the same
+      }
+    }
+
+    if (error.code === 'ENOENT') {
+      return Boom.notFound();
+    }
+
+    return Boom.boomify(error);
+  }
+}

src/optimize/bundles_route/file_hash.js

@@ -0,0 +1,45 @@
+import { createHash } from 'crypto';
+import { createReadStream } from 'fs';
+
+import Rx from 'rxjs/Rx';
+
+const $fromEvent = Rx.Observable.fromEvent;
+const $throw = Rx.Observable.throw;
+
+/**
+ *  Get the hash of a file via a file descriptor
+ *  @param  {LruCache} cache
+ *  @param  {string} path
+ *  @param  {Fs.Stat} stat
+ *  @param  {Fs.FileDescriptor} fd
+ *  @return {Promise<string>}
+ */
+export async function getFileHash(cache, path, stat, fd) {
+  const key = `${path}:${stat.ino}:${stat.size}:${stat.mtime.getTime()}`;
+
+  const cached = cache.get(key);
+  if (cached) {
+    return await cached;
+  }
+
+  const hash = createHash('sha1');
+  const read = createReadStream(null, {
+    fd,
+    start: 0,
+    autoClose: false
+  });
+
+  const promise = $fromEvent(read, 'data')
+    .merge($fromEvent(read, 'error').mergeMap($throw))
+    .takeUntil($fromEvent(read, 'end'))
+    .forEach(chunk => hash.update(chunk))
+    .then(() => hash.digest('hex'))
+    .catch((error) => {
+      // don't cache failed attempts
+      cache.del(key);
+      throw error;
+    });
+
+  cache.set(key, promise);
+  return await promise;
+}

src/optimize/bundles_route/index.js

@@ -0,0 +1 @@
+export { createBundlesRoute } from './bundles_route';

src/optimize/index.js

@@ -1,4 +1,5 @@
 import FsOptimizer from './fs_optimizer';
+import { createBundlesRoute } from './bundles_route';
 
 export default async (kbnServer, server, config) => {
   if (!config.get('optimize.enabled')) return;
@@ -17,7 +18,11 @@ export default async (kbnServer, server, config) => {
   }
 
   const bundles = kbnServer.bundles;
-  server.exposeStaticDir('/bundles/{path*}', bundles.env.workingDir);
+  server.route(createBundlesRoute({
+    bundlesPath: bundles.env.workingDir,
+    basePublicPath: config.get('server.basePath')
+  }));
+
   await bundles.writeEntryFiles();
 
   // in prod, only bundle when someing is missing or invalid
@@ -37,7 +42,6 @@ export default async (kbnServer, server, config) => {
     env: bundles.env,
     bundles: bundles,
     profile: config.get('optimize.profile'),
-    urlBasePath: config.get('server.basePath'),
     sourceMaps: config.get('optimize.sourceMaps'),
     unsafeCache: config.get('optimize.unsafeCache'),
   });

src/optimize/lazy/lazy_optimizer.js

@@ -3,6 +3,8 @@ import WeirdControlFlow from './weird_control_flow';
 import { once } from 'lodash';
 import { join } from 'path';
 
+import { createBundlesRoute } from '../bundles_route';
+
 export default class LazyOptimizer extends BaseOptimizer {
   constructor(opts) {
     super(opts);
@@ -67,20 +69,22 @@ export default class LazyOptimizer extends BaseOptimizer {
     return join(this.compiler.outputPath, relativePath);
   }
 
-  bindToServer(server) {
-    server.route({
-      path: '/bundles/{asset*}',
-      method: 'GET',
-      handler: async (request, reply) => {
-        try {
-          const path = await this.getPath(request.params.asset);
-          return reply.file(path);
-        } catch (error) {
-          console.log(error.stack);
-          return reply(error);
-        }
-      }
+  bindToServer(server, basePath) {
+
+    // calling `build.get()` resolves when the build is
+    // "stable" (the compiler is not running) so this pauses
+    // all requests received while the compiler is running
+    // and lets the continue once it is done.
+    server.ext('onRequest', (request, reply) => {
+      this.build.get()
+        .then(() => reply.continue())
+        .catch(reply);
     });
+
+    server.route(createBundlesRoute({
+      bundlesPath: this.compiler.outputPath,
+      basePublicPath: basePath
+    }));
   }
 
   logRunStart() {

src/optimize/lazy/lazy_server.js

@@ -4,7 +4,8 @@ import { fromNode } from 'bluebird';
 import registerHapiPlugins from '../../server/http/register_hapi_plugins';
 
 export default class LazyServer {
-  constructor(host, port, optimizer) {
+  constructor(host, port, basePath, optimizer) {
+    this.basePath = basePath;
     this.optimizer = optimizer;
     this.server = new Server();
 
@@ -18,7 +19,7 @@ export default class LazyServer {
 
   async init() {
     await this.optimizer.init();
-    this.optimizer.bindToServer(this.server);
+    this.optimizer.bindToServer(this.server, this.basePath);
     await fromNode(cb => this.server.start(cb));
   }
 }

src/optimize/lazy/optmzr_role.js

@@ -5,6 +5,7 @@ export default async (kbnServer, kibanaHapiServer, config) => {
   const server = new LazyServer(
     config.get('optimize.lazyHost'),
     config.get('optimize.lazyPort'),
+    config.get('server.basePath'),
     new LazyOptimizer({
       log: (tags, data) => kibanaHapiServer.log(tags, data),
       env: kbnServer.bundles.env,
@@ -12,7 +13,6 @@ export default async (kbnServer, kibanaHapiServer, config) => {
       profile: config.get('optimize.profile'),
       sourceMaps: config.get('optimize.sourceMaps'),
       prebuild: config.get('optimize.lazyPrebuild'),
-      urlBasePath: config.get('server.basePath'),
       unsafeCache: config.get('optimize.unsafeCache'),
     })
   );

src/optimize/public_path_placeholder.js

@@ -0,0 +1,29 @@
+import { createReplaceStream } from '../utils';
+
+import Rx from 'rxjs/Rx';
+
+const $fromEvent = Rx.Observable.fromEvent;
+
+export const PUBLIC_PATH_PLACEHOLDER = '__REPLACE_WITH_PUBLIC_PATH__';
+
+export function replacePlaceholder(read, replacement) {
+  const replace = createReplaceStream(PUBLIC_PATH_PLACEHOLDER, replacement);
+
+  // handle errors on the read stream by proxying them
+  // to the replace stream so that the consumer can
+  // choose what to do with them.
+  $fromEvent(read, 'error')
+    .take(1)
+    .takeUntil($fromEvent(read, 'end'))
+    .forEach(error => {
+      replace.emit('error', error);
+      replace.end();
+    });
+
+  replace.close = () => {
+    read.unpipe();
+    read.close();
+  };
+
+  return read.pipe(replace);
+}

src/ui/index.js

@@ -27,7 +27,6 @@ export default async (kbnServer, server, config) => {
 
   const bundlerEnv = new UiBundlerEnv(config.get('optimize.bundleDir'));
   bundlerEnv.addContext('env', config.get('env.name'));
-  bundlerEnv.addContext('urlBasePath', config.get('server.basePath'));
   bundlerEnv.addContext('sourceMaps', config.get('optimize.sourceMaps'));
   bundlerEnv.addContext('kbnVersion', config.get('pkg.version'));
   bundlerEnv.addContext('buildNum', config.get('pkg.buildNum'));

src/utils/index.js

@@ -25,6 +25,7 @@ export {
   createReduceStream,
   createSplitStream,
   createMapStream,
+  createReplaceStream,
 } from './streams';
 
 export {

src/utils/streams/__tests__/replace_stream.js

@@ -0,0 +1,104 @@
+import expect from 'expect.js';
+
+import {
+  createReplaceStream,
+  createConcatStream,
+  createPromiseFromStreams,
+  createListStream,
+  createMapStream,
+} from '../';
+
+async function concatToString(streams) {
+  return await createPromiseFromStreams([
+    ...streams,
+    createMapStream(buff => buff.toString('utf8')),
+    createConcatStream('')
+  ]);
+}
+
+describe('replaceStream', () => {
+  it('produces buffers when it receives buffers', async () => {
+    const chunks = await createPromiseFromStreams([
+      createListStream([Buffer.from('foo'), Buffer.from('bar')]),
+      createReplaceStream('o', '0'),
+      createConcatStream([])
+    ]);
+
+    chunks.forEach(chunk => {
+      expect(chunk).to.be.a(Buffer);
+    });
+  });
+
+  it('produces buffers when it receives strings', async () => {
+    const chunks = await createPromiseFromStreams([
+      createListStream(['foo', 'bar']),
+      createReplaceStream('o', '0'),
+      createConcatStream([])
+    ]);
+
+    chunks.forEach(chunk => {
+      expect(chunk).to.be.a(Buffer);
+    });
+  });
+
+  it('expects toReplace to be a string', () => {
+    expect(() => createReplaceStream(Buffer.from('foo')))
+      .to.throwError(error => {
+        expect(error.message).to.match(/be a string/);
+      });
+  });
+
+  it('replaces multiple single-char instances in a single chunk', async () => {
+    expect(await concatToString([
+      createListStream([Buffer.from('f00 bar')]),
+      createReplaceStream('0', 'o'),
+    ])).to.be('foo bar');
+  });
+
+  it('replaces multiple single-char instances in multiple chunks', async () => {
+    expect(await concatToString([
+      createListStream([Buffer.from('f0'), Buffer.from('0 bar')]),
+      createReplaceStream('0', 'o'),
+    ])).to.be('foo bar');
+  });
+
+  it('replaces single multi-char instances in single chunks', async () => {
+    expect(await concatToString([
+      createListStream([Buffer.from('f0'), Buffer.from('0 bar')]),
+      createReplaceStream('0', 'o'),
+    ])).to.be('foo bar');
+  });
+
+  it('replaces multiple multi-char instances in single chunks', async () => {
+    expect(await concatToString([
+      createListStream([Buffer.from('foo ba'), Buffer.from('r b'), Buffer.from('az bar')]),
+      createReplaceStream('bar', '*'),
+    ])).to.be('foo * baz *');
+  });
+
+  it('replaces multi-char instance that stretches multiple chunks', async () => {
+    expect(await concatToString([
+      createListStream([
+        Buffer.from('foo supe'),
+        Buffer.from('rcalifra'),
+        Buffer.from('gilistic'),
+        Buffer.from('expialid'),
+        Buffer.from('ocious bar'),
+      ]),
+      createReplaceStream('supercalifragilisticexpialidocious', '*'),
+    ])).to.be('foo * bar');
+  });
+
+  it('ignores missing multi-char instance', async () => {
+    expect(await concatToString([
+      createListStream([
+        Buffer.from('foo supe'),
+        Buffer.from('rcalifra'),
+        Buffer.from('gili stic'),
+        Buffer.from('expialid'),
+        Buffer.from('ocious bar'),
+      ]),
+      createReplaceStream('supercalifragilisticexpialidocious', '*'),
+    ])).to.be('foo supercalifragili sticexpialidocious bar');
+  });
+});

src/utils/streams/index.js

@@ -6,3 +6,4 @@ export { createJsonParseStream, createJsonStringifyStream } from './json_streams
 export { createPromiseFromStreams } from './promise_from_streams';
 export { createConcatStream } from './concat_stream';
 export { createMapStream } from './map_stream';
+export { createReplaceStream } from './replace_stream';

src/utils/streams/replace_stream.js

@@ -0,0 +1,66 @@
+import { Transform } from 'stream';
+
+export function createReplaceStream(toReplace, replacement) {
+  if (typeof toReplace !== 'string') {
+    throw new TypeError('toReplace must be a string');
+  }
+
+  let buffer = Buffer.alloc(0);
+  return new Transform({
+    objectMode: false,
+    async transform(value, enc, done) {
+      try {
+        buffer = Buffer.concat([buffer, value], buffer.length + value.length);
+
+        while (true) {
+          // try to find the next instance of `toReplace` in buffer
+          const index = buffer.indexOf(toReplace);
+
+          // if there is no next instance, break
+          if (index === -1) {
+            break;
+          }
+
+          // flush everything to the left of the next instance
+          // of `toReplace`
+          this.push(buffer.slice(0, index));
+
+          // then flush an instance of `replacement`
+          this.push(replacement);
+
+          // and finally update the buffer to include everything
+          // to the right of `toReplace`, dropping to replace from the buffer
+          buffer = buffer.slice(index + toReplace.length);
+        }
+
+        // until now we have only flushed data that is to the left
+        // of a discovered instance of `toReplace`. If `toReplace` is
+        // never found this would lead to us buffering the entire stream.
+        //
+        // Instead, we only keep enough buffer to complete a potentially
+        // patial instance of `toReplace`
+        if (buffer.length > toReplace.length) {
+          // the entire buffer except the last `toReplace.length` bytes
+          // so that if all but one byte from `toReplace` is in the buffer,
+          // and the next chunk delivers the necessary byte, the buffer will then
+          // contain a complete `toReplace` token.
+          this.push(buffer.slice(0, buffer.length - toReplace.length));
+          buffer = buffer.slice(-toReplace.length);
+        }
+
+        done();
+      } catch (err) {
+        done(err);
+      }
+    },
+
+    flush(callback) {
+      if (buffer.length) {
+        this.push(buffer);
+      }
+
+      buffer = null;
+      callback();
+    }
+  });
+}