feat(images): Support rebuild on other file changes

README.md

@@ -126,6 +126,20 @@ The above binci.yml will, in the event that Binci needs to build a new container
 addition to the two listed tags. When Binci is done running, the command `docker push myorg/myrepo:latest` would work
 as expected.
 
+## Rebuilding
+
+When a `dockerfile` is used, Binci will automatically rebuild it if the `dockerfile` changes. However, it may be necessary to trigger a rebuild when other files change that may impact the build. To list these files, specify `rebuildOnChange`:
+
+```yaml
+dockerfile: ./Dockerfile
+rebuildOnChange:
+  - ./Gemfile
+  - ./Gemfile.lock
+  - ./Rakefile
+```
+
+When any of those files are changed, created, or deleted, the next Binci run will rebuild the image from the dockerfile before executing the task. 
+
 ## Services
 
 Services add links into the primary container, exposing the services for utilization. For the most part, services utilize the same format for definition as the primary container.

src/images.js

@@ -6,6 +6,7 @@ const cp = require('child_process')
 const fs = require('fs')
 const path = require('path')
 const crypto = require('crypto')
+const Promise = require('bluebird')
 
 const images = {
   /**
@@ -72,19 +73,29 @@ const images = {
     }))
   }),
   /**
-   * Gets the SHA-1 checksum, truncated to 12 hexadecimal digits, of the contents of the file at path.
-   * @param {string} path The path of the file for the checksum
-   * @returns {Promise.<string|null>} The sha1 as a hex string, or null if the file does not exist.
+   * Gets the SHA-1 checksum, truncated to 12 hexadecimal digits, of the combined contents of the
+   * files at the paths provided.
+   * @param {Array<string>} paths An array of paths for the files to include in the checksum
+   * @returns {Promise.<string>} The sha1 as a hex string.
    */
-  getHash: (path) => new Promise((resolve, reject) => {
-    const shasum = crypto.createHash('sha1')
+  getHash: (paths) => {
+    return Promise.reduce(paths, images.updateHash, crypto.createHash('sha1'))
+      .then(hash => hash ? hash.digest('hex').substr(0, 12) : null)
+  },
+  /**
+   * Updates an existing hash object with the contents of a file at a given path.
+   * @param {Hash} hash A crypto hash object to be updated
+   * @param {string} path The path to a file which will be calculated into the hash
+   * @returns {Promise<Hash>} resolves with the updated Hash object
+   */
+  updateHash: (hash, path) => new Promise((resolve, reject) => {
     const stream = fs.createReadStream(path)
     stream.on('error', err => {
       if (err.code && err.code === 'ENOENT') resolve(null)
       else reject(err)
     })
-    stream.on('data', data => shasum.update(data))
-    stream.on('close', () => resolve(shasum.digest('hex').substr(0, 12)))
+    stream.on('data', data => hash.update(data))
+    stream.on('close', () => resolve(hash))
   }),
   /**
    * Gets a valid image name:tag that can be used to run a new docker container.
@@ -94,13 +105,16 @@ const images = {
    * deleted (if one exists).
    * @param {String} [dockerfile="./Dockerfile"] The path to the dockerfile to be
    * used for building the new image or retrieving the existing one
+   * @param {Array<string>} [monitorPaths=[]] An optional array of file paths to monitor
+   * for changes, causing a rebuild of the docker container if any of them are updated
    * @param {Array<string>} [tags=[]] An optional array of tags with which to tag a new
    * image, if one needs to be built
    * @returns {Promise.<string>} the name:tag of the image to be used
    */
-  getImage: (dockerfile = './Dockerfile', tags = []) => {
+  getImage: (dockerfile = './Dockerfile', monitorPaths = [], tags = []) => {
+    monitorPaths.push(dockerfile)
     return Promise.all([
-      images.getHash(dockerfile),
+      images.getHash(monitorPaths),
       images.getBuiltImages()
     ]).then(([ hash, imgs ]) => {
       if (!hash) {

src/index.js

@@ -121,7 +121,7 @@ const instance = {
    */
   attachFrom: (cfg) => {
     if (!cfg.from) {
-      return images.getImage(cfg.dockerfile, cfg.tags || [])
+      return images.getImage(cfg.dockerfile, cfg.rebuildOnChange, cfg.tags)
         .then(imageId => {
           cfg.from = imageId
           return cfg

test/src/images.spec.js

@@ -29,12 +29,17 @@ describe('images', () => {
   })
   describe('getHash', () => {
     it('determines the SHA-1 hash of an existing file', () => {
-      return images.getHash(knownShaPath).then(hash => {
+      return images.getHash([knownShaPath]).then(hash => {
         expect(hash).to.equal(knownSha.substr(0, 12))
       })
     })
+    it('determines the SHA-1 hash of multiple files', () => {
+      return images.getHash([knownShaPath, knownShaPath]).then(hash => {
+        expect(hash).to.equal('cdb39cef22e6')
+      })
+    })
     it('returns null if the file does not exist', () => {
-      return images.getHash(knownShaPath + 'notfound').then(hash => {
+      return images.getHash([knownShaPath + 'notfound']).then(hash => {
         expect(hash).to.be.null()
       })
     })

test/src/index.spec.js

@@ -164,7 +164,7 @@ describe('index', () => {
       conf.tags = ['foo', 'bar']
       const stub = sandbox.stub(images, 'getImage', () => Promise.resolve('foo'))
       return instance.attachFrom(conf).then(() => {
-        expect(stub).to.be.calledWith(undefined, ['foo', 'bar'])
+        expect(stub).to.be.calledWith(undefined, undefined, ['foo', 'bar'])
       })
     })
   })