Resolve ${var} values in component-config.json

App variables can now be specified in component-config.json using
the ${var} format. The value of var is looked up using app.get().

This allows loopback explorer and other loopback components which
require app variables, to be loaded declaratively using
component-config.json.

lib/executor.js

@@ -316,12 +316,12 @@ function setupMiddleware(app, instructions) {
     }
     assert(typeof factory === 'function',
       'Middleware factory must be a function');
-    data.config = getUpdatedConfigObject(data.config, app);
+    data.config = getUpdatedConfigObject(app, data.config);
     app.middlewareFromConfig(factory, data.config);
   });
 }
 
-function getUpdatedConfigObject(config, app) {
+function getUpdatedConfigObject(app, config) {
 
   var DYNAMIC_CONFIG_PARAM = /\$\{(\w+)\}$/;
 
@@ -364,6 +364,7 @@ function setupComponents(app, instructions) {
   instructions.components.forEach(function(data) {
     debug('Configuring component %j', data.sourceFile);
     var configFn = require(data.sourceFile);
+    data.config = getUpdatedConfigObject(app, data.config);
     configFn(app, data.config);
   });
 }

test/executor.test.js

@@ -496,6 +496,77 @@ describe('executor', function() {
 
   });
 
+  describe('with component-config.json', function() {
+
+    it('should parse a simple config variable', function(done) {
+      boot.execute(app, simpleComponentConfig(
+        { path: '${restApiRoot}' }
+      ));
+
+      supertest(app).get('/component').end(function(err, res) {
+        if (err) return done(err);
+        expect(res.body.path).to.equal(app.get('restApiRoot'));
+        done();
+      });
+    });
+
+    it('should parse multiple config variables', function(done) {
+      boot.execute(app, simpleComponentConfig(
+        { path: '${restApiRoot}', env: '${env}' }
+      ));
+
+      supertest(app).get('/component').end(function(err, res) {
+        if (err) return done(err);
+        expect(res.body.path).to.equal(app.get('restApiRoot'));
+        expect(res.body.env).to.equal(app.get('env'));
+        done();
+      });
+    });
+
+    it('should parse config variables in an array', function(done) {
+      boot.execute(app, simpleComponentConfig(
+        { paths: ['${restApiRoot}'] }
+      ));
+
+      supertest(app).get('/component').end(function(err, res) {
+        if (err) return done(err);
+        expect(res.body.paths).to.eql(
+          [app.get('restApiRoot')]
+          );
+        done();
+      });
+    });
+
+    it('should parse config variables in an object', function(done) {
+      boot.execute(app, simpleComponentConfig(
+        { info: { path: '${restApiRoot}' } }
+      ));
+
+      supertest(app).get('/component').end(function(err, res) {
+        if (err) return done(err);
+        expect(res.body.info).to.eql({
+          path: app.get('restApiRoot')
+        });
+        done();
+      });
+    });
+
+    it('should parse config variables in a nested object', function(done) {
+      boot.execute(app, simpleComponentConfig(
+        { nested: { info: { path: '${restApiRoot}' } } }
+      ));
+
+      supertest(app).get('/component').end(function(err, res) {
+        if (err) return done(err);
+        expect(res.body.nested).to.eql({
+          info: { path: app.get('restApiRoot') }
+        });
+        done();
+      });
+    });
+
+  });
+
   it('calls function exported by boot/init.js', function() {
     var file = appdir.writeFileSync('boot/init.js',
       'module.exports = function(app) { app.fnCalled = true; };');
@@ -671,6 +742,17 @@ function simpleMiddlewareConfig(phase, params) {
   });
 }
 
+function simpleComponentConfig(config) {
+  return someInstructions({
+    components: [
+      {
+        sourceFile: path.join(__dirname, './fixtures/simple-component.js'),
+        config: config
+      }
+    ]
+  });
+}
+
 function assertValidDataSource(dataSource) {
   // has methods
   assert.isFunc(dataSource, 'createModel');

test/fixtures/simple-component.js

@@ -0,0 +1,7 @@
+module.exports = function(loopbackApp, params) {
+
+  loopbackApp.use('/component', function(req, res, next) {
+    res.send(params);
+  });
+
+};