Allow simple string images (#961)

* Add test case and fixes usage of image param when simple remote string is used
* Update documentation

Co-authored-by: Vicary A <[email protected]>

Author: gwdp

README.md

@@ -592,6 +592,15 @@ functions:
         - app.handler2
 ```
 
+If you want to use a remote docker image but still need the webpack process before doing so, you can specify it as indicated below:
+
+```yaml
+# serverless.yml
+functions:
+  myFunction1:
+    image: public.ecr.aws/lambda/nodejs:latest
+```
+
 ## Usage
 
 ### Automatic bundling

lib/utils.js

@@ -118,8 +118,9 @@ function getAllNodeFunctions() {
   return _.filter(functions, funcName => {
     const func = this.serverless.service.getFunction(funcName);
 
-    // if `uri` is provided, it means the image isn't built by Serverless so we shouldn't take care of it
-    if (func.image && func.image.uri) {
+    // if `uri` is provided or simple remote image path, it means the 
+    // image isn't built by Serverless so we shouldn't take care of it
+    if ((func.image && func.image.uri) || (func.image && typeof func.image == 'string')) {
       return false;
     }
 

lib/validate.js

@@ -25,6 +25,8 @@ module.exports = {
         return handlerProp;
       }
 
+      if (imageProp && typeof imageProp == 'string') return imageProp;
+
       if (!imageProp || !imageProp.command || imageProp.command.length < 1) {
         const docsLink = 'https://www.serverless.com/blog/container-support-for-lambda';
         throw new this.serverless.classes.Error(

tests/validate.test.js

@@ -795,6 +795,51 @@ describe('validate', () => {
         }).to.throw(/Either function.handler or function.image must be defined/);
       });
 
+      it('should not throw error if container image is a simple string', () => {
+        const testOutPath = 'test';
+        const testFunctionsConfig = {
+          func1: {
+            artifact: 'artifact-func1.zip',
+            events: [
+              {
+                http: {
+                  method: 'POST',
+                  path: 'func1path'
+                }
+              },
+              {
+                nonhttp: 'non-http'
+              }
+            ],
+            image: 'XXXX.dkr.ecr.ca-central-1.amazonaws.com/myproject/customNode:latest'
+          }
+        };
+
+        const testConfig = {
+          entry: 'test',
+          context: 'testcontext',
+          output: {
+            path: testOutPath
+          },
+          getFunction: func => {
+            return testFunctionsConfig[func];
+          }
+        };
+
+        _.set(module.serverless.service, 'custom.webpack.config', testConfig);
+        module.serverless.service.functions = testFunctionsConfig;
+        globSyncStub.callsFake(filename => [_.replace(filename, '*', 'js')]);
+        return expect(module.validate()).to.be.fulfilled.then(() => {
+          const lib = require('../lib/index');
+          const expectedLibEntries = {};
+
+          expect(lib.entries).to.deep.equal(expectedLibEntries);
+          expect(globSyncStub).to.have.callCount(0);
+          expect(serverless.cli.log).to.not.have.been.called;
+          return null;
+        });
+      });
+
       describe('google provider', () => {
         beforeEach(() => {
           _.set(module.serverless, 'service.provider.name', 'google');