add a flag to ssm variables to resolve as string instead of object

docs/providers/aws/guide/variables.md

@@ -354,6 +354,26 @@ custom:
       - false
 ```
 
+If the variable value is valid JSON but you expect the plaintext form, then you can use the extended syntax `~decryptAsPlaintext`.
+
+```
+custom:
+  supersecret: ${ssm:/aws/reference/secretsmanager/secret_ID_in_Secrets_Manager~decryptAsPlaintext}
+```
+
+variables will be resolved like
+
+```yml
+service: new-service
+provider: aws
+functions:
+  hello:
+    name: hello
+    handler: handler.hello
+custom:
+  supersecret: '{"num": 1,"str": "secret","arr": [true, false]}' # a plain text string
+```
+
 ## Reference Variables in Other Files
 
 You can reference variables in other YAML or JSON files. To reference variables in other YAML files use the `${file(./myFile.yml):someProperty}` syntax in your `serverless.yml` configuration file. To reference variables in other JSON files use the `${file(./myFile.json):someProperty}` syntax. It is important that the file you are referencing has the correct suffix, or file extension, for its file type (`.yml` for YAML or `.json` for JSON) in order for it to be interpreted correctly. Here's an example:

lib/classes/Variables.js

@@ -54,7 +54,7 @@ class Variables {
     this.stringRefSyntax = RegExp(/(?:('|").*?\1)/g);
     this.cfRefSyntax = RegExp(/^(?:\${)?cf(\.[a-zA-Z0-9-]+)?:/g);
     this.s3RefSyntax = RegExp(/^(?:\${)?s3:(.+?)\/(.+)$/);
-    this.ssmRefSyntax = RegExp(/^(?:\${)?ssm:([a-zA-Z0-9_.\-/]+)[~]?(true|false|split)?/);
+    this.ssmRefSyntax = RegExp(/^(?:\${)?ssm:([a-zA-Z0-9_.\-/]+)[~]?(true|false|split|decryptAsPlaintext)?/);
   }
 
   loadVariableSyntax() {
@@ -761,8 +761,10 @@ class Variables {
   getValueFromSsm(variableString) {
     const groups = variableString.match(this.ssmRefSyntax);
     const param = groups[1];
-    const decrypt = groups[2] === 'true';
+    const decrypt = groups[2] === 'true' || groups[2] === 'decryptAsPlaintext';
     const split = groups[2] === 'split';
+    const decryptAsPlaintext = groups[2] === 'decryptAsPlaintext';
+
     return this.serverless
       .getProvider('aws')
       .request(
@@ -778,8 +780,12 @@ class Variables {
         const plainText = response.Parameter.Value;
         const type = response.Parameter.Type;
         // Only if Secrets Manager. Parameter Store does not support JSON.
+        // if decryptAsPlaintext skip json parsing
         // We cannot parse StringList types, so don't try
-        if (type !== 'StringList' && param.startsWith('/aws/reference/secretsmanager')) {
+        if (type !== 'StringList'
+          && param.startsWith('/aws/reference/secretsmanager')
+          && ! decryptAsPlaintext
+        ) {
           try {
             const json = JSON.parse(plainText);
             return BbPromise.resolve(json);

lib/classes/Variables.test.js

@@ -2290,6 +2290,24 @@ module.exports = {
           .then()
           .finally(() => ssmStub.restore());
       });
+      it('should get value as text if extended syntax matches ~decryptAsPlaintext', () => {
+        const secretParam = '/aws/reference/secretsmanager/foo-bar';
+        const jsonLikeText = '{"str":"abc","num":123}';
+
+        const awsResponse = {
+          Parameter: {
+            Value: jsonLikeText,
+          },
+        };
+        const ssmStub = sinon
+          .stub(awsProvider, 'request')
+          .callsFake(() => BbPromise.resolve(awsResponse));
+        return serverless.variables
+          .getValueFromSsm(`ssm:${secretParam}~decryptAsPlaintext`)
+          .should.become(jsonLikeText)
+          .then()
+          .finally(() => ssmStub.restore());
+      });
       it('should get value as text if returned value is NOT json-like', () => {
         const secretParam = '/aws/reference/secretsmanager/foo-bar';
         const plainText = 'I am plain text';