feat: allow CloudFormation overrides

- We keep having to add new options to the config when someone needs to use an option in the CloudFormation template we haven't mapped yet
- This should future proof the plugin to allow users to just pass whatever they need through to override the generated template
- Eventually we could also deprecate and remove some of the other options that could just be overrides
- Fixes #213

Author: Sean Dawson

.gitignore

@@ -12,4 +12,8 @@ node_modules
 .history
 
 # tsc output
-dist
+dist
+
+#misc
+yarn-error.log
+*.tgz

README.md

@@ -15,8 +15,6 @@ boilerplate to add a Queue and a Dead Letter Queue between the Lambda and the
 SNS topic. This plugin allows you to define an sns subscriber with a `batchSize`
 and a `maxRetryCount` as simply as subscribing directly to the sns topic.
 
-![Plugin Architecture](./plant-uml-files/plugin-arch.png?raw=true "Plugin Architecture")
-
 # Table of Contents
 
 - [Install](#install)
@@ -60,6 +58,25 @@ functions:
               - dog
               - cat
 
+            # Overrides for generated CloudFormation templates
+            # Mirrors the CloudFormation docs but uses camel case instead of title case
+            #
+            # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-sqs-queues.html
+            mainQueueOverride:
+              maximumMessageSize: 1024
+              ...
+            deadLetterQueueOverride:
+              maximumMessageSize: 1024
+              ...
+            # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-lambda-eventsourcemapping.html
+            eventSourceMappingOverride:
+              sourceAccessConfigurations:
+                - Type: SASL_SCRAM_256_AUTH
+                  URI: arn:aws:secretsmanager:us-east-1:01234567890:secret:MyBrokerSecretName
+            # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-sns-subscription.html
+            subscriptionOverride:
+              region: ap-southeast-2
+
 resources:
   Resources:
     Topic:
@@ -70,3 +87,26 @@ resources:
 plugins:
   - "@agiledigital/serverless-sns-sqs-lambda"
 ```
+
+### CloudFormation Overrides
+
+If you would like to override a part of the CloudFormation template
+that is generated by this plugin, you can pass raw CloudFormation
+to the override config options outlined above.
+
+The configuration must be provided with camel case keys,
+but apart from that, you can use the CloudFormation config
+as specified by AWS.
+
+For example, if you wanted to override the maximumMessageSize for the main queue
+you could find the "MaximumMessageSize" config option in the [AWS documentation](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-sqs-queues.html)
+make the key camel case ("maximumMessageSize") and pass it into the override section:
+
+```yaml
+    events:
+      - snsSqs:
+          name: Example
+          ...
+          mainQueueOverride:
+            maximumMessageSize: 1024
+```

example-service/serverless.yml

@@ -28,6 +28,22 @@ functions:
               - dog
               - cat
 
+          # Overrides for generated CloudFormation templates
+          # Mirrors the CloudFormation docs but uses camel case instead of title case
+          #
+          #
+          # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-sqs-queues.html
+          mainQueueOverride:
+            maximumMessageSize: 1024
+          deadLetterQueueOverride:
+            delaySeconds: 120
+          # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-lambda-eventsourcemapping.html
+          eventSourceMappingOverride:
+            enabled: false
+          # https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-sns-subscription.html
+          subscriptionOverride:
+            rawMessageDelivery: true
+
 resources:
   Resources:
     Topic: