Create an API Gateway Proxy Resource using SAM

Question

I have an apparently-simple requirement to create a proxy resource in SAM (Amazon's Serverless Application Model). So simple in fact that Amazon's documentation appears to leave this as an exercise to the reader!

I want to create an AWS API Gateway catch-all endpoint to proxy everything to another HTTP service.

In the AWS Console, the configuration I am trying to build looks as follows:

I have seen this excellent post by Christian Johansen and his related Stack Overflow question here for how to do the same thing in CloudFormation. I suppose I could just use that code in SAM, however, SAM has its implicit and explicit APIs, so I want to avoid creating explicit resources if the "right way" is to refer to implicit resources.

Does anyone know how to do this?

Answer 1

After a lot of playing around, I believe I found the answer in an example here. The diff relative to the Hello World example that SAM sets up for you out of the box is:

diff --git a/sam-app/template.yaml b/sam-app/template.yaml
index 02cd901..f349dcc 100644
--- a/sam-app/template.yaml
+++ b/sam-app/template.yaml
@@ -17,11 +17,11 @@ Resources:
         Variables:
           PARAM1: VALUE
       Events:
-        HelloWorld:
+        ProxyApiGreedy:
           Type: Api
           Properties:
-            Path: /hello
-            Method: get
+            Path: /{proxy+}
+            Method: ANY
 Outputs:
   HelloWorldApi:
     Description: API Gateway endpoint URL for Prod stage for Hello World function

In other words, like this:

Resources:
  MyFunction:
    Type: AWS::Serverless::Function
    Properties:
      ...
      Events:
        ProxyApiGreedy:
          Type: Api
          Properties:
            Path: /{proxy+}
            Method: ANY