Add rancid code so CloudFormation will deploy the API.

emily/api-definition/models/emily.smithy

@@ -10,7 +10,7 @@ use aws.protocols#restJson1
     // Specifies the integration's HTTP method type (for example, POST). For
     // Lambda function invocations, the value must be POST.
     httpMethod: "POST",
-    uri: "arn:${AWS::Partition}:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${OperationLambda.Arn}/invocations",
+    uri: "arn:${AWS::Partition}:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${OperationLambda}/invocations",
 )
 @title("Emily")
 service Emily {

emily/api-definition/smithy-build.json

@@ -18,7 +18,7 @@
         "openapi": {
           "service": "stacks.sbtc#Emily",
           "protocol": "aws.protocols#restJson1",
-          "version": "3.1.0",
+          "version": "3.0.2",
           "apiGatewayDefaults": "2023-08-11"
         }
       }

emily/cdk/lib/emily-stack-utils.ts

@@ -1,4 +1,5 @@
 import { ApiDefinition } from "aws-cdk-lib/aws-apigateway";
+import * as lambda from 'aws-cdk-lib/aws-lambda';
 import * as fs from 'fs';
 import { resolve } from "path";
 import { EmilyStackProps } from "./emily-stack-props";
@@ -93,14 +94,59 @@ export class EmilyStackUtils {
     }
 
     /**
-     * @description Generate an api definition asset from a local OpenAPI definition, replacing the lambda
-     * integration tags with the appropriate resource values.
+     * @description Generate an api definition asset from a local OpenAPI definition and modifies the
+     * template such that CloudFormation can replace the lambda identifiers with the correct lambda arn.
      * @param {fs.PathOrFileDescriptor} restApiPathOrFileDescriptor the location of the definition asset
+     * @param {string} lambdaFunctionId lambdaFunction Id.
+     * @param {CloudFormationStackProps} props properties of the cloud formation stack.
+     * @returns {ApiDefinition} The name of the resource.
      */
-    public static restApiDefinition(
+    public static restApiDefinitionWithLambdaIntegration(
         restApiPathOrFileDescriptor: fs.PathOrFileDescriptor,
+        apiLambdas: [lambdaIdentifier: string, lambdaFunction: lambda.Function][],
     ): ApiDefinition {
-        // Replace our `${API_LAMBDA_URI}` token with the calculated lambda invokation URI.
-        return ApiDefinition.fromInline(JSON.parse(fs.readFileSync(restApiPathOrFileDescriptor, 'utf-8')))
+
+        // This whole section is unfortunate but there's not a standard solution. The autogenerated OpenAPI
+        // template will always setup the `uri` to have injected substitution with `Fn::Sub`, and the only
+        // way to gather the ARN of the lambda as a string at build time is build the whole arn yourself which
+        // is worse than this solution; if the arn format changes the api will break without an obvious error.
+        // When we get the ARN from lambda.Function object it generates a template function that will gather
+        // the ARN and pretend it's a string, so you cannot substitute anything with it directly.
+        //
+        // In this loop we go through the OpenAPI json and inject it with a parameter such that the
+        // `Fn::Sub` can replace with our desired lambda's arn.
+        //
+        // https://repost.aws/knowledge-center/cloudformation-fn-sub-function
+        //
+        // If you look at the template that spawns from this you'll see that the `Fn::Sub` actually defines
+        // the key to be ANOTHER `Fn::XXX` template function that resolves to be the lambda's Arn.
+        //
+        // It would be nice if there were a solution that didn't involve doing this ourselves.
+        // At the moment, there isn't.
+        let apiJsonDefiniton = JSON.parse(fs.readFileSync(restApiPathOrFileDescriptor, 'utf-8'));
+        let paths = apiJsonDefiniton["paths"];
+        Object.keys(paths).forEach(path => {
+            let verbs = paths[path];
+            Object.keys(verbs).forEach(verb => {
+                if (Object.keys(verbs[verb]).includes("x-amazon-apigateway-integration")) {
+                    let awsIntegration = verbs[verb]["x-amazon-apigateway-integration"];
+                    let originalSubString: string = awsIntegration["uri"]["Fn::Sub"];
+                    apiLambdas.forEach(([lambdaIdentifier, lambdaFunction]) => {
+                        if (originalSubString.includes(`\${${lambdaIdentifier}}`)) {
+                            // If the identifier is present in the uri string then generate the template function to
+                            // replace the identifier with the lambda arn.
+                            //
+                            // This will incorrectly handle the already invalid case where two function ARNS are in the uri.
+                            // Handling multiple replacements is left as an exercize for the reader.
+                            apiJsonDefiniton["paths"][path][verb]["x-amazon-apigateway-integration"]["uri"]["Fn::Sub"] =
+                                [ originalSubString, { [lambdaIdentifier] : lambdaFunction.functionArn } ]
+                        }
+                    })
+                }
+            })
+        })
+
+        // Return the modified template as an ApiDefinition.
+        return ApiDefinition.fromInline(apiJsonDefiniton)
     }
 }

emily/cdk/lib/emily-stack.ts

@@ -161,10 +161,7 @@ export class EmilyStack extends cdk.Stack {
         props: EmilyStackProps
     ): lambda.Function {
 
-        // This must match the Lambda name from the @aws.apigateway#integration trait in the
-        // smithy operations and resources that should be handled by this Lambda.
         const operationLambdaId: string = "OperationLambda";
-
         const operationLambda: lambda.Function = new lambda.Function(this, operationLambdaId, {
             functionName: EmilyStackUtils.getResourceName(operationLambdaId, props),
             architecture: lambda.Architecture.ARM_64, // <- Will need to change when run locally for x86
@@ -187,7 +184,7 @@ export class EmilyStack extends cdk.Stack {
             }
         });
 
-        // Give the server lambda full access to the DynamoDB table.
+        // Give the server lambda full access to the DynamoDB tables.
         depositTable.grantReadWriteData(operationLambda);
         withdrawalTable.grantReadWriteData(operationLambda);
         chainstateTable.grantReadWriteData(operationLambda);
@@ -198,27 +195,34 @@ export class EmilyStack extends cdk.Stack {
 
     /**
      * Creates or updates the API Gateway to connect with the Lambda function.
-     * @param {lambda.Function} serverLambda The Lambda function to connect to the API.
+     * @param {lambda.Function} operationLambda The Lambda function to connect to the API.
      * @param {EmilyStackProps} props The stack properties.
      * @returns {apig.SpecRestApi} The created or updated API Gateway.
      * @post An API Gateway with execute permissions linked to the Lambda function is returned.
      */
     createOrUpdateApi(
-        serverLambda: lambda.Function,
+        operationLambda: lambda.Function,
         props: EmilyStackProps
     ): apig.SpecRestApi {
 
         const restApiId: string  = "EmilyAPI";
         const restApi: apig.SpecRestApi = new apig.SpecRestApi(this, restApiId, {
             restApiName: EmilyStackUtils.getResourceName(restApiId, props),
-            apiDefinition: EmilyStackUtils.restApiDefinition(EmilyStackUtils.getPathFromProjectRoot(
-                ".generated-sources/openapi/openapi/Emily.openapi.json"
-            )),
+            apiDefinition: EmilyStackUtils.restApiDefinitionWithLambdaIntegration(
+                EmilyStackUtils.getPathFromProjectRoot(
+                    ".generated-sources/openapi/openapi/Emily.openapi.json"
+                ),
+                [
+                    // This must match the Lambda name from the @aws.apigateway#integration trait in the
+                    // smithy operations and resources that should be handled by this Lambda.
+                    ["OperationLambda", operationLambda]
+                ],
+            ),
             deployOptions: { stageName: props.stageName },
         });
 
         // Give the the rest api execute ARN permission to invoke the lambda.
-        serverLambda.addPermission("ApiInvokeLambdaPermission", {
+        operationLambda.addPermission("ApiInvokeLambdaPermission", {
             principal: new iam.ServicePrincipal("apigateway.amazonaws.com"),
             action: "lambda:InvokeFunction",
             sourceArn: restApi.arnForExecuteApi(),