fix: BasePath not included in AWS::ApiGateway::BasePathMapping when defined as ["/"] (#3740)

Author: mbfreder

samtranslator/model/api/api_generator.py

@@ -805,7 +805,7 @@ def _create_basepath_mapping(
         basepath_mapping.DomainName = ref(api_domain_name)
         basepath_mapping.RestApiId = ref(rest_api.logical_id)
         basepath_mapping.Stage = ref(rest_api.logical_id + ".Stage")
-        if basepath:
+        if basepath is not None:
             basepath_mapping.BasePath = basepath
         return basepath_mapping
 

tests/translator/input/api_with_custom_domains_edge_basePath.yaml

@@ -0,0 +1,51 @@
+Parameters:
+  MyEdgeDomainName:
+    Type: String
+  MyEdgeDomainCert:
+    Type: String
+  HostedZoneId:
+    Type: String
+
+Resources:
+  MyFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      InlineCode: |
+        exports.handler = async (event) => {
+          const response = {
+            statusCode: 200,
+            body: JSON.stringify('Hello from Lambda!'),
+          };
+          return response;
+        };
+      Handler: index.handler
+      Runtime: nodejs18.x
+      Events:
+        Fetch:
+          Type: Api
+          Properties:
+            RestApiId:
+              Ref: MyApi
+            Method: Get
+            Path: /get
+
+  MyApi:
+    Type: AWS::Serverless::Api
+    Properties:
+      OpenApiVersion: 3.0.1
+      StageName: Prod
+      Domain:
+        DomainName:
+          Ref: MyEdgeDomainName
+        CertificateArn:
+          Ref: MyEdgeDomainCert
+        EndpointConfiguration: EDGE
+        BasePath:
+        - /
+        - /get
+        Route53:
+          HostedZoneId:
+            Ref: HostedZoneId
+          IpV6: true
+Metadata:
+  SamTransformTest: true

tests/translator/input/api_with_custom_domains_private_basePath.yaml

@@ -0,0 +1,65 @@
+Parameters:
+  DomainName:
+    Type: String
+    Default: private.example.com
+    Description: Custom domain name for the API
+
+  CertificateArn:
+    Type: String
+    Default: another-api-arn
+    Description: ARN of the ACM certificate for the domain
+
+  VpcEndpointId:
+    Type: String
+    Default: vpce-abcd1234efg
+    Description: VPC Endpoint ID for private API access
+
+Resources:
+  MyApi:
+    Type: AWS::Serverless::Api
+    Properties:
+      StageName: prod
+      Domain:
+        DomainName: !Ref DomainName
+        CertificateArn: !Ref CertificateArn
+        EndpointConfiguration: PRIVATE
+        BasePath:
+        - /
+        - /post
+        Policy:
+          Version: '2012-10-17'
+          Statement:
+          - Effect: Allow
+            Principal: '*'
+            Action: execute-api:Invoke
+            Resource: execute-api:/*
+          - Effect: Deny
+            Principal: '*'
+            Action: execute-api:Invoke
+            Resource: execute-api:/*
+            Condition:
+              StringNotEquals:
+                aws:SourceVpce: !Ref VpcEndpointId
+      Auth:
+        ResourcePolicy:
+          CustomStatements:
+          - Effect: Allow
+            Principal: '*'
+            Action: execute-api:Invoke
+            Resource: execute-api:/*
+          - Effect: Deny
+            Principal: '*'
+            Action: execute-api:Invoke
+            Resource: execute-api:/*
+            Condition:
+              StringNotEquals:
+                aws:SourceVpce: !Ref VpcEndpointId
+
+Outputs:
+  ApiDomainName:
+    Description: Custom Domain Name for the API
+    Value: !Ref MyApi.DomainNameV2
+
+  ApiEndpoint:
+    Description: API Gateway endpoint URL
+    Value: !Sub https://${MyApi}.execute-api.${AWS::Region}.amazonaws.com/prod/

tests/translator/input/api_with_custom_domains_regional_basePath.yaml

@@ -0,0 +1,54 @@
+Parameters:
+  MyRestRegionalDomainName:
+    Type: String
+  MyRestRegionalDomainCert:
+    Type: String
+  HostedZoneId:
+    Type: String
+
+Globals:
+  Api:
+    Domain:
+      DomainName:
+        Ref: MyRestRegionalDomainName
+      CertificateArn:
+        Ref: MyRestRegionalDomainCert
+      EndpointConfiguration: REGIONAL
+      MutualTlsAuthentication:
+        TruststoreUri: ${mtlsuri}
+        TruststoreVersion: 0
+      SecurityPolicy: TLS_1_2
+      BasePath:
+      - /
+      - /post
+      Route53:
+        HostedZoneId:
+          Ref: HostedZoneId
+
+Resources:
+  MyFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      InlineCode: |
+        exports.handler = async (event) => {
+          const response = {
+            statusCode: 200,
+            body: JSON.stringify('Hello from Lambda!'),
+          };
+          return response;
+        };
+      Handler: index.handler
+      Runtime: nodejs18.x
+      Events:
+        ImplicitGet:
+          Type: Api
+          Properties:
+            Method: Get
+            Path: /get
+        ImplicitPost:
+          Type: Api
+          Properties:
+            Method: Post
+            Path: /post
+Metadata:
+  SamTransformTest: true