How to specify image name in sam build with template containing multiple functions

I’ve had a look through the extensive documentation for AWS SAM and which CLI parameters are supported for the sam build command but I couldn’t see any option to specify the name of the docker image that gets built? I am already using the Metadata section with the DockerTag option to specify the tag but I’d like to specify the image name.

I have two Functions defined which are built as a single Docker image which builds and runs perfectly fine, however, when I run a sam build it seems to just select the Logical Resource ID of the first AWS::Serverless::Function defined in the template.

Here is my template:

Transform: AWS::Serverless-2016-10-31

Parameters:
  DockerTag:
    Type: String
    Default: local-dev

Resources:
  TestFunction1:
    Type: AWS::Serverless::Function
    Properties:
      FunctionName: TestFunction1
      PackageType: Image
      ImageUri: !Sub 'testfunction1:${DockerTag}'
      ImageConfig:
        Command:
          - TestLambdas::TestLambdas.TestFunction1::Invoke
      Role: !Sub 'arn:aws:iam::${AWS::AccountId}:role/lambda-execution-role'
      MemorySize: 256
      Timeout: 30
      Events:
        ScheduledEvent:
          Type: Schedule
          Properties:
            Schedule: rate(3 minutes)
            Name: test-schedule-rule
            Enabled: true
    Metadata:
      DockerTag: !Ref DockerTag
      DockerContext: .
      Dockerfile: ./Dockerfile

  TestFunction2:
    Type: AWS::Serverless::Function
    Properties:
      FunctionName: TestFunction2
      PackageType: Image
      ImageUri: !Sub 'testfunction1:${DockerTag}'
      ImageConfig:
        Command:
          - TestLambdas::TestLambdas.TestFunction2::Invoke
      Role: !Sub 'arn:aws:iam::${AWS::AccountId}:role/lambda-execution-role'
      MemorySize: 256
      Timeout: 30
      Events:
        ScheduledEvent:
          Type: Schedule
          Properties:
            Schedule: rate(3 minutes)
            Name: test-schedule-rule
            Enabled: true
    Metadata:
      DockerTag: !Ref DockerTag
      DockerContext: .
      Dockerfile: ./Dockerfile

And here is the output of running sam build (Notice this one image being built contains two functions)

PS C:\Workspace\Lambda.Handlers\Lambda.Handlers.Test> sam build
Building codeuri: C:\Workspace\Lambda.Handlers\Lambda.Handlers.Test runtime: None metadata: {'DockerTag': 'local-dev', 'DockerContext': 'C:\\Workspace\\Lambda.Handlers\\Lambda.Handlers.Test', 'Dockerfile': './Dockerfile'} functions: ['TestFunction1', 'TestFunction2']
Building image for TestFunction1 function
Setting DockerBuildArgs: {} for TestFunction1 function
Step 1/3 : FROM public.ecr.aws/lambda/dotnet:5.0
 ---> 41fed005ba97
Step 2/3 : COPY ./* /var/task/
 ---> Using cache
 ---> 6fac8005ce03
Step 3/3 : ENTRYPOINT ["/lambda-entrypoint.sh"]
 ---> Using cache
 ---> d691b293f1c1
Successfully built d691b293f1c1
Successfully tagged testfunction1:local-dev             <--------- I WOULD LIKE TO SET testfunction1 TO SOMETHING ELSE

Build Succeeded

Built Artifacts  : .aws-sam\build
Built Template   : .aws-sam\build\template.yaml

Commands you can use next
=========================
[*] Invoke Function: sam local invoke
[*] Deploy: sam deploy --guided

If I re-order TestFunction1 and TestFunction2, then the built image is then named testfunction2.

Looking forward to any help/advice if what I’m trying to achieve is even possible…

Thanks

[solarmosaic-kflorence]

It would be nice to be able to specify the name of the image, instead of it having to be the lowercase version of the function resource name. For example, if my resource name is “MyFunction”, it would result in an image name of “myfunction” – I’d prefer if it were “my-function”.

[mr-davidc]

@qingchm Yes, I think if that page is at least updated to mention all the discovery we did above for this issue ☝️ ,that would be a good start. As @solarmosaic-kflorence said, I think long term, a nice feature would be having the option to specify the image name somehow.