Change Trust Policy in Serverless IAM Role (or any other params other than policy)

serverless-with-trust-policy-change.yml

## all other serverless.yml configuration
functions:
 # your functions
 
provider:
  name: aws
  # your provider config

resources:
  Resources:
    IamRoleLambdaExecution: # has to be this exact name, https://serverless.com/framework/docs/providers/aws/guide/resources/
      Type: AWS::IAM::Role
      Properties:
        AssumeRolePolicyDocument: # OVERWRITE assume role policy, rest is populated by serverless
          Version: "2012-10-17"
          Statement:
            - Effect: Allow
              Principal:
                Service:
                  - lambda.amazonaws.com
                AWS:
                  - arn:aws:iam::123456789:root
                  - arn:aws:iam::012345678:root
              Action: sts:AssumeRole

@ezmiller it means that those AWS accounts can assume roles, but it's not something required - this whole block of AssumeRolePolicyDocument is just an example of how you can overwrite trust policy, so change it to whatever you need. Here is the CloudFormation reference

Is this approach necessary if one is trying to set roles for a resource other than lambda that is created in custom resources? I'm trying to link an Eventbridge rule to other targets and running into what I think are permissions errors, but I have been unable to explicitly set the resource policies. See question here: https://forum.serverless.com/t/permissions-for-custom-resource-directing-eventbridge-events-to-targets/17241

bardzo dziękuję kolego!