What is SourceArn in aws lambda permission - amazon-web-services

Question

This is my cft for lambda, I upload the jar file to s3 and then upload to lambda through s3, I completed the LambdaRole and LambdaFunction section, in the permission section, what should be the SourceArn? I went through the lambda official doc but didn't find any example.
Also, can anyone take a look to see if this cft is correct or not? Thanks!
ConfigurationLambdaRole:
Type: "AWS::IAM::Role"
Properties:
RoleName: 'configuration-sqs-lambda'
AssumeRolePolicyDocument:
Version: '2012-10-17'
Statement:
- Effect: Allow
Principal:
Service:
- lambda.amazonaws.com
- events.amazonaws.com
- s3.amazonaws.com
Action:
- sts:AssumeRole
ManagedPolicyArns:
- arn:aws:iam::aws:policy/AmazonSQSFullAccess
- arn:aws:iam::aws:policy/CloudWatchLogsFullAccess
ConfigurationLambdaFunction:
Type: AWS::Lambda::Function
Properties:
Description: 'configuration service with lambda'
FunctionName: 'configuration-lambda'
Handler: com.lambda.handler.EventHandler::handleRequest
Runtime: Java 11
MemorySize: 128
Timeout: 120
Code:
S3Bucket: configurationlambda
S3Key: lambda-service-1.0.0-SNAPSHOT.jar
Role: !GetAtt ConfiguratioLambdaRole.Arn
ConfigurationLambdaInvokePermission:
Type: AWS::Lambda::Permission
Properties:
FunctionName:
Fn::GetAtt:
- ConfigurationLambdaFunction
- Arn
Action: 'lambda:InvokeFunction'
Principal: s3.amazonaws.com
SourceArn: ''

Answer 1

You are creating a Role to run your lambda, a lambda function, and permissions for something to invoke that lambda. The SourceArn is the thing that will invoke the lambda. So in your case it sounds like you want an S3 bucket to invoke the lambda, so the SourceArn would be the ARN of the S3 bucket.
This tutorial relates to what you are doing--specifically step 8 under the "Create the Lambda function" section.
Your CF template generally looks correct. The only thing I see that will be assuming this role is lambda.amazonaws.com, so the role may not need to list the following in the AssumeRolePolicyDocument section:
- events.amazonaws.com
- s3.amazonaws.com
Also see https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-lambda-permission.html