HEREDOC got truncated

I’m using the docker action, and in my entrypoint.sh i have this snippet like so…

#!/usr/bin/bash -l
# running FROM amazon/aws-cli:latest

aws iam create-role --role-name sls-lambda-dev --assume-role-policy-document << EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": [
          "apigateway.amazonaws.com",
          "events.amazonaws.com",
          "lambda.amazonaws.com"
        ]
      },
      "Action": "sts:AssumeRole"
    }
  ]
}
EOF

and unbeknown to me the final result got truncated to just aws iam create-role --role-name sls-lambda-dev --assume-role-policy-document and nothing else… anyone know what kind of sorcery is this? or is this syntax not supported somehow?