Working with resource-based IAM policies in Lambda - AWS Lambda
Supported API actions

Working with resource-based IAM policies in Lambda

Lambda supports resource-based permissions policies for Lambda functions and layers. You can use resource-based policies to grant access to other AWS accounts, organizations, or services. Resource-based policies apply to a single function, version, alias, or layer version.

Console
To view a function's resource-based policy

  1. Open the Functions page of the Lambda console.

  2. Choose a function.

  3. Choose Configuration and then choose Permissions.

  4. Scroll down to Resource-based policy and then choose View policy document. The resource-based policy shows the permissions that are applied when another account or AWS service attempts to access the function. The following example shows a statement that allows Amazon S3 to invoke a function named my-function for a bucket named amzn-s3-demo-bucket in account 123456789012.

    Example Resource-based policy
    {
    "Version": "2012-10-17",
    "Id": "default",
    "Statement": [
        {
            "Sid": "lambda-allow-s3-my-function",
            "Effect": "Allow",
            "Principal": {
              "Service": "s3.amazonaws.com"
            },
            "Action": "lambda:InvokeFunction",
            "Resource":  "arn:aws:lambda:us-east-2:123456789012:function:my-function",
            "Condition": {
              "StringEquals": {
                "AWS:SourceAccount": "123456789012"
              },
              "ArnLike": {
                "AWS:SourceArn": "arn:aws:s3:::amzn-s3-demo-bucket"
              }
            }
        }
     ]
}
AWS CLI

To view a function's resource-based policy, use the get-policy command.

aws lambda get-policy \
  --function-name my-function \
  --output text

You should see the following output:

{"Version":"2012-10-17","Id":"default","Statement":[{"Sid":"sns","Effect":"Allow","Principal":{"Service":"s3.amazonaws.com"},"Action":"lambda:InvokeFunction","Resource":"arn:aws:lambda:us-east-2:123456789012:function:my-function","Condition":{"ArnLike":{"AWS:SourceArn":"arn:aws:sns:us-east-2:123456789012:lambda*"}}}]}      7c681fc9-b791-4e91-acdf-eb847fdaa0f0

For versions and aliases, append the version number or alias to the function name.

aws lambda get-policy --function-name my-function:PROD

To remove permissions from your function, use remove-permission.

aws lambda remove-permission \
  --function-name example \
  --statement-id sns

Use the get-layer-version-policy command to view the permissions on a layer.

aws lambda get-layer-version-policy \
  --layer-name my-layer \
  --version-number 3 \
  --output text

You should see the following output:

b0cd9796-d4eb-4564-939f-de7fe0b42236    {"Sid":"engineering-org","Effect":"Allow","Principal":"*","Action":"lambda:GetLayerVersion","Resource":"arn:aws:lambda:us-west-2:123456789012:layer:my-layer:3","Condition":{"StringEquals":{"aws:PrincipalOrgID":"o-t194hfs8cz"}}}"

Use remove-layer-version-permission to remove statements from the policy.

aws lambda remove-layer-version-permission --layer-name my-layer --version-number 3 --statement-id engineering-org

Supported API actions

The following Lambda API actions support resource-based policies: