serverless-simplify-default-exec-role-plugin

** This is a fork of serverless-simplify-default-exec-role-plugin by woebot

which in itself was a fork of serverless-simplify-default-exec-role-plugin by shelfio **

A quick solution for the IamRoleLambdaExecution error: Maximum policy size of 10240 bytes exceeded.

• This plugin modifies the IamRoleLambdaExecution policy to reduce its size.
• Unlike the original version, this maintains any custom IAM statements attached to the Lambda role.
• It also doesn't collapse "logs:CreateLogStream", "logs:CreateLogGroup", and "logs:PutLogEvents" permissions into the same IAM statement.

Installation

$ npm install --dev @lendi/serverless-simplify-default-exec-role-plugin

Usage

In your serverless.yml file:

plugins:
  - "@lendi/serverless-simplify-default-exec-role-plugin"

IAM simplification for logs: statements

By default the Serverless framework adds something like the IAM statement below in order to allow write access to CloudWatch log groups that are part of the deployment stack. For stacks with a lot of lambda functions, this can cause the role to exceed the maximum allowed size of 10240 bytes. This plugin reduces the size of the generated lambda role by replacing the resource list with a single ARN to grants write access to all log groups that are part of the same region and account.

Before

{
  "Effect": "Allow",
  "Action": ["logs:CreateLogStream", "logs:CreateLogGroup"],
  "Resource": [
    {
      "Fn::Sub": "arn:${AWS::Partition}:logs:${AWS::Region}:${AWS::AccountId}:log-group:/aws/lambda/production-users-createUser:*",
    },
    {
      "Fn::Sub": "arn:${AWS::Partition}:logs:${AWS::Region}:${AWS::AccountId}:log-group:/aws/lambda/production-users-updateUser:*",
    },
    {
      "Fn::Sub": "arn:${AWS::Partition}:logs:${AWS::Region}:${AWS::AccountId}:log-group:/aws/lambda/production-users-deleteUser:*",
    },
    // ... and so on, for each lambda function that logs to cloudwatch
  ],
}

After

{
  "Effect": "Allow",
  "Action": ["logs:CreateLogStream", "logs:CreateLogGroup"],
  "Resource": [
    {
      "Fn::Sub": "arn:${AWS::Partition}:logs:${AWS::Region}:${AWS::AccountId}:log-group:*",
    },
  ],
}

IAM simplification for kinesis:* statements

Needs more testing

When you attach a kinesis stream as an event source, it creates an IAM policy per kinesis stream

Before

{
    "Effect": "Allow",
    "Action": [
        "kinesis:GetRecords",
        "kinesis:GetShardIterator",
        "kinesis:DescribeStreamSummary",
        "kinesis:ListShards"
    ],
    "Resource": [
        "arn:aws:kinesis:<region>:<account>:stream/<stream-name>"
    ]
},
...many depending on number of input events to lambdas
{
    "Effect": "Allow",
    "Action": [
        "kinesis:GetRecords",
        "kinesis:GetShardIterator",
        "kinesis:DescribeStreamSummary",
        "kinesis:ListShards"
    ],
    "Resource": [
        "arn:aws:kinesis:<region>:<account>:stream/<stream-name>"
    ]
},

After

{
    "Effect": "Allow",
    "Action": [
        "kinesis:GetRecords",
        "kinesis:GetShardIterator",
        "kinesis:DescribeStreamSummary",
        "kinesis:ListShards"
    ],
    "Resource": [
        "arn:aws:kinesis:<region>:<account>:stream/<stream-name>"
    ]
},

tests

We have every intention of creating more tests to validate this plugin...

License

MIT ©