Distributed Load Testing on AWS Lambda

This guide describes Artillery’s support for running highly-distributed serverless load tests on AWS Lambda.

You’ll learn:

  • How to scale out your Artillery tests using built-in AWS Lambda support
  • What AWS resources Artillery creates on your behalf to run your tests
  • Current limitations in AWS Lambda support in Artillery

AWS credentials

To execute tests in AWS Lambda the Artillery CLI makes use of the official AWS SDK (opens in a new tab) to create the resources needed to run your tests (see the AWS Resources section for details on what Artillery creates).

The SDK requires AWS credentials (opens in a new tab) to be present to work. Please refer to the official AWS documentation if you don't have one set up already: https://docs.aws.amazon.com/cli/latest/userguide/cli-chap-configure.html (opens in a new tab)

Please see the IAM Permissions section for details on permissions required to run tests from AWS Lambda.

Running tests from AWS Lambda

To run an existing test script from AWS Lambda, simply run an existing test using the run-lambda command.

For example, if you have a test script saved in blitz.yml and you want to run it from eu-west-1 region, run the following command:

artillery run-lambda \
   --region eu-west-1 \
   blitz.yml

How it works

AWS resources created

Artillery will create a number of AWS resources behind the scenes to be able to execute your tests. All resources created by Artillery are serverless and created on-demand. There are no long-running infrastructure components involved.

  • An S3 bucket to store an AWS Lambda deployment package generated from your test script
  • An AWS Lambda function. This function is reused by tests using the same Artillery version.
  • An SQS queue for communication between Lambda workers executing your test and the Artillery CLI. This queue is deleted once the test run completes.
  • (Optional) An IAM role named artilleryio-default-lambda-role for Lambda functions running your test. This role uses the official AWS-managed AWSLambdaBasicExecutionRole and AWSLambdaVPCAccessExecutionRole (opens in a new tab) policies, and an additional policy which grants access to the SQS queues created for these tests. If a role with that name already exists, Artillery will use it instead of creating it.

IAM permissions

The AWS profile that the Artillery CLI runs under when you run artillery run-lambda needs to have sufficient permissions to be able to create the resources listed above. If running in a sandbox/developer account, the easiest way is to run with admin privileges using the default AWS AdministratorAccess (opens in a new tab) managed policy.

Example IAM policy definition to use instead of AdministratorAccess

Notes:

  • Create an IAM Role with the following policy and attach it to the IAM user you're using to run Artillery tests.
  • 123456789000 will need to be replaced with the id of the AWS account you'll be using.
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "CreateOrGetLambdaRole",
      "Effect": "Allow",
      "Action": [
        "iam:CreateRole",
        "iam:GetRole",
        "iam:PassRole",
        "iam:AttachRolePolicy"
      ],
      "Resource": "arn:aws:iam::123456789000:role/artilleryio-default-lambda-role-*"
    },
    {
      "Sid": "CreateLambdaPolicy",
      "Effect": "Allow",
      "Action": ["iam:CreatePolicy"],
      "Resource": "arn:aws:iam::123456789000:policy/artilleryio-lambda-policy-*"
    },
    {
      "Sid": "SQSPermissions",
      "Effect": "Allow",
      "Action": ["sqs:*"],
      "Resource": "arn:aws:sqs:*:123456789000:artilleryio*"
    },
    {
      // ListQueues does cannot be scoped to individual resources
      // https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazonsqs.html#amazonsqs-queue
      "Sid": "SQSListQueues",
      "Effect": "Allow",
      "Action": ["sqs:ListQueues"],
      "Resource": "*"
    },
    {
      "Sid": "LambdaPermissions",
      "Effect": "Allow",
      "Action": [
        "lambda:InvokeFunction",
        "lambda:CreateFunction",
        "lambda:DeleteFunction",
        "lambda:GetFunctionConfiguration"
      ],
      "Resource": "arn:aws:lambda:*:123456789000:function:artilleryio-*"
    },
    {
      "Sid": "EcrPullImagePermissions",
      "Effect": "Allow",
      "Action": [
        "ecr:GetDownloadUrlForLayer",
        "ecr:BatchGetImage"
      ],
      "Resource": "arn:aws:ecr:*:248481025674:repository/artillery-worker"
    },
    {
      "Sid": "S3Permissions",
      "Effect": "Allow",
      "Action": [
        "s3:CreateBucket",
        "s3:DeleteObject",
        "s3:GetObject",
        "s3:PutObject",
        "s3:ListBucket",
        "s3:GetLifecycleConfiguration",
        "s3:PutLifecycleConfiguration"
      ],
      "Resource": [
        "arn:aws:s3:::artilleryio-test-data-*",
        "arn:aws:s3:::artilleryio-test-data-*/*"
      ]
    }
  ]
}

Setting up the IAM Policy and Role in AWS

You do not need to set these up if you're running as admin using the default AdministratorAccess policy.

To help you get started, we've set up a CloudFormation stack (opens in a new tab) you can use to automatically provision the IAM role with required permissions. The stack will create:

  • An IAM role named ArtilleryDistributedTestingLambdaRole
  • An ArtilleryDistributedTestingLambdaPolicy (the policy definition outlined above) that will be attached to the role.
Create the IAM Permissions using the CloudFormation stack
Launch Stack
  1. Click the Launch Stack button above to open the AWS CloudFormation Quick create stack page.
  2. Adjust the trust relationship if needed:
    • By default, the role will trust your AWS account, meaning any principal (opens in a new tab) from your account (e.g. IAM User, IAM Role) will be trusted to assume the role. If you would prefer to configure the role to trust only a specific IAM user or role, enter their name in the appropriate User/Role parameter field before creating the stack.
  3. Click Create stack.
  4. Once the stack is created, the ArtilleryDistributedTestingLambdaRole will be ready to use.

Note: Ensure the AWS entity (e.g. IAM user) you are using has permission to assume the role you just created. This is necessary to run Artillery tests.

(Alternative) Create the IAM Permissions manually

If you would prefer to create the IAM role manually, you can follow the steps below:

You should first create the policy. You can do that from the AWS UI or CLI. To do it from the UI:

  1. Go to IAM -> Policies and select Create Policy. Select JSON.
  2. Copy the example JSON policy definition from the section above. You’ll need to change the following:
    • Change the AWS account from 123456789000 to your account ID;
    • Remove any comments from the JSON policy, as that is not allowed;
  3. Press Next and give the policy a meaningful name.

After the policy created, you'll need to use that policy in a role:

  1. Go to IAM -> Roles and select Create Role;
  2. Select Custom Trust Policy:
    • The trust policy of a role is used to define principals (opens in a new tab) that you trust to assume the role (e.g. IAM user, IAM role, service).
    • If you're using a specific IAM user when running Artillery tests, you can use the following trust policy: 
      {
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::123456789000:user/iam-user-name" // Replace the value with the ARN of your user
      },
      "Action": "sts:AssumeRole"
    }
  ]
}
    • If you are using a specific IAM role when running Artillery tests set the AWS in Principal to your IAM role ARN instead of the user ARN.
    • For more info about how to configure the trust policy, check out this blog post (opens in a new tab) and the AWS documentation (opens in a new tab).
  3. After, on the Add Permissions UI, select the policy created in the previous step;
  4. Finally, press Next and give the role a meaningful name.

That's it! You should now be able to use this role to run Artillery tests in Lambda.

If you're setting up OIDC, for example to interact with GitHub Actions, then you might need to set a different Custom Trust Policy for the role created above (added in step 3). Follow the GH Actions guide (opens in a new tab) to get the appropriate Trust Policy.

Limitations

  • Test Duration: AWS Lambda is limited to 15 minutes (opens in a new tab) of running time, which means that the entire load test cannot run for longer than 15 minutes at the moment.
  • A running test cannot be stopped: Once a load test starts, it will run to completion. This is because once an AWS Lambda starts, there is no way to stop it (using the AWS SDK or AWS console). Be mindful of this, and ramp up load on your applications gradually.
  • Artillery features:
    • before and after hooks run once in each Lambda worker rather than once per test run
    • --target, and --insecure flags for the run command are unavailable in Lambda tests

Retention Settings

S3 Lifecycle Configuration

Added inv2.0.5

Objects created in Artillery's s3 bucket in your AWS account have the following lifecycle rules by default:

  • Test Run artifacts: 2 days
  • Test Run metadata: 7 days

Questions?

Load Testing at ScaleAWS Fargate