Launching Ray Clusters on AWS¶

This guide details the steps needed to start a Ray cluster on AWS.

To start an AWS Ray cluster, you should use the Ray cluster launcher with the AWS Python SDK.

Install Ray cluster launcher¶

The Ray cluster launcher is part of the ray CLI. Use the CLI to start, stop and attach to a running ray cluster using commands such as ray up, ray down and ray attach. You can use pip to install the ray CLI with cluster launcher support. Follow the Ray installation documentation for more detailed instructions.

# install ray
pip install -U ray[default]

Install and Configure AWS Python SDK (Boto3)¶

Next, install AWS SDK using pip install -U boto3 and configure your AWS credentials following the AWS guide.

# install AWS Python SDK (boto3)
pip install -U boto3

# setup AWS credentials using environment variables
export AWS_ACCESS_KEY_ID=foo

# alternatively, you can setup AWS credentials using ~/.aws/credentials file
echo "[default]
aws_session_token=baz" >> ~/.aws/credentials

Start Ray with the Ray cluster launcher¶

Once Boto3 is configured to manage resources in your AWS account, you should be ready to launch your cluster using the cluster launcher. The provided cluster config file will create a small cluster with an m5.large head node (on-demand) configured to autoscale to up to two m5.large spot-instance workers.

Test that it works by running the following commands from your local machine:

# Download the example-full.yaml

# Create or update the cluster. When the command finishes, it will print
# out the command that can be used to SSH into the cluster head node.
ray up example-full.yaml

# Get a remote shell on the head node.
ray attach example-full.yaml

# Try running a Ray program.
python -c 'import ray; ray.init()'

# Tear down the cluster.
ray down example-full.yaml

Congrats, you have started a Ray cluster on AWS!

If you want to learn more about the Ray cluster launcher, see this blog post for a step by step guide.

AWS Configurations¶

Using Amazon EFS¶

To utilize Amazon EFS in the Ray cluster, you will need to install some additional utilities and mount the EFS in setup_commands. Note that these instructions only work if you are using the Ray cluster launcher on AWS.

# Note You need to replace the {{FileSystemId}} with your own EFS ID before using the config.
# You may also need to modify the SecurityGroupIds for the head and worker nodes in the config file.

    - sudo kill -9 `sudo lsof /var/lib/dpkg/lock-frontend | awk '{print $2}' | tail -n 1`;
        sudo pkill -9 apt-get;
        sudo pkill -9 dpkg;
        sudo dpkg --configure -a;
        sudo apt-get -y install binutils;
        cd $HOME;
        git clone;
        cd $HOME/efs-utils;
        sudo apt-get -y install ./build/amazon-efs-utils*deb;
        cd $HOME;
        mkdir efs;
        sudo mount -t efs {{FileSystemId}}:/ efs;
        sudo chmod 777 efs;

Accessing S3¶

In various scenarios, worker nodes may need write access to an S3 bucket, e.g., Ray Tune has an option to write checkpoints to S3 instead of syncing them directly back to the driver.

If you see errors like “Unable to locate credentials”, make sure that the correct IamInstanceProfile is configured for worker nodes in your cluster config file. This may look like:


You can verify if the set up is correct by SSHing into a worker node and running

aws configure list

You should see something like

      Name                    Value             Type    Location
      ----                    -----             ----    --------
   profile                <not set>             None    None
access_key     ****************XXXX         iam-role
secret_key     ****************YYYY         iam-role
    region                <not set>             None    None

Please refer to this discussion for more details on accessing S3.

Monitor Ray using Amazon CloudWatch¶

Amazon CloudWatch is a monitoring and observability service that provides data and actionable insights to monitor your applications, respond to system-wide performance changes, and optimize resource utilization. CloudWatch integration with Ray requires an AMI (or Docker image) with the Unified CloudWatch Agent pre-installed.

AMIs with the Unified CloudWatch Agent pre-installed are provided by the Amazon Ray Team, and are currently available in the us-east-1, us-east-2, us-west-1, and us-west-2 regions. Please direct any questions, comments, or issues to the Amazon Ray Team.

The table below lists AMIs with the Unified CloudWatch Agent pre-installed in each region, and you can also find AMIs at amazon-ray README.

All available unified CloudWatch agent images¶

Base AMI



Unified CloudWatch Agent Version

AWS Deep Learning AMI (Ubuntu 18.04, 64-bit)




AWS Deep Learning AMI (Ubuntu 18.04, 64-bit)




AWS Deep Learning AMI (Ubuntu 18.04, 64-bit)




AWS Deep Learning AMI (Ubuntu 18.04, 64-bit)





Using Amazon CloudWatch will incur charges, please refer to CloudWatch pricing for details.

Getting started¶

1. Create a minimal cluster config YAML named cloudwatch-basic.yaml with the following contents:¶

    type: aws
    region: us-west-2
    availability_zone: us-west-2a
    # Start by defining a `cloudwatch` section to enable CloudWatch integration with your Ray cluster.
            # Path to Unified CloudWatch Agent config file
            config: "cloudwatch/example-cloudwatch-agent-config.json"
            # CloudWatch Dashboard name
            name: "example-dashboard-name"
            # Path to the CloudWatch Dashboard config file
            config: "cloudwatch/example-cloudwatch-dashboard-config.json"

    ssh_user: ubuntu

        InstanceType: c5a.large
        ImageId: ami-0d88d9cbe28fac870  # Unified CloudWatch agent pre-installed AMI, us-west-2
        resources: {}
            InstanceType: c5a.large
            ImageId: ami-0d88d9cbe28fac870  # Unified CloudWatch agent pre-installed AMI, us-west-2
                Name: ray-autoscaler-cloudwatch-v1
        resources: {}
        min_workers: 0

2. Download CloudWatch Agent and Dashboard config.¶

First, create a cloudwatch directory in the same directory as cloudwatch-basic.yaml. Then, download the example CloudWatch Agent and CloudWatch Dashboard config files to the cloudwatch directory.

$ mkdir cloudwatch
$ cd cloudwatch
$ wget
$ wget

3. Run ray up cloudwatch-basic.yaml to start your Ray Cluster.¶

This will launch your Ray cluster in us-west-2 by default. When launching a cluster for a different region, you’ll need to change your cluster config YAML file’s region AND ImageId. See the “Unified CloudWatch Agent Images” table above for available AMIs by region.

4. Check out your Ray cluster’s logs, metrics, and dashboard in the CloudWatch Console!¶

A tail can be acquired on all logs written to a CloudWatch log group by ensuring that you have the AWS CLI V2+ installed and then running:

aws logs tail $log_group_name --follow

Advanced Setup¶

Refer to example-cloudwatch.yaml for a complete example.

1. Choose an AMI with the Unified CloudWatch Agent pre-installed.¶

Ensure that you’re launching your Ray EC2 cluster in the same region as the AMI, then specify the ImageId to use with your cluster’s head and worker nodes in your cluster config YAML file.

The following CLI command returns the latest available Unified CloudWatch Agent Image for us-west-2:

aws ec2 describe-images --region us-west-2 --filters "Name=owner-id,Values=160082703681" "Name=name,Values=*cloudwatch*" --query 'Images[*].[ImageId,CreationDate]' --output text | sort -k2 -r | head -n1
        InstanceType: c5a.large
        ImageId: ami-0d88d9cbe28fac870
        InstanceType: c5a.large
        ImageId: ami-0d88d9cbe28fac870

To build your own AMI with the Unified CloudWatch Agent installed:

  1. Follow the CloudWatch Agent Installation user guide to install the Unified CloudWatch Agent on an EC2 instance.

  2. Follow the EC2 AMI Creation user guide to create an AMI from this EC2 instance.

2. Define your own CloudWatch Agent, Dashboard, and Alarm JSON config files.¶

You can start by using the example CloudWatch Agent, CloudWatch Dashboard and CloudWatch Alarm config files.

These example config files include the following features:

Logs and Metrics: Logs written to /tmp/ray/session_*/logs/**.out will be available in the {cluster_name}-ray_logs_out log group, and logs written to /tmp/ray/session_*/logs/**.err will be available in the {cluster_name}-ray_logs_err log group. Log streams are named after the EC2 instance ID that emitted their logs. Extended EC2 metrics including CPU/Disk/Memory usage and process statistics can be found in the {cluster_name}-ray-CWAgent metric namespace.

Dashboard: You will have a cluster-level dashboard showing total cluster CPUs and available object store memory. Process counts, disk usage, memory usage, and CPU utilization will be displayed as both cluster-level sums and single-node maximums/averages.

Alarms: Node-level alarms tracking prolonged high memory, disk, and CPU usage are configured. Alarm actions are NOT set, and must be manually provided in your alarm config file.

For more advanced options, see the Agent, Dashboard and Alarm config user guides.

CloudWatch Agent, Dashboard, and Alarm JSON config files support the following variables:

{instance_id}: Replaced with each EC2 instance ID in your Ray cluster.

{region}: Replaced with your Ray cluster’s region.

{cluster_name}: Replaced with your Ray cluster name.

See CloudWatch Agent Configuration File Details for additional variables supported natively by the Unified CloudWatch Agent.


Remember to replace the AlarmActions placeholder in your CloudWatch Alarm config file!

    "TODO: Add alarm actions! See"

3. Reference your CloudWatch JSON config files in your cluster config YAML.¶

Specify the file path to your CloudWatch JSON config files relative to the working directory that you will run ray up from:

           config: "cloudwatch/example-cloudwatch-agent-config.json"

4. Set your IAM Role and EC2 Instance Profile.¶

By default the ray-autoscaler-cloudwatch-v1 IAM role and EC2 instance profile is created at Ray cluster launch time. This role contains all additional permissions required to integrate CloudWatch with Ray, namely the CloudWatchAgentAdminPolicy, AmazonSSMManagedInstanceCore, ssm:SendCommand, ssm:ListCommandInvocations, and iam:PassRole managed policies.

Ensure that all worker nodes are configured to use the ray-autoscaler-cloudwatch-v1 EC2 instance profile in your cluster config YAML:

        InstanceType: c5a.large
            Name: ray-autoscaler-cloudwatch-v1

5. Export Ray system metrics to CloudWatch.¶

To export Ray’s Prometheus system metrics to CloudWatch, first ensure that your cluster has the Ray Dashboard installed, then uncomment the head_setup_commands section in example-cloudwatch.yaml file file. You can find Ray Prometheus metrics in the {cluster_name}-ray-prometheus metric namespace.

# Make `` executable.
- >-
  RAY_INSTALL_DIR=`pip show ray | grep -Po "(?<=Location:).*"`
  && sudo chmod +x $RAY_INSTALL_DIR/ray/autoscaler/aws/cloudwatch/
# Copy `prometheus.yml` to Unified CloudWatch Agent folder
- >-
  RAY_INSTALL_DIR=`pip show ray | grep -Po "(?<=Location:).*"`
  && sudo cp -f $RAY_INSTALL_DIR/ray/autoscaler/aws/cloudwatch/prometheus.yml /opt/aws/amazon-cloudwatch-agent/etc
# First get current cluster name, then let the Unified CloudWatch Agent restart and use `AmazonCloudWatch-ray_agent_config_{cluster_name}` parameter at SSM Parameter Store.
- >-
  nohup sudo sh -c "`pip show ray | grep -Po "(?<=Location:).*"`/ray/autoscaler/aws/cloudwatch/
  `cat ~/ray_bootstrap_config.yaml | jq '.cluster_name'`
  >> '/opt/aws/amazon-cloudwatch-agent/logs/ray_prometheus_waiter.out' 2>> '/opt/aws/amazon-cloudwatch-agent/logs/ray_prometheus_waiter.err'" &

6. Update CloudWatch Agent, Dashboard and Alarm config files.¶

You can apply changes to the CloudWatch Logs, Metrics, Dashboard, and Alarms for your cluster by simply modifying the CloudWatch config files referenced by your Ray cluster config YAML and re-running ray up example-cloudwatch.yaml. The Unified CloudWatch Agent will be automatically restarted on all cluster nodes, and your config changes will be applied.