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Configure Teleport to Automatically Enroll EC2 instances

The Teleport Discovery Service can connect to Amazon EC2 and automatically discover and enroll EC2 instances matching configured labels. It will then execute an install script on these discovered instances using AWS Systems Manager that will install Teleport, start it and join the cluster.

In this scenario, Teleport Discovery Service uses an IAM invite token with a long time-to-live (TTL), so that new instances can be discovered and added to the Teleport cluster for the lifetime of the token.

Prerequisites​

  • A running Teleport cluster version 15.4.22 or above. If you want to get started with Teleport, sign up for a free trial or set up a demo environment.

  • The tctl admin tool and tsh client tool.

    On Teleport Enterprise, you must use the Enterprise version of tctl, which you can download from your Teleport account workspace. Otherwise, visit Installation for instructions on downloading tctl and tsh for Teleport Community Edition.

  • AWS account with EC2 instances and permissions to create and attach IAM policies.
  • EC2 instances running Ubuntu/Debian/RHEL/Amazon Linux 2/Amazon Linux 2023 and SSM agent version 3.1 or greater if making use of the default Teleport install script. (For other Linux distributions, you can install Teleport manually.)
  • To check that you can connect to your Teleport cluster, sign in with tsh login, then verify that you can run tctl commands using your current credentials. tctl is supported on macOS and Linux machines. For example: 
    $ tsh login --proxy=teleport.example.com --user=email@example.com
    $ tctl status
    # Cluster  teleport.example.com
    # Version  15.4.22
    # CA pin   sha256:abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678abdc1245efgh5678
    If you can connect to the cluster and run the tctl status command, you can use your current credentials to run subsequent tctl commands from your workstation. If you host your own Teleport cluster, you can also run tctl commands on the computer that hosts the Teleport Auth Service for full permissions.

Step 1/7. Create an EC2 invite token​

When discovering EC2 instances, Teleport makes use of IAM invite tokens for authenticating joining Nodes.

Create a file called token.yaml:

# token.yaml
kind: token
version: v2
metadata:
  # the token name is not a secret because instances must prove that they are
  # running in your AWS account to use this token
  name: aws-discovery-iam-token
spec:
  # use the minimal set of roles required (e.g. Node, App, Kube, DB, WindowsDesktop)
  roles: [Node]

  # set the join method allowed for this token
  join_method: iam

  allow:
  # specify the AWS account which Nodes may join from
  - aws_account: "123456789"

Assign the aws_account field to your AWS account number. Add the token to the Teleport cluster with:

$ tctl create -f token.yaml

Step 2/7. Define an IAM policy​

The teleport discovery bootstrap command will automate the process of defining and implementing IAM policies required to make auto-discovery work. It requires only a single pre-defined policy, attached to the EC2 instance running the command:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "iam:GetPolicy",
                "iam:TagPolicy",
                "iam:ListPolicyVersions",
                "iam:CreatePolicyVersion",
                "iam:CreatePolicy",
                "ssm:CreateDocument",
                "iam:DeletePolicyVersion",
                "iam:AttachRolePolicy",
                "iam:PutRolePermissionsBoundary"
            ],
            "Resource": "*"
        }
    ]
}

Create this policy and apply it to the Node (EC2 instance) that will run the Discovery Service.

Step 3/7. Install Teleport on the Discovery Node​

tip

If you plan on running the Discovery Service on the same Node already running another Teleport service (Auth or Proxy, for example), you can skip this step.

Install Teleport on the EC2 instance that will run the Discovery Service:

Install Teleport on your Linux server:

  1. Assign edition to one of the following, depending on your Teleport edition:

    EditionValue
    Teleport Enterprise Cloudcloud
    Teleport Enterprise (Self-Hosted)enterprise
    Teleport Community Editionoss

  2. Get the version of Teleport to install. If you have automatic agent updates enabled in your cluster, query the latest Teleport version that is compatible with the updater:

    $ TELEPORT_DOMAIN=example.teleport.com
    $ TELEPORT_VERSION="$(curl https://$TELEPORT_DOMAIN/v1/webapi/automaticupgrades/channel/default/version | sed 's/v//')"

    Otherwise, get the version of your Teleport cluster:

    $ TELEPORT_DOMAIN=example.teleport.com
    $ TELEPORT_VERSION="$(curl https://$TELEPORT_DOMAIN/v1/webapi/ping | jq -r '.server_version')"

  3. Install Teleport on your Linux server:

    $ curl https://cdn.teleport.dev/install-v15.4.22.sh | bash -s ${TELEPORT_VERSION} edition

    The installation script detects the package manager on your Linux server and uses it to install Teleport binaries. To customize your installation, learn about the Teleport package repositories in the installation guide.

Step 4/7. Configure Teleport to discover EC2 instances​

If you are running the Discovery Service on its own host, the service requires a valid invite token to connect to the cluster. Generate one by running the following command against your Teleport Auth Service:

$ tctl tokens add --type=discovery

Save the generated token in /tmp/token on the Node (EC2 instance) that will run the Discovery Service.

In order to enable EC2 instance discovery the discovery_service.aws section of teleport.yaml must include at least one entry:

version: v3
teleport:
  join_params:
    token_name: "/tmp/token"
    method: token
  proxy_server: "teleport.example.com:443"
auth_service:
  enabled: off
proxy_service:
  enabled: off
ssh_service:
  enabled: off
discovery_service:
  enabled: "yes"
  aws:
   - types: ["ec2"]
     regions: ["us-east-1","us-west-1"]
     install:
        join_params:
          token_name: aws-discovery-iam-token
          method: iam
     tags:
       "env": "prod" # Match EC2 instances where tag:env=prod
  • Edit the teleport.auth_servers key to match your Auth Service or Proxy Service's URI and port.
  • Adjust the keys under discovery_service.aws to match your EC2 environment, specifically the regions and tags you want to associate with the Discovery Service.

Step 5/7. Bootstrap the Discovery Service AWS configuration​

On the same Node as above, run teleport discovery bootstrap. This command will generate and display the additional IAM policies and AWS Systems Manager (SSM) documents required to enable the Discovery Service:

$ sudo teleport discovery bootstrap
Reading configuration at "/etc/teleport.yaml"...

AWS
1. Create IAM Policy "TeleportEC2Discovery":
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeInstances",
                "ssm:DescribeInstanceInformation",
                "ssm:GetCommandInvocation",
                "ssm:ListCommandInvocations",
                "ssm:SendCommand"
            ],
            "Resource": [
                "*"
            ]
        }
    ]
}

2. Create IAM Policy "TeleportEC2DiscoveryBoundary":
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeInstances",
                "ssm:DescribeInstanceInformation",
                "ssm:GetCommandInvocation",
                "ssm:ListCommandInvocations",
                "ssm:SendCommand"
            ],
            "Resource": [
                "*"
            ]
        }
    ]
}

3. Create SSM Document "TeleportDiscoveryInstaller":

schemaVersion: '2.2'
description: aws:runShellScript
parameters:
  token:
    type: String
    description: "(Required) The Teleport invite token to use when joining the cluster."
  scriptName:
    type: String
    description: "(Required) The Teleport installer script to use when joining the cluster."
mainSteps:
- action: aws:downloadContent
  name: downloadContent
  inputs:
    sourceType: "HTTP"
    destinationPath: "/tmp/installTeleport.sh"
    sourceInfo:
      url: "https://teleport.example.com:443/webapi/scripts/installer/{{ scriptName }}"
- action: aws:runShellScript
  name: runShellScript
  inputs:
    timeoutSeconds: '300'
    runCommand:
      - /bin/sh /tmp/installTeleport.sh "{{ token }}"

4. Attach IAM policies to "yourUser-discovery-role".

Confirm? [y/N]: y

Review the policies and confirm:

Confirm? [y/N]: y
✅[AWS] Create IAM Policy "TeleportEC2Discovery"... done.
✅[AWS] Create IAM Policy "TeleportEC2DiscoveryBoundary"... done.
✅[AWS] Create IAM SSM Document "TeleportDiscoveryInstaller"... done.
✅[AWS] Attach IAM policies to "alex-discovery-role"... done.

All EC2 instances that are to be added to the Teleport cluster by the Discovery Service must include the AmazonSSMManagedInstanceCore IAM policy in order to receive commands from the Discovery Service.

This policy includes the following permissions:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ssm:DescribeAssociation",
                "ssm:GetDeployablePatchSnapshotForInstance",
                "ssm:GetDocument",
                "ssm:DescribeDocument",
                "ssm:GetManifest",
                "ssm:GetParameter",
                "ssm:GetParameters",
                "ssm:ListAssociations",
                "ssm:ListInstanceAssociations",
                "ssm:PutInventory",
                "ssm:PutComplianceItems",
                "ssm:PutConfigurePackageResult",
                "ssm:UpdateAssociationStatus",
                "ssm:UpdateInstanceAssociationStatus",
                "ssm:UpdateInstanceInformation"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "ssmmessages:CreateControlChannel",
                "ssmmessages:CreateDataChannel",
                "ssmmessages:OpenControlChannel",
                "ssmmessages:OpenDataChannel"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "ec2messages:AcknowledgeMessage",
                "ec2messages:DeleteMessage",
                "ec2messages:FailMessage",
                "ec2messages:GetEndpoint",
                "ec2messages:GetMessages",
                "ec2messages:SendReply"
            ],
            "Resource": "*"
        }
    ]
}

Step 6/7. [Optional] Customize the default installer script​

To customize an installer, your user must have a role that allows list, create, read and update verbs on the installer resource.

Create a file called installer-manager.yaml with the following content:

kind: role
version: v5
metadata:
  name: installer-manager
spec:
  allow:
    rules:
      - resources: [installer]
        verbs: [list, create, read, update]

Create the role:

$ tctl create -f installer-manager.yaml
# role 'installer-manager' has been created

The preset editor role has the required permissions by default.

To customize the default installer script, execute the following command on your workstation:

$ tctl get installer/default-installer > teleport-default-installer.yaml

The resulting teleport-default-installer.yaml can be edited to change what gets executed when enrolling discovered instances.

After making the desired changes to the default installer, the resource can be updated by executing:

$ tctl create -f teleport-default-installer.yaml

Multiple installer resources can exist and be specified in the aws.install.script_name section of a discovery_service.aws list item in teleport.yaml:

discovery_service:
  aws:
    - types: ["ec2"]
      tags:
       - "env": "prod"
      install: # optional section when default-installer is used.
        script_name: "default-installer"
    - types: ["ec2"]
      tags:
       - "env": "devel"
      install:
        script_name: "devel-installer"

The installer resource has the following templating options:

  • {{ .MajorVersion }}: the major version of Teleport to use when installing from the repository.
  • {{ .PublicProxyAddr }}: the public address of the Teleport Proxy Service to connect to.
  • {{ .RepoChannel }}: Optional package repository (apt/yum) channel name. Has format <channel>/<version> e.g. stable/v15. See installation for more details.
  • {{ .AutomaticUpgrades }}: indicates whether Automatic Updates are enabled or disabled. Its value is either true or false. See Automatic Agent Updates for more information.
  • {{ .TeleportPackage }}: the Teleport package to use. Its value is either teleport-ent or teleport depending on whether the cluster is enterprise or not.

These can be used as follows:

kind: installer
metadata:
  name: default-installer
spec:
  script: |
    echo {{ .PublicProxyAddr }}
    echo Teleport-{{ .MajorVersion }}
    echo Repository Channel: {{ .RepoChannel }}
version: v1

Which, when retrieved for installation, will evaluate to a script with the following contents:

echo teleport.example.com
echo Teleport-15.4.22
echo Repository Channel: stable/v15.4.22

The default installer will take the following actions:

  • Add an official Teleport repository to supported Linux distributions.
  • Install Teleport via apt or yum.
  • Generate the Teleport config file and write it to /etc/teleport.yaml.
  • Enable and start the Teleport service.

Step 7/7. Start Teleport​

Grant the Discovery Service access to credentials that it can use to authenticate to AWS. If you are running the Discovery Service on an EC2 instance, you may use the EC2 Instance Metadata Service method. Otherwise, you must use environment variables:

Teleport will detect when it is running on an EC2 instance and use the Instance Metadata Service to fetch credentials.

The EC2 instance should be configured to use an EC2 instance profile. For more information, see: Using Instance Profiles.

Have multiple sources of AWS credentials?

Teleport's AWS client loads credentials from different sources in the following order:

  • Environment Variables
  • Shared credentials file
  • Shared configuration file (Teleport always enables shared configuration)
  • EC2 Instance Metadata (credentials only)

While you can provide AWS credentials via a shared credentials file or shared configuration file, you will need to run the Discovery Service with the AWS_PROFILE environment variable assigned to the name of your profile of choice.

If you have a specific use case that the instructions above do not account for, consult the documentation for the AWS SDK for Go for a detailed description of credential loading behavior.

Configure the Discovery Service to start automatically when the host boots up by creating a systemd service for it. The instructions depend on how you installed the Discovery Service.

On the host where you will run the Discovery Service, enable and start Teleport:

$ sudo systemctl enable teleport
$ sudo systemctl start teleport

You can check the status of the Discovery Service with systemctl status teleport and view its logs with journalctl -fu teleport.

Once you have started the Discovery Service, EC2 instances matching the tags you specified earlier will begin to be added to the Teleport cluster automatically.

Troubleshooting​

If Installs are showing failed or instances are failing to appear check the Command history in AWS System Manager -> Node Management -> Run Command. Select the instance-id of the Target to review Errors.

cannot unmarshal object into Go struct field​

If you encounter an error similar to the following:

invalid format in plugin properties map[destinationPath:/tmp/installTeleport.sh sourceInfo:map[url:[https://example.teleport.sh:443/webapi/scripts/installer/preprod-installer](https://example.teleport.sh/webapi/scripts/installer/preprod-installer)] sourceType:HTTP];
error json: cannot unmarshal object into Go struct field DownloadContentPlugin.sourceInfo of type string

It is likely that you're running an older SSM agent version. Upgrade to SSM agent version 3.1 or greater to resolve.

InvalidInstanceId: Instances [[i-123]] not in a valid state for account 456​

The following problems can cause this error:

  • The Discovery Service doesn't have permission to access the managed node.
  • AWS Systems Manager Agent (SSM Agent) isn't running. Verify that SSM Agent is running.
  • SSM Agent isn't registered with the SSM endpoint. Try reinstalling SSM Agent.
  • The discovered instance does not have permission to receive SSM commands, verify the instance includes the AmazonSSMManagedInstanceCore IAM policy.

See SSM RunCommand error codes and troubleshooting information in AWS documentation for more details:

Next steps​