Skip to content

Latest commit

 

History

History
401 lines (332 loc) · 11.8 KB

ec2-discovery.mdx

File metadata and controls

401 lines (332 loc) · 11.8 KB
Raw
title description
Configure Teleport to Automatically Enroll EC2 instances (Preview)
How to 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

(!docs/pages/includes/edition-prereqs-tabs.mdx!)

  • AWS account with EC2 instances and permissions to create and attach IAM policies.
  • EC2 instances running Ubuntu/Debian/RHEL/Amazon Linux 2 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.)
  • (!docs/pages/includes/tctl.mdx!)

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
  # set a long expiry time, as the default for tokens is only 30 minutes
  expires: "3000-01-01T00:00:00Z"
spec:
  # use the minimal set of roles required
  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

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:

(!docs/pages/includes/install-linux.mdx!)

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: v2
teleport:
  join_params:
    token_name: "/tmp/token"
    method: token
  auth_servers:
  - "teleport.example.com:3080"
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"]
     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:GetCommandInvocation",
                "ssm:SendCommand"
            ],
            "Resource": [
                "*"
            ]
        }
    ]
}

2. Create IAM Policy "TeleportEC2DiscoveryBoundary":
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeInstances",
                "ssm:GetCommandInvocation",
                "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 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 the be edited to change what gets executed when enrolling discovered EC2 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/v12. See installation for more details.

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 by the Systems Manager document will evaluate to a script with the following contents:

echo teleport.example.com
echo Teleport-(=teleport.version=)
echo Repository Channel: stable/v(=teleport.version=)

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

(!docs/pages/includes/aws-credentials.mdx service="the Discovery Service"!)

(!docs/pages/includes/start-teleport.mdx service="the Discovery Service"!)

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.

Next steps