Securing Infrastructure Access at Scale in Large Enterprises
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Teleport Role Templates

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As organizations grow, infrastructure teams have to figure out how to define access control policies that don't require manual configuration every time people join, leave, and form new teams.

Here are some common examples of such policies:

  • Grant every single sign-on user an SSH login generated from their email.
  • Assign each team member to their team's Kubernetes group.
  • Limit the dev team to a read-only replica of a database.

Let's explore how Teleport's role templates provide a way to describe these and other policies.

Prerequisites

  • A running Teleport cluster version 16.4.7 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.

    Visit Installation for instructions on downloading tctl and tsh.

  • 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. For example: 
    tsh login --proxy=teleport.example.com --user=email@example.com
    tctl status
    Cluster  teleport.example.com
    Version  16.4.7
    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.

Local users

Imagine you have two users, Alice and Bob. We would like to set the following access policies:

  • Alice can log in as SSH user admin and Kubernetes group edit
  • Bob can log in as ubuntu and Kubernetes group view

We can create two roles, one for each user in file roles.yaml:

kind: role
version: v7
metadata:
  name: alice
spec:
  allow:
    logins: ['admin']
    kubernetes_groups: ['edit']
    node_labels:
      '*': '*'
    kubernetes_labels:
      '*': '*'
    kubernetes_resources:
      - kind: '*'
        namespace: '*'
        name: '*'
        verbs: ['*']
---
kind: role
version: v7
metadata:
  name: bob
spec:
  allow:
    logins: ['ubuntu']
    kubernetes_groups: ['view']
    node_labels:
      '*': '*'
    kubernetes_labels:
      '*': '*'
    kubernetes_resources:
      - kind: '*'
        namespace: '*'
        name: '*'
        verbs: ['*']

You can create roles and invite Alice and Bob as local users:

tctl create -f roles.yaml
tctl users add alice --roles=alice
tctl users add bob --roles=bob

Having one role per user is not going to scale well. Because the roles are so similar, we can assign variables to each user, and use just one role template for both Alice and Bob.

Let's create a role template called devs.yaml:

kind: role
version: v7
metadata:
  name: devs
spec:
  allow:
    logins: ['{{internal.logins}}']
    kubernetes_groups: ['{{internal.kubernetes_groups}}']
    node_labels:
      '*': '*'
    kubernetes_labels:
      '*': '*'
    kubernetes_resources:
      - kind: '*'
        namespace: '*'
        name: '*'
        verbs: ['*']

Any role becomes a template once it starts using template variables.

Just like roles, role templates are valid YAML and validate both the structure and types.

The role template devs is using the internal notation to refer to the local user's traits logins and kubernetes_groups. The internal notation only supports a limited set of predefined traits. Use the external.<trait-name> syntax if using a custom trait with a local user.

Use tctl to create a role template:

tctl create -f devs.yaml

The last step is to update Alice's and Bob's users with traits. Here is an example of user resources in a file called traits.yaml:

kind: user
version: v2
metadata:
  name: alice
spec:
  roles: ['devs']
  traits:
    logins: ['admin']
    kubernetes_groups: ['edit']
---
kind: user
version: v2
metadata:
  name: bob
spec:
  roles: ['devs']
  traits:
    logins: ['ubuntu']
    kubernetes_groups: ['view']

Update both users' entries with the tctl create -f command:

tctl create -f traits.yaml
user "alice" has been updated

Once Alice logs in, she will receive SSH and X.509 certificates with a new role. SSH logins and Kubernetes groups will also be set:

tsh login --proxy=teleport.example.com --user=alice

> Profile URL:        https://teleport.example.com:443
Logged in as:       alice
Cluster:            teleport.example.com
Roles:              devs*
Logins:             admin
Kubernetes:         enabled
Kubernetes groups:  edit
Valid until:        2021-03-26 07:13:57 -0700 PDT [valid for 12h0m0s]
Extensions:         permit-port-forwarding, permit-pty
tsh login --proxy=mytenant.teleport.sh --user=alice

> Profile URL:        https://mytenant.teleport.sh:443
Logged in as:       alice
Cluster:            mytenant.teleport.sh
Roles:              devs*
Logins:             admin
Kubernetes:         enabled
Kubernetes groups:  edit
Valid until:        2021-03-26 07:13:57 -0700 PDT [valid for 12h0m0s]
Extensions:         permit-port-forwarding, permit-pty

SSO users

Identity provider admins can assign metadata to a user such as group membership or access permissions. Administrators configure what metadata is shared with Teleport. Teleport receives user metadata keys and values as OIDC claims or SAML attributes during the single sign-on redirect flow:

# Alice has email alice@example.com. Email is a standard OIDC claim.
email: "alice@example.com"
# Alice is a member of groups admins and devs
groups: ["admins", "devs"]
# She can access prod and staging environments
env: ["prod", "staging"]

Let's create a role template called sso-users that expects external attribute logins to be set by an identity provider. Save this role as sso-users.yaml:

kind: role
version: v7
metadata:
  name: sso-users
spec:
  allow:
    logins: ['{{external.logins}}']
    node_labels:
      '*': '*'
    kubernetes_labels:
      '*': '*'
    kubernetes_resources:
      - kind: '*'
        namespace: '*'
        name: '*'
        verbs: ['*']

A GitHub connector called github.yaml maps every member of team cyber in organization octocats to the role sso-users:

kind: github
version: v3
metadata:
  name: github
spec:
  # Client ID of GitHub OAuth app
  client_id: client-id
  # Client secret of GitHub OAuth app
  client_secret: secret-data-here
  # Connector display name that will be shown on the Web UI login screen
  display: GitHub
  # Callback URL that will be called after successful authentication
  redirect_url: https://teleport.example.com/v1/webapi/github/callback
  # Mapping of org/team memberships onto allowed Teleport roles
  teams_to_roles:
    - organization: octocats # GitHub organization name
      team: cyber # GitHub team name within that organization
      # Role names to map to
      roles:
        - sso-users

Create this connector using tctl:

tctl create -f github.yaml

Once Bob logs in using SSO, he will receive SSH and X.509 certificates with a new role and SSH logins generated using the sso-users role template:

tsh login --proxy=teleport.example.com --auth=github

> Profile URL:        https://teleport.example.com:443
Logged in as:       bob
Cluster:            teleport.example.com
Roles:              sso-users*
Logins:             bob
Kubernetes:         enabled
Kubernetes groups:  edit
Valid until:        2021-03-26 07:13:57 -0700 PDT [valid for 12h0m0s]
Extensions:         permit-port-forwarding, permit-pty
tsh login --proxy=mytenant.teleport.sh --auth=github

> Profile URL:        https://mytenant.teleport.sh:443
Logged in as:       bob
Cluster:            mytenant.teleport.sh
Roles:              sso-users*
Logins:             bob
Kubernetes:         enabled
Kubernetes groups:  edit
Valid until:        2021-03-26 07:13:57 -0700 PDT [valid for 12h0m0s]
Extensions:         permit-port-forwarding, permit-pty

Interpolation rules

Administrators can configure what attributes identity providers return during single-sign on and present to Teleport. Let's review a couple of scenarios and see how Teleport interpolates the variables.

Let's go back to to the list of attributes for Alice's user entry:

# Alice has an email alice@example.com. Email is a standard OIDC claim.
email: "alice@example.com"
# Alice is a member of groups admins and devs
groups: ["admins", "devs"]
# She can access prod and staging environments
env: ["prod", "staging"]

Let's see how these variables are used with role template interpolation:

kind: role
version: v7
metadata:
  name: interpolation
spec:
  allow:
    # Role template fields can mix hard-coded values and variables.
    logins: ['{{external.logins}}', 'admin']

    # Roles support interpolation in string values.
    kubernetes_users: ['IAM#{{external.email}};']

    # Lists get expanded into lists.
    kubernetes_groups: ['{{external.groups}}']

    # Functions transform variables.
    database_users: ['{{email.local(external.email)}}']
    db_labels:
      'env': '{{regexp.replace(external.env, "^(staging)$", "$1")}}'

    # Labels can mix template and hard-coded values.
    node_labels:
      'env': '{{external.env}}'
      'region': 'us-west-2'

    kubernetes_labels:
      '*': '*'
    kubernetes_resources:
      - kind: '*'
        namespace: '*'
        name: '*'
        verbs: ['*']

After interpolation with Alice's SSO user attributes, the role template will behave as the following role:

kind: role
version: v7
metadata:
  name: interpolation
spec:
  allow:
    # The variable external.logins is not sent by provider and it renders empty,
    # leaving only hard-coded admin value
    logins: ['admin']

    # The variable external.email is expanded in a string.
    kubernetes_users: ['IAM#alice@example.com;']

    # The variable external.groups gets replaced with a list.
    kubernetes_groups: ['devs', 'admins']

    # The function email.local will take a local part of the external.email attribute.
    database_users: ['alice']

    # The function regexp.replace will transform and filter only matching values.
    db_labels:
      'env': 'staging'

    # Node labels have 'env' replaced from a variable and 'region' hard-coded.
    node_labels:
      'env': ['prod', 'staging']
      'region': 'us-west-2'

    kubernetes_labels:
      '*': '*'

    kubernetes_resources:
      - kind: '*'
        namespace: '*'
        name: '*'
        verbs: ['*']

Available interpolation functions include:

FunctionDescription
email.local(variable)Extracts the local part of an email address. email.local(alice@example.com) evaluates to alice.
regexp.replace(variable, expression, replacement)Finds all matches of expression and replaces them with replacement. This supports expansion, e.g. regexp.replace(external.email, "^(.*)@example.com$", "$1"). Values which do not match the expression will be filtered out. $N is used to refer to the Nth captured group, starting at $1.

Templating in Access Requests

Access and Reviewer Request specifications do not use the same interpolation system as logins, labels etc. Instead, you can use the claims_to_roles clause in the request and review rules to specify one or more patterns to match.

For example, given the following rule template:

kind: role
version: v3
metadata:
  name: product-admin
spec:
  allow:
    request:
      # `roles` is a static list of roles a user with the `product-admin` role may
      # request temporary access to
      roles: [access]

      claims_to_roles:
        - claim: 'projects'
          value: '^product-(.*)$' # matches all group names with a leading 'product-'
          roles: ['$1-admin']     # generates a role name from the value capture

For example, we could grant Alice the product-admin role and add some entries to the projects trait:

kind: user
version: v2
metadata:
  name: alice
spec:
  roles: ['dev', 'product-admin']
  traits:
    projects: ['internal-tooling', 'product-alpha', 'product-beta']

In this case, Alice would be allowed to request access to the RBAC roles access (from the static role list) and alpha-admin and beta-admin (from the claims_to_roles mapping).

The same syntax applies for Review Requests.