A simple dynamic Ansible inventory which uses node (server) information from teleport.

teleport-inventory.py

#!/usr/bin/env python3

"""Teleport Inventory Documentation.

Very simple inventory script which will use teleport as a dynamic inventory source.
The script assumes you've logged in and have access to the teleport service.

The script will read machines and return JSON information from teleport. Once the
return information is sourced, it will format the inventory using the node name
as the target host and the labels as hostvars and groups.


Example Setup

When running this inventory ansible requires some basic instructions which can
be set via environment variables or through the ansible config file.

$ export ANSIBLE_SCP_IF_SSH=False
$ export ANSIBLE_SSH_ARGS="-F ${HOME}/.ssh/teleport.cfg"
$ export ANSIBLE_INVENTORY_ENABLED=script
$ export ANSIBLE_HOST_KEY_CHECKING=False

NOTE(cloudnull): The ${HOME}/.ssh/teleport.cfg file is generated by using the
                `tsh config` command then customized based on individual
                needs.


Example ssh configuration entry to proxy commands through teleport.

$ export TELEPORT_DOMAIN=teleport.example.com
$ export TELEPORT_USER=cloudnull
$ cat > ~/.ssh/teleport.cfg <<EOF
Host * !${TELEPORT_DOMAIN}
    UserKnownHostsFile "${HOME}/.tsh/known_hosts"
    IdentityFile "${HOME}/.tsh/keys/${TELEPORT_DOMAIN}/${TELEPORT_USER}"
    CertificateFile "${HOME}/.tsh/keys/${TELEPORT_DOMAIN}/${TELEPORT_USER}-ssh/${TELEPORT_DOMAIN}-cert.pub"
    PubkeyAcceptedKeyTypes +ssh-rsa-cert-v01@openssh.com
    Port 3022
    CheckHostIP no
    ProxyCommand "$(which tsh)" proxy ssh --cluster=${TELEPORT_DOMAIN} --proxy=${TELEPORT_DOMAIN} %r@%h:%p
EOF

NOTE(cloudnull): The above ssh configuration needs to have all variables
                 replaced to work.


Example login process

$ tsh login --proxy=teleport.example.com --user=teleport-admin
If browser window does not open automatically, open it by clicking on the link:
 http://127.0.0.1:42337/83facfc0-e899-44dc-aa6c-32179e3d5b0b
> Profile URL:        https://teleport.example.com:443
  Logged in as:       teleport-admin
  Cluster:            teleport.example.com
  Roles:              access
  Logins:             root, ubuntu, debian, fedora, centos, -teleport-internal-join
  Kubernetes:         enabled
  Valid until:        2022-09-16 08:03:05 -0500 CDT [valid for 12h0m0s]
  Extensions:         permit-agent-forwarding, permit-port-forwarding, permit-pty

NOTE(cloudnull): The above tsh login will provide access to the teleport cluster, which
                 will allow you to run inventory script which will return an Ansible
                 inventory JSON.


Inventory return example.

>>> {
...     "_meta": {
...         "hostvars": {
...             "alluvial-0": {
...                 "ansible_user": "ubuntu",
...                 "teleport_id": 1663292578982084621,
...                 "arch": "x86_64",
...                 "codename": "jammy",
...                 "environment": "dev"
...             },
...             "compute-0": {
...                 "ansible_user": "carter",
...                 "teleport_id": 1663292546493240726,
...                 "arch": "x86_64",
...                 "codename": "jammy",
...                 "environment": "prod"
...             },
...             "curator-0": {
...                 "ansible_user": "debian",
...                 "teleport_id": 1663292584620339609,
...                 "arch": "x86_64",
...                 "codename": "bullseye",
...                 "environment": "prod"
...             },
...             "plexmediaserver-0": {
...                 "ansible_user": "debian",
...                 "teleport_id": 1663292540612813467,
...                 "arch": "x86_64",
...                 "codename": "bullseye",
...                 "environment": "prod"
...             },
...             "rtmprelay-0": {
...                 "ansible_user": "debian",
...                 "teleport_id": 1663292583673456110,
...                 "arch": "x86_64",
...                 "codename": "bullseye",
...                 "environment": "prod"
...             },
...             "teleport-0": {
...                 "ansible_user": "debian",
...                 "teleport_id": 1663292588270337453,
...                 "arch": "x86_64",
...                 "codename": "bullseye",
...                 "environment": "prod"
...             },
...             "thelounge-0": {
...                 "ansible_user": "debian",
...                 "teleport_id": 1663292533524229273,
...                 "arch": "x86_64",
...                 "codename": "bullseye",
...                 "environment": "prod"
...             },
...             "unbound-0": {
...                 "ansible_user": "debian",
...                 "teleport_id": 1663292535344206453,
...                 "arch": "x86_64",
...                 "codename": "bullseye",
...                 "environment": "prod"
...             },
...             "unifi-0": {
...                 "ansible_user": "debian",
...                 "teleport_id": 1663292528952201832,
...                 "arch": "x86_64",
...                 "codename": "bullseye",
...                 "environment": "prod"
...             },
...             "wireguard-0": {
...                 "ansible_user": "debian",
...                 "teleport_id": 1663292535570354336,
...                 "arch": "x86_64",
...                 "codename": "bullseye",
...                 "environment": "prod"
...             }
...         }
...     },
...     "all": {
...         "hosts": [
...             "alluvial-0",
...             "compute-0",
...             "curator-0",
...             "plexmediaserver-0",
...             "rtmprelay-0",
...             "teleport-0",
...             "thelounge-0",
...             "unbound-0",
...             "unifi-0",
...             "wireguard-0"
...         ],
...         "children": []
...     },
...     "x86_64": {
...         "hosts": [
...             "alluvial-0",
...             "compute-0",
...             "curator-0",
...             "plexmediaserver-0",
...             "rtmprelay-0",
...             "teleport-0",
...             "thelounge-0",
...             "unbound-0",
...             "unifi-0",
...             "wireguard-0"
...         ],
...         "children": []
...     },
...     "jammy": {
...         "hosts": [
...             "alluvial-0",
...             "compute-0"
...         ],
...         "children": []
...     },
...     "dev": {
...         "hosts": [
...             "alluvial-0"
...         ],
...         "children": []
...     },
...     "teleport_cloudnull_dev": {
...         "hosts": [
...             "wireguard-0"
...         ],
...         "children": []
...     },
...     "prod": {
...         "hosts": [
...             "compute-0",
...             "curator-0",
...             "plexmediaserver-0",
...             "rtmprelay-0",
...             "teleport-0",
...             "thelounge-0",
...             "unbound-0",
...             "unifi-0",
...             "wireguard-0"
...         ],
...         "children": []
...     },
...     "bullseye": {
...         "hosts": [
...             "curator-0",
...             "plexmediaserver-0",
...             "rtmprelay-0",
...             "teleport-0",
...             "thelounge-0",
...             "unbound-0",
...             "unifi-0",
...             "wireguard-0"
...         ],
...         "children": []
...     }
... }

NOTE(cloudnull): Once the ssh config is in place, the Ansible configuration is set, and
                 teleport is logged in, Ansible can be run natively.


Example Ansible Ad-Hoc command

$ ansible -i teleport-inventory.py -m ping all

Example Ansible Playbook command

$ ansible-playbook -i teleport-inventory.py example-playbook.yaml
"""


import json
import subprocess


INVENTORY = {
    "_meta": {"hostvars": {}},
    "all": {
        "hosts": [],
        "children": [],
    },
}


def _group_add(group_name, hostname):
    """Set group information for a given name and host.

    :param group_name: String
    :param hostname: String
    """
    try:
        group = INVENTORY[group_name]
    except KeyError:
        # Per ansible spec, group names can not have dashes in them.
        group_name = group_name.replace("-", "_")
        # Per ansible spec, group names can not have periods in them.
        group_name = group_name.replace(".", "_")
        # Per ansible spec, group names can not start with an int.
        try:
            int(group_name[0])
        except ValueError:
            pass
        else:
            return

        INVENTORY.setdefault(group_name, {"hosts": [], "children": []})
        group = INVENTORY[group_name]

    group["hosts"].append(hostname)
    group["hosts"] = sorted(set(group["hosts"]))


def main():
    """Return dynamic inventory using teleport data.

    :returns: String
    """
    # Presently using subprocess to get the node JSON, may revise this later.
    tsh_return = subprocess.run(
        "tsh ls --all --format=json", shell=True, capture_output=True
    )
    try:
        teleport_items = json.loads(tsh_return.stdout)
    except Exception:
        raise SystemExit("No inventory JSON data found. Check for valid login via tsh.")
    else:
        if not teleport_items:
            raise SystemExit(
                "Nothing available via teleport, check for valid login via tsh."
            )

    for item in teleport_items:
        node = item["node"]
        hostname = node["spec"]["hostname"]

        _group_add(group_name=item["cluster"], hostname=hostname)

        meta_data = INVENTORY["_meta"]["hostvars"]
        all_data = INVENTORY["all"]
        all_data["hosts"].append(hostname)
        all_data["hosts"] = sorted(set(all_data["hosts"]))

        for k, v in node["metadata"]["labels"].items():
            try:
                host_vars = meta_data[hostname]
            except KeyError:
                host_vars = meta_data[hostname] = dict()

            host_vars[k] = v
            host_vars["teleport_id"] = node["metadata"]["id"]

            # If a label is an ansible variable, omit it from groups
            if k.startswith("ansible_"):
                continue

            _group_add(group_name=v, hostname=hostname)

    return json.dumps(INVENTORY, indent=4)


if __name__ == "__main__":
    print(main())

This gist has been promoted to a real repository. You can find the repository here: https://github.com/cloudnull/teleport-ansible

The repo is also installable via pip, just run pip install teleport-ansible. Once installed you can access the inventory script with the command teleport-ansible. Once installed, set the script into Ansible config and profit.

export ANSIBLE_INVENTORY="$(command -v teleport-ansible)"

You can also download the maintained inventory script and run without installing.

curl https://raw.githubusercontent.com/cloudnull/teleport-ansible/master/teleport-inventory.py -o teleport-inventory.py