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Forwarding Access Logs using FluentD
Forwarding Access Logs using FluentD

Length: 18:36

Version: 14.x

Export Events with Fluentd

Fluentd is an open source data collector for a unified logging layer. In this guide, we will:

  • Set up Teleport's Event Handler plugin.
  • Forward events with Fluentd.

This guide also serves as an explanation for the Teleport Event Handler plugin, using Fluentd as the target service. We'll create a local Docker container as a destination for the Event Handler:

The Teleport Fluentd plugin

You can follow the instructions below for a local proof-of-concept demo, or use any of the additional installation instructions to configure the Teleport Event Handler to integrate with your infrastructure.

Prerequisites​

  • A running Teleport cluster version 14.3.33 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.

Recommended: Configure Machine ID to provide short-lived Teleport credentials to the plugin. Before following this guide, follow a Machine ID deployment guide to run the tbot binary on your infrastructure.

  • Fluentd version v1.12.4 or greater.

  • Docker version v20.10.7.

  • 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 [email protected]
    $ tctl status
    # Cluster  teleport.example.com
    # Version  14.3.33
    # 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.

  • On your workstation, create a folder called event-handler, to hold configuration files and plugin state:

    $ mkdir -p event-handler
    $ cd event-handler

Step 1/6. Install the event handler plugin​

The Teleport event handler runs alongside the Fluentd forwarder, receives events from Teleport's events API, and forwards them to Fluentd.

$ curl -L -O https://get.gravitational.com/teleport-event-handler-v14.3.3-linux-amd64-bin.tar.gz
$ tar -zxvf teleport-event-handler-v14.3.3-linux-amd64-bin.tar.gz
$ sudo ./teleport-event-handler/install

We currently only build the Event Handler plugin for amd64 machines. For ARM architecture, you can build from source.

Step 2/6. Generate a plugin configuration​

Run the configure command to generate a sample configuration. Replace mytenant.teleport.sh with the DNS name of your Teleport Enterprise Cloud tenant:

$ teleport-event-handler configure . mytenant.teleport.sh:443

You'll see the following output:

Teleport event handler 14.3.33

[1] mTLS Fluentd certificates generated and saved to ca.crt, ca.key, server.crt, server.key, client.crt, client.key
[2] Generated sample teleport-event-handler role and user file teleport-event-handler-role.yaml
[3] Generated sample fluentd configuration file fluent.conf
[4] Generated plugin configuration file teleport-event-handler.toml

The plugin generates several setup files:

$ ls -l
# -rw------- 1 bob bob     1038 Jul  1 11:14 ca.crt
# -rw------- 1 bob bob     1679 Jul  1 11:14 ca.key
# -rw------- 1 bob bob     1042 Jul  1 11:14 client.crt
# -rw------- 1 bob bob     1679 Jul  1 11:14 client.key
# -rw------- 1 bob bob      541 Jul  1 11:14 fluent.conf
# -rw------- 1 bob bob     1078 Jul  1 11:14 server.crt
# -rw------- 1 bob bob     1766 Jul  1 11:14 server.key
# -rw------- 1 bob bob      260 Jul  1 11:14 teleport-event-handler-role.yaml
# -rw------- 1 bob bob      343 Jul  1 11:14 teleport-event-handler.toml
File(s)Purpose
ca.crt and ca.keySelf-signed CA certificate and private key for Fluentd
server.crt and server.keyFluentd server certificate and key
client.crt and client.keyFluentd client certificate and key, all signed by the generated CA
teleport-event-handler-role.yamluser and role resource definitions for Teleport's event handler
fluent.confFluentd plugin configuration
Running the Event Handler separately from the log forwarder

This guide assumes that you are running the Event Handler on the same host or Kubernetes pod as your log forwarder. If you are not, you will need to instruct the Event Handler to generate mTLS certificates for subjects besides localhost. To do this, use the --cn and --dns-names flags of the teleport-event-handler configure command.

For example, if your log forwarder is addressable at forwarder.example.com and the Event Handler at handler.example.com, you would run the following configure command:

$ teleport-event-handler configure --cn=handler.example.com --dns-names=forwarder.example.com

The command generates client and server certificates with the subjects set to the value of --cn.

The --dns-names flag accepts a comma-separated list of DNS names. It will append subject alternative names (SANs) to the server certificate (the one you will provide to your log forwarder) for each DNS name in the list. The Event Handler looks up each DNS name before appending it as an SAN and exits with an error if the lookup fails.

If you have an existing Fluentd setup with TLS, issue a client certificate and key from the same certificate authority for the Teleport Event Handler to use.

Step 3/6. Create a user and role for reading audit events​

The teleport-event-handler configure command generated a file called teleport-event-handler-role.yaml. This file defines a teleport-event-handler role and a user with read-only access to the event API:

kind: role
metadata:
  name: teleport-event-handler
spec:
  allow:
    rules:
      - resources: ['event', 'session']
        verbs: ['list','read']
version: v5
---
kind: user
metadata:
  name: teleport-event-handler
spec:
  roles: ['teleport-event-handler']
version: v2

Move this file to your workstation (or recreate it by pasting the snippet above) and use tctl on your workstation to create the role and the user:

$ tctl create -f teleport-event-handler-role.yaml
# user "teleport-event-handler" has been created
# role 'teleport-event-handler' has been created

Step 4/6. Create teleport-event-handler credentials​

Enable impersonation of the Fluentd plugin user​

In order for the Event Handler plugin to forward events from your Teleport cluster, it needs signed credentials from the cluster's certificate authority. The teleport-event-handler user cannot request this itself, and requires another user to impersonate this account in order to request credentials.

Create a role that enables your user to impersonate the teleport-event-handler user. First, paste the following YAML document into a file called teleport-event-handler-impersonator.yaml:

kind: role
version: v5
metadata:
  name: teleport-event-handler-impersonator
spec:
  options:
    # max_session_ttl defines the TTL (time to live) of SSH certificates
    # issued to the users with this role.
    max_session_ttl: 10h

  # This section declares a list of resource/verb combinations that are
  # allowed for the users of this role. By default nothing is allowed.
  allow:
    impersonate:
      users: ["teleport-event-handler"]
      roles: ["teleport-event-handler"]

Next, create the role:

$ tctl create teleport-event-handler-impersonator.yaml

If you are using Machine ID to provide short-lived credentials to the Event Handler, add this role to the Machine ID bot user. Otherwise, add this role to the user that generates signed credentials for the Event Handler:

Assign the teleport-event-handler-impersonator role to your Teleport user by running the appropriate commands for your authentication provider:

  1. Retrieve your local user's configuration resource:

    $ tctl get users/$(tsh status -f json | jq -r '.active.username') > out.yaml

  2. Edit out.yaml, adding teleport-event-handler-impersonator to the list of existing roles:

      roles:
       - access
       - auditor
       - editor
    +  - teleport-event-handler-impersonator

  3. Apply your changes:

    $ tctl create -f out.yaml

  4. Sign out of the Teleport cluster and sign in again to assume the new role.

Export an identity file for the Fluentd plugin user​

Give the plugin access to a Teleport identity file. We recommend using Machine ID for this in order to produce short-lived identity files that are less dangerous if exfiltrated, though in demo deployments, you can generate longer-lived identity files with tctl:

Configure tbot with an output that will produce the credentials needed by the plugin. As the plugin will be accessing the Teleport API, the correct output type to use is identity.

For this guide, the directory destination will be used. This will write these credentials to a specified directory on disk. Ensure that this directory can be written to by the Linux user that tbot runs as, and that it can be read by the Linux user that the plugin will run as.

Modify your tbot configuration to add an identity output.

If running tbot on a Linux server, use the directory output to write identity files to the /opt/machine-id directory:

outputs:
- type: identity
  destination:
    type: directory
    # For this guide, /opt/machine-id is used as the destination directory.
    # You may wish to customize this. Multiple outputs cannot share the same
    # destination.
    path: /opt/machine-id

If running tbot on Kubernetes, write the identity file to Kubernetes secret instead:

outputs:
  - type: identity
    destination:
      type: kubernetes_secret
      name: teleport-event-handler-identity

If operating tbot as a background service, restart it. If running tbot in one-shot mode, execute it now.

You should now see an identity file under /opt/machine-id or a Kubernetes secret named teleport-event-handler-identity. This contains the private key and signed certificates needed by the plugin to authenticate with the Teleport Auth Service.

Step 5/6. Start the Fluentd forwarder​

The Fluentd plugin will send events to your Fluentd instance using keys generated on the previous step.

The fluent.conf file generated earlier configures your Fluentd instance to accept events using TLS and print them:

<source>
    @type http
    port 8888

    <transport tls>
        client_cert_auth true

        # We are going to run fluentd in Docker. /keys will be mounted from the host file system.
        ca_path /keys/ca.crt
        cert_path /keys/server.crt
        private_key_path /keys/server.key
        private_key_passphrase ********** # Passphrase generated along with the keys
    </transport>

    <parse>
      @type json
      json_parser oj

      # This time format is used by the plugin. This field is required.
      time_type string
      time_format %Y-%m-%dT%H:%M:%S
    </parse>

    # If the number of events is high, fluentd will start failing the ingestion
    # with the following error message: buffer space has too many data errors.
    # The following configuration prevents data loss in case of a restart and
    # overcomes the limitations of the default fluentd buffer configuration.
    # This configuration is optional.
    # See https://docs.fluentd.org/configuration/buffer-section for more details.
    <buffer>
      @type file
      flush_thread_count 8
      flush_interval 1s
      chunk_limit_size 10M
      queue_limit_length 16
      retry_max_interval 30
      retry_forever true
    </buffer>
</source>

# Events sent to test.log will be dumped to STDOUT.
<match test.log>
  @type stdout
</match>

To try out this Fluentd configuration, start your fluentd instance:

$ docker run -u $(id -u ${USER}):$(id -g ${USER}) -p 8888:8888 -v $(pwd):/keys -v $(pwd)/fluent.conf:/fluentd/etc/fluent.conf fluent/fluentd:edge

This will consume your current terminal, so open a new one to continue following along.

Step 6/6. Run the Event Handler plugin​

Configure the Event Handler​

In this section, you will configure the Teleport Event Handler for your environment.

Earlier, we generated a file called teleport-event-handler.toml to configure the Fluentd event handler. This file includes setting similar to the following:

storage = "./storage"
timeout = "10s"
batch = 20
namespace = "default"

[forward.fluentd]
ca = "/home/bob/event-handler/ca.crt"
cert = "/home/bob/event-handler/client.crt"
key = "/home/bob/event-handler/client.key"
url = "https://fluentd.example.com:8888/test.log"
session-url = "https://fluentd.example.com:8888/session"

[teleport]
addr = "example.teleport.com:443"
identity = "identity"

Modify the configuration to replace fluentd.example.com with the domain name of your Fluentd deployment.

Next, modify the configuration file as follows:

addr: Include the hostname and HTTPS port of your Teleport Proxy Service or Teleport Enterprise Cloud tenant (e.g., teleport.example.com:443 or mytenant.teleport.sh:443).

identity: Fill this in with the path to the identity file you exported earlier.

client_key, client_crt, root_cas: Comment these out, since we are not using them in this configuration.

If you are providing credentials to the Event Handler using a tbot binary that runs on a Linux server, make sure the value of identity in the Event Handler configuration is the same as the path of the identity file you configured tbot to generate, /opt/machine-id/identity.

Start the Teleport Event Handler​

Start the Teleport Teleport Event Handler by following the instructions below.

Copy the teleport-event-handler.toml file to /etc on your Linux server. Update the settings within the toml file to match your environment. Make sure to use absolute paths on settings such as identity and storage. Files and directories in use should only be accessible to the system user executing the teleport-event-handler service such as /var/lib/teleport-event-handler.

Next, create a systemd service definition at the path /usr/lib/systemd/system/teleport-event-handler.service with the following content:

[Unit]
Description=Teleport Event Handler
After=network.target

[Service]
Type=simple
Restart=always
ExecStart=/usr/local/bin/teleport-event-handler start --config=/etc/teleport-event-handler.toml --teleport-refresh-enabled=true
ExecReload=/bin/kill -HUP $MAINPID
PIDFile=/run/teleport-event-handler.pid

[Install]
WantedBy=multi-user.target

If you are not using Machine ID to provide short-lived credentials to the Event Handler, you can remove the --teleport-refresh-enabled true flag.

Enable and start the plugin:

$ sudo systemctl enable teleport-event-handler
$ sudo systemctl start teleport-event-handler
Choose when to start exporting events

You can configure when you would like the Teleport Event Handler to begin exporting events when you run the start command. This example will start exporting from May 5th, 2021:

$ teleport-event-handler start --config /etc/teleport-event-handler.toml --start-time "2021-05-05T00:00:00Z"

You can only determine the start time once, when first running the Teleport Event Handler. If you want to change the time frame later, remove the plugin state directory that you specified in the storage field of the handler's configuration file.

Once the Teleport Event Handler starts, you will see notifications about scanned and forwarded events:

$ sudo journalctl -u teleport-event-handler
DEBU   Event sent id:f19cf375-4da6-4338-bfdc-e38334c60fd1 index:0 ts:2022-09-21
18:51:04.849 +0000 UTC type:cert.create event-handler/app.go:140
...

Troubleshooting connection issues​

If the Teleport Event Handler is displaying error logs while connecting to your Teleport Cluster, ensure that:

  • The certificate the Teleport Event Handler is using to connect to your Teleport cluster is not past its expiration date. This is the value of the --ttl flag in the tctl auth sign command, which is 12 hours by default.
  • Ensure that in your Teleport Event Handler configuration file (teleport-event-handler.toml), you have provided the correct host and port for the Teleport Proxy Service or Auth Service.

Next Steps​

Read more about impersonation here.

While this guide uses the tctl auth sign command to issue credentials for the Teleport Event Handler, production clusters should use Machine ID for safer, more reliable renewals. Read our guide to getting started with Machine ID.

To see all of the options you can set in the values file for the teleport-plugin-event-handler Helm chart, consult our reference guide.