Metrics

GoToSocial uses the OpenTelemetry Go SDK to enable instance admins to expose runtime metrics in the Prometheus metrics format.

Currently, the following metrics are collected:

• Go performance and runtime metrics
• Gin (HTTP server) metrics
• Bun (database) metrics

Enabling metrics

To enable metrics, first set the metrics-enabled configuration value to true in your config.yaml file:

metrics-enabled: true

Then, you will need to set some additional environment variables on the GoToSocial process in order to configure OpenTelemetry to expose metrics in the Prometheus format:

OTEL_METRICS_PRODUCERS=prometheus
OTEL_METRICS_EXPORTER=prometheus

By default, this configuration will instantiate an additional HTTP server running alongside the standard GoToSocial HTTP server, which exposes a Prometheus metrics endpoint at localhost:9464/metrics.

If you wish, you can further customize this metrics HTTP server by using the following environment variables to change the host and port:

OTEL_EXPORTER_PROMETHEUS_HOST=example.org
OTEL_EXPORTER_PROMETHEUS_PORT=9999

Serving metrics to the outside world

Bare metal, no reverse proxy

If you have deployed GoToSocial in a "bare-metal" fashion without a reverse proxy, you can expose the metrics endpoint to the outside world by setting OTEL_EXPORTER_PROMETHEUS_HOST to your host value. For example, if your GtS instance host configuration value is set to example.org, you should set OTEL_EXPORTER_PROMETHEUS_HOST=example.org. You should then be able to access your metrics at http://example.org:9464/metrics. GoToSocial running in this fashion will not serve LetsEncrypt certificates at the metrics endpoint, so you will be limited to using HTTP rather than HTTPS.

Bare metal, with reverse proxy

If you are using a reverse proxy like Nginx, you can expose the metrics endpoint to the outside world with HTTPS certificates, by putting an additional location stanza in your Nginx configuration above the catch-all location / stanza:

location /metrics {
  proxy_pass http://127.0.0.1:9464;
}

This will instruct Nginx to forward requests to example.org/metrics to the separate Prometheus server running on port 9464.

Docker

If you are running GoToSocial inside a Docker container, to make the metrics endpoint reachable from outside of the container, you will have to set OTEL_EXPORTER_PROMETHEUS_HOST to either 0.0.0.0 or the ip address / hostname of the Docker container. If you do not set this, you will only be able to access the metrics endpoint from within the Docker container itself, which is probably not what you want.

Enabling basic authentication

Although there is no sensitive data contained in the OTEL runtime statistics exported by Prometheus, you may nevertheless wish to gate access to the /metrics endpoint behind some kind of authentication, to prevent every Tom, Dick, and Harry from looking at your runtime stats.

You can do this by configuring your reverse proxy to require basic authentication for access to /metrics.

In Nginx, for example, you could do this by creating an htpasswd file alongside your site in the sites-available directory of Nginx, and instructing Nginx to use that file to gate access.

Assuming you followed the guide for setting up Nginx as your reverse proxy, you will already have a file for your Nginx service definition at /etc/nginx/sites-available/example.org, where example.org is the hostname of your instance.

You can create an htpasswd file alongside this file using the following command:

htpasswd -c /etc/nginx/sites-available/example.org.htpasswd username

In the command, be sure to replace example.org with your hostname, and username with whatever username you want to use.

Now, edit /etc/nginx/sites-available/example.org and update your /metrics stanza to use the httpasswd file. After editing it should look something like this:

location /metrics {
  proxy_pass http://127.0.0.1:9464;
  auth_basic           "Metrics";
  auth_basic_user_file /etc/nginx/sites-available/example.org.htpasswd;
}

Again, replace example.org in that snippet with your instance hostname.

When you're finished editing, reload + restart Nginx, and you should see a basic authentication prompt when visiting the /metrics endpoint of your instance in your browser.

Prometheus scrape configuration

You can scrape your /metrics endpoint with a Prometheus instance using the following configuration in your scrape_configs:

- job_name: gotosocial
  metrics_path: /metrics
  scheme: https
  basic_auth:
    username: some_username
    password: some_password
  static_configs:
  - targets:
    - example.org

Change example.org to your hostname in the above snippet. If you are not using HTTPS, change the scheme value to http. If you are not using basic authentication, you can remove the basic_auth section. If you are not using a reverse proxy, and metrics are exposed on port 9464, add the port to the host (eg., example.org -> example.org:9464).

Viewing metrics on Grafana

Instructions on how to set up Grafana are beyond the scope of this document. However, once you have set up a Grafana to pull from your Prometheus instance, you can import the example Grafana dashboard into your Grafana frontend to easily view GoToSocial Go runtime and HTTP metrics.