Pleroma

Pleroma is a lightweight activity pub server.

Generating the Pleroma config

The pleroma_ctl CLI utility will prompt you some questions and it will generate an initial config file. This is an example of usage

$ mkdir tmp-pleroma
$ cd tmp-pleroma
$ nix-shell -p pleroma-otp
$ pleroma_ctl instance gen --output config.exs --output-psql setup.psql

The config.exs file can be further customized following the instructions on the upstream documentation. Many refinements can be applied also after the service is running.

Initializing the database

First, the Postgresql service must be enabled in the NixOS configuration

services.postgresql = {
  enable = true;
  package = pkgs.postgresql_13;
};

and activated with the usual

$ nixos-rebuild switch

Then you can create and seed the database, using the setup.psql file that you generated in the previous section, by running

$ sudo -u postgres psql -f setup.psql

Enabling the Pleroma service locally

In this section we will enable the Pleroma service only locally, so its configurations can be improved incrementally.

This is an example of configuration, where option contains the content of the file config.exs, generated in the first section, but with the secrets (database password, endpoint secret key, salts, etc.) removed. Removing secrets is important, because otherwise they will be stored publicly in the Nix store.

services.pleroma = {
  enable = true;
  secretConfigFile = "/var/lib/pleroma/secrets.exs";
  configs = [
    ''
    import Config

    config :pleroma, Pleroma.Web.Endpoint,
      url: [host: "pleroma.example.net", scheme: "https", port: 443],
      http: [ip: {127, 0, 0, 1}, port: 4000]

    config :pleroma, :instance,
      name: "Test",
      email: "admin@example.net",
      notify_email: "admin@example.net",
      limit: 5000,
      registrations_open: true

    config :pleroma, :media_proxy,
      enabled: false,
      redirect_on_failure: true

    config :pleroma, Pleroma.Repo,
      adapter: Ecto.Adapters.Postgres,
      username: "pleroma",
      database: "pleroma",
      hostname: "localhost"

    # Configure web push notifications
    config :web_push_encryption, :vapid_details,
      subject: "mailto:admin@example.net"

    # ... TO CONTINUE ...
    ''
  ];
};

Secrets must be moved into a file pointed by , in our case /var/lib/pleroma/secrets.exs. This file can be created copying the previously generated config.exs file and then removing all the settings, except the secrets. This is an example

# Pleroma instance passwords

import Config

config :pleroma, Pleroma.Web.Endpoint,
   secret_key_base: "<the secret generated by pleroma_ctl>",
   signing_salt: "<the secret generated by pleroma_ctl>"

config :pleroma, Pleroma.Repo,
  password: "<the secret generated by pleroma_ctl>"

# Configure web push notifications
config :web_push_encryption, :vapid_details,
  public_key: "<the secret generated by pleroma_ctl>",
  private_key: "<the secret generated by pleroma_ctl>"

# ... TO CONTINUE ...

Note that the lines of the same configuration group are comma separated (i.e. all the lines end with a comma, except the last one), so when the lines with passwords are added or removed, commas must be adjusted accordingly.

The service can be enabled with the usual

$ nixos-rebuild switch

The service is accessible only from the local 127.0.0.1:4000 port. It can be tested using a port forwarding like this

$ ssh -L 4000:localhost:4000 myuser@example.net

and then accessing http://localhost:4000 from a web browser.

Creating the admin user

After Pleroma service is running, all Pleroma administration utilities can be used. In particular an admin user can be created with

$ pleroma_ctl user new <nickname> <email>  --admin --moderator --password <password>

Configuring Nginx

In this configuration, Pleroma is listening only on the local port 4000. Nginx can be configured as a Reverse Proxy, for forwarding requests from public ports to the Pleroma service. This is an example of configuration, using Let's Encrypt for the TLS certificates

security.acme = {
  email = "root@example.net";
  acceptTerms = true;
};

services.nginx = {
  enable = true;
  addSSL = true;

  recommendedTlsSettings = true;
  recommendedOptimisation = true;
  recommendedGzipSettings = true;

  recommendedProxySettings = false;
  # NOTE: if enabled, the NixOS proxy optimizations will override the Pleroma
  # specific settings, and they will enter in conflict.

  virtualHosts = {
    "pleroma.example.net" = {
      http2 = true;
      enableACME = true;
      forceSSL = true;

      locations."/" = {
        proxyPass = "http://127.0.0.1:4000";

        extraConfig = ''
          etag on;
          gzip on;

          add_header 'Access-Control-Allow-Origin' '*' always;
          add_header 'Access-Control-Allow-Methods' 'POST, PUT, DELETE, GET, PATCH, OPTIONS' always;
          add_header 'Access-Control-Allow-Headers' 'Authorization, Content-Type, Idempotency-Key' always;
          add_header 'Access-Control-Expose-Headers' 'Link, X-RateLimit-Reset, X-RateLimit-Limit, X-RateLimit-Remaining, X-Request-Id' always;
          if ($request_method = OPTIONS) {
            return 204;
          }
          add_header X-XSS-Protection "1; mode=block";
          add_header X-Permitted-Cross-Domain-Policies none;
          add_header X-Frame-Options DENY;
          add_header X-Content-Type-Options nosniff;
          add_header Referrer-Policy same-origin;
          add_header X-Download-Options noopen;
          proxy_http_version 1.1;
          proxy_set_header Upgrade $http_upgrade;
          proxy_set_header Connection "upgrade";
          proxy_set_header Host $host;

          client_max_body_size 16m;
          # NOTE: increase if users need to upload very big files
        '';
      };
    };
  };
};

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