Nginx

PostgREST is a fast way to construct a RESTful API. Its default behavior is great for scaffolding in development. When it’s time to go to production it works great too, as long as you take precautions. PostgREST is a small sharp tool that focuses on performing the API-to-database mapping. We rely on a reverse proxy like Nginx for additional safeguards.

The first step is to create an Nginx configuration file that proxies requests to an underlying PostgREST server.

http {
  # ...
  # upstream configuration
  upstream postgrest {
    server localhost:3000;
  }
  # ...
  server {
    # ...
    # expose to the outside world
    location /api/ {
      default_type  application/json;
      proxy_hide_header Content-Location;
      add_header Content-Location  /api/$upstream_http_content_location;
      proxy_set_header  Connection "";
      proxy_http_version 1.1;
      proxy_pass http://postgrest/;
    }
    # ...
  }
}

Note

For ubuntu, if you already installed nginx through apt you can add this to the config file in /etc/nginx/sites-enabled/default.

HTTPS

PostgREST aims to do one thing well: add an HTTP interface to a PostgreSQL database. To keep the code small and focused we do not implement HTTPS. Use a reverse proxy such as NGINX to add this, here’s how.

Rate Limiting

Nginx supports “leaky bucket” rate limiting (see official docs). Using standard Nginx configuration, routes can be grouped into request zones for rate limiting. For instance we can define a zone for login attempts:

limit_req_zone $binary_remote_addr zone=login:10m rate=1r/s;

This creates a shared memory zone called “login” to store a log of IP addresses that access the rate limited urls. The space reserved, 10 MB (10m) will give us enough space to store a history of 160k requests. We have chosen to allow only allow one request per second (1r/s).

Next we apply the zone to certain routes, like a hypothetical function called login.

location /rpc/login/ {
  # apply rate limiting
  limit_req zone=login burst=5;
}

The burst argument tells Nginx to start dropping requests if more than five queue up from a specific IP.

Nginx rate limiting is general and indiscriminate. To rate limit each authenticated request individually you will need to add logic in a Custom Validation function.

Alternate URL Structure

As discussed in Singular or Plural, there are no special URL forms for singular resources in PostgREST, only operators for filtering. Thus there are no URLs like /people/1. It would be specified instead as

curl "http://localhost:3000/people?id=eq.1" \
  -H "Accept: application/vnd.pgrst.object+json"

This allows compound primary keys and makes the intent for singular response independent of a URL convention.

Nginx rewrite rules allow you to simulate the familiar URL convention. The following example adds a rewrite rule for all table endpoints, but you’ll want to restrict it to those tables that have a numeric simple primary key named “id.”

# support /endpoint/:id url style
location ~ ^/([a-z_]+)/([0-9]+) {

  # make the response singular
  proxy_set_header Accept 'application/vnd.pgrst.object+json';

  # assuming an upstream named "postgrest"
  proxy_pass http://postgrest/$1?id=eq.$2;

}