Backend Server Monitoring

If you have turned on the feature backend_server_monitoring, Nauthilus is able to do liveness probes for backend servers. The result is updated every 20 seconds (hard-coded for now). This information can be used in Lua scripts. The initial idea was to chose a backend server for the Nginx-based authentication process. Other usecases are also possible, depending on your needs.

Configuration Options

backend_server_monitoring::backend_servers

This configuration block defines servers to be monitored.

The following protocols can be used to monitor a backend server:

smtp
lmtp
pop3
imap
sieve
http

Servers can have a lightweight check, where only the connection is tested.

note

A connect timeout of 5 seconds is used. Also for reading and writing to an established connection.

If the HAproxy flag is set, this is checked as well.

Having TLS settings for a backend, a handshake is done on top of the connection.

warning

We currently only support plain or TLS-on-connect connections. Only sieve has STARTTLS support

If deep checks are enabled, Nauthilus talks the configured protocol with each backend. Optionally, a givven test user and its password can be used to verify a successful connection to the backend. We recommend to have one test user for each backend to prevent technical problems with backend servers (for example index issues with Dovecot).

Example Configuration

backend_server_monitoring:
  backend_servers:
    - protocol: imap
      host: 192.168.0.2
      port: 993
      deep_check: true
      test_username: some_unique_test_user
      test_password: some_password
      tls: true
      tls_skip_verify: true
      haproxy_v2: true

The settings should be self-explained.

Configuration Options​