Logging

Multiple log backends are available for vSMTP.

vSMTP default logs

Default vSMTP log system. By default, it writes logs in the /var/log/vsmtp/vsmtp.log file.

fn on_config(config) {
    // Change the location of the logs.
    config.server.logs.filename = "./tmp/system/vsmtp.log";
    // Set global logging level to "info".
    //
    // The configuration for the level here is an array because vSMTP
    // will support log levels for specific modules of the server in future releases.
    config.server.logs.level = [ "info" ];

    config
}

Configuring logs in the root configuration file

Application logs

Application logs are written using the log(level, message) function in filtering scripts. The default output location is of application logs is the /var/log/vsmtp/app.log file. It can be changed in the root configuration.

fn on_config(config) {
    config.app.logs.filename = "./tmp/system/app.log";
    config
}

Change the location of the application logs.

System logs

vSMTP also supports system logs through the following services.

Journald

vSMTP will send server logs to the journald daemon.

fn on_config(config) {
    config.server.logs.system = #{
        level: "info",
        backend: "journald",
    };

    config
}

Configure journald for vSMTP

Syslogd

vSMTP will send logs to the syslog daemon using the mail facility.

fn on_config(config) {
    config.server.logs.system = #{
        level: "info",
        backend: "syslogd",

        // Format used by the logger.
        // See https://www.rfc-editor.org/rfc/rfc3164 and https://www.rfc-editor.org/rfc/rfc5424
        // for more details.
        format: "3164",

        // Writing syslogs on disk using a unix socket.
        socket: #{ type: "unix", path: "/dev/log" },
        // It is possible to use:
        // `socket: #{ type: "tcp", server: "127.0.0.1:601" }`
        //
        // or
        // `socket: #{ type: "udp", server: "127.0.0.1:514", local: "127.0.0.1:0" }`
        //
        // note: address can be ipv4 / ipv6
    };

    config
}

Configure syslogs for vSMTP

Levels

Available log levels

Debug and Trace levels are, for the time being, not available in the production version of vSMTP.