Network Logging Example

This example demonstrates how to use Logly's network sinks to send logs over TCP and UDP, including support for JSON formatting and compression.

Overview

Network logging allows you to centralize logs from multiple applications or instances. Logly supports:

• TCP: Reliable, connection-oriented logging.
• UDP: Fast, fire-and-forget logging.
• JSON: Structured logging for easy parsing by aggregators.
• Compression: Reduce bandwidth usage.

Code Example

const std = @import("std");
const logly = @import("logly");

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();

    // Initialize logger
    var logger = try logly.Logger.init(allocator);
    defer logger.deinit();

    // 1. TCP Sink with Standard Format & Colors
    // Sends plain text logs to a TCP server.
    // We force enable colors so they show up on the remote viewer.
    var tcp_sink = logly.SinkConfig.network("tcp://127.0.0.1:9000");
    tcp_sink.name = "tcp-standard";
    tcp_sink.color = true; // Force ANSI colors
    const tcp_idx = try logger.addSink(tcp_sink);

    // Apply a custom theme to the TCP sink
    var theme = logly.Formatter.Theme{};
    theme.info = "36"; // Cyan
    theme.warning = "33"; // Yellow
    theme.err = "31"; // Red
    logger.sinks.items[tcp_idx].formatter.setTheme(theme);

    // 2. UDP Sink with JSON Format
    // Sends structured JSON logs to a UDP server.
    // Ideal for log aggregators like Logstash, Fluentd, or Graylog.
    var udp_json_sink = logly.SinkConfig.network("udp://127.0.0.1:9001");
    udp_json_sink.name = "udp-json";
    udp_json_sink.json = true;
    _ = try logger.addSink(udp_json_sink);

    // 3. Register Custom Levels
    try logger.addCustomLevel("AUDIT", 35, "34"); // Blue
    try logger.addCustomLevel("SECURITY", 45, "31"); // Red

    // Log some messages
    try logger.info("Application started", @src());
    try logger.warn("Connection latency high", @src());
    
    // Log with custom levels
    try logger.custom("AUDIT", "User login attempt", null);
    try logger.custom("SECURITY", "Invalid password attempt", null);

    // Ensure all logs are sent before exiting
    for (logger.sinks.items) |sink| {
        try sink.flush();
    }
}

Running a Test Server

To test the network logging, you can use netcat (nc) to listen on the ports:

TCP Listener:

nc -l -p 9000

UDP Listener:

nc -u -l -p 9001

Best Practices

1. Use JSON for Aggregators: Most log management systems prefer structured data.
2. Use UDP for High Volume: If dropping a few logs is acceptable in exchange for performance, UDP avoids head-of-line blocking.
3. Enable Compression for WAN: If sending logs over the internet, compression can significantly reduce data transfer costs.
4. Handle Reconnections: The TCP sink automatically attempts to reconnect if the connection is lost, but be aware that logs generated during downtime might be lost if the buffer fills up.