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How to Monitor Your Zig HTTP Server with Vigilmon

#zig #http #monitoring #systems

How to Monitor Your Zig HTTP Server with Vigilmon

Zig is a systems programming language that's gaining traction for building high-performance, memory-safe HTTP servers. Whether you're using Zig's standard library HTTP server, zap, http.zig, or another Zig web framework, this guide shows you how to monitor your Zig HTTP service with Vigilmon.

Why Monitor a Zig HTTP Server?

Zig is fast and efficient, but your server can still go down due to:

  • Unhandled errors — Zig's error handling is explicit, but uncaught panics can crash the process
  • Resource exhaustion — high traffic or memory leaks in long-running services
  • Infrastructure failures — the host, network, or reverse proxy fails
  • Bad deployments — a new binary that fails to start or crashes immediately

Vigilmon monitors your endpoint from the outside, alerting you within a minute of any failure.

Step 1: Add a Health Endpoint

Here's a minimal health endpoint using Zig's standard library HTTP server:

const std = @import("std");
const http = std.http;
const net = std.net;

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

    const address = try net.Address.parseIp("0.0.0.0", 3000);
    var server = try address.listen(.{ .reuse_address = true });
    defer server.deinit();

    std.debug.print("Listening on port 3000
", .{});

    while (true) {
        var connection = try server.accept();
        defer connection.stream.close();

        var buf: [4096]u8 = undefined;
        var http_server = http.Server.init(connection, &buf);

        var request = try http_server.receiveHead();

        if (std.mem.eql(u8, request.head.target, "/health")) {
            try request.respond("OK", .{
                .status = .ok,
                .extra_headers = &.{
                    .{ .name = "Content-Type", .value = "text/plain" },
                },
            });
        } else {
            try request.respond("Not Found", .{ .status = .not_found });
        }
    }
}
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For zap (a popular Zig HTTP framework):

const zap = @import("zap");

fn onRequest(r: zap.Request) void {
    if (r.path) |path| {
        if (std.mem.eql(u8, path, "/health")) {
            r.setStatus(.ok);
            r.sendBody("OK") catch return;
            return;
        }
    }
    // ... handle other routes
}

pub fn main() !void {
    var listener = zap.HttpListener.init(.{
        .port = 3000,
        .on_request = onRequest,
        .log = true,
    });
    try listener.listen();
    zap.start(.{ .threads = 4, .workers = 4 });
}
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Verify it works:

curl http://localhost:3000/health
# Expected: OK
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Step 2: Set Up Vigilmon

  1. Go to vigilmon.online
  2. Click + New Monitor
  3. Configure:
    • URL: https://your-zig-service.com/health
    • Method: GET
    • Expected status: 200
    • Expected body contains: OK
    • Check interval: every 1 minute
  4. Add alert channels (email, Slack)
  5. Save

Vigilmon will alert you within 60 seconds if your Zig server stops responding.

Step 3: Handle the Reverse Proxy Layer

Most Zig HTTP servers run behind a reverse proxy (nginx, Caddy, or a cloud load balancer). Both layers need monitoring:

  1. Vigilmon monitors the public-facing URL (through the proxy) — catches both proxy and Zig failures
  2. Optionally, monitor the Zig server directly on its internal port if your infrastructure allows it

This gives you layer-by-layer visibility.

Step 4: SSL Monitoring

If your Zig server is behind a TLS-terminating proxy, enable SSL monitoring in Vigilmon:

  • Domain: your public domain
  • Expiry alert: 14 days before expiry

Step 5: Configure Alerts

For a Zig HTTP server (likely performance-critical infrastructure):

  • Slack webhook for immediate team visibility
  • Email as a backup
  • PagerDuty if you need 24/7 on-call

Because Zig servers are often used for high-performance or latency-sensitive workloads, fast incident detection is critical.

Step 6: Process Management

Zig doesn't have a runtime that restarts crashed processes. Use a process supervisor:

# systemd service
[Unit]
Description=My Zig HTTP Server
After=network.target

[Service]
ExecStart=/usr/local/bin/my-zig-server
Restart=always
RestartSec=5

[Install]
WantedBy=multi-user.target
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Or use supervisord, Docker with restart: always, or Fly.io's process management. This handles restarts automatically — but Vigilmon still tells you how often the service is crashing.

Zig-Specific Tips

Error handling: Zig's error union types make it easy to handle and propagate errors. Ensure your health endpoint catches and handles all errors rather than propagating them as 500s to Vigilmon.

Comptime vs runtime: Health checks should be minimal. Avoid comptime calculations in the hot path of your health handler.

Debug vs release builds: Build your production binary with zig build -Doptimize=ReleaseFast and make sure Vigilmon tests that binary, not a debug build.

Conclusion

Zig HTTP servers can be extremely fast and reliable, but they still need external monitoring. A simple /health endpoint plus Vigilmon gives you peace of mind — and fast alerts when something goes wrong.

Monitor your Zig server with Vigilmon →

Vigilmon offers free uptime monitoring for any HTTP/HTTPS endpoint, with instant alerts via email, Slack, and webhooks.

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