libtower

Network health-check primitives for Go — TCP, TLS, HTTP, HTTPS, DNS, ICMP ping, WebSocket, and certificate expiry. Flat package, no sub-packages.

Install

go get github.com/mismatched/libtower

Quick start

package main

import (
    "context"
    "net/url"
    "time"

    "github.com/mismatched/libtower"
)

func main() {
    ctx := context.Background()

    // TCP port check
    u, _ := url.Parse("tcp://example.com:443")
    tcp := &libtower.TCP{URL: u, Timeout: 5 * time.Second}
    ok, _ := tcp.TCPPortCheck(ctx)

    // DNS lookup
    ip, dur, _ := libtower.DNSLookup("example.com")

    // TLS cert check with expiry warning
    hs := &libtower.HTTPS{
        Host:                  "example.com",
        Timeout:               5 * time.Second,
        WarnIfExpiringWithin:  30 * 24 * time.Hour,
    }
    r := hs.Check(ctx)
    if r.Warning != nil {
        println("cert expiring soon:", r.Warning.Error())
    }

    _ = ok
    _ = ip
    _ = dur
}

Checks

Check	Type/Function	Returns
TCP port	TCP.TCPPortCheck(ctx)	(bool, error)
TLS port (client cert)	TCP.TLSPortCheck(ctx)	(bool, error)
HTTP status	HTTP.HTTPStatus()	error (receiver populated)
HTTP trace (per-phase timing)	HTTPTrace.Trace()	error (receiver populated)
TLS cert validity	HTTPS.HTTPSCheck(ctx)	(bool, time.Time, error)
DNS lookup	DNSLookup(addr)	(*net.IPAddr, time.Duration, error)
Direct DNS query	DNSLookupFrom(addr, server)	(*net.IPAddr, time.Duration, error)
ICMP ping ⚠️	Ping(addr, seq)	(*net.IPAddr, time.Duration, error)
WebSocket	WebSocket.WSCheck(ctx)	error

⚠️ Ping requires root (or CAP_NET_RAW on Linux).

Composing checks

All types implement Checker, so you can run them uniformly:

checks := []libtower.Checker{
    &libtower.TCP{URL: u, Timeout: time.Second},
    &libtower.HTTPS{Host: "example.com", WarnIfExpiringWithin: 30 * 24 * time.Hour},
    &libtower.DNS{ADDR: "example.com"},
}
for _, c := range checks {
    r := c.Check(ctx)
    if !r.OK { panic(r.Error) }
}

Context variants

Short names (Ping, DNSLookup) use context.Background(). Use the ...Context variants for cancellation:

PingContext(ctx, addr, seq)
DNSLookupContext(ctx, addr)
DNSLookupFromContext(ctx, addr, server)
HTTPStatusContext(ctx)
TraceContext(ctx)

License

MIT