mirror of https://github.com/divan/expvarmon.git
47 lines
992 B
Go
47 lines
992 B
Go
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package main
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import (
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"expvar"
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"fmt"
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"net"
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"net/http"
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"runtime"
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"time"
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)
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var startTime = time.Now().UTC()
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func goroutines() interface{} {
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return runtime.NumGoroutine()
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}
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// uptime is an expvar.Func compliant wrapper for uptime info.
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func uptime() interface{} {
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uptime := time.Since(startTime)
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return int64(uptime)
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}
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// startPort defines lower port for bind
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const startPort = 32768
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// StartSelfMonitor starts http server on random port and exports expvars.
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//
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// It tries 1024 ports, starting from startPort and registers some expvars if ok.
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func StartSelfMonitor() (string, error) {
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for port := startPort; port < startPort+1024; port++ {
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bind := fmt.Sprintf("localhost:%d", port)
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l, err := net.Listen("tcp", bind)
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if err != nil {
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continue
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}
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l.Close()
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expvar.Publish("Goroutines", expvar.Func(goroutines))
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expvar.Publish("Uptime", expvar.Func(uptime))
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go http.ListenAndServe(bind, nil)
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return bind, nil
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}
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return "", fmt.Errorf("no free ports found")
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}
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