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cmd/microproxy: adjust to export node stats and a Go expvar server's stats.

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This is a temporary specialization to what tailscale prod needs right now,
it'll go back to something more generic later.
This commit is contained in:
David Anderson 2020-04-01 16:50:02 -07:00
parent 8ca796d144
commit 48d7ee1c6a
1 changed files with 50 additions and 5 deletions
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55
cmd/microproxy/microproxy.go
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@ -9,8 +9,10 @@
import (
"crypto/tls"
"encoding/json"
"flag"
"fmt"
"io"
"io/ioutil"
"log"
"net/http"
@ -29,7 +31,8 @@
certdir = flag.String("certdir", "", "directory to borrow LetsEncrypt certificates from")
hostname = flag.String("hostname", "", "hostname to serve")
logCollection = flag.String("logcollection", "", "If non-empty, logtail collection to log to")
target = flag.String("target", "", "URL to proxy to (usually http://localhost:...")
nodeExporter = flag.String("node-exporter", "http://localhost:9100", "URL of the local prometheus node exporter")
goVarsURL = flag.String("go-vars-url", "http://localhost:8383/debug/vars", "URL of a local Go server's /debug/vars endpoint")
)
func main() {
@ -39,14 +42,20 @@ func main() {
logpolicy.New(*logCollection)
}
u, err := url.Parse(*target)
ne, err := url.Parse(*nodeExporter)
if err != nil {
log.Fatalf("Couldn't parse URL %q: %v", *target, err)
log.Fatalf("Couldn't parse URL %q: %v", *nodeExporter, err)
}
proxy := httputil.NewSingleHostReverseProxy(u)
proxy := httputil.NewSingleHostReverseProxy(ne)
proxy.FlushInterval = time.Second
if _, err = url.Parse(*goVarsURL); err != nil {
log.Fatalf("Couldn't parse URL %q: %v", *goVarsURL, err)
}
mux := tsweb.NewMux(http.HandlerFunc(debugHandler))
mux.Handle("/", tsweb.Protected(proxy))
mux.Handle("/metrics", tsweb.Protected(proxy))
mux.Handle("/varz", tsweb.Protected(tsweb.StdHandler(&goVarsHandler{*goVarsURL}, log.Printf)))
ch := &certHolder{
hostname: *hostname,
@ -66,6 +75,42 @@ func main() {
}
}
type goVarsHandler struct {
url string
}
func promPrint(w io.Writer, prefix string, obj map[string]interface{}) {
for k, i := range obj {
if prefix != "" {
k = prefix + "_" + k
}
switch v := i.(type) {
case map[string]interface{}:
promPrint(w, k, v)
case float64:
fmt.Fprintf(w, "%s %f\n", k, v)
default:
fmt.Fprintf(w, "# Skipping key %q, unhandled type %T\n", k, v)
}
}
}
func (h *goVarsHandler) ServeHTTPErr(w http.ResponseWriter, r *http.Request) error {
resp, err := http.Get(h.url)
if err != nil {
return tsweb.Error(http.StatusInternalServerError, "fetch failed", err)
}
defer resp.Body.Close()
var mon map[string]interface{}
if err := json.NewDecoder(resp.Body).Decode(&mon); err != nil {
return tsweb.Error(http.StatusInternalServerError, "fetch failed", err)
}
w.WriteHeader(http.StatusOK)
promPrint(w, "", mon)
return nil
}
// certHolder loads and caches a TLS certificate from disk, reloading
// it every hour.
type certHolder struct {