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tsweb: also support LabelMaps from expvar.Map, without metrics 

We want to use tsweb to format Prometheus-style metrics from
our temporary golang.org/x/net/http2 fork, but we don't want http2
to depend on the tailscale.com module to use the concrete type
tailscale.com/metrics.LabelMap. Instead, let a expvar.Map be used
instead of it's annotated sufficiently in its name.

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick 2021-08-10 13:56:15 -07:00 committed by Brad Fitzpatrick
parent 5f45d8f8e6
commit 3700cf9ea4
2 changed files with 44 additions and 6 deletions
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24
tsweb/tsweb.go
View File

@ -364,18 +364,25 @@ func VarzHandler(w http.ResponseWriter, r *http.Request) {
var dump func(prefix string, kv expvar.KeyValue)
dump = func(prefix string, kv expvar.KeyValue) {
name := prefix + kv.Key
key := kv.Key
var typ string
var label string
switch {
case strings.HasPrefix(kv.Key, "gauge_"):
typ = "gauge"
name = prefix + strings.TrimPrefix(kv.Key, "gauge_")
key = strings.TrimPrefix(kv.Key, "gauge_")
case strings.HasPrefix(kv.Key, "counter_"):
typ = "counter"
name = prefix + strings.TrimPrefix(kv.Key, "counter_")
key = strings.TrimPrefix(kv.Key, "counter_")
}
if strings.HasPrefix(key, "labelmap_") {
key = strings.TrimPrefix(key, "labelmap_")
if i := strings.Index(key, "_"); i != -1 {
label, key = key[:i], key[i+1:]
}
}
name := prefix + key
switch v := kv.Value.(type) {
case *expvar.Int:
@ -422,6 +429,15 @@ func VarzHandler(w http.ResponseWriter, r *http.Request) {
v.Do(func(kv expvar.KeyValue) {
fmt.Fprintf(w, "%s{%s=%q} %v\n", name, v.Label, kv.Key, kv.Value)
})
case *expvar.Map:
if label != "" && typ != "" {
fmt.Fprintf(w, "# TYPE %s %s\n", name, typ)
v.Do(func(kv expvar.KeyValue) {
fmt.Fprintf(w, "%s{%s=%q} %v\n", name, label, kv.Key, kv.Value)
})
} else {
fmt.Fprintf(w, "# skipping expvar.Map %q with incomplete metadata: label %q, Prometheus type %q\n", name, label, typ)
}
}
}
expvarDo(func(kv expvar.KeyValue) {

26
tsweb/tsweb_test.go
View File

@ -343,7 +343,7 @@ func TestVarzHandler(t *testing.T) {
"# TYPE s_bar counter\ns_bar 2\n# TYPE s_foo counter\ns_foo 1\n",
},
{
"metrics_set_TODO_guage_type",
"metrics_set_TODO_gauge_type",
"gauge_s", // TODO(bradfitz): arguably a bug; should pass down type
&metrics.Set{
Map: *(func() *expvar.Map {
@ -375,7 +375,7 @@ func TestVarzHandler(t *testing.T) {
"# skipping expvar \"x\" (Go type expvar.Func returning float64) with undeclared Prometheus type\n",
},
{
"label_map",
"metrics_label_map",
"counter_m",
&metrics.LabelMap{
Label: "label",
@ -389,6 +389,28 @@ func TestVarzHandler(t *testing.T) {
},
"# TYPE m counter\nm{label=\"bar\"} 2\nm{label=\"foo\"} 1\n",
},
{
"expvar_label_map",
"counter_labelmap_keyname_m",
func() *expvar.Map {
m := new(expvar.Map)
m.Init()
m.Add("foo", 1)
m.Add("bar", 2)
return m
}(),
"# TYPE m counter\nm{keyname=\"bar\"} 2\nm{keyname=\"foo\"} 1\n",
},
{
"expvar_label_map_malformed",
"counter_labelmap_lackslabel",
func() *expvar.Map {
m := new(expvar.Map)
m.Init()
return m
}(),
"# skipping expvar.Map \"lackslabel\" with incomplete metadata: label \"\", Prometheus type \"counter\"\n",
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {