webnet
/
tailscale
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

tsweb: make VarzHandler capable of walking structs with reflect

Browse Source 
To be used by control, per linked bug's plan.

Updates #2635

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
main
Brad Fitzpatrick 5 years ago committed by Brad Fitzpatrick
parent b9bd7dbc5d
commit 5aba620fb9
2 changed files with 278 additions and 80 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Show Stats Download Patch File Download Diff File
  1. 257
      tsweb/tsweb.go
  2. 101
      tsweb/tsweb_test.go

257
tsweb/tsweb.go
Unescape View File

@ -19,6 +19,7 @@ import (
_ "net/http/pprof"
"os"
"path/filepath"
"reflect"
"runtime"
"strings"
"time"
@ -342,109 +343,168 @@ func Error(code int, msg string, err error) HTTPError {
return HTTPError{Code: code, Msg: msg, Err: err}
}
// VarzHandler is an HTTP handler to write expvar values into the
// prometheus export format:
//
// https://github.com/prometheus/docs/blob/master/content/docs/instrumenting/exposition_formats.md
//
// It makes the following assumptions:
//
// * *expvar.Int are counters (unless marked as a gauge_; see below)
// * a *tailscale/metrics.Set is descended into, joining keys with
// underscores. So use underscores as your metric names.
// * an expvar named starting with "gauge_" or "counter_" is of that
// Prometheus type, and has that prefix stripped.
// * anything else is untyped and thus not exported.
// * expvar.Func can return an int or int64 (for now) and anything else
// is not exported.
// WritePrometheusExpvar writes kv to w in Prometheus metrics format.
//
// This will evolve over time, or perhaps be replaced.
func VarzHandler(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/plain; version=0.0.4")
// See VarzHandler for conventions. This is exported primarily for
// people to test their varz.
func WritePrometheusExpvar(w io.Writer, kv expvar.KeyValue) {
writePromExpVar(w, "", kv)
}
func writePromExpVar(w io.Writer, prefix string, kv expvar.KeyValue) {
key := kv.Key
var typ string
var label string
switch {
case strings.HasPrefix(kv.Key, "gauge_"):
typ = "gauge"
key = strings.TrimPrefix(kv.Key, "gauge_")
case strings.HasPrefix(kv.Key, "counter_"):
typ = "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
var dump func(prefix string, kv expvar.KeyValue)
dump = func(prefix string, kv expvar.KeyValue) {
key := kv.Key
var typ string
var label string
switch {
case strings.HasPrefix(kv.Key, "gauge_"):
typ = "gauge"
key = strings.TrimPrefix(kv.Key, "gauge_")
case strings.HasPrefix(kv.Key, "counter_"):
switch v := kv.Value.(type) {
case *expvar.Int:
if typ == "" {
typ = "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:]
fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", name, typ, name, v.Value())
return
case *metrics.Set:
v.Do(func(kv expvar.KeyValue) {
writePromExpVar(w, name+"_", kv)
})
return
case PrometheusMetricsReflectRooter:
root := v.PrometheusMetricsReflectRoot()
rv := reflect.ValueOf(root)
if rv.Type().Kind() == reflect.Ptr {
if rv.IsNil() {
return
}
rv = rv.Elem()
}
name := prefix + key
switch v := kv.Value.(type) {
case *expvar.Int:
if typ == "" {
typ = "counter"
}
fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", name, typ, name, v.Value())
return
case *metrics.Set:
v.Do(func(kv expvar.KeyValue) {
dump(name+"_", kv)
})
if rv.Type().Kind() != reflect.Struct {
fmt.Fprintf(w, "# skipping expvar %q; unknown root type\n", name)
return
}
if typ == "" {
var funcRet string
if f, ok := kv.Value.(expvar.Func); ok {
v := f()
if ms, ok := v.(runtime.MemStats); ok && name == "memstats" {
writeMemstats(w, &ms)
return
foreachExportedStructField(rv, func(fieldOrJSONName, metricType string, rv reflect.Value) {
mname := name + "_" + fieldOrJSONName
switch rv.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", mname, metricType, mname, rv.Int())
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", mname, metricType, mname, rv.Uint())
case reflect.Float32, reflect.Float64:
fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", mname, metricType, mname, rv.Float())
case reflect.Struct:
if rv.CanAddr() {
// Slight optimization, not copying big structs if they're addressable:
writePromExpVar(w, name+"_", expvar.KeyValue{Key: fieldOrJSONName, Value: expVarPromStructRoot{rv.Addr().Interface()}})
} else {
writePromExpVar(w, name+"_", expvar.KeyValue{Key: fieldOrJSONName, Value: expVarPromStructRoot{rv.Interface()}})
}
funcRet = fmt.Sprintf(" returning %T", v)
}
return
})
return
}
if typ == "" {
var funcRet string
if f, ok := kv.Value.(expvar.Func); ok {
v := f()
if ms, ok := v.(runtime.MemStats); ok && name == "memstats" {
writeMemstats(w, &ms)
return
}
funcRet = fmt.Sprintf(" returning %T", v)
}
switch kv.Value.(type) {
default:
fmt.Fprintf(w, "# skipping expvar %q (Go type %T%s) with undeclared Prometheus type\n", name, kv.Value, funcRet)
return
case *metrics.LabelMap:
// Permit typeless LabelMap for compatibility
// with old expvar-registered
// metrics.LabelMap.
}
}
switch v := kv.Value.(type) {
case expvar.Func:
val := v()
switch val.(type) {
case float64, int64, int:
fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", name, typ, name, val)
default:
fmt.Fprintf(w, "# skipping expvar func %q returning unknown type %T\n", name, val)
}
switch v := kv.Value.(type) {
case expvar.Func:
val := v()
switch val.(type) {
case float64, int64, int:
fmt.Fprintf(w, "# TYPE %s %s\n%s %v\n", name, typ, name, val)
default:
fmt.Fprintf(w, "# skipping expvar func %q returning unknown type %T\n", name, val)
}
case *metrics.LabelMap:
case *metrics.LabelMap:
if typ != "" {
fmt.Fprintf(w, "# TYPE %s %s\n", name, typ)
}
// IntMap uses expvar.Map on the inside, which presorts
// keys. The output ordering is deterministic.
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)
// IntMap uses expvar.Map on the inside, which presorts
// keys. The output ordering is deterministic.
v.Do(func(kv expvar.KeyValue) {
fmt.Fprintf(w, "%s{%s=%q} %v\n", name, v.Label, kv.Key, kv.Value)
fmt.Fprintf(w, "%s{%s=%q} %v\n", name, 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)
}
} else {
fmt.Fprintf(w, "# skipping expvar.Map %q with incomplete metadata: label %q, Prometheus type %q\n", name, label, typ)
}
}
}
// VarzHandler is an HTTP handler to write expvar values into the
// prometheus export format:
//
// https://github.com/prometheus/docs/blob/master/content/docs/instrumenting/exposition_formats.md
//
// It makes the following assumptions:
//
// * *expvar.Int are counters (unless marked as a gauge_; see below)
// * a *tailscale/metrics.Set is descended into, joining keys with
// underscores. So use underscores as your metric names.
// * an expvar named starting with "gauge_" or "counter_" is of that
// Prometheus type, and has that prefix stripped.
// * anything else is untyped and thus not exported.
// * expvar.Func can return an int or int64 (for now) and anything else
// is not exported.
//
// This will evolve over time, or perhaps be replaced.
func VarzHandler(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/plain; version=0.0.4")
expvarDo(func(kv expvar.KeyValue) {
dump("", kv)
writePromExpVar(w, "", kv)
})
}
// PrometheusMetricsReflectRooter is an optional interface that expvar.Var implementations
// can implement to indicate that they should be walked recursively with reflect to find
// sets of fields to export.
type PrometheusMetricsReflectRooter interface {
expvar.Var
// PrometheusMetricsReflectRoot returns the struct or struct pointer to walk.
PrometheusMetricsReflectRoot() interface{}
}
var expvarDo = expvar.Do // pulled out for tests
func writeMemstats(w io.Writer, ms *runtime.MemStats) {
@ -463,3 +523,42 @@ func writeMemstats(w io.Writer, ms *runtime.MemStats) {
c("frees", ms.Frees, "cumulative count of heap objects freed")
c("num_gc", uint64(ms.NumGC), "number of completed GC cycles")
}
func foreachExportedStructField(rv reflect.Value, f func(fieldOrJSONName, metricType string, rv reflect.Value)) {
t := rv.Type()
for i, n := 0, t.NumField(); i < n; i++ {
sf := t.Field(i)
name := sf.Name
if v := sf.Tag.Get("json"); v != "" {
if i := strings.Index(v, ","); i != -1 {
v = v[:i]
}
if v == "-" {
// Skip it, regardless of its metrictype.
continue
}
if v != "" {
name = v
}
}
metricType := sf.Tag.Get("metrictype")
if metricType != "" || sf.Type.Kind() == reflect.Struct {
f(name, metricType, rv.Field(i))
} else if sf.Type.Kind() == reflect.Ptr && sf.Type.Elem().Kind() == reflect.Struct {
fv := rv.Field(i)
if !fv.IsNil() {
f(name, metricType, fv.Elem())
}
}
}
}
type expVarPromStructRoot struct{ v interface{} }
func (r expVarPromStructRoot) PrometheusMetricsReflectRoot() interface{} { return r.v }
func (r expVarPromStructRoot) String() string { panic("unused") }
var (
_ PrometheusMetricsReflectRooter = expVarPromStructRoot{}
_ expvar.Var = expVarPromStructRoot{}
)

101
tsweb/tsweb_test.go
Unescape View File

@ -12,6 +12,7 @@ import (
"net"
"net/http"
"net/http/httptest"
"strings"
"testing"
"time"
@ -304,6 +305,12 @@ func BenchmarkLog(b *testing.B) {
}
func TestVarzHandler(t *testing.T) {
t.Run("globals_log", func(t *testing.T) {
rec := httptest.NewRecorder()
VarzHandler(rec, httptest.NewRequest("GET", "/", nil))
t.Logf("Got: %s", rec.Body.Bytes())
})
tests := []struct {
name string
k string // key name
@ -389,6 +396,18 @@ func TestVarzHandler(t *testing.T) {
},
"# TYPE m counter\nm{label=\"bar\"} 2\nm{label=\"foo\"} 1\n",
},
{
"metrics_label_map_untyped",
"control_save_config",
(func() *metrics.LabelMap {
m := &metrics.LabelMap{Label: "reason"}
m.Add("new", 1)
m.Add("updated", 1)
m.Add("fun", 1)
return m
})(),
"control_save_config{reason=\"fun\"} 1\ncontrol_save_config{reason=\"new\"} 1\ncontrol_save_config{reason=\"updated\"} 1\n",
},
{
"expvar_label_map",
"counter_labelmap_keyname_m",
@ -411,6 +430,37 @@ func TestVarzHandler(t *testing.T) {
}(),
"# skipping expvar.Map \"lackslabel\" with incomplete metadata: label \"\", Prometheus type \"counter\"\n",
},
{
"struct_reflect",
"foo",
someExpVarWithJSONAndPromTypes(),
strings.TrimSpace(`
# TYPE foo_nestvalue_foo gauge
foo_nestvalue_foo 1
# TYPE foo_nestvalue_bar counter
foo_nestvalue_bar 2
# TYPE foo_nestptr_foo gauge
foo_nestptr_foo 10
# TYPE foo_nestptr_bar counter
foo_nestptr_bar 20
# TYPE foo_curX gauge
foo_curX 3
# TYPE foo_totalY counter
foo_totalY 4
# TYPE foo_curTemp gauge
foo_curTemp 20.6
# TYPE foo_AnInt8 counter
foo_AnInt8 127
# TYPE foo_AUint16 counter
foo_AUint16 65535
`) + "\n",
},
{
"struct_reflect_nil_root",
"foo",
expvarAdapter{(*SomeStats)(nil)},
"",
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
@ -421,9 +471,58 @@ func TestVarzHandler(t *testing.T) {
rec := httptest.NewRecorder()
VarzHandler(rec, httptest.NewRequest("GET", "/", nil))
if got := rec.Body.Bytes(); string(got) != tt.want {
t.Errorf("mismatch\n got: %q\nwant: %q\n", got, tt.want)
t.Errorf("mismatch\n got: %q\n%s\nwant: %q\n%s\n", got, got, tt.want, tt.want)
}
})
}
}
type SomeNested struct {
FooG int64 `json:"foo" metrictype:"gauge"`
BarC int64 `json:"bar" metrictype:"counter"`
Omit int `json:"-" metrictype:"counter"`
}
type SomeStats struct {
Nested SomeNested `json:"nestvalue"`
NestedPtr *SomeNested `json:"nestptr"`
NestedNilPtr *SomeNested `json:"nestnilptr"`
CurX int `json:"curX" metrictype:"gauge"`
NoMetricType int `json:"noMetric" metrictype:""`
TotalY int64 `json:"totalY,omitempty" metrictype:"counter"`
CurTemp float64 `json:"curTemp" metrictype:"gauge"`
AnInt8 int8 `metrictype:"counter"`
AUint16 uint16 `metrictype:"counter"`
}
// someExpVarWithJSONAndPromTypes returns an expvar.Var that
// implements PrometheusMetricsReflectRooter for TestVarzHandler.
func someExpVarWithJSONAndPromTypes() expvar.Var {
st := &SomeStats{
Nested: SomeNested{
FooG: 1,
BarC: 2,
Omit: 3,
},
NestedPtr: &SomeNested{
FooG: 10,
BarC: 20,
},
CurX: 3,
TotalY: 4,
CurTemp: 20.6,
AnInt8: 127,
AUint16: 65535,
}
return expvarAdapter{st}
}
type expvarAdapter struct {
st *SomeStats
}
func (expvarAdapter) String() string { return "{}" } // expvar JSON; unused in test
func (a expvarAdapter) PrometheusMetricsReflectRoot() interface{} {
return a.st
}

Write Preview
Loading…
Cancel
Save