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feat(pprof): add profiling route handler to debug runtime (project-zo…
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…t#1818)

(cherry picked from commit 56ddb70)

Signed-off-by: Alex Stan <[email protected]>
Signed-off-by: Andrei Aaron <[email protected]>
Co-authored-by: Alex Stan <[email protected]>
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andaaron and alexstan12 authored Sep 18, 2023
1 parent f8002c7 commit a11fe2d
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Showing 8 changed files with 400 additions and 2 deletions.
4 changes: 2 additions & 2 deletions Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -33,8 +33,8 @@ OS ?= $(shell go env GOOS)
ARCH ?= $(shell go env GOARCH)

BENCH_OUTPUT ?= stdout
ALL_EXTENSIONS = debug,imagetrust,lint,metrics,mgmt,scrub,search,sync,ui,userprefs
EXTENSIONS ?= sync,search,scrub,metrics,lint,ui,mgmt,userprefs,imagetrust
ALL_EXTENSIONS = debug,imagetrust,lint,metrics,mgmt,profile,scrub,search,sync,ui,userprefs
EXTENSIONS ?= sync,search,scrub,metrics,lint,ui,mgmt,profile,userprefs,imagetrust
UI_DEPENDENCIES := search,mgmt,userprefs
# freebsd/arm64 not supported for pie builds
BUILDMODE_FLAGS := -buildmode=pie
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3 changes: 3 additions & 0 deletions pkg/api/routes.go
Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,7 @@ import (
apiErr "zotregistry.io/zot/pkg/api/errors"
zcommon "zotregistry.io/zot/pkg/common"
gqlPlayground "zotregistry.io/zot/pkg/debug/gqlplayground"
pprof "zotregistry.io/zot/pkg/debug/pprof"
debug "zotregistry.io/zot/pkg/debug/swagger"
ext "zotregistry.io/zot/pkg/extensions"
syncConstants "zotregistry.io/zot/pkg/extensions/sync/constants"
Expand Down Expand Up @@ -178,6 +179,8 @@ func (rh *RouteHandler) SetupRoutes() {
debug.SetupSwaggerRoutes(rh.c.Config, rh.c.Router, authHandler, rh.c.Log)
// gql playground
gqlPlayground.SetupGQLPlaygroundRoutes(prefixedRouter, rh.c.StoreController, rh.c.Log)
// pprof
pprof.SetupPprofRoutes(rh.c.Config, prefixedRouter, authHandler, rh.c.Log)

// Preconditions for enabling the actual extension routes are part of extensions themselves
ext.SetupMetricsRoutes(rh.c.Config, rh.c.Router, authHandler, rh.c.Log, rh.c.Metrics)
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1 change: 1 addition & 0 deletions pkg/debug/constants/consts.go
Original file line number Diff line number Diff line change
Expand Up @@ -3,4 +3,5 @@ package constants
const (
Debug = "/_zot/debug"
GQLPlaygroundEndpoint = Debug + "/graphql-playground"
ProfilingEndpoint = "/_zot/pprof/"
)
153 changes: 153 additions & 0 deletions pkg/debug/pprof/pprof.go
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@@ -0,0 +1,153 @@
//go:build profile
// +build profile

package pprof

import (
"bytes"
"fmt"
"html"
"io"
"net/http"
"net/http/pprof"
"net/url"
runPprof "runtime/pprof"
"sort"
"strings"

"github.com/gorilla/mux"

"zotregistry.io/zot/pkg/api/config"
registryConst "zotregistry.io/zot/pkg/api/constants"
zcommon "zotregistry.io/zot/pkg/common"
"zotregistry.io/zot/pkg/debug/constants"
"zotregistry.io/zot/pkg/log"
)

type profileEntry struct {
Name string
Href string
Desc string
Count int
}

var profileDescriptions = map[string]string{ //nolint: gochecknoglobals
"allocs": "A sampling of all past memory allocations",
"block": "Stack traces that led to blocking on synchronization primitives",
"cmdline": "The command line invocation of the current program",
"goroutine": "Stack traces of all current goroutines. Use debug=2 as a query parameter to export in the same format as an unrecovered panic.", //nolint: lll
"heap": "A sampling of memory allocations of live objects. You can specify the gc GET parameter to run GC before taking the heap sample.", //nolint: lll
"mutex": "Stack traces of holders of contended mutexes",
"profile": "CPU profile. You can specify the duration in the seconds GET parameter. After you get the profile file, use the go tool pprof command to investigate the profile.", //nolint: lll
"threadcreate": "Stack traces that led to the creation of new OS threads",
"trace": "A trace of execution of the current program. You can specify the duration in the seconds GET parameter. After you get the trace file, use the go tool trace command to investigate the trace.", //nolint: lll
}

func SetupPprofRoutes(conf *config.Config, router *mux.Router, authFunc mux.MiddlewareFunc,
log log.Logger,
) {
// If authn/authz are enabled the endpoints for pprof should be available only to admins
pprofRouter := router.PathPrefix(constants.ProfilingEndpoint).Subrouter()
pprofRouter.Use(zcommon.AuthzOnlyAdminsMiddleware(conf))
pprofRouter.Methods(http.MethodGet).Handler(http.HandlerFunc(
func(w http.ResponseWriter, r *http.Request) {
if name, found := strings.CutPrefix(r.URL.Path,
registryConst.RoutePrefix+constants.ProfilingEndpoint); found {
if name != "" {
switch name {
case "profile": // not available through pprof.Handler
pprof.Profile(w, r)

return
case "trace": // not available through pprof.Handler
pprof.Trace(w, r)

return
default:
pprof.Handler(name).ServeHTTP(w, r)

return
}
}
}

var profiles []profileEntry
for _, p := range runPprof.Profiles() {
profiles = append(profiles, profileEntry{
Name: p.Name(),
Href: p.Name(),
Desc: profileDescriptions[p.Name()],
Count: p.Count(),
})
}

// Adding other profiles exposed from within this package
for _, p := range []string{"cmdline", "profile", "trace"} {
profiles = append(profiles, profileEntry{
Name: p,
Href: p,
Desc: profileDescriptions[p],
})
}

sort.Slice(profiles, func(i, j int) bool {
return profiles[i].Name < profiles[j].Name
})

if err := indexTmplExecute(w, profiles); err != nil {
log.Print(err)
}
}))
}

func indexTmplExecute(writer io.Writer, profiles []profileEntry) error {
var buff bytes.Buffer

buff.WriteString(`<html>
<head>
<title>/v2/_zot/pprof/</title>
<style>
.profile-name{
display:inline-block;
width:6rem;
}
</style>
</head>
<body>
/debug/pprof/
<br>
<p>Set debug=1 as a query parameter to export in legacy text format</p>
<br>
Types of profiles available:
<table>
<thead><td>Count</td><td>Profile</td></thead>
`)

for _, profile := range profiles {
link := &url.URL{Path: profile.Href, RawQuery: "debug=1"}
fmt.Fprintf(&buff, "<tr><td>%d</td><td><a href='%s'>%s</a></td></tr>\n",
profile.Count, link, html.EscapeString(profile.Name))
}

buff.WriteString(`</table>
<a href="goroutine?debug=2">full goroutine stack dump</a>
<br>
<p>
Profile Descriptions:
<ul>
`)

for _, profile := range profiles {
fmt.Fprintf(&buff, "<li><div class=profile-name>%s: </div> %s</li>\n",
html.EscapeString(profile.Name), html.EscapeString(profile.Desc))
}

buff.WriteString(`</ul>
</p>
</body>
</html>`)

_, err := writer.Write(buff.Bytes())

return err
}
33 changes: 33 additions & 0 deletions pkg/debug/pprof/pprof.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,33 @@
# Profiling in Zot

This project gives the user the posibility to debug and profile the runtime to find relevant data such as CPU intensive function calls. An in-depth article on profiling in Go can be found [here](https://go.dev/blog/pprof).

A call to http://localhost:8080/v2/_zot/pprof/ would list the following available profiles, wrapped in an HTML file, with count values prior to change due to the runtime:

```
Types of profiles available:
Count Profile
95 allocs
0 block
0 cmdline
11 goroutine
95 heap
0 mutex
0 profile
13 threadcreate
0 trace
full goroutine stack dump
```

For example, the following can be used to gather the cpu profile for the amount of seconds specified as a query parameter, and then the results are stored in `cpu.prof` file:
```
curl -sK -v http://localhost:8080/v2/_zot/pprof/profile?seconds=30 > cpu.prof
```

Then, the user can use the `go tool pprof` to analyze the information generated previously in `cpu.prof`. The following command boots up an http server with a GUI and multiple charts that represent the data.
```
go tool pprof -http=:9090 cpu.prof
```
A flamegraph example would look like the following:

<img src="flamegraph.png" height="50%">
18 changes: 18 additions & 0 deletions pkg/debug/pprof/pprof_disabled.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
//go:build !profile
// +build !profile

package pprof

import (
"github.com/gorilla/mux"

"zotregistry.io/zot/pkg/api/config"
"zotregistry.io/zot/pkg/log" //nolint:goimports
)

func SetupPprofRoutes(conf *config.Config, router *mux.Router, authFunc mux.MiddlewareFunc,
log log.Logger,
) {
log.Warn().Msg("skipping enabling pprof extension because given zot binary " +
"doesn't include this feature, please build a binary that does so")
}
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