Use web configuration from exporter-toolkit

[lucacome]

Proposed changes

• Replaces manual implementation of TLS and Unix socket support with Web Configuration
• Adds Basic Auth support.

Thanks @lucian-vanghele for opening #231 and bringing this to my attention.

Closes #232
Closes #393
Closes #425

[n-rodriguez]

LGTM! (almost ^^)

SIGINT :

nicolas@MacBook-Pro-de-Nicolas:~/go/src/github.com/n-rodriguez/nginx-prometheus-exporter$ ./nginx-prometheus-exporter
level=info ts=2023-07-20T17:27:44.004Z caller=exporter.go:137 msg="Starting nginx-prometheus-exporter" version="(version=0.11.0, branch=, revision=c722e30e951cd1fae380543e6ac993b73e6a6d63)"
level=info ts=2023-07-20T17:27:44.004Z caller=exporter.go:138 msg="Build context" build_context="(go=go1.20.3, platform=darwin/arm64, user=, date=, tags=unknown)"
level=info ts=2023-07-20T17:27:44.006Z caller=tls_config.go:274 msg="Listening on" address=[::]:9113
level=info ts=2023-07-20T17:27:44.006Z caller=tls_config.go:277 msg="TLS is disabled." http2=false address=[::]:9113
^Clevel=info ts=2023-07-20T17:27:44.830Z caller=exporter.go:259 msg="Shutting down"
level=info ts=2023-07-20T17:27:44.830Z caller=exporter.go:250 msg="HTTP server closed"
nicolas@MacBook-Pro-de-Nicolas:~/go/src/github.com/n-rodriguez/nginx-prometheus-exporter$ echo $?
0

SIGTERM :

nicolas@MacBook-Pro-de-Nicolas:~/go/src/github.com/n-rodriguez/nginx-prometheus-exporter$ ./nginx-prometheus-exporter
level=info ts=2023-07-20T17:30:39.388Z caller=exporter.go:137 msg="Starting nginx-prometheus-exporter" version="(version=0.11.0, branch=, revision=c722e30e951cd1fae380543e6ac993b73e6a6d63)"
level=info ts=2023-07-20T17:30:39.388Z caller=exporter.go:138 msg="Build context" build_context="(go=go1.20.3, platform=darwin/arm64, user=, date=, tags=unknown)"
level=info ts=2023-07-20T17:30:39.390Z caller=tls_config.go:274 msg="Listening on" address=[::]:9113
level=info ts=2023-07-20T17:30:39.390Z caller=tls_config.go:277 msg="TLS is disabled." http2=false address=[::]:9113
Terminated: 15
nicolas@MacBook-Pro-de-Nicolas:~/go/src/github.com/n-rodriguez/nginx-prometheus-exporter$ echo $?
143

There is an issue with SIGTERM : the signal is not caught and thus "Shutting down"is not showing in the logs.

It works with this patch :

diff --git a/exporter.go b/exporter.go
index 6c81376..2de83a5 100644
--- a/exporter.go
+++ b/exporter.go
@@ -11,6 +11,7 @@ import (
        "os"
        "os/signal"
        "strings"
+       "syscall"
        "time"

        plusclient "github.com/nginxinc/nginx-plus-go-client/client"
@@ -237,7 +238,7 @@ func main() {
                http.Handle("/", landingPage)
        }

-       ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, os.Kill)
+       ctx, cancel := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
        defer cancel()

        srv := &http.Server{

nicolas@MacBook-Pro-de-Nicolas:~/go/src/github.com/n-rodriguez/nginx-prometheus-exporter$ ./nginx-prometheus-exporter
level=info ts=2023-07-20T17:44:25.176Z caller=exporter.go:138 msg="Starting nginx-prometheus-exporter" version="(version=0.11.0, branch=, revision=c722e30e951cd1fae380543e6ac993b73e6a6d63-modified)"
level=info ts=2023-07-20T17:44:25.176Z caller=exporter.go:139 msg="Build context" build_context="(go=go1.20.3, platform=darwin/arm64, user=, date=, tags=unknown)"
level=info ts=2023-07-20T17:44:25.178Z caller=tls_config.go:274 msg="Listening on" address=[::]:9113
level=info ts=2023-07-20T17:44:25.178Z caller=tls_config.go:277 msg="TLS is disabled." http2=false address=[::]:9113
level=info ts=2023-07-20T17:44:33.863Z caller=exporter.go:260 msg="Shutting down"
level=info ts=2023-07-20T17:44:33.863Z caller=exporter.go:251 msg="HTTP server closed"
nicolas@MacBook-Pro-de-Nicolas:~/go/src/github.com/n-rodriguez/nginx-prometheus-exporter$ echo $?
0

[lucacome]

Thanks for reviewing @n-rodriguez

From:

https://github.com/golang/go/blob/master/src/os/exec_posix.go#L16-L24

// The only signal values guaranteed to be present in the os package on all
// systems are os.Interrupt (send the process an interrupt) and os.Kill (force
// the process to exit). On Windows, sending os.Interrupt to a process with
// os.Process.Signal is not implemented; it will return an error instead of
// sending a signal.
var (
        Interrupt Signal = syscall.SIGINT
        Kill      Signal = syscall.SIGKILL
)

so os.Kill and os.Interrupt are syscall.SIGKILL and syscall.SIGINT and are the only two that are guaranteed to be present. But for example k8s sends a SIGTERM to the container, so we should probably add it?

Like this I think:

signal.NotifyContext(context.Background(), os.Interrupt, os.Kill, syscall.SIGTERM)

To be honest I'm not entirely sure I see the value of waiting for a shutdown in the first place, we're not serving traffic or anything like that, since it's just exposing metrics, but I guess it doesn't hurt.

[n-rodriguez]

But for example k8s sends a SIGTERM to the container, so we should probably add it?

yes, please 👍

[lucacome]

Added SIGTERM to the list.

[n-rodriguez]

LGTM!

[n-rodriguez]

we're not serving traffic or anything like that, since it's just exposing metrics

basically it's the same thing : an http request => in all cases you don't want clients to receive a truncated response from the server. (https://pkg.go.dev/net/http#Server.Shutdown)

[github-actions]

Dependency Review

The following issues were found:

• ✅ 0 vulnerable package(s)
• ✅ 0 package(s) with incompatible licenses
• ✅ 0 package(s) with invalid SPDX license definitions
• ⚠️ 6 package(s) with unknown licenses.

See the Details below.

License Issues

go.mod

Package	Version	License	Issue Type
golang.org/x/crypto	0.8.0	Null	Unknown License
golang.org/x/net	0.10.0	Null	Unknown License
golang.org/x/oauth2	0.8.0	Null	Unknown License
golang.org/x/sync	0.2.0	Null	Unknown License
golang.org/x/text	0.9.0	Null	Unknown License
gopkg.in/yaml.v2	2.4.0	Null	Unknown License

Allowed Licenses: Apache-1.1, Apache-2.0, BSD-2-Clause, BSD-3-Clause, BSL-1.0, ISC, MIT, NCSA, OpenSSL, Python-2.0, X11

Scanned Manifest Files

go.mod

• github.com/coreos/go-systemd/v22@22.5.0
• github.com/jpillora/backoff@1.0.0
• github.com/kr/text@0.2.0
• github.com/mwitkow/go-conntrack@0.0.0-20190716064945-2f068394615f
• github.com/prometheus/exporter-toolkit@0.10.0
• golang.org/x/crypto@0.8.0
• golang.org/x/net@0.10.0
• golang.org/x/oauth2@0.8.0
• golang.org/x/sync@0.2.0
• golang.org/x/text@0.9.0
• google.golang.org/appengine@1.6.7
• gopkg.in/yaml.v2@2.4.0