Support reload using signal

CHANGELOG.md

@@ -17,6 +17,7 @@ We use *breaking :warning:* to mark changes that are not backward compatible (re
 ### Added
 
 - [#6891](https://github.com/thanos-io/thanos/pull/6891) Objstore: Bump `objstore` which adds support for Azure Workload Identity.
+- [#6453](https://github.com/thanos-io/thanos/pull/6453) Sidecar: Added `--reloader.method` to support configuration reloads via SIHUP signal.
 
 ### Changed
 

cmd/thanos/config.go

@@ -114,8 +114,18 @@ type reloaderConfig struct {
 	ruleDirectories []string
 	watchInterval   time.Duration
 	retryInterval   time.Duration
+	method          string
+	processName     string
 }
 
+const (
+	// HTTPReloadMethod reloads the configuration using the HTTP reload endpoint.
+	HTTPReloadMethod = "http"
+
+	// SignalReloadMethod reloads the configuration sending a SIGHUP signal to the process.
+	SignalReloadMethod = "signal"
+)
+
 func (rc *reloaderConfig) registerFlag(cmd extkingpin.FlagClause) *reloaderConfig {
 	cmd.Flag("reloader.config-file",
 		"Config file watched by the reloader.").
@@ -132,6 +142,12 @@ func (rc *reloaderConfig) registerFlag(cmd extkingpin.FlagClause) *reloaderConfi
 	cmd.Flag("reloader.retry-interval",
 		"Controls how often reloader retries config reload in case of error.").
 		Default("5s").DurationVar(&rc.retryInterval)
+	cmd.Flag("reloader.method",
+		"Method used to reload the configuration.").
+		Default(HTTPReloadMethod).EnumVar(&rc.method, HTTPReloadMethod, SignalReloadMethod)
+	cmd.Flag("reloader.process-name",
+		"Executable name used to match the process being reloaded when using the signal method.").
+		Default("prometheus").StringVar(&rc.processName)
 
 	return rc
 }

cmd/thanos/sidecar.go

@@ -5,7 +5,9 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"math"
+	"net/http"
 	"net/url"
 	"sync"
 	"time"
@@ -62,18 +64,44 @@ func registerSidecar(app *extkingpin.App) {
 			return errors.Wrap(err, "error while parsing config for request logging")
 		}
 
+		httpConfContentYaml, err := conf.prometheus.httpClient.Content()
+		if err != nil {
+			return errors.Wrap(err, "getting http client config")
+		}
+		httpClientConfig, err := httpconfig.NewClientConfigFromYAML(httpConfContentYaml)
+		if err != nil {
+			return errors.Wrap(err, "parsing http config YAML")
+		}
+
+		httpClient, err := httpconfig.NewHTTPClient(*httpClientConfig, "thanos-sidecar")
+		if err != nil {
+			return errors.Wrap(err, "Improper http client config")
+		}
+
+		opts := reloader.Options{
+			HTTPClient:    *httpClient,
+			CfgFile:       conf.reloader.confFile,
+			CfgOutputFile: conf.reloader.envVarConfFile,
+			WatchedDirs:   conf.reloader.ruleDirectories,
+			WatchInterval: conf.reloader.watchInterval,
+			RetryInterval: conf.reloader.retryInterval,
+		}
+
+		switch conf.reloader.method {
+		case HTTPReloadMethod:
+			opts.ReloadURL = reloader.ReloadURLFromBase(conf.prometheus.url)
+		case SignalReloadMethod:
+			opts.ProcessName = conf.reloader.processName
+			opts.RuntimeInfoURL = reloader.RuntimeInfoURLFromBase(conf.prometheus.url)
+		default:
+			return fmt.Errorf("invalid reload method: %s", conf.reloader.method)
+		}
+
 		rl := reloader.New(log.With(logger, "component", "reloader"),
 			extprom.WrapRegistererWithPrefix("thanos_sidecar_", reg),
-			&reloader.Options{
-				ReloadURL:     reloader.ReloadURLFromBase(conf.prometheus.url),
-				CfgFile:       conf.reloader.confFile,
-				CfgOutputFile: conf.reloader.envVarConfFile,
-				WatchedDirs:   conf.reloader.ruleDirectories,
-				WatchInterval: conf.reloader.watchInterval,
-				RetryInterval: conf.reloader.retryInterval,
-			})
+			&opts)
 
-		return runSidecar(g, logger, reg, tracer, rl, component.Sidecar, *conf, grpcLogOpts, tagOpts)
+		return runSidecar(g, logger, reg, tracer, rl, component.Sidecar, *conf, httpClient, grpcLogOpts, tagOpts)
 	})
 }
 
@@ -85,28 +113,13 @@ func runSidecar(
 	reloader *reloader.Reloader,
 	comp component.Component,
 	conf sidecarConfig,
+	httpClient *http.Client,
 	grpcLogOpts []grpc_logging.Option,
 	tagOpts []tags.Option,
 ) error {
-	httpConfContentYaml, err := conf.prometheus.httpClient.Content()
-	if err != nil {
-		return errors.Wrap(err, "getting http client config")
-	}
-	httpClientConfig, err := httpconfig.NewClientConfigFromYAML(httpConfContentYaml)
-	if err != nil {
-		return errors.Wrap(err, "parsing http config YAML")
-	}
-
-	httpClient, err := httpconfig.NewHTTPClient(*httpClientConfig, "thanos-sidecar")
-	if err != nil {
-		return errors.Wrap(err, "Improper http client config")
-	}
-
-	reloader.SetHttpClient(*httpClient)
 
 	var m = &promMetadata{
 		promURL: conf.prometheus.url,
-
 		// Start out with the full time range. The shipper will constrain it later.
 		// TODO(fabxc): minimum timestamp is never adjusted if shipping is disabled.
 		mint: conf.limitMinTime.PrometheusTimestamp(),

docs/components/sidecar.md

@@ -153,6 +153,10 @@ Flags:
                                  Output file for environment variable
                                  substituted config file.
       --reloader.config-file=""  Config file watched by the reloader.
+      --reloader.method=http     Method used to reload the configuration.
+      --reloader.process-name="prometheus"
+                                 Executable name used to match the process being
+                                 reloaded when using the signal method.
       --reloader.retry-interval=5s
                                  Controls how often reloader retries config
                                  reload in case of error.

go.mod

@@ -117,6 +117,7 @@ require (
 )
 
 require (
+	github.com/mitchellh/go-ps v1.0.0
 	github.com/onsi/gomega v1.27.10
 	go.opentelemetry.io/contrib/propagators/autoprop v0.38.0
 	go4.org/intern v0.0.0-20230525184215-6c62f75575cb

go.sum

@@ -733,6 +733,8 @@ github.com/mitchellh/cli v1.0.0/go.mod h1:hNIlj7HEI86fIcpObd7a0FcrxTWetlwJDGcceT
 github.com/mitchellh/go-homedir v1.0.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
 github.com/mitchellh/go-homedir v1.1.0 h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG+4E0Y=
 github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
+github.com/mitchellh/go-ps v1.0.0 h1:i6ampVEEF4wQFF+bkYfwYgY+F/uYJDktmvLPf7qIgjc=
+github.com/mitchellh/go-ps v1.0.0/go.mod h1:J4lOc8z8yJs6vUwklHw2XEIiT4z4C40KtWVN3nvg8Pg=
 github.com/mitchellh/go-testing-interface v1.0.0/go.mod h1:kRemZodwjscx+RGhAo8eIhFbs2+BFgRtFPeD/KE+zxI=
 github.com/mitchellh/gox v0.4.0/go.mod h1:Sd9lOJ0+aimLBi73mGofS1ycjY8lL3uZM3JPS42BGNg=
 github.com/mitchellh/iochan v1.0.0/go.mod h1:JwYml1nuB7xOzsp52dPpHFffvOCDupsG0QubkSMEySY=