Merge pull request #15020 from prometheus/rel-2.55-revert-14769

[Release 2.55] Revert pull request #14769 - auto config reload

CHANGELOG.md

@@ -5,7 +5,6 @@
 ## 2.55.0-rc.0 / 2024-09-20
 
 * [FEATURE] Support UTF-8 characters in label names - feature flag `utf8-names`. #14482, #14880, #14736, #14727
-* [FEATURE] Support config reload automatically - feature flag `auto-reload-config`. #14769
 * [FEATURE] Scraping: Add the ability to set custom `http_headers` in config. #14817
 * [FEATURE] Scraping: Support feature flag `created-timestamp-zero-ingestion` in OpenMetrics. #14356, #14815
 * [FEATURE] Scraping: `scrape_failure_log_file` option to log failures to a file. #14734

cmd/prometheus/main.go

@@ -154,9 +154,6 @@ type flagConfig struct {
 	RemoteFlushDeadline model.Duration
 	nameEscapingScheme  string
 
-	enableAutoReload   bool
-	autoReloadInterval model.Duration
-
 	featureList   []string
 	memlimitRatio float64
 	// These options are extracted from featureList
@@ -215,12 +212,6 @@ func (c *flagConfig) setFeatureListOptions(logger log.Logger) error {
 			case "auto-gomaxprocs":
 				c.enableAutoGOMAXPROCS = true
 				level.Info(logger).Log("msg", "Automatically set GOMAXPROCS to match Linux container CPU quota")
-			case "auto-reload-config":
-				c.enableAutoReload = true
-				if s := time.Duration(c.autoReloadInterval).Seconds(); s > 0 && s < 1 {
-					c.autoReloadInterval, _ = model.ParseDuration("1s")
-				}
-				level.Info(logger).Log("msg", fmt.Sprintf("Enabled automatic configuration file reloading. Checking for configuration changes every %s.", c.autoReloadInterval))
 			case "auto-gomemlimit":
 				c.enableAutoGOMEMLIMIT = true
 				level.Info(logger).Log("msg", "Automatically set GOMEMLIMIT to match Linux container or system memory limit")
@@ -311,9 +302,6 @@ func main() {
 	a.Flag("config.file", "Prometheus configuration file path.").
 		Default("prometheus.yml").StringVar(&cfg.configFile)
 
-	a.Flag("config.auto-reload-interval", "Specifies the interval for checking and automatically reloading the Prometheus configuration file upon detecting changes.").
-		Default("30s").SetValue(&cfg.autoReloadInterval)
-
 	a.Flag("web.listen-address", "Address to listen on for UI, API, and telemetry. Can be repeated.").
 		Default("0.0.0.0:9090").StringsVar(&cfg.web.ListenAddresses)
 
@@ -504,7 +492,7 @@ func main() {
 
 	a.Flag("scrape.name-escaping-scheme", `Method for escaping legacy invalid names when sending to Prometheus that does not support UTF-8. Can be one of "values", "underscores", or "dots".`).Default(scrape.DefaultNameEscapingScheme.String()).StringVar(&cfg.nameEscapingScheme)
 
-	a.Flag("enable-feature", "Comma separated feature names to enable. Valid options: agent, auto-gomaxprocs, auto-gomemlimit, auto-reload-config, concurrent-rule-eval, created-timestamp-zero-ingestion, delayed-compaction, exemplar-storage, expand-external-labels, extra-scrape-metrics, memory-snapshot-on-shutdown, native-histograms, new-service-discovery-manager, no-default-scrape-port, otlp-write-receiver, promql-experimental-functions, promql-delayed-name-removal, promql-per-step-stats, remote-write-receiver (DEPRECATED), utf8-names. See https://prometheus.io/docs/prometheus/latest/feature_flags/ for more details.").
+	a.Flag("enable-feature", "Comma separated feature names to enable. Valid options: agent, auto-gomaxprocs, auto-gomemlimit, concurrent-rule-eval, created-timestamp-zero-ingestion, delayed-compaction, exemplar-storage, expand-external-labels, extra-scrape-metrics, memory-snapshot-on-shutdown, native-histograms, new-service-discovery-manager, no-default-scrape-port, otlp-write-receiver, promql-experimental-functions, promql-delayed-name-removal, promql-per-step-stats, remote-write-receiver (DEPRECATED), utf8-names. See https://prometheus.io/docs/prometheus/latest/feature_flags/ for more details.").
 		Default("").StringsVar(&cfg.featureList)
 
 	promlogflag.AddFlags(a, &cfg.promlogConfig)
@@ -1142,15 +1130,6 @@ func main() {
 		hup := make(chan os.Signal, 1)
 		signal.Notify(hup, syscall.SIGHUP)
 		cancel := make(chan struct{})
-
-		var checksum string
-		if cfg.enableAutoReload {
-			checksum, err = config.GenerateChecksum(cfg.configFile)
-			if err != nil {
-				level.Error(logger).Log("msg", "Failed to generate initial checksum for configuration file", "err", err)
-			}
-		}
-
 		g.Add(
 			func() error {
 				<-reloadReady.C
@@ -1160,12 +1139,6 @@ func main() {
 					case <-hup:
 						if err := reloadConfig(cfg.configFile, cfg.enableExpandExternalLabels, cfg.tsdb.EnableExemplarStorage, logger, noStepSubqueryInterval, reloaders...); err != nil {
 							level.Error(logger).Log("msg", "Error reloading config", "err", err)
-						} else if cfg.enableAutoReload {
-							if currentChecksum, err := config.GenerateChecksum(cfg.configFile); err == nil {
-								checksum = currentChecksum
-							} else {
-								level.Error(logger).Log("msg", "Failed to generate checksum during configuration reload", "err", err)
-							}
 						}
 					case rc := <-webHandler.Reload():
 						if err := reloadConfig(cfg.configFile, cfg.enableExpandExternalLabels, cfg.tsdb.EnableExemplarStorage, logger, noStepSubqueryInterval, reloaders...); err != nil {
@@ -1173,32 +1146,6 @@ func main() {
 							rc <- err
 						} else {
 							rc <- nil
-							if cfg.enableAutoReload {
-								if currentChecksum, err := config.GenerateChecksum(cfg.configFile); err == nil {
-									checksum = currentChecksum
-								} else {
-									level.Error(logger).Log("msg", "Failed to generate checksum during configuration reload", "err", err)
-								}
-							}
-						}
-					case <-time.Tick(time.Duration(cfg.autoReloadInterval)):
-						if !cfg.enableAutoReload {
-							continue
-						}
-						currentChecksum, err := config.GenerateChecksum(cfg.configFile)
-						if err != nil {
-							level.Error(logger).Log("msg", "Failed to generate checksum during configuration reload", "err", err)
-							continue
-						}
-						if currentChecksum == checksum {
-							continue
-						}
-						level.Info(logger).Log("msg", "Configuration file change detected, reloading the configuration.")
-
-						if err := reloadConfig(cfg.configFile, cfg.enableExpandExternalLabels, cfg.tsdb.EnableExemplarStorage, logger, noStepSubqueryInterval, reloaders...); err != nil {
-							level.Error(logger).Log("msg", "Error reloading config", "err", err)
-						} else {
-							checksum = currentChecksum
 						}
 					case <-cancel:
 						return nil

config/reload.go

@@ -1,92 +0,0 @@
-// Copyright 2024 The Prometheus Authors
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package config
-
-import (
-	"crypto/sha256"
-	"encoding/hex"
-	"fmt"
-	"os"
-	"path/filepath"
-
-	"gopkg.in/yaml.v2"
-)
-
-type ExternalFilesConfig struct {
-	RuleFiles         []string `yaml:"rule_files"`
-	ScrapeConfigFiles []string `yaml:"scrape_config_files"`
-}
-
-// GenerateChecksum generates a checksum of the YAML file and the files it references.
-func GenerateChecksum(yamlFilePath string) (string, error) {
-	hash := sha256.New()
-
-	yamlContent, err := os.ReadFile(yamlFilePath)
-	if err != nil {
-		return "", fmt.Errorf("error reading YAML file: %w", err)
-	}
-	_, err = hash.Write(yamlContent)
-	if err != nil {
-		return "", fmt.Errorf("error writing YAML file to hash: %w", err)
-	}
-
-	var config ExternalFilesConfig
-	if err := yaml.Unmarshal(yamlContent, &config); err != nil {
-		return "", fmt.Errorf("error unmarshalling YAML: %w", err)
-	}
-
-	dir := filepath.Dir(yamlFilePath)
-
-	for i, file := range config.RuleFiles {
-		config.RuleFiles[i] = filepath.Join(dir, file)
-	}
-	for i, file := range config.ScrapeConfigFiles {
-		config.ScrapeConfigFiles[i] = filepath.Join(dir, file)
-	}
-
-	files := map[string][]string{
-		"r": config.RuleFiles,         // "r" for rule files
-		"s": config.ScrapeConfigFiles, // "s" for scrape config files
-	}
-
-	for _, prefix := range []string{"r", "s"} {
-		for _, pattern := range files[prefix] {
-			matchingFiles, err := filepath.Glob(pattern)
-			if err != nil {
-				return "", fmt.Errorf("error finding files with pattern %q: %w", pattern, err)
-			}
-
-			for _, file := range matchingFiles {
-				// Write prefix to the hash ("r" or "s") followed by \0, then
-				// the file path.
-				_, err = hash.Write([]byte(prefix + "\x00" + file + "\x00"))
-				if err != nil {
-					return "", fmt.Errorf("error writing %q path to hash: %w", file, err)
-				}
-
-				// Read and hash the content of the file.
-				content, err := os.ReadFile(file)
-				if err != nil {
-					return "", fmt.Errorf("error reading file %s: %w", file, err)
-				}
-				_, err = hash.Write(append(content, []byte("\x00")...))
-				if err != nil {
-					return "", fmt.Errorf("error writing %q content to hash: %w", file, err)
-				}
-			}
-		}
-	}
-
-	return hex.EncodeToString(hash.Sum(nil)), nil
-}

config/reload_test.go

@@ -1,222 +0,0 @@
-// Copyright 2024 The Prometheus Authors
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package config
-
-import (
-	"os"
-	"path/filepath"
-	"testing"
-
-	"github.com/stretchr/testify/require"
-)
-
-func TestGenerateChecksum(t *testing.T) {
-	tmpDir := t.TempDir()
-
-	// Define paths for the temporary files.
-	yamlFilePath := filepath.Join(tmpDir, "test.yml")
-	ruleFilePath := filepath.Join(tmpDir, "rule_file.yml")
-	scrapeConfigFilePath := filepath.Join(tmpDir, "scrape_config.yml")
-
-	// Define initial and modified content for the files.
-	originalRuleContent := "groups:\n- name: example\n  rules:\n  - alert: ExampleAlert"
-	modifiedRuleContent := "groups:\n- name: example\n  rules:\n  - alert: ModifiedAlert"
-
-	originalScrapeConfigContent := "scrape_configs:\n- job_name: example"
-	modifiedScrapeConfigContent := "scrape_configs:\n- job_name: modified_example"
-
-	// Define YAML content referencing the rule and scrape config files.
-	yamlContent := `
-rule_files:
-  - rule_file.yml
-scrape_config_files:
-  - scrape_config.yml
-`
-
-	// Write initial content to files.
-	require.NoError(t, os.WriteFile(ruleFilePath, []byte(originalRuleContent), 0o644))
-	require.NoError(t, os.WriteFile(scrapeConfigFilePath, []byte(originalScrapeConfigContent), 0o644))
-	require.NoError(t, os.WriteFile(yamlFilePath, []byte(yamlContent), 0o644))
-
-	// Generate the original checksum.
-	originalChecksum := calculateChecksum(t, yamlFilePath)
-
-	t.Run("Rule File Change", func(t *testing.T) {
-		// Modify the rule file.
-		require.NoError(t, os.WriteFile(ruleFilePath, []byte(modifiedRuleContent), 0o644))
-
-		// Checksum should change.
-		modifiedChecksum := calculateChecksum(t, yamlFilePath)
-		require.NotEqual(t, originalChecksum, modifiedChecksum)
-
-		// Revert the rule file.
-		require.NoError(t, os.WriteFile(ruleFilePath, []byte(originalRuleContent), 0o644))
-
-		// Checksum should return to the original.
-		revertedChecksum := calculateChecksum(t, yamlFilePath)
-		require.Equal(t, originalChecksum, revertedChecksum)
-	})
-
-	t.Run("Scrape Config Change", func(t *testing.T) {
-		// Modify the scrape config file.
-		require.NoError(t, os.WriteFile(scrapeConfigFilePath, []byte(modifiedScrapeConfigContent), 0o644))
-
-		// Checksum should change.
-		modifiedChecksum := calculateChecksum(t, yamlFilePath)
-		require.NotEqual(t, originalChecksum, modifiedChecksum)
-
-		// Revert the scrape config file.
-		require.NoError(t, os.WriteFile(scrapeConfigFilePath, []byte(originalScrapeConfigContent), 0o644))
-
-		// Checksum should return to the original.
-		revertedChecksum := calculateChecksum(t, yamlFilePath)
-		require.Equal(t, originalChecksum, revertedChecksum)
-	})
-
-	t.Run("Rule File Deletion", func(t *testing.T) {
-		// Delete the rule file.
-		require.NoError(t, os.Remove(ruleFilePath))
-
-		// Checksum should change.
-		deletedChecksum := calculateChecksum(t, yamlFilePath)
-		require.NotEqual(t, originalChecksum, deletedChecksum)
-
-		// Restore the rule file.
-		require.NoError(t, os.WriteFile(ruleFilePath, []byte(originalRuleContent), 0o644))
-
-		// Checksum should return to the original.
-		revertedChecksum := calculateChecksum(t, yamlFilePath)
-		require.Equal(t, originalChecksum, revertedChecksum)
-	})
-
-	t.Run("Scrape Config Deletion", func(t *testing.T) {
-		// Delete the scrape config file.
-		require.NoError(t, os.Remove(scrapeConfigFilePath))
-
-		// Checksum should change.
-		deletedChecksum := calculateChecksum(t, yamlFilePath)
-		require.NotEqual(t, originalChecksum, deletedChecksum)
-
-		// Restore the scrape config file.
-		require.NoError(t, os.WriteFile(scrapeConfigFilePath, []byte(originalScrapeConfigContent), 0o644))
-
-		// Checksum should return to the original.
-		revertedChecksum := calculateChecksum(t, yamlFilePath)
-		require.Equal(t, originalChecksum, revertedChecksum)
-	})
-
-	t.Run("Main File Change", func(t *testing.T) {
-		// Modify the main YAML file.
-		modifiedYamlContent := `
-global:
-  scrape_interval: 3s
-rule_files:
-  - rule_file.yml
-scrape_config_files:
-  - scrape_config.yml
-`
-		require.NoError(t, os.WriteFile(yamlFilePath, []byte(modifiedYamlContent), 0o644))
-
-		// Checksum should change.
-		modifiedChecksum := calculateChecksum(t, yamlFilePath)
-		require.NotEqual(t, originalChecksum, modifiedChecksum)
-
-		// Revert the main YAML file.
-		require.NoError(t, os.WriteFile(yamlFilePath, []byte(yamlContent), 0o644))
-
-		// Checksum should return to the original.
-		revertedChecksum := calculateChecksum(t, yamlFilePath)
-		require.Equal(t, originalChecksum, revertedChecksum)
-	})
-
-	t.Run("Rule File Removed from YAML Config", func(t *testing.T) {
-		// Modify the YAML content to remove the rule file.
-		modifiedYamlContent := `
-scrape_config_files:
-  - scrape_config.yml
-`
-		require.NoError(t, os.WriteFile(yamlFilePath, []byte(modifiedYamlContent), 0o644))
-
-		// Checksum should change.
-		modifiedChecksum := calculateChecksum(t, yamlFilePath)
-		require.NotEqual(t, originalChecksum, modifiedChecksum)
-
-		// Revert the YAML content.
-		require.NoError(t, os.WriteFile(yamlFilePath, []byte(yamlContent), 0o644))
-
-		// Checksum should return to the original.
-		revertedChecksum := calculateChecksum(t, yamlFilePath)
-		require.Equal(t, originalChecksum, revertedChecksum)
-	})
-
-	t.Run("Scrape Config Removed from YAML Config", func(t *testing.T) {
-		// Modify the YAML content to remove the scrape config file.
-		modifiedYamlContent := `
-rule_files:
-  - rule_file.yml
-`
-		require.NoError(t, os.WriteFile(yamlFilePath, []byte(modifiedYamlContent), 0o644))
-
-		// Checksum should change.
-		modifiedChecksum := calculateChecksum(t, yamlFilePath)
-		require.NotEqual(t, originalChecksum, modifiedChecksum)
-
-		// Revert the YAML content.
-		require.NoError(t, os.WriteFile(yamlFilePath, []byte(yamlContent), 0o644))
-
-		// Checksum should return to the original.
-		revertedChecksum := calculateChecksum(t, yamlFilePath)
-		require.Equal(t, originalChecksum, revertedChecksum)
-	})
-
-	t.Run("Empty Rule File", func(t *testing.T) {
-		// Write an empty rule file.
-		require.NoError(t, os.WriteFile(ruleFilePath, []byte(""), 0o644))
-
-		// Checksum should change.
-		emptyChecksum := calculateChecksum(t, yamlFilePath)
-		require.NotEqual(t, originalChecksum, emptyChecksum)
-
-		// Restore the rule file.
-		require.NoError(t, os.WriteFile(ruleFilePath, []byte(originalRuleContent), 0o644))
-
-		// Checksum should return to the original.
-		revertedChecksum := calculateChecksum(t, yamlFilePath)
-		require.Equal(t, originalChecksum, revertedChecksum)
-	})
-
-	t.Run("Empty Scrape Config File", func(t *testing.T) {
-		// Write an empty scrape config file.
-		require.NoError(t, os.WriteFile(scrapeConfigFilePath, []byte(""), 0o644))
-
-		// Checksum should change.
-		emptyChecksum := calculateChecksum(t, yamlFilePath)
-		require.NotEqual(t, originalChecksum, emptyChecksum)
-
-		// Restore the scrape config file.
-		require.NoError(t, os.WriteFile(scrapeConfigFilePath, []byte(originalScrapeConfigContent), 0o644))
-
-		// Checksum should return to the original.
-		revertedChecksum := calculateChecksum(t, yamlFilePath)
-		require.Equal(t, originalChecksum, revertedChecksum)
-	})
-}
-
-// calculateChecksum generates a checksum for the given YAML file path.
-func calculateChecksum(t *testing.T, yamlFilePath string) string {
-	checksum, err := GenerateChecksum(yamlFilePath)
-	require.NoError(t, err)
-	require.NotEmpty(t, checksum)
-	return checksum
-}

docs/command-line/prometheus.md

@@ -15,7 +15,6 @@ The Prometheus monitoring server
 | <code class="text-nowrap">-h</code>, <code class="text-nowrap">--help</code> | Show context-sensitive help (also try --help-long and --help-man). |  |
 | <code class="text-nowrap">--version</code> | Show application version. |  |
 | <code class="text-nowrap">--config.file</code> | Prometheus configuration file path. | `prometheus.yml` |
-| <code class="text-nowrap">--config.auto-reload-interval</code> | Specifies the interval for checking and automatically reloading the Prometheus configuration file upon detecting changes. | `30s` |
 | <code class="text-nowrap">--web.listen-address</code> <code class="text-nowrap">...<code class="text-nowrap"> | Address to listen on for UI, API, and telemetry. Can be repeated. | `0.0.0.0:9090` |
 | <code class="text-nowrap">--auto-gomemlimit.ratio</code> | The ratio of reserved GOMEMLIMIT memory to the detected maximum container or system memory | `0.9` |
 | <code class="text-nowrap">--web.config.file</code> | [EXPERIMENTAL] Path to configuration file that can enable TLS or authentication. |  |
@@ -58,7 +57,7 @@ The Prometheus monitoring server
 | <code class="text-nowrap">--query.max-concurrency</code> | Maximum number of queries executed concurrently. Use with server mode only. | `20` |
 | <code class="text-nowrap">--query.max-samples</code> | Maximum number of samples a single query can load into memory. Note that queries will fail if they try to load more samples than this into memory, so this also limits the number of samples a query can return. Use with server mode only. | `50000000` |
 | <code class="text-nowrap">--scrape.name-escaping-scheme</code> | Method for escaping legacy invalid names when sending to Prometheus that does not support UTF-8. Can be one of "values", "underscores", or "dots". | `values` |
-| <code class="text-nowrap">--enable-feature</code> <code class="text-nowrap">...<code class="text-nowrap"> | Comma separated feature names to enable. Valid options: agent, auto-gomaxprocs, auto-gomemlimit, auto-reload-config, concurrent-rule-eval, created-timestamp-zero-ingestion, delayed-compaction, exemplar-storage, expand-external-labels, extra-scrape-metrics, memory-snapshot-on-shutdown, native-histograms, new-service-discovery-manager, no-default-scrape-port, otlp-write-receiver, promql-experimental-functions, promql-delayed-name-removal, promql-per-step-stats, remote-write-receiver (DEPRECATED), utf8-names. See https://prometheus.io/docs/prometheus/latest/feature_flags/ for more details. |  |
+| <code class="text-nowrap">--enable-feature</code> <code class="text-nowrap">...<code class="text-nowrap"> | Comma separated feature names to enable. Valid options: agent, auto-gomaxprocs, auto-gomemlimit, concurrent-rule-eval, created-timestamp-zero-ingestion, delayed-compaction, exemplar-storage, expand-external-labels, extra-scrape-metrics, memory-snapshot-on-shutdown, native-histograms, new-service-discovery-manager, no-default-scrape-port, otlp-write-receiver, promql-experimental-functions, promql-delayed-name-removal, promql-per-step-stats, remote-write-receiver (DEPRECATED), utf8-names. See https://prometheus.io/docs/prometheus/latest/feature_flags/ for more details. |  |
 | <code class="text-nowrap">--log.level</code> | Only log messages with the given severity or above. One of: [debug, info, warn, error] | `info` |
 | <code class="text-nowrap">--log.format</code> | Output format of log messages. One of: [logfmt, json] | `logfmt` |
 

docs/feature_flags.md

@@ -265,16 +265,3 @@ This allows optionally preserving the `__name__` label via the `label_replace` a
 When enabled, changes the metric and label name validation scheme inside Prometheus to allow the full UTF-8 character set.
 By itself, this flag does not enable the request of UTF-8 names via content negotiation.
 Users will also have to set `metric_name_validation_scheme` in scrape configs to enable the feature either on the global config or on a per-scrape config basis.
-
-## Auto Reload Config
-
-`--enable-feature=auto-reload-config`
-
-When enabled, Prometheus will automatically reload its configuration file at a
-specified interval. The interval is defined by the
-`--config.auto-reload-interval` flag, which defaults to `30s`.
-
-Configuration reloads are triggered by detecting changes in the checksum of the
-main configuration file or any referenced files, such as rule and scrape
-configurations. To ensure consistency and avoid issues during reloads, it's
-recommended to update these files atomically.