func appendMetricRelabelConfig()

in otelcollector/shared/configmap/ccp/prometheus-ccp-config-merger.go [46:118]
55 lines of code
12 McCabe index (conditional complexity)

func appendMetricRelabelConfig(yamlConfigFile, keepListRegex string) {
	fmt.Printf("Adding keep list regex or minimal ingestion regex for %s\n", yamlConfigFile)

	content, err := os.ReadFile(yamlConfigFile)
	if err != nil {
		fmt.Printf("Error reading config file %s: %v. The keep list regex will not be used\n", yamlConfigFile, err)
		return
	}

	var config map[string]interface{}
	if err := yaml.Unmarshal(content, &config); err != nil {
		fmt.Printf("Error unmarshalling YAML for %s: %v. The keep list regex will not be used\n", yamlConfigFile, err)
		return
	}

	keepListMetricRelabelConfig := map[string]interface{}{
		"source_labels": []interface{}{"__name__"},
		"action":        "keep",
		"regex":         keepListRegex,
	}

	if scrapeConfigs, ok := config["scrape_configs"].([]interface{}); ok {
		for i, scfg := range scrapeConfigs {
			// Ensure scfg is a map with string keys
			if scfgMap, ok := scfg.(map[interface{}]interface{}); ok {
				// Convert to map[string]interface{}
				stringScfgMap := make(map[string]interface{})
				for k, v := range scfgMap {
					if key, ok := k.(string); ok {
						stringScfgMap[key] = v
					} else {
						fmt.Printf("Encountered non-string key in scrape config map: %v\n", k)
						return
					}
				}

				// Update or add metric_relabel_configs
				if metricRelabelCfgs, ok := stringScfgMap["metric_relabel_configs"].([]interface{}); ok {
					stringScfgMap["metric_relabel_configs"] = append(metricRelabelCfgs, keepListMetricRelabelConfig)
				} else {
					stringScfgMap["metric_relabel_configs"] = []interface{}{keepListMetricRelabelConfig}
				}

				// Convert back to map[interface{}]interface{} for YAML marshalling
				interfaceScfgMap := make(map[interface{}]interface{})
				for k, v := range stringScfgMap {
					interfaceScfgMap[k] = v
				}

				// Update the scrape_configs list
				scrapeConfigs[i] = interfaceScfgMap
			}
		}

		// Write updated scrape_configs back to config
		config["scrape_configs"] = scrapeConfigs

		// Marshal the updated config to YAML
		cfgYamlWithMetricRelabelConfig, err := yaml.Marshal(config)
		if err != nil {
			fmt.Printf("Error marshalling YAML for %s: %v. The keep list regex will not be used\n", yamlConfigFile, err)
			return
		}

		// Write the updated YAML back to the file
		if err := os.WriteFile(yamlConfigFile, cfgYamlWithMetricRelabelConfig, fs.FileMode(0644)); err != nil {
			fmt.Printf("Error writing to file %s: %v. The keep list regex will not be used\n", yamlConfigFile, err)
			return
		}
	} else {
		fmt.Printf("No 'scrape_configs' found in the YAML. The keep list regex will not be used.\n")
	}
}