fix: fails to auto-reload on changes to rule and scrape config files

Signed-off-by: Benjamin Godding <ben.godding@bright.ai>

config/reload.go

@@ -20,6 +20,7 @@ import (
 	"os"
 	"path/filepath"
 
+	promconfig "github.com/prometheus/common/config"
 	"gopkg.in/yaml.v2"
 )
 
@@ -49,10 +50,10 @@ func GenerateChecksum(yamlFilePath string) (string, error) {
 	dir := filepath.Dir(yamlFilePath)
 
 	for i, file := range config.RuleFiles {
-		config.RuleFiles[i] = filepath.Join(dir, file)
+		config.RuleFiles[i] = promconfig.JoinDir(dir, file)
 	}
 	for i, file := range config.ScrapeConfigFiles {
-		config.ScrapeConfigFiles[i] = filepath.Join(dir, file)
+		config.ScrapeConfigFiles[i] = promconfig.JoinDir(dir, file)
 	}
 
 	files := map[string][]string{

config/reload_test.go

@@ -14,6 +14,7 @@
 package config
 
 import (
+	"fmt"
 	"os"
 	"path/filepath"
 	"testing"
@@ -26,8 +27,10 @@ func TestGenerateChecksum(t *testing.T) {
 
 	// 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")
+	ruleFile := "rule_file.yml"
+	ruleFilePath := filepath.Join(tmpDir, ruleFile)
+	scrapeConfigFile := "scrape_config.yml"
+	scrapeConfigFilePath := filepath.Join(tmpDir, scrapeConfigFile)
 
 	// Define initial and modified content for the files.
 	originalRuleContent := "groups:\n- name: example\n  rules:\n  - alert: ExampleAlert"
@@ -36,13 +39,32 @@ func TestGenerateChecksum(t *testing.T) {
 	originalScrapeConfigContent := "scrape_configs:\n- job_name: example"
 	modifiedScrapeConfigContent := "scrape_configs:\n- job_name: modified_example"
 
+	testCases := []struct {
+		name                 string
+		ruleFilePath         string
+		scrapeConfigFilePath string
+	}{
+		{
+			name:                 "Auto reload using relative path.",
+			ruleFilePath:         ruleFile,
+			scrapeConfigFilePath: scrapeConfigFile,
+		},
+		{
+			name:                 "Auto reload using absolute path.",
+			ruleFilePath:         ruleFilePath,
+			scrapeConfigFilePath: scrapeConfigFilePath,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
 			// Define YAML content referencing the rule and scrape config files.
-	yamlContent := `
+			yamlContent := fmt.Sprintf(`
 rule_files:
-  - rule_file.yml
+  - %s
 scrape_config_files:
-  - scrape_config.yml
-`
+  - %s
+`, tc.ruleFilePath, tc.scrapeConfigFilePath)
 
 			// Write initial content to files.
 			require.NoError(t, os.WriteFile(ruleFilePath, []byte(originalRuleContent), 0o644))
@@ -118,14 +140,14 @@ scrape_config_files:
 
 			t.Run("Main File Change", func(t *testing.T) {
 				// Modify the main YAML file.
-		modifiedYamlContent := `
+				modifiedYamlContent := fmt.Sprintf(`
 global:
   scrape_interval: 3s
 rule_files:
-  - rule_file.yml
+  - %s
 scrape_config_files:
-  - scrape_config.yml
-`
+  - %s
+`, tc.ruleFilePath, tc.scrapeConfigFilePath)
 				require.NoError(t, os.WriteFile(yamlFilePath, []byte(modifiedYamlContent), 0o644))
 
 				// Checksum should change.
@@ -142,10 +164,10 @@ scrape_config_files:
 
 			t.Run("Rule File Removed from YAML Config", func(t *testing.T) {
 				// Modify the YAML content to remove the rule file.
-		modifiedYamlContent := `
+				modifiedYamlContent := fmt.Sprintf(`
 scrape_config_files:
-  - scrape_config.yml
-`
+  - %s
+`, tc.scrapeConfigFilePath)
 				require.NoError(t, os.WriteFile(yamlFilePath, []byte(modifiedYamlContent), 0o644))
 
 				// Checksum should change.
@@ -162,10 +184,10 @@ scrape_config_files:
 
 			t.Run("Scrape Config Removed from YAML Config", func(t *testing.T) {
 				// Modify the YAML content to remove the scrape config file.
-		modifiedYamlContent := `
+				modifiedYamlContent := fmt.Sprintf(`
 rule_files:
-  - rule_file.yml
-`
+  - %s
+`, tc.ruleFilePath)
 				require.NoError(t, os.WriteFile(yamlFilePath, []byte(modifiedYamlContent), 0o644))
 
 				// Checksum should change.
@@ -211,6 +233,8 @@ rule_files:
 				revertedChecksum := calculateChecksum(t, yamlFilePath)
 				require.Equal(t, originalChecksum, revertedChecksum)
 			})
+		})
+	}
 }
 
 // calculateChecksum generates a checksum for the given YAML file path.