func checkConfig()

in cmd/promtool/main.go [496:621]
117 lines of code
40 McCabe index (conditional complexity)

func checkConfig(agentMode bool, filename string, checkSyntaxOnly bool) ([]string, error) {
	fmt.Println("Checking", filename)

	cfg, err := config.LoadFile(filename, agentMode, false, log.NewNopLogger())
	if err != nil {
		return nil, err
	}

	var ruleFiles []string
	if !checkSyntaxOnly {
		for _, rf := range cfg.RuleFiles {
			rfs, err := filepath.Glob(rf)
			if err != nil {
				return nil, err
			}
			// If an explicit file was given, error if it is not accessible.
			if !strings.Contains(rf, "*") {
				if len(rfs) == 0 {
					return nil, fmt.Errorf("%q does not point to an existing file", rf)
				}
				if err := checkFileExists(rfs[0]); err != nil {
					return nil, fmt.Errorf("error checking rule file %q: %w", rfs[0], err)
				}
			}
			ruleFiles = append(ruleFiles, rfs...)
		}
	}

	var scfgs []*config.ScrapeConfig
	if checkSyntaxOnly {
		scfgs = cfg.ScrapeConfigs
	} else {
		var err error
		scfgs, err = cfg.GetScrapeConfigs()
		if err != nil {
			return nil, fmt.Errorf("error loading scrape configs: %w", err)
		}
	}

	for _, scfg := range scfgs {
		if !checkSyntaxOnly && scfg.HTTPClientConfig.Authorization != nil {
			if err := checkFileExists(scfg.HTTPClientConfig.Authorization.CredentialsFile); err != nil {
				return nil, fmt.Errorf("error checking authorization credentials or bearer token file %q: %w", scfg.HTTPClientConfig.Authorization.CredentialsFile, err)
			}
		}

		if err := checkTLSConfig(scfg.HTTPClientConfig.TLSConfig, checkSyntaxOnly); err != nil {
			return nil, err
		}

		for _, c := range scfg.ServiceDiscoveryConfigs {
			switch c := c.(type) {
			case *kubernetes.SDConfig:
				if err := checkTLSConfig(c.HTTPClientConfig.TLSConfig, checkSyntaxOnly); err != nil {
					return nil, err
				}
			case *file.SDConfig:
				if checkSyntaxOnly {
					break
				}
				for _, file := range c.Files {
					files, err := filepath.Glob(file)
					if err != nil {
						return nil, err
					}
					if len(files) != 0 {
						for _, f := range files {
							var targetGroups []*targetgroup.Group
							targetGroups, err = checkSDFile(f)
							if err != nil {
								return nil, fmt.Errorf("checking SD file %q: %w", file, err)
							}
							if err := checkTargetGroupsForScrapeConfig(targetGroups, scfg); err != nil {
								return nil, err
							}
						}
						continue
					}
					fmt.Printf("  WARNING: file %q for file_sd in scrape job %q does not exist\n", file, scfg.JobName)
				}
			case discovery.StaticConfig:
				if err := checkTargetGroupsForScrapeConfig(c, scfg); err != nil {
					return nil, err
				}
			}
		}
	}

	alertConfig := cfg.AlertingConfig
	for _, amcfg := range alertConfig.AlertmanagerConfigs {
		for _, c := range amcfg.ServiceDiscoveryConfigs {
			switch c := c.(type) {
			case *file.SDConfig:
				if checkSyntaxOnly {
					break
				}
				for _, file := range c.Files {
					files, err := filepath.Glob(file)
					if err != nil {
						return nil, err
					}
					if len(files) != 0 {
						for _, f := range files {
							var targetGroups []*targetgroup.Group
							targetGroups, err = checkSDFile(f)
							if err != nil {
								return nil, fmt.Errorf("checking SD file %q: %w", file, err)
							}

							if err := checkTargetGroupsForAlertmanager(targetGroups, amcfg); err != nil {
								return nil, err
							}
						}
						continue
					}
					fmt.Printf("  WARNING: file %q for file_sd in alertmanager config does not exist\n", file)
				}
			case discovery.StaticConfig:
				if err := checkTargetGroupsForAlertmanager(c, amcfg); err != nil {
					return nil, err
				}
			}
		}
	}
	return ruleFiles, nil
}