worker: factor out config parsing

The struct is factored out 1:1. The only functional change in this commit is
worker now logging in case of a missing config (which means just loading the
defaults).

Signed-off-by: Ondřej Budai <ondrej@budai.cz>

cmd/osbuild-worker/config.go

@@ -0,0 +1,67 @@
+package main
+
+import (
+	"os"
+
+	"github.com/BurntSushi/toml"
+	"github.com/sirupsen/logrus"
+)
+
+type workerConfig struct {
+	Composer *struct {
+		Proxy string `toml:"proxy"`
+	} `toml:"composer"`
+	Koji map[string]struct {
+		Kerberos *struct {
+			Principal string `toml:"principal"`
+			KeyTab    string `toml:"keytab"`
+		} `toml:"kerberos,omitempty"`
+		RelaxTimeoutFactor uint `toml:"relax_timeout_factor"`
+	} `toml:"koji"`
+	GCP *struct {
+		Credentials string `toml:"credentials"`
+	} `toml:"gcp"`
+	Azure *struct {
+		Credentials string `toml:"credentials"`
+	} `toml:"azure"`
+	AWS *struct {
+		Credentials string `toml:"credentials"`
+		Bucket      string `toml:"bucket"`
+	} `toml:"aws"`
+	GenericS3 *struct {
+		Credentials         string `toml:"credentials"`
+		Endpoint            string `toml:"endpoint"`
+		Region              string `toml:"region"`
+		Bucket              string `toml:"bucket"`
+		CABundle            string `toml:"ca_bundle"`
+		SkipSSLVerification bool   `toml:"skip_ssl_verification"`
+	} `toml:"generic_s3"`
+	Authentication *struct {
+		OAuthURL         string `toml:"oauth_url"`
+		OfflineTokenPath string `toml:"offline_token"`
+		ClientId         string `toml:"client_id"`
+		ClientSecretPath string `toml:"client_secret"`
+	} `toml:"authentication"`
+	// default value: /api/worker/v1
+	BasePath string `toml:"base_path"`
+	DNFJson  string `toml:"dnf-json"`
+}
+
+func parseConfig(file string) (*workerConfig, error) {
+	var config workerConfig
+	_, err := toml.DecodeFile(file, &config)
+	if err != nil {
+		// Return error only when we failed to decode the file.
+		// A non-existing config isn't an error, use defaults in this case.
+		if !os.IsNotExist(err) {
+			return nil, err
+		}
+
+		logrus.Info("Configuration file not found, using defaults")
+	}
+	if config.BasePath == "" {
+		config.BasePath = "/api/worker/v1"
+	}
+
+	return &config, nil
+}