parse dbos config file

Author: maxdml

dbos/config.go

@@ -0,0 +1,80 @@
+package dbos
+
+import (
+	"fmt"
+	"net/url"
+	"os"
+
+	"github.com/spf13/viper"
+)
+
+const dbosConfigFileName = "dbos_config.yaml"
+
+type configFile struct {
+	Name        string `yaml:"name"`
+	DatabaseURL string `yaml:"database_url"`
+}
+
+func LoadConfig() (*configFile, error) {
+	v := viper.New()
+	v.SetConfigFile(dbosConfigFileName)
+	v.AutomaticEnv()
+
+	if err := v.ReadInConfig(); err != nil {
+		return nil, err
+	}
+
+	var config configFile
+	if err := v.Unmarshal(&config); err != nil {
+		return nil, fmt.Errorf("failed to parse config: %w", err)
+	}
+
+	return &config, nil
+}
+
+// ProcessConfig merges configuration from three sources in order of precedence:
+// 1. programmatic configuration (highest precedence)
+// 2. configuration file
+// 3. environment variables (lowest precedence)
+func ProcessConfig(programmaticConfig config) *config {
+	fileConfig, err := LoadConfig()
+	if err != nil && !os.IsNotExist(err) {
+		panic(err)
+	}
+
+	dbosConfig := &config{}
+
+	// Start with environment variables (lowest precedence)
+	if dbURL := os.Getenv("DBOS_DATABASE_URL"); dbURL != "" {
+		dbosConfig.databaseURL = dbURL
+	}
+
+	// Override with file configuration if available
+	if fileConfig != nil {
+		if fileConfig.DatabaseURL != "" {
+			dbosConfig.databaseURL = fileConfig.DatabaseURL
+		}
+		if fileConfig.Name != "" {
+			dbosConfig.appName = fileConfig.Name
+		}
+	}
+
+	// Override with programmatic configuration (highest precedence)
+	if len(programmaticConfig.databaseURL) > 0 {
+		dbosConfig.databaseURL = programmaticConfig.databaseURL
+	}
+	if len(programmaticConfig.appName) > 0 {
+		dbosConfig.appName = programmaticConfig.appName
+	}
+	// Copy over parameters that can only be set programmatically
+	dbosConfig.logger = programmaticConfig.logger
+	dbosConfig.adminServer = programmaticConfig.adminServer
+
+	// Load defaults
+	if len(dbosConfig.databaseURL) == 0 {
+		fmt.Println("DBOS_DATABASE_URL not set, using default: postgres://postgres:${PGPASSWORD}@localhost:5432/dbos?sslmode=disable")
+		password := url.QueryEscape(os.Getenv("PGPASSWORD"))
+		dbosConfig.databaseURL = fmt.Sprintf("postgres://postgres:%s@localhost:5432/dbos?sslmode=disable", password)
+	}
+	return dbosConfig
+}

dbos/dbos.go

@@ -6,7 +6,6 @@ import (
 	"encoding/hex"
 	"fmt"
 	"log/slog"
-	"net/url"
 	"os"
 	"reflect"
 	"runtime"
@@ -94,6 +93,7 @@ type config struct {
 	logger      *slog.Logger
 	adminServer bool
 	databaseURL string
+	appName     string
 }
 
 type LaunchOption func(*config)
@@ -146,19 +146,10 @@ func Launch(options ...LaunchOption) error {
 
 	APP_ID = os.Getenv("DBOS__APPID")
 
+	config = ProcessConfig(*config)
+
 	// Create the system database
-	var databaseURL string
-	if config.databaseURL != "" {
-		databaseURL = config.databaseURL
-	} else {
-		databaseURL = os.Getenv("DBOS_DATABASE_URL")
-		if databaseURL == "" {
-			fmt.Println("DBOS_DATABASE_URL not set, using default: postgres://postgres:${PGPASSWORD}@localhost:5432/dbos?sslmode=disable")
-			password := url.QueryEscape(os.Getenv("PGPASSWORD"))
-			databaseURL = fmt.Sprintf("postgres://postgres:%s@localhost:5432/dbos?sslmode=disable", password)
-		}
-	}
-	systemDB, err := NewSystemDatabase(databaseURL)
+	systemDB, err := NewSystemDatabase(config.databaseURL)
 	if err != nil {
 		return NewInitializationError(fmt.Sprintf("failed to create system database: %v", err))
 	}