Add config system

config.toml

@@ -0,0 +1,2 @@
+[General]
+database_path="postgres://linstrom:ugachaka@localhost/linstrom"

config/config.go

@@ -0,0 +1,80 @@
+// Copyright (c) 2024 mStar
+//
+// Licensed under the EUPL, Version 1.2
+//
+// You may not use this work except in compliance with the Licence.
+// You should have received a copy of the Licence along with this work. If not, see:
+// <https://joinup.ec.europa.eu/collection/eupl/eupl-text-eupl-12>.
+// See the Licence for the specific language governing permissions and limitations under the Licence.
+//
+
+package config
+
+import (
+	"flag"
+	"os"
+
+	"github.com/BurntSushi/toml"
+	"github.com/kelseyhightower/envconfig"
+	log "github.com/sirupsen/logrus"
+)
+
+type CLIArguments struct {
+	// Path to a config file
+	ConfigFile string
+	// Path to a postgres database
+	// Nil if not provided
+	DbPath *string
+}
+
+type Config struct {
+	General struct {
+		DbPath string `envconfig:"database" toml:"database_path"`
+	}
+}
+
+// Reads arguments passed to the application
+func ReadCLIArguments() CLIArguments {
+	configFlag := flag.String("config", "config.toml", "Path to a config file")
+	dbFlag := flag.String("db", "", "Path to a postgres database")
+
+	flag.Parse()
+
+	var dbString *string
+	if *dbFlag != "" {
+		dbString = dbFlag
+	}
+
+	return CLIArguments{
+		ConfigFile: *configFlag,
+		DbPath:     dbString,
+	}
+}
+
+// Read a config from the given CLI arguments as well as the config file specified in the cli args (default is config.toml)
+func ReadConfig(cliArgs *CLIArguments) Config {
+	file, err := os.Open(cliArgs.ConfigFile)
+	if err != nil {
+		log.Fatalf("Failed to open file %s with error %v. Does it exist?\n", cliArgs.ConfigFile, err)
+	}
+	defer file.Close()
+
+	var cfg Config
+
+	decoder := toml.NewDecoder(file)
+	_, err = decoder.Decode(&cfg)
+	if err != nil {
+		log.Fatalf("Failed to parse config file %s with error %v\n", cliArgs.ConfigFile, err)
+	}
+
+	err = envconfig.Process("", &cfg)
+	if err != nil {
+		log.Fatalf("Failed to overwrite config from env. Error %v\n", err)
+	}
+
+	if cliArgs.DbPath != nil && *cliArgs.DbPath != "" {
+		cfg.General.DbPath = *cliArgs.DbPath
+	}
+
+	return cfg
+}