Add CLI option for providing configfile. (#824)

README.md

@@ -153,7 +153,8 @@ The command line arguments always take priority over the config file and environ
 ## Configuration file
 Default values are placed in the configuration file. They can be overridden with environment variables and command line arguments.
 
-The configuration file must named **indexer**, **indexer.yml**, or **indexer.yaml**. It must also be in the correct location. Only one configuration file is loaded, the path is searched in the following order:
+The configuration file must named **indexer**, **indexer.yml**, or **indexer.yaml**. The filepath may be set on the CLI using `--configfile` or `-c`. 
+When the filepath is not provided on the CLI, it must also be in the correct location. Only one configuration file is loaded, the path is searched in the following order:
 * `./` (current working directory)
 * `$HOME`
 * `$HOME/.algorand-indexer`
@@ -172,6 +173,11 @@ If it is in the current working directory along with the indexer command we can
 ~$ ./algorand-indexer daemon
 ```
 
+If it is not in the current working directory along with the indexer command we can start the indexer daemon with:
+```
+~$ ./algorand-indexer daemon -c <full-file-location>/indexer.yml
+```
+
 ## Example environment variable
 
 Environment variables are also available to configure indexer. Environment variables override settings in the config file and are overridden by command line arguments.

cmd/algorand-indexer/main.go

@@ -58,6 +58,18 @@ var rootCmd = &cobra.Command{
 			err = pprof.StartCPUProfile(profFile)
 			maybeFail(err, "%s: start pprof, %v", cpuProfile, err)
 		}
+		if configFile != "" {
+			configs, err := os.Open(configFile)
+			if err != nil {
+				maybeFail(err, "%v", err)
+			}
+			defer configs.Close()
+			err = viper.ReadConfig(configs)
+			if err != nil {
+				maybeFail(err, "invalid config file (%s): %v", viper.ConfigFileUsed(), err)
+			}
+			fmt.Printf("Using configuration file: %s\n", configFile)
+		}
 	},
 	PersistentPostRun: func(cmd *cobra.Command, args []string) {
 		if cpuProfile != "" {
@@ -83,6 +95,7 @@ var (
 	logLevel       string
 	logFile        string
 	logger         *log.Logger
+	configFile     string
 )
 
 func indexerDbFromFlags(opts idb.IndexerDbOptions) (idb.IndexerDb, chan struct{}) {
@@ -117,6 +130,7 @@ func init() {
 	rootCmd.PersistentFlags().BoolVarP(&dummyIndexerDb, "dummydb", "n", false, "use dummy indexer db")
 	rootCmd.PersistentFlags().StringVarP(&cpuProfile, "cpuprofile", "", "", "file to record cpu profile to")
 	rootCmd.PersistentFlags().StringVarP(&pidFilePath, "pidfile", "", "", "file to write daemon's process id to")
+	rootCmd.PersistentFlags().StringVarP(&configFile, "configfile", "c", "", "file path to configuration file (indexer.yml)")
 	rootCmd.PersistentFlags().BoolVarP(&doVersion, "version", "v", false, "print version and exit")
 
 	viper.RegisterAlias("postgres", "postgres-connection-string")