app-name

Database migration

Database changes are executed using golang-migrate.

Each migration consists of two files which have the following naming convention:

• <version>_<title>.up.<json|sql>
• <version>_<title>.down.<json|sql>

The up file should describe the transformation you’d like to make to your database schema, and the down file should revert the transformations done by the up file. In other words, the database schema should be unchanged if you do an up followed by a down. For example, if you create a table in the up file, you should drop it in the down file. It is wise to perform the transformations in precisely the reverse order they were made in the up file.

The file extension of the migration file is json for MongoDB migrations Each MongoDB migration file should contain a valid MongoDB database command

The migration files can be found at internal/migration

The path where the migration files are located can be configured using the environment variable MIGRATION_SOURCE_PATH.
Multi stage Docker images typically contain the compiled go binary and other supporting files to run that binary. Migration files is an example of such supporting files. The migration files are mounted in a desired path, and that path is set as the above environment variable.

Graceful shutdown

var osSignal = make(chan os.Signal, 1)
signal.Notify(osSignal, syscall.SIGINT, syscall.SIGKILL, syscall.SIGTERM)

We create a channel and use it to listen for OS signals.

When our server receives an OS signal to shut down we do the following:

• Stop receiving new requests
• Wait for ongoing requests to complete
• Release shared resources like database connections

server.Shutdown(ctx) first stops receiving new requests, then closes all idle connections, and then waits for ongoing requests to complete.

The following code executes before the main func returns. All code to release shared resources are executed here.

defer func() {
	log.Info().Msg("Server shutdown successful")

	// Release all shared resources
	mongo.Disconnect(mongoDbClient)

	log.Info().Msg("Released all shared resources")

	cancel()

	os.Exit(0)
}()

Logging

Logs are generated using zerolog.

The log level can be set using the environment variable LOG_LEVEL.

LOG_LEVEL can take the following values:

• trace
• debug
• info
• warn
• error
• fatal
• panic