Go Music Player App

This document will guide you through the code to build a simple media player in Golang. In this app, we show you how to retrieve your media from Minio server. The media files inside a bucket are listed as the playlist, secure URLs are generated on demand whenever we play a song. Full code is available here: https://github.com/minio/minio-go-media-player, released under Apache 2.0 License.

1. Prerequisites

• Install mc from here.
• Install Minio Server from here.
• A working Golang environment. If you do not have a working Golang environment, please follow - How to install Golang?.

2. Dependencies

• Media files (mp3) for your playlist bucket.

3. Installing media-player

Let's go ahead and use 'go get' to fetch the example as shown below, 'go get' will install all necessary dependencies as needed.

go get -u github.com/minio/minio-go-media-player/media-player

Now media-player is ready to be used.

4. Running media-player

Environment Variables bash

Set Access key and Secret key environment variables.

export AWS_ACCESS_KEY=Q3AM3UQ867SPQQA43P2F
export AWS_SECRET_KEY=zuf+tfteSlswRu7BJ86wekitnifILbZam1KYY3TG

Environment Variables tcsh

setenv AWS_ACCESS_KEY Q3AM3UQ867SPQQA43P2F
setenv AWS_SECRET_KEY zuf+tfteSlswRu7BJ86wekitnifILbZam1KYY3TG

Environment Variables Windows command prompt

set AWS_ACCESS_KEY=Q3AM3UQ867SPQQA43P2F
set AWS_SECRET_KEY=zuf+tfteSlswRu7BJ86wekitnifILbZam1KYY3TG

Set Up Bucket

1. We've created a public minio server at https://play.minio.io:9000 for developers to use as a sandbox. Create a bucket called media-assets on play.minio.io:9000. We are going to use mc mb command to accomplish this.

mc mb play/media-assets

2. Upload your media assets into this bucket. You can again use mc to do this. Let's move few mp3's from the local disk into the bucket we created on play.

mc cp ~/Music/*.mp3 play/media-assets

Note : We have already created a media-assets bucket on play.minio.io and copied the assets used in this example.

Run Media Player

Now we are all set to run the media-player example. Use -b command line option to specify the bucket we have already created in the previous step.

cd $GOPATH/bin
./media-player -b media-assets
2016/04/02 17:24:54 Starting media player, please visit your browser at http://localhost:8080

Now if you visit http://localhost:8080 you should be able to see the example application.

Optional Arguments

1. Endpoint defaults to 'https://play.minio.io:9000', to set a custom endpoint use `-e

cd $GOPATH/bin
./media-player -b <bucket-name> -e https://s3.amazonaws.com
2016/04/02 17:24:54 Starting media player, please visit your browser at http://localhost:8080

2. For using an endpoint as Minio server running locally.

media-player -b <bucket-name> -e http://localhost:9000

5. Building Playlist

The first thing the player does is build a playlist, by using ListObjects method, to lists all the media assets in the media bucket specified. These objects will be rendered as a playlist for the media player as shown in the player image above. Each object is collected and sent to the browser in JSON format.

The following flow diagram and sample code provides an overview on how this is achieved.

 for objectInfo := range api.minioClient.ListObjects(*bucketName, "", isRecursive, doneCh) {
  if objectInfo.Err != nil {
		http.Error(w, objectInfo.Err.Error(), http.StatusInternalServerError)
			return
		}
		objectName := objectInfo.Key // object name.
		playListEntry := mediaPlayList{
			Key: objectName,
		}
		playListEntries = append(playListEntries, playListEntry)
	}
	playListEntriesJSON, err := json.Marshal(playListEntries)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	// Successfully wrote play list in json.
	w.Write(playListEntriesJSON)

6. Streaming Media

When an user clicks to play media on the browser, secure URLs are generated on demand by the media player. In order to do this the player uses PresignedGetObject.

The secure URL generated by PresignedGetObject is used by the player to stream the media from the server directly. The following flow diagram and sample code provide an overview on how this is achieved.

 // GetPresignedURLHandler - generates presigned access URL for an object.
func (api mediaHandlers) GetPresignedURLHandler(w http.ResponseWriter, r *http.Request) {
	// The object for which the presigned URL has to be generated is sent as a query
	// parameter from the client.
	objectName := r.URL.Query().Get("objName")
	if objectName == "" {
		http.Error(w, "No object name set, invalid request.", http.StatusBadRequest)
		return
	}
	presignedURL, err := api.storageClient.PresignedGetObject(*bucketName, objectName, 1000*time.Second, nil)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	w.Write([]byte(presignedURL))
}

7. Explore Further

• Using minio-go client SDK with Minio Server
• Minio Golang Client SDK API Reference