RTMP Server (Go Implementation)

This is a RTMP (Real Time Messaging Protocol) server for live streaming broadcasting, implemented in Go.

Compilation

In order to install dependencies, type:

go get github.com/AgustinSRG/rtmp-server

To compile the code type:

go build

The build command will create a binary in the current directory, called rtmp-server, or rtmp-server.exe if you are using Windows.

Docker image

You can find the docker image for this project available in Docker Hub: https://hub.docker.com/r/asanrom/rtmp-server

To pull it type:

docker pull asanrom/rtmp-server

Example compose file:

version: '3.7'

services:
    rtmp_server:
        image: asanrom/rtmp-server
        ports:
            - '1935:1935'
            #- '443:443'
        environment:
            # Configure it using env vars:
            - PLAY_ALLOWED_FROM=*
            - CONCURRENT_LIMIT_WHITELIST=*
            - REDIS_USE=NO
            - RTMP_CHUNK_SIZE=5000
            - LOG_REQUESTS=YES
            - LOG_DEBUG=NO
            - GOP_CACHE_SIZE_MB=0

Usage

In order to run the server you have to run the binary or the docker container. That will run the server in the port 1935.

The server will accept RTMP connections with the following schema:

rtmp://{HOST}/{CHANNEL}/{KEY}

Note: Both CHANNEL and KEY are restricted to letters a-z, numbers 0-9, dashes - and undescores _.

By default, it will accept any connections. If you need to restrict the access or customize the server in any way, you can use environment variables.

RTMP play restrict

You probably only want external users to be able to publish to the RTMP server, since spectartors probably receive the stream using other protocol, like HLS or MPEG-Dash.

In order to do that, set the RTMP_PLAY_WHITELIST to a list of allowed internet addresses split by commas. Example: 127.0.0.1,10.0.0.0/8. You can set IPs, or subnets. It supports both IP version 4 and version 6.

Event callback

In order to restrict the access and have control over who publishes, the RTMP server can send requests to a remote server with the information of certain events.

Set the CALLBACK_URL environment variable to the remote server that is going to handle those events:

• When an user wants to publish, to validate the streaming channel and key. (start)
• When a session is closed, meaning the live streaming has ended. (stop)

The events are sent as HTTP(S) POST requests to the given URL, with empty body, and with a header with name rtmp-event, containing the event data encoded as a Base 64 JWT (JSON Web Token), signed using a secret you must provide using the JWT_SECRET environment variable.

The JWT is signed using the algorithm HMAC_256.

The JWT contains the following fields:

• Subject (sub) is rtmp_event.
• Event name (event) can be start or stop.
• Channel (channel) is the requested channel to publish.
• Key (key) is the given key to publish.
• Stream ID (stream_id) is the unique ID for the stream session, It is undefined for the start event, since is not known yet.
• Client IP (client_ip) is the client IP for logging purposes.

For the start event, the event handler server must return with status code 200, and with a header with name stream-id, containing the unique identifier for the RTMP publishing session. If the server does not return with 200, the server will consider the key is invalid and it will close the connection with the client. You can use this to validate streaming keys.

Redis

This server supports listening for commands using Redis Pub/Sub.

To configure it, set the following variables:

Variable Name	Description
REDIS_USE	Set it to YES in order to enable Redis.
REDIS_PORT	Port to connect to Redis Pub/Sub. Default is 6379
REDIS_HOST	Host to connect to Redis Pub/Sub. Default is 127.0.0.1
REDIS_PASSWORD	Redis authentication password, if required.
REDIS_CHANNEL	Redis channel to listen for commands. By default is rtmp_commands
REDIS_TLS	Set it to YES in order to use TLS for the connection.

The commands have the following structure:

COMMAND>ARG_1|ARG2|...

Each command goes in a separate message.

List of commands:

• kill-session>CHANNEL - Closes any sessions for that specific channel.
• close-stream>CHANNEL|STREAM_ID - Closes specific connection.

These commands are meant to stop a streaming session once started, to enforce application-specific limits.

TLS

If you want to use TLS, you have to set 3 variables in order for it to work:

Variable Name	Description
SSL_PORT	RTMPS (RTMP over TLS) listening port. Default is 443
SSL_CERT	Path to SSL certificate.
SSL_KEY	Path to SSL private key.
SSL_CHECK_RELOAD_SECONDS	Number of seconds to check for changes in the certificates (for auto renewal)

More options

Here is a list with more options you can configure:

Variable Name	Description
RTMP_HOST	RTMP host to add in the JWT as rtmp_host in order for the callback handler to know the origin host.
RTMP_PORT	RTMP listening port. It will be added in the JWT as rtmp_port. Default is 1935.
BIND_ADDRESS	Bind address for RTMP and RTMPS. By default it binds to all network interfaces.
RTMP_CHUNK_SIZE	RTMP Chunk size in bytes. Default is 128
LOG_REQUESTS	Set to YES or NO. By default is YES
LOG_DEBUG	Set to YES or NO. By default is NO
ID_MAX_LENGTH	Max length for CHANNEL and KEY. By default is 128 characters
MAX_IP_CONCURRENT_CONNECTIONS	Max number of concurrent connections to accept from a single IP. By default is 4.
CONCURRENT_LIMIT_WHITELIST	List of IP ranges not affected by the max number of concurrent connections limit. Split by commas. Example: 127.0.0.1,10.0.0.0/8
CUSTOM_JWT_SUBJECT	Custom subject to use for tokens sent to the callback URL
GOP_CACHE_SIZE_MB	Size limit in megabytes of packet cache. By default is 256. Set it to 0 to disable cache