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Supabase Logo

Supabase Realtime

Send ephemeral messages, track and synchronize shared state, and listen to Postgres changes all over WebSockets.
Multiplayer Demo · Request Feature · Report Bug

Status

Features v1 v2 Status
Postgres Changes ✔ ✔ GA
Broadcast ✔ Beta
Presence ✔ Beta

This repository focuses on version 2 but you can still access the previous version's code and Docker image. For the latest Docker images go to https://hub.docker.com/r/supabase/realtime.

The codebase is under heavy development and the documentation is constantly evolving. Give it a try and let us know what you think by creating an issue. Watch releases of this repo to get notified of updates. And give us a star if you like it!

Overview

What is this?

This is a server built with Elixir using the Phoenix Framework that enables the following functionality:

  • Broadcast: Send ephemeral messages from client to clients with low latency.
  • Presence: Track and synchronize shared state between clients.
  • Postgres Changes: Listen to Postgres database changes and send them to authorized clients.

For a more detailed overview head over to Realtime guides.

Does this server guarantee message delivery?

The server does not guarantee that every message will be delivered to your clients so keep that in mind as you're using Realtime.

Quick start

You can check out the Multiplayer demo that features Broadcast, Presence and Postgres Changes under the demo directory: https://github.com/supabase/realtime/tree/main/demo.

Client libraries

Server Setup

To get started, spin up your Postgres database and Realtime server containers defined in docker-compose.yml. As an example, you may run docker-compose -f docker-compose.yml up.

Note Supabase runs Realtime in production with a separate database that keeps track of all tenants. However, a schema, _realtime, is created when spinning up containers via docker-compose.yml to simplify local development.

A tenant has already been added on your behalf. You can confirm this by checking the _realtime.tenants and _realtime.extensions tables inside the database.

You can add your own by making a POST request to the server. You must change both name and external_id while you may update other values as you see fit:

  curl -X POST \
  -H 'Content-Type: application/json' \
  -H 'Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiIiLCJpYXQiOjE2NzEyMzc4NzMsImV4cCI6MTcwMjc3Mzk5MywiYXVkIjoiIiwic3ViIjoiIn0._ARixa2KFUVsKBf3UGR90qKLCpGjxhKcXY4akVbmeNQ' \
  -d $'{
    "tenant" : {
      "name": "realtime-dev",
      "external_id": "realtime-dev",
      "jwt_secret": "a1d99c8b-91b6-47b2-8f3c-aa7d9a9ad20f",
      "extensions": [
        {
          "type": "postgres_cdc_rls",
          "settings": {
            "db_name": "postgres",
            "db_host": "host.docker.internal",
            "db_user": "postgres",
            "db_password": "postgres",
            "db_port": "5432",
            "region": "us-west-1",
            "poll_interval_ms": 100,
            "poll_max_record_bytes": 1048576
          }
        }
      ]
    }
  }' \
  http://localhost:4000/api/tenants

Note The Authorization token is signed with the secret set by API_JWT_SECRET in docker-compose.yml.

If you want to listen to Postgres changes, you can create a table and then add the table to the supabase_realtime publication:

create table test (
  id serial primary key
);

alter publication supabase_realtime add table test;

You can start playing around with Broadcast, Presence, and Postgres Changes features either with the client libs (e.g. @supabase/realtime-js), or use the built in Realtime Inspector on localhost, http://localhost:4000/inspector/new (make sure the port is correct for your development environment).

The WebSocket URL must contain the subdomain, external_id of the tenant on the _realtime.tenants table, and the token must be signed with the jwt_secret that was inserted along with the tenant.

If you're using the default tenant, the URL is ws://realtime-dev.localhost:4000/socket (make sure the port is correct for your development environment), and you can use eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE3MDMwMjgwODcsInJvbGUiOiJwb3N0Z3JlcyJ9.tz_XJ89gd6bN8MBpCl7afvPrZiBH6RB65iA1FadPT3Y for the token. The token must have exp and role (database role) keys.

Environment Variables

Variable Type Description
PORT number Port which you can connect your client/listeners
DB_HOST string Database host URL
DB_PORT number Database port
DB_USER string Database user
DB_PASSWORD string Database password
DB_NAME string Postgres database name
DB_ENC_KEY string Key used to encrypt sensitive fields in _realtime.tenants and _realtime.extensions tables. Recommended: 16 characters.
DB_AFTER_CONNECT_QUERY string Query that is run after server connects to database.
API_JWT_SECRET string Secret that is used to sign tokens used to manage tenants and their extensions via HTTP requests.
SECRET_KEY_BASE string Secret used by the server to sign cookies. Recommended: 64 characters.
ERL_AFLAGS string Set to either "-proto_dist inet_tcp" or "-proto_dist inet6_tcp" depending on whether or not your network uses IPv4 or IPv6, respectively.
APP_NAME string A name of the server.
DNS_NODES string Node name used when running server in a cluster.
MAX_CONNECTIONS string Set the soft maximum for WebSocket connections. Defaults to '16384'.
MAX_HEADER_LENGTH string Set the maximum header length for connections (in bytes). Defaults to '4096'.
NUM_ACCEPTORS string Set the number of server processes that will relay incoming WebSocket connection requests. Defaults to '100'.
DB_QUEUE_TARGET string Maximum time to wait for a connection from the pool. Defaults to '5000' or 5 seconds. See for more info: DBConnection.
DB_QUEUE_INTERVAL string Interval to wait to check if all connections were checked out under DB_QUEUE_TARGET. If all connections surpassed the target during this interval than the target is doubled. Defaults to '5000' or 5 seconds. See for more info: DBConnection.
DB_POOL_SIZE string Sets the number of connections in the database pool. Defaults to '5'.
SLOT_NAME_SUFFIX string This is appended to the replication slot which allows making a custom slot name. May contain lowercase letters, numbers, and the underscore character. Together with the default supabase_realtime_replication_slot, slot name should be up to 64 characters long.
TENANT_MAX_BYTES_PER_SECOND string The default value of maximum bytes per second that each tenant can support, used when creating a tenant for the first time. Defaults to '100_000'.
TENANT_MAX_CHANNELS_PER_CLIENT string The default value of maximum number of channels each tenant can support, used when creating a tenant for the first time. Defaults to '100'.
TENANT_MAX_CONCURRENT_USERS string The default value of maximum concurrent users per channel that each tenant can support, used when creating a tenant for the first time. Defaults to '200'.
TENANT_MAX_EVENTS_PER_SECOND string The default value of maximum events per second that each tenant can support, used when creating a tenant for the first time. Defaults to '100'.
TENANT_MAX_JOINS_PER_SECOND string The default value of maximum channel joins per second that each tenant can support, used when creating a tenant for the first time. Defaults to '100'.
SEED_SELF_HOST boolean Seeds the system with default tenant
RUN_JANITOR boolean Do you want to janitor tasks to run
JANITOR_SCHEDULE_TIMER_IN_MS number Time in ms to run the janitor task
JANITOR_SCHEDULE_RANDOMIZE boolean Adds a randomized value of minutes to the timer
JANITOR_RUN_AFTER_IN_MS number Tells system when to start janitor tasks after boot
JANITOR_CLEANUP_MAX_CHILDREN number Maximum number of concurrent tasks working on janitor cleanup
JANITOR_CLEANUP_CHILDREN_TIMEOUT number Timeout for each async task for janitor cleanup
JANITOR_CHUNK_SIZE number Number of tenants to process per chunk. Each chunk will be processed by a Task

WebSocket URL

The WebSocket URL is in the following format for local development: ws://[external_id].localhost:4000/socket/websocket

If you're using Supabase's hosted Realtime in production the URL is wss://[project-ref].supabase.co/realtime/v1/websocket?apikey=[anon-token]&log_level=info&vsn=1.0.0"

WebSocket Connection Authorization

WebSocket connections are authorized via symmetric JWT verification. Only supports JWTs signed with the following algorithms:

  • HS256
  • HS384
  • HS512

Verify JWT claims by setting JWT_CLAIM_VALIDATORS:

e.g. {'iss': 'Issuer', 'nbf': 1610078130}

Then JWT's "iss" value must equal "Issuer" and "nbf" value must equal 1610078130.

Note:

JWT expiration is checked automatically. exp and role (database role) keys are mandatory.

Authorizing Client Connection: You can pass in the JWT by following the instructions under the Realtime client lib. For example, refer to the Usage section in the @supabase/realtime-js client library.

Error Operational Codes

This is the list of operational codes that can help you understand your deployment and your usage.

Code Description
RealtimeDisabledForConfiguration The configuration provided to Realtime on connect will not be able to provide you any Postgres Changes
TenantNotFound The tenant you are trying to connect to does not exist
ErrorConnectingToWebsocket Error when trying to connect to the WebSocket server
ErrorAuthorizingWebsocket Error when trying to authorize the WebSocket connection
TableHasSpacesInName The table you are trying to listen to has spaces in its name which we are unable to support
UnableToDeleteTenant Error when trying to delete a tenant
UnableToSetPolicies Error when setting up Authorization Policies
UnableCheckoutConnection Error when trying to checkout a connection from the tenant pool
UnableToSubscribeToPostgres Error when trying to subscribe to Postgres changes
ChannelRateLimitReached The number of channels you can create has reached its limit
ConnectionRateLimitReached The number of connected clients as reached its limit
ClientJoinRateLimitReached The rate of joins per second from your clients as reached the channel limits
UnableToConnectToTenantDatabase Realtime was not able to connect to the tenant's database
RealtimeNodeDisconnected Realtime is a distributed application and this means that one the system is unable to communicate with one of the distributed nodes
MigrationsFailedToRun Error when running the migrations against the Tenant database that are required by Realtime
ErrorStartingPostgresCDCStream Error when starting the Postgres CDC stream which is used for Postgres Changes
UnknownDataProcessed An unknown data type was processed by the Realtime system
ErrorStartingPostgresCDC Error when starting the Postgres CDC extension which is used for Postgres Changes
ReplicationSlotBeingUsed The replication slot is being used by another transaction
PoolingReplicationPreparationError Error when preparing the replication slot
PoolingReplicationError Error when pooling the replication slot
SubscriptionDeletionFailed Error when trying to delete a subscription for postgres changes
UnableToDeletePhantomSubscriptions Error when trying to delete subscriptions that are no longer being used
UnableToCheckProcessesOnRemoteNode Error when trying to check the processes on a remote node
UnableToCreateCounter Error when trying to create a counter to track rate limits for a tenant
UnableToIncrementCounter Error when trying to increment a counter to track rate limits for a tenant
UnableToDecrementCounter Error when trying to decrement a counter to track rate limits for a tenant
UnableToUpdateCounter Error when trying to update a counter to track rate limits for a tenant
UnableToFindCounter Error when trying to find a counter to track rate limits for a tenant
UnhandledProcessMessage Unhandled message received by a Realtime process
UnableToProcessListenPayload Payload sent in NOTIFY operation was JSON parsable
UnableToListenToTenantDatabase Unable to LISTEN for notifications against the Tenant Database
UnprocessableEntity Received a HTTP request with a body that was not able to be processed by the endpoint
InitializingProjectConnection Connection against Tenant database is still starting
ErrorOnRpcCall Error when calling another realtime node
ErrorExecutingTransaction Error executing a database transaction in tenant database
SynInitializationError Our framework to syncronize processes has failed to properly startup a connection to the database
JanitorFailedToDeleteOldMessages Scheduled task for realtime.message cleanup was unable to run
UnknownError An unknown error occurred

License

This repo is licensed under Apache 2.0.

Credits