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		✔	GA
Presence		✔	GA

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 Supabase UI Library Realtime components and the multiplayer.dev demo app source code here

Client libraries

• JavaScript
• Flutter/Dart
• Python
• Swift

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,
            "ssl_enforced": false
          }
        }
      ]
    }
  }' \
  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.
DB_IP_VERSION	string	Sets the IP Version to be used. Allowed values are "ipv6" and "ipv4". If none are set we will try to infer the correct version
DB_SSL	boolean	Whether or not the connection will be set-up using SSL
DB_SSL_CA_CERT	string	Filepath to a CA trust store (e.g.: /etc/cacert.pem). If defined it enables server certificate verification
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_CACHE_EXPIRATION_IN_MS	string	Set tenant cache TTL in milliseconds
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
SELF_HOST_TENANT_NAME	string	Tenant reference to be used for self host. Do keep in mind to use a URL compatible name
LOG_LEVEL	string	Sets log level for Realtime logs. Defaults to info, supported levels are: info, emergency, alert, critical, error, warning, notice, debug
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
MIGRATION_PARTITION_SLOTS	number	Number of dynamic supervisor partitions used by the migrations process
CONNECT_PARTITION_SLOTS	number	Number of dynamic supervisor partitions used by the Connect, ReplicationConnect processes
METRICS_CLEANER_SCHEDULE_TIMER_IN_MS	number	Time in ms to run the Metric Cleaner task
METRICS_RPC_TIMEOUT_IN_MS	number	Time in ms to wait for RPC call to fetch Metric per node
WEBSOCKET_MAX_HEAP_SIZE	number	Max number of bytes to be allocated as heap for the WebSocket transport process. If the limit is reached the process is brutally killed. Defaults to 50MB.
REQUEST_ID_BAGGAGE_KEY	string	OTEL Baggage key to be used as request id
OTEL_SDK_DISABLED	boolean	Disable OpenTelemetry tracing completely when 'true'
OTEL_TRACES_EXPORTER	string	Possible values: otlp or none. See [https://github.com/open-telemetry/opentelemetry-erlang/tree/v1.4.0/apps#os-environment] for more details on how to configure the traces exporter.
OTEL_TRACES_SAMPLER	string	Default to parentbased_always_on . More info here
GEN_RPC_TCP_SERVER_PORT	number	Port served by gen_rpc. Must be secured just like the Erlang distribution port. Defaults to 5369
GEN_RPC_TCP_CLIENT_PORT	number	gen_rpc connects to another node using this port. Most of the time it should be the same as GEN_RPC_TCP_SERVER_PORT. Defaults to 5369
GEN_RPC_SSL_SERVER_PORT	number	Port served by gen_rpc secured with TLS. Must also define GEN_RPC_CERTFILE, GEN_RPC_KEYFILE and GEN_RPC_CACERTFILE. If this is defined then only TLS connections will be set-up.
GEN_RPC_SSL_CLIENT_PORT	number	gen_rpc connects to another node using this port. Most of the time it should be the same as GEN_RPC_SSL_SERVER_PORT. Defaults to 6369
GEN_RPC_CERTFILE	string	Path to the public key in PEM format. Only needs to be provided if GEN_RPC_SSL_SERVER_PORT is defined
GEN_RPC_KEYFILE	string	Path to the private key in PEM format. Only needs to be provided if GEN_RPC_SSL_SERVER_PORT is defined
GEN_RPC_CACERTFILE	string	Path to the certificate authority public key in PEM format. Only needs to be provided if GEN_RPC_SSL_SERVER_PORT is defined
GEN_RPC_CONNECT_TIMEOUT_IN_MS	number	gen_rpc client connect timeout in milliseconds. Defaults to 10000.
GEN_RPC_SEND_TIMEOUT_IN_MS	number	gen_rpc client and server send timeout in milliseconds. Defaults to 10000.
GEN_RPC_SOCKET_IP	string	Interface which gen_rpc will bind to. Defaults to "0.0.0.0" (ipv4) which means that all interfaces are going to expose the gen_rpc port.
GEN_RPC_IPV6_ONLY	boolean	Configure gen_rpc to use IPv6 only.
GEN_RPC_MAX_BATCH_SIZE	integer	Configure gen_rpc to batch when possible RPC casts. Defaults to 0
GEN_RPC_COMPRESS	integer	Configure gen_rpc to compress or not payloads. 0 means no compression and 9 max compression level. Defaults to 0.
GEN_RPC_COMPRESSION_THRESHOLD_IN_BYTES	integer	Configure gen_rpc to compress only above a certain threshold in bytes. Defaults to 1000.
MAX_GEN_RPC_CLIENTS	number	Max amount of gen_rpc TCP connections per node-to-node channel
REBALANCE_CHECK_INTERVAL_IN_MS	number	Time in ms to check if process is in the right region
DISCONNECT_SOCKET_ON_NO_CHANNELS_INTERVAL_IN_MS	number	Time in ms to check if a socket has no channels open and if so, disconnect it
BROADCAST_POOL_SIZE	number	Number of processes to relay Phoenix.PubSub messages across the cluster
POSTGRES_CDC_SCOPE_SHARDS	number	Number of dynamic supervisor partitions used by the Postgres CDC extension. Defaults to 5.
USERS_SCOPE_SHARDS	number	Number of dynamic supervisor partitions used by the Users extension. Defaults to 5.

The OpenTelemetry variables mentioned above are not an exhaustive list of all supported environment variables.

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
TopicNameRequired	You are trying to use Realtime without a topic name set
InvalidJoinPayload	The payload provided to Realtime on connect is invalid
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
ReconnectSubscribeToPostgres	Postgres changes still waiting to be subscribed
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 has reached the channel limits
DatabaseConnectionRateLimitReached	The rate of attempts to connect to tenants database has reached the limit
MessagePerSecondRateLimitReached	The rate of messages per second from your clients has reached the channel limits
RealtimeDisabledForTenant	Realtime has been disabled for the tenant
UnableToConnectToTenantDatabase	Realtime was not able to connect to the tenant's database
DatabaseLackOfConnections	Realtime was not able to connect to the tenant's database due to not having enough available connections
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
StartReplicationFailed	Error when starting the replication and listening of errors for database broadcasting
ReplicationMaxWalSendersReached	Maximum number of WAL senders reached in tenant database, check how to increase this value in this link
MigrationCheckFailed	Check to see if we require to run migrations fails
PartitionCreationFailed	Error when creating partitions for realtime.messages
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
UnhandledProcessMessage	Unhandled message received by a Realtime process
UnableToTrackPresence	Error when handling track presence for this socket
UnknownPresenceEvent	Presence event type not recognized by service
IncreaseConnectionPool	The number of connections you have set for Realtime are not enough to handle your current use case
RlsPolicyError	Error on RLS policy used for authorization
ConnectionInitializing	Database is initializing connection
DatabaseConnectionIssue	Database had connection issues and connection was not able to be established
UnableToConnectToProject	Unable to connect to Project database
InvalidJWTExpiration	JWT exp claim value it's incorrect
JwtSignatureError	JWT signature was not able to be validated
MalformedJWT	Token received does not comply with the JWT format
Unauthorized	Unauthorized access to Realtime channel
RealtimeRestarting	Realtime is currently restarting
UnableToProcessListenPayload	Payload sent in NOTIFY operation was JSON parsable
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
TimeoutOnRpcCall	RPC request within the Realtime server as timed out.
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
UnableToEncodeJson	An error were we are not handling correctly the response to be sent to the end user
UnknownErrorOnController	An error we are not handling correctly was triggered on a controller
UnknownErrorOnChannel	An error we are not handling correctly was triggered on a channel
PresenceRateLimitReached	Limit of presence events reached
UnableToReplayMessages	An error while replaying messages

License

This repo is licensed under Apache 2.0.

Credits

• Phoenix - Realtime server is built with the amazing Elixir framework.
• Phoenix Channels JavaScript Client - @supabase/realtime-js client library heavily draws from the Phoenix Channels client library.