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https://github.com/reconbot/graphql-lambda-subscriptions
Graphql-WS compatible Lambda Powered Subscriptions
https://github.com/reconbot/graphql-lambda-subscriptions
api-gateway aws-lambda dynamodb graphql graphql-subscriptions serverless serverless-framework
Last synced: 6 days ago
JSON representation
Graphql-WS compatible Lambda Powered Subscriptions
- Host: GitHub
- URL: https://github.com/reconbot/graphql-lambda-subscriptions
- Owner: reconbot
- License: other
- Created: 2021-08-06T20:41:47.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2024-10-29T05:40:02.000Z (15 days ago)
- Last Synced: 2024-10-30T05:34:31.335Z (14 days ago)
- Topics: api-gateway, aws-lambda, dynamodb, graphql, graphql-subscriptions, serverless, serverless-framework
- Language: TypeScript
- Homepage: https://www.npmjs.com/package/graphql-lambda-subscriptions
- Size: 5.81 MB
- Stars: 49
- Watchers: 3
- Forks: 13
- Open Issues: 37
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Security: SECURITY.md
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README
# Graphql Lambda Subscriptions
[](https://github.com/reconbot/graphql-lambda-subscriptions/actions/workflows/test.yml)
Amazon Lambda Powered GraphQL Subscriptions. This is an Amazon Lambda Serverless equivalent to [`graphql-ws`](https://github.com/enisdenjo/graphql-ws). It follows the [`graphql-ws prototcol`](https://github.com/enisdenjo/graphql-ws/blob/master/PROTOCOL.md). It is tested with the [Architect Sandbox](https://arc.codes/docs/en/reference/cli/sandbox) against `graphql-ws` directly and run in production today. For many applications `graphql-lambda-subscriptions` should do what `graphql-ws` does for you today without having to run a server. This started as fork of `subscriptionless` another library with similar goals.
As `subscriptionless`'s tagline goes;
> Have all the functionality of GraphQL subscriptions on a stateful server without the cost.
## Why a fork?
I had different requirements and needed more features. This project wouldn't exist without [`subscriptionless`](https://github.com/andyrichardson/subscriptionless) and you should totally check it out.
## Features
- Only needs DynamoDB, API Gateway and Lambda (no [app sync](https://www.serverless.com/aws-appsync#benefits) or other managed graphql platform required, can use step functions for ping/pong support)
- Provides a Pub/Sub system to broadcast events to subscriptions
- Provides hooks for the full lifecycle of a subscription
- Type compatible with GraphQL and [`nexus.js`](https://nexusjs.org)
- Optional Logging
## Quick Start
Since there are many ways to deploy to amazon lambda I'm going to have to get opinionated in the quick start and pick [Architect](https://arc.codes). `graphql-lambda-subscriptions` should work on Lambda regardless of your deployment and packaging framework. Take a look at the [arc-basic-events](mocks/arc-basic-events) mock used for integration testing for an example of using it with Architect.
## API Docs
Can be found in our [docs folder](docs/README.md). You'll want to start with [`makeServer()`](docs/README.md#makeserver) and [`subscribe()`](dosc/README.md#subscribe).
## Setup
### Create a graphql-lambda-subscriptions server
```ts
import { makeServer } from 'graphql-lambda-subscriptions'
// define a schema and create a configured DynamoDB instance from aws-sdk
// and make a schema with resolvers (maybe look at) '@graphql-tools/schema
const subscriptionServer = makeServer({
dynamodb,
schema,
})
```
### Export the handler
```ts
export const handler = subscriptionServer.webSocketHandler
```
### Configure API Gateway
Set up API Gateway to route WebSocket events to the exported handler.
📖 Architect Example
```arc
@app
basic-events
@ws
```
📖 Serverless Framework Example
```yaml
functions:
websocket:
name: my-subscription-lambda
handler: ./handler.handler
events:
- websocket:
route: $connect
- websocket:
route: $disconnect
- websocket:
route: $default
```
### Create DynamoDB tables for state
In-flight connections and subscriptions need to be persisted.
#### Changing DynamoDB table names
Use the `tableNames` argument to override the default table names.
```ts
const instance = makeServer({
/* ... */
tableNames: {
connections: 'my_connections',
subscriptions: 'my_subscriptions',
},
})
// or use an async function to retrieve the names
const fetchTableNames = async () => {
// do some work to get your table names
return {
connections,
subscriptions,
}
}
const instance = makeServer({
/* ... */
tableNames: fetchTableNames(),
})
```
💾 Architect Example
```arc
@tables
Connection
id *String
ttl TTL
Subscription
id *String
ttl TTL
@indexes
Subscription
connectionId *String
name ConnectionIndex
Subscription
topic *String
name TopicIndex
```
```ts
import { tables as arcTables } from '@architect/functions'
const fetchTableNames = async () => {
const tables = await arcTables()
const ensureName = (table) => {
const actualTableName = tables.name(table)
if (!actualTableName) {
throw new Error(`No table found for ${table}`)
}
return actualTableName
}
return {
connections: ensureName('Connection'),
subscriptions: ensureName('Subscription'),
}
}
const subscriptionServer = makeServer({
dynamodb: tables._db,
schema,
tableNames: fetchTableNames(),
})
```
💾 Serverless Framework Example
```yaml
resources:
Resources:
# Table for tracking connections
connectionsTable:
Type: AWS::DynamoDB::Table
Properties:
TableName: ${self:provider.environment.CONNECTIONS_TABLE}
AttributeDefinitions:
- AttributeName: id
AttributeType: S
KeySchema:
- AttributeName: id
KeyType: HASH
ProvisionedThroughput:
ReadCapacityUnits: 1
WriteCapacityUnits: 1
# Table for tracking subscriptions
subscriptionsTable:
Type: AWS::DynamoDB::Table
Properties:
TableName: ${self:provider.environment.SUBSCRIPTIONS_TABLE}
AttributeDefinitions:
- AttributeName: id
AttributeType: S
- AttributeName: topic
AttributeType: S
- AttributeName: connectionId
AttributeType: S
KeySchema:
- AttributeName: id
KeyType: HASH
GlobalSecondaryIndexes:
- IndexName: ConnectionIndex
KeySchema:
- AttributeName: connectionId
KeyType: HASH
Projection:
ProjectionType: ALL
ProvisionedThroughput:
ReadCapacityUnits: 1
WriteCapacityUnits: 1
- IndexName: TopicIndex
KeySchema:
- AttributeName: topic
KeyType: HASH
Projection:
ProjectionType: ALL
ProvisionedThroughput:
ReadCapacityUnits: 1
WriteCapacityUnits: 1
ProvisionedThroughput:
ReadCapacityUnits: 1
WriteCapacityUnits: 1
```
💾 terraform example
```tf
resource "aws_dynamodb_table" "connections-table" {
name = "graphql_connections"
billing_mode = "PROVISIONED"
read_capacity = 1
write_capacity = 1
hash_key = "id"
attribute {
name = "id"
type = "S"
}
}
resource "aws_dynamodb_table" "subscriptions-table" {
name = "graphql_subscriptions"
billing_mode = "PROVISIONED"
read_capacity = 1
write_capacity = 1
hash_key = "id"
attribute {
name = "id"
type = "S"
}
attribute {
name = "topic"
type = "S"
}
attribute {
name = "connectionId"
type = "S"
}
global_secondary_index {
name = "ConnectionIndex"
hash_key = "connectionId"
write_capacity = 1
read_capacity = 1
projection_type = "ALL"
}
global_secondary_index {
name = "TopicIndex"
hash_key = "topic"
write_capacity = 1
read_capacity = 1
projection_type = "ALL"
}
}
```
### PubSub
`graphql-lambda-subscriptions` uses it's own _PubSub_ implementation.
#### Subscribing to Topics
Use the [`subscribe`](docs/README.md#subscribe) function to associate incoming subscriptions with a topic.
```ts
import { subscribe } from 'graphql-lambda-subscriptions'
export const resolver = {
Subscribe: {
mySubscription: {
subscribe: subscribe('MY_TOPIC'),
resolve: (event, args, context) => {/* ... */}
}
}
}
```
📖 Filtering events
Use the [`subscribe`](docs/README.md#subscribe) with [`SubscribeOptions`](docs/interfaces/SubscribeOptions.md) to allow for filtering.
> Note: If a function is provided, it will be called **on subscription start** and must return a serializable object.
```ts
import { subscribe } from 'graphql-lambda-subscriptions'
// Subscription agnostic filter
subscribe('MY_TOPIC', {
filter: {
attr1: '`attr1` must have this value',
attr2: {
attr3: 'Nested attributes work fine',
},
}
})
// Subscription specific filter
subscribe('MY_TOPIC',{
filter: (root, args, context, info) => ({
userId: args.userId,
}),
})
```
#### Publishing events
Use the [`publish()`](docs/interfaces/SubscriptionServer.md#publish) function on your graphql-lambda-subscriptions server to publish events to active subscriptions. Payloads must be of type `Record` so they can be filtered and stored.
```ts
subscriptionServer.publish({
topic: 'MY_TOPIC',
payload: {
message: 'Hey!',
},
})
```
Events can come from many sources
```ts
// SNS Event
export const snsHandler = (event) =>
Promise.all(
event.Records.map((r) =>
subscriptionServer.publish({
topic: r.Sns.TopicArn.substring(r.Sns.TopicArn.lastIndexOf(':') + 1), // Get topic name (e.g. "MY_TOPIC")
payload: JSON.parse(r.Sns.Message),
})
)
)
// Manual Invocation
export const invocationHandler = (payload) => subscriptionServer.publish({ topic: 'MY_TOPIC', payload })
```
#### Completing Subscriptions
Use the `complete` on your graphql-lambda-subscriptions server to complete active subscriptions. Payloads are optional and match against filters like events do.
```ts
subscriptionServer.complete({
topic: 'MY_TOPIC',
// optional payload
payload: {
message: 'Hey!',
},
})
```
### Context
[Context](docs/interfaces/ServerArgs.md#context) is provided on the [`ServerArgs`](docs/interfaces/ServerArgs.md) object when creating a server. The values are accessible in all callback and resolver functions (eg. `resolve`, `filter`, `onAfterSubscribe`, `onSubscribe` and `onComplete`).
Assuming no `context` argument is provided when creating the server, the default value is an object with `connectionInitPayload`, `connectionId` properties and the [`publish()`](docs/interfaces/SubscriptionServer.md#publish) and [`complete()`](docs/interfaces/SubscriptionServer.md#complete) functions. These properties are merged into a provided object or passed into a provided function.
#### Setting static context value
An object can be provided via the `context` attribute when calling `makeServer`.
```ts
const instance = makeServer({
/* ... */
context: {
myAttr: 'hello',
},
})
```
The default values (above) will be appended to this object prior to execution.
#### Setting dynamic context value
A function (optionally async) can be provided via the `context` attribute when calling `makeServer`.
The default context value is passed as an argument.
```ts
const instance = makeServer({
/* ... */
context: ({ connectionInitPayload }) => ({
myAttr: 'hello',
user: connectionInitPayload.user,
}),
})
```
#### Using the context
```ts
export const resolver = {
Subscribe: {
mySubscription: {
subscribe: subscribe('GREETINGS', {
filter(_, _, context) {
console.log(context.connectionId) // the connectionId
},
async onAfterSubscribe(_, _, { connectionId, publish }) {
await publish('GREETINGS', { message: `HI from ${connectionId}!` })
}
})
resolve: (event, args, context) => {
console.log(context.connectionInitPayload) // payload from connection_init
return event.payload.message
},
},
},
}
```
### Side effects
Side effect handlers can be declared on subscription fields to handle `onSubscribe` (start) and `onComplete` (stop) events.
📖 Adding side-effect handlers
```ts
export const resolver = {
Subscribe: {
mySubscription: {
resolve: (event, args, context) => {
/* ... */
},
subscribe: subscribe('MY_TOPIC', {
// filter?: object | ((...args: SubscribeArgs) => object)
// onSubscribe?: (...args: SubscribeArgs) => void | Promise
// onComplete?: (...args: SubscribeArgs) => void | Promise
// onAfterSubscribe?: (...args: SubscribeArgs) => PubSubEvent | Promise | undefined | Promise
}),
},
},
}
```
### Events
Global events can be provided when calling `makeServer` to track the execution cycle of the lambda.
📖 Connect (onConnect)
Called when a WebSocket connection is first established.
```ts
const instance = makeServer({
/* ... */
onConnect: ({ event }) => {
/* */
},
})
```
📖 Disconnect (onDisconnect)
Called when a WebSocket connection is disconnected.
```ts
const instance = makeServer({
/* ... */
onDisconnect: ({ event }) => {
/* */
},
})
```
📖 Authorization (connection_init)
`onConnectionInit` can be used to verify the `connection_init` payload prior to persistence.
> **Note:** Any sensitive data in the incoming message should be removed at this stage.
```ts
const instance = makeServer({
/* ... */
onConnectionInit: ({ message }) => {
const token = message.payload.token
if (!myValidation(token)) {
throw Error('Token validation failed')
}
// Prevent sensitive data from being written to DB
return {
...message.payload,
token: undefined,
}
},
})
```
By default, the (optionally parsed) payload will be accessible via [context](#context).
📖 Subscribe (onSubscribe)
#### Subscribe (onSubscribe)
Called when any subscription message is received.
```ts
const instance = makeServer({
/* ... */
onSubscribe: ({ event, message }) => {
/* */
},
})
```
📖 Complete (onComplete)
Called when any complete message is received.
```ts
const instance = makeServer({
/* ... */
onComplete: ({ event, message }) => {
/* */
},
})
```
📖 Error (onError)
Called when any error is encountered
```ts
const instance = makeServer({
/* ... */
onError: (error, context) => {
/* */
},
})
```
## Caveats
### Ping/Pong
For whatever reason, AWS API Gateway does not support WebSocket protocol level ping/pong. So you can use Step Functions to do this. See [`pingPong`](docs/interfaces/ServerArgs.md#pingpong).
### Socket idleness
API Gateway considers an idle connection to be one where no messages have been sent on the socket for a fixed duration [(currently 10 minutes)](https://docs.aws.amazon.com/apigateway/latest/developerguide/limits.html#apigateway-execution-service-websocket-limits-table). The WebSocket spec has support for detecting idle connections (ping/pong) but API Gateway doesn't use it. This means, in the case where both parties are connected, and no message is sent on the socket for the defined duration (direction agnostic), API Gateway will close the socket. A fix for this is to set up immediate reconnection on the client side.
### Socket Close Reasons
API Gateway doesn't support custom reasons or codes for WebSockets being closed. So the codes and reason strings wont match `graphql-ws`.