Lambda Server - Graphql

Documentation
1

In this article you’ll learn how to setup a Dgraph database with a lambda server.

Dgraph Lambda

Dgraph Lambda is a serverless platform for running JavaScript on Dgraph and Slash GraphQL.

You can download the latest version or review the implementation in our open-source repository.

Running with Docker

To run a Dgraph Lambda server with Docker:

docker run -it --rm -p 8686:8686 -v /path/to/script.js:/app/script/script.js -e DGRAPH_URL=http://host.docker.internal:8080 dgraph/dgraph-lambda

Note host.docker.internal doesn’t work on older versions of Docker on Linux. You can use DGRAPH_URL=http://172.17.0.1:8080 instead.

Adding libraries

If you would like to add libraries to Dgraph Lambda, use webpack --target=webworker to compile your script.

Working with TypeScript

You can import @slash-graph/lambda-types to get types for addGraphQLResolver and addGraphQLMultiParentResolver.

Dgraph Alpha

To set up Dgraph Alpha, you need to define the --graphql_lambda_url flag, which is used to set the URL of the lambda server. All the @lambda fields will be resolved through the lambda functions implemented on the given lambda server.

For example:

dgraph alpha --graphql_lambda_url=http://localhost:8686/graphql-worker

Then test it out with the following curl command:

curl localhost:8686/graphql-worker -H "Content-Type: application/json" -d '{"resolver":"MyType.customField","parent":[{"customField":"Dgraph Labs"}]}'

Docker settings

If you’re using Docker, you need to add the --graphql_lambda_url to your Alpha configuration. For example:

    command: /gobin/dgraph alpha --zero=zero1:5180 -o 100 --expose_trace --trace 1.0
      --profile_mode block --block_rate 10 --logtostderr -v=2
      --whitelist 10.0.0.0/8,172.16.0.0/12,192.168.0.0/16 --my=alpha1:7180
      --graphql_lambda_url=http://lambda:8686/graphql-worker

Next, you need to add the Dgraph Lambda server configuration, and map the JavaScript file that contains the code for lambda functions to the /app/script/script.js file. Remember to set the DGRAPH_URL environment variable to your Alpha server.

For example:

  lambda:
    image: dgraph/dgraph-lambda:latest
    container_name: lambda
    labels:
      cluster: test
    ports:
      - 8686:8686
    depends_on:
      - alpha
    environment:
      DGRAPH_URL: http://alpha:8180
    volumes:
      - type: bind
        source: ./script.js
        target: /app/script/script.js
        read_only: true

Here’s a complete Docker example, including:

version: "3.5"
services:
  zero:
    image: dgraph/dgraph:latest
    container_name: zero1
    working_dir: /data/zero1
    ports:
      - 5180:5180
      - 6180:6180
    labels:
      cluster: test
      service: zero1
    volumes:
      - type: bind
        source: $GOPATH/bin
        target: /gobin
        read_only: true
    command: /gobin/dgraph zero -o 100 --logtostderr -v=2 --bindall --expose_trace --profile_mode block --block_rate 10 --my=zero1:5180
  alpha:
    image: dgraph/dgraph:latest
    container_name: alpha1
    working_dir: /data/alpha1
    volumes:
      - type: bind
        source: $GOPATH/bin
        target: /gobin
        read_only: true
    ports:
      - 8180:8180
      - 9180:9180
    labels:
      cluster: test
      service: alpha1
    command: /gobin/dgraph alpha --zero=zero1:5180 -o 100 --expose_trace --trace 1.0
      --profile_mode block --block_rate 10 --logtostderr -v=2
      --whitelist 10.0.0.0/8,172.16.0.0/12,192.168.0.0/16 --my=alpha1:7180
      --graphql_lambda_url=http://lambda:8686/graphql-worker
  lambda:
    image: dgraph/dgraph-lambda:latest
    container_name: lambda
    labels:
      cluster: test
    ports:
      - 8686:8686
    depends_on:
      - alpha
    environment:
      DGRAPH_URL: http://alpha:8180
    volumes:
      - type: bind
        source: ./script.js
        target: /app/script/script.js
        read_only: true
This is a companion discussion topic for the original entry at https://dgraph.io/docs/graphql/lambda/server/
2

Some suggestions w/ docker-compose example:

  1. single alpha + zero does not need to use a port offset
  2. using dgraph binary from outside of the container is unusual unless you are developing dgraph itself.
  3. instead of specifying the version latest, as this changes, could the same version in docs be used?
  4. use array instead of long string for command