Super Graph

Instant GraphQL API for Rails. Zero code.

Get an high-performance GraphQL API for your Rails app in seconds. Super Graph will auto learn your database structure and relationships. Built in support for Rails authentication and JWT tokens.

Back story and motivation

I have a Rails app that gets a bit of traffic. Having planned to improve the UI using React or Vue I found that my current APIs didn't have the data I needed and I was too lazy to build new endpoints. My controllers were esentially wrappers around database queries and I didn't enjoy having to figure out new REST APIs with paths, names and methods to fetch all this new data or write the active record code needed.

I always liked GraphQL and how simple it makes things for web devs. On the backend however GraphQL seemed overly complex as it still required me to write a lot of the same database query code. I wanted a GraphQL server that just worked the second you deployed it without having to write a line of code.

And so after a lot of coffee and some avocado toasts we now have Super Graph, an instant GraphQL API that is high performance and quick to deploy. One service to rule all your database querying needs.

Features

• Support for Rails database conventions
• Belongs-To, One-To-Many and Many-To-Many table relationships
• Devise, Warden encrypted and signed session cookies
• Redis, Memcache and Cookie session stores
• Generates highly optimized Postgres SQL queries
• Customize through a simple config file
• High performance GO codebase
• Tiny docker image and low memory requirements

GraphQL (GQL)

We currently support the query action which is used for fetching data. Support for mutation and subscriptions is currently work in progress. For example the below query fetches two products that belong to the current user where the price is greater than 10

GQL Query

query { 
  users {
    id
    email
    picture : avatar
    password
    full_name
    products(limit: 2, where: { price: { gt: 10 } }) {
      id
      name
      description
      price
    }
  }
}

The above GQL query returns the JSON result below. It handles all kinds of complexity without you writing a line of code. For example there is a while greater than gt and a limit clause on a child field. And the avatar field is renamed to picture. The password field is blocked and not returned. Finally the relationship between the users table and the products table is auto discovered and used.

JSON Result

{
  "data": {
    "users": [
      {
        "id": 1,
        "email": "odilia@west.info",
        "picture": "https://robohash.org/simur.png?size=300x300",
        "full_name": "Edwin Orn",
        "products": [
          {
            "id": 16,
            "name": "Sierra Nevada Style Ale",
            "description": "Belgian Abbey, 92 IBU, 4.7%, 17.4°Blg",
            "price": 16.47
          },
          ...
        ]
      }
    ]
  }
}

Try it out

$ docker-compose run web rake db:create db:migrate db:seed
$ docker-compose -f docker-compose.image.yml up
$ open http://localhost:8080

The above command will download the latest docker image for Super Graph and use it to run an example that includes a Postgres DB and a simple Rails ecommerce store app.

If you want to build and run Super Graph from code then the below commands will build the web ui and launch Super Graph in developer mode with a water for code changes.

$ brew install yarn
$ (cd web && yarn install && yarn build)
$ go generate ./...
$ docker-compose up

How to try with an authenticated user

In development mode you can use the X-User-ID: 4 header to set a user id so you don't have to worries about cookies etc. This can be set using the HTTP Headers tab at the bottom of the web UI you'll see when you visit the above link. You can also directly run quries from the commandline like shown below.

Querying the GQL endpoint

curl 'http://localhost:8080/api/v1/graphql' \
  -H 'content-type: application/json' \
  -H 'X-User-ID: 5' \
  --data-binary '{"query":"{ products { name price users { email }}}"}'

How to GraphQL

GraphQL / GQL is a simple query syntax that is fast replacing REST APIs. GQL is great since it allows web developers to fetch the exact data that they need without depending on changes to backend code. Also if you squint hard enough it looks a little bit like JSON :)

The below query will fetch a users name, email and avatar image renamed as picture. If you also need the users id then just add it to the query.

query {
  user {
    full_name
    email
    picture : avatar
  }
}

Super Graph support complex quries where you can add filters, ordering, offsets and limits on the query.

Logical Operators

Name	Example	Explained
and	price : { and : { gt: 10.5, lt: 20 }	price > 10.5 AND price < 20
or	or : { price : { greater_than : 20 }, quantity: { gt : 0 } }	price >= 20 OR quantity > 0
not	not: { or : { quantity : { eq: 0 }, price : { eq: 0 } } }	NOT (quantity = 0 OR price = 0)

Other conditions

Name	Example	Explained
eq, equals	id : { eq: 100 }	id = 100
neq, not_equals	id: { not_equals: 100 }	id != 100
gt, greater_than	id: { gt: 100 }	id > 100
lt, lesser_than	id: { gt: 100 }	id < 100
gte, greater_or_equals	id: { gte: 100 }	id >= 100
lte, lesser_or_equals	id: { lesser_or_equals: 100 }	id <= 100
in	status: { in: [ "A", "B", "C" ] }	status IN ('A', 'B', 'C)
nin, not_in	status: { in: [ "A", "B", "C" ] }	status IN ('A', 'B', 'C)
like	name: { like "phil%" }	Names starting with 'phil'
nlike, not_like	name: { nlike "v%m" }	Not names starting with 'v' and ending with 'm'
ilike	name: { ilike "%wOn" }	Names ending with 'won' case-insensitive
nilike, not_ilike	name: { nilike "%wOn" }	Not names ending with 'won' case-insensitive
similar	name: { similar: "%(b|d)%" }	Similar Docs
nsimilar, not_similar	name: { nsimilar: "%(b|d)%" }	Not Similar Docs
has_key	column: { has_key: 'b' }	Does JSON column contain this key
has_key_any	column: { has_key_any: [ a, b ] }	Does JSON column contain any of these keys
has_key_all	column: [ a, b ]	Does JSON column contain all of this keys
contains	column: { contains: [1, 2, 4] }	Is this array/json column a subset of value
contained_in	column: { contains: "{'a':1, 'b':2}" }	Is this array/json column a subset of these value
is_null	column: { is_null: true }	Is column value null or not

Aggregation

You will often find the need to fetch aggregated values from the database such as count, max, min, etc. This is simple to go with GraphQL just prefix the aggregation name to the field name that you want to aggregrate. The below query will group products by name and find the minimum price for each group. Notice the min_price field we're adding min_ to price.

query {
  products {
    name
    min_price
  }
}

Name	Explained
avg	Average value
count	Count the values
max	Maximum value
min	Minimum value
stddev	Standard Deviation
stddev_pop	Population Standard Deviation
stddev_samp	Sample Standard Deviation
variance	Variance
var_pop	Population Standard Variance
var_samp	Sample Standard variance

All kinds of quries are possible with GraphQL below is an example that uses a lot of the features available to web devs using GraphQL to get the exact data they need. Comments are also valid within queries.

query {
  products(
    # returns only 30 items
    limit: 30,

    # starts from item 10, commented out for now
    # offset: 10,

    # orders the response items by highest price
    order_by: { price: desc },

    # no duplicate prices returned
    distinct: [ price ]
    
    # only items with an id >= 30 and < 30 are returned
    where: { id: { and: { greater_or_equals: 20, lt: 28 } } }) {
    id
    name
    price
  }
}

Configuration

Config files can either be in YAML or JSON their names are derived from the GO_ENV variable, for example GO_ENV=prod will cause the prod.yaml config file to be used. or GO_ENV=dev will use the dev.yaml. A path to the config files can be specified using the -path <folder> command line argument.

host_port: 0.0.0.0:8080
web_ui: true
debug_level: 1

# When to throw a 401 on auth failure 
# valid values: always, per_query, never
auth_fail_block: never

# Postgres related enviroment Variables
# SG_DATABASE_HOST
# SG_DATABASE_PORT
# SG_DATABASE_USER
# SG_DATABASE_PASSWORD

# Auth related enviroment Variables
# SG_AUTH_SECRET_KEY_BASE
# SG_AUTH_PUBLIC_KEY_FILE
# SG_AUTH_URL
# SG_AUTH_PASSWORD

# inflections:
#   person: people
#   sheep: sheep

auth:
  type: header
  field_name: X-User-ID

# auth:
#   type: rails
#   cookie: _app_session
#   store: cookie
#   secret_key_base: caf335bfcfdb04e50db5bb0a4d67ab9...

# auth:
#   type: rails
#   cookie: _app_session
#   store: memcache
#   host: 127.0.0.1

# auth:
#   type: rails
#   cookie: _app_session
#   store: redis
#   max_idle: 80,
#   max_active: 12000,
#   url: redis://127.0.0.1:6379
#   password: ""

# auth:
#   type: jwt
#   cookie: _app_session
#   secret: abc335bfcfdb04e50db5bb0a4d67ab9
#   public_key_file: /secrets/public_key.pem
#   public_key_type: ecdsa #rsa

database:
  type: postgres
  host: db
  port: 5432
  dbname: app_development
  user: postgres
  password: ''
  #pool_size: 10
  #max_retries: 0
  #log_level: "debug" 

  # Define variables here that you want to use in filters 
  variables:
    account_id: "select account_id from users where id = $user_id"

  # Used to add access to tables 
  filters:
    users: "{ id: { _eq: $user_id } }"
    posts: "{ account_id: { _eq: $account_id } }"

  # Fields and table names that you wish to block
  blacklist:
    - secret
    - password
    - encrypted
    - token

If deploying into enviroments like Kubernetes it's useful to be able to configure things like secrets and hosts though enviroment variables so we expose the following. This is escpecially useful for secrets since they are usually injected in via a secrets management framework ie. Kubernetes Secrets

Postgres related enviroment Variables

SG_DATABASE_HOST
SG_DATABASE_PORT
SG_DATABASE_USER
SG_DATABASE_PASSWORD

Auth related enviroment Variables

SG_AUTH_SECRET_KEY_BASE
SG_AUTH_PUBLIC_KEY_FILE
SG_AUTH_URL
SG_AUTH_PASSWORD

Authentication

You can only have one type of authentication enabled. You can either pick Rails or JWT. Uncomment the one you use and leave the rest commented out.

JWT Tokens

auth:
  type: jwt
  provider: auth0 #none
  cookie: _app_session
  secret: abc335bfcfdb04e50db5bb0a4d67ab9
  public_key_file: /secrets/public_key.pem
  public_key_type: ecdsa #rsa

For JWT tokens we currently support tokens from a provider like Auth0 or if you have a custom solution then we look for the user_id in the subject claim of of the id token. If you pick Auth0 then we derive two variables from the token user_id and user_id_provider for to use in your filters.

We can get the JWT token either from the authorization header where we expect it to be a bearer token or if cookie is specified then we look there.

For verified either a secret or a public key (ecdsa or rsa) is required. When using public keys they have to be in a PEM format file.

Deployment

How do I deploy the Super Graph service with my existing rails app? You have several options here. Esentially you need to ensure your app's session cookie will be passed to this service.

Custom Docker Image

Create a Dockerfile like the one below to roll your own custom Super Graph docker image. And to build it docker build -t my-super-graph .

FROM dosco/super-graph:latest
WORKDIR /app
COPY *.yml ./

Deploy under a subdomain

For this to work you have to ensure that the option :domain => :all is added to your rails app config Application.config.session_store this will cause your rails app to create session cookies that can be shared with sub-domains. More info here http://excid3.com/blog/sharing-a-devise-user-session-across-subdomains-with-rails-3/

We have this NGINX loadbalancer

I'm sure you know how to configure it so that the graphql endpoint path is routed to wherever you have this service installed within your architecture.

On Kubernetes

If your existing rails app runs on Kubernetes then ensure you have an ingress config deployed that points the path /api/v1/graphql to the service that you have deployed Super Graph under.

We use JWT tokens like those from Auth0

In that case deploy under a subdomain and configure this service to use JWT authentication. You will need the public key file or secret key. Ensure your web app passes the JWT token with every GQL request in the Authorize header as a bearer token.

Contact me

twitter.com/dosco

License

MIT

Copyright (c) 2019-present Vikram Rangnekar