dgraph/dgraph-lambda

dgraph-lambda helm chart

TL;DR

helm repo add dgraph https://charts.dgraph.io
helm install "my-lambda" dgraph/dgraph-lambda

Introduction

Prerequisites

• Kubernetes 1.16+
• Helm 3.0+
• Dgraph v20.11.0 or greater
  • configured with graphql_lambda_url

Configuration

In order to use dgraph-lambda, you must do the following:

1. deploy Dgraph Alpha configured to point to dgraph-lambda
2. configure lambda script helm override values for dgraph-lambda
3. deploy Dgraph Lambda service configured to point to Dgraph Alpha services
4. add GraphQL schema for the resolvers added by the lambda script

Environment

For these steps, set up the following environment variables:

export NS=default
export LAMBDA_REL=my-lambda
export DGRAPH_REL=my-release

Deploy Dgraph Alpha

Dgraph Alpha will need to be configured with the --graphql_lambda_url argument (see: lambda server) to support dgraph-lambda. You can use environment variables to configure this:

helm install $DGRAPH_REL dgraph/dgraph \
  --namespace $NS \
  --set alpha.extraEnvs[0].name=DGRAPH_ALPHA_GRAPHQL_LAMBDA_URL \
  --set alpha.extraEnvs[0].value=http://$LAMBDA_REL-dgraph-lambda.$NS.svc:80/graphql-worker

The DGRAPH_ALPHA_GRAPHQL_LAMBDA_URL environment variable will point to Dgraph Lambda service that will be deployed in the next step. The format Dgraph Lambda domain name is formatted as the following:

http://<helm-chart-release-name>-dgraph-lambda.<namesapce>.svc/graphql-worker

Configure Lambda script

First we can create a Helm override values with the lambda script embedded into it like the example below:

# my-lambda.yaml
script:
  enabled: true
  script: |
    async function authorsByName({args, dql}) {
        const results = await dql.query(`query queryAuthor($name: string) {
            queryAuthor(func: type(Author)) @filter(eq(Author.name, $name)) {
                name: Author.name
                dob: Author.dob
                reputation: Author.reputation
            }
        }`, {"$name": args.name})
        return results.data.queryAuthor
    }

    async function newAuthor({args, graphql}) {
        // lets give every new author a reputation of 3 by default
        const results = await graphql(`mutation ($name: String!) {
            addAuthor(input: [{name: $name, reputation: 3.0 }]) {
                author {
                    id
                    reputation
                }
            }
        }`, {"name": args.name})
        return results.data.addAuthor.author[0].id
    }

    self.addGraphQLResolvers({
        "Query.authorsByName": authorsByName,
        "Mutation.newAuthor": newAuthor
    })

Deploy Dgraph Lambda

We can deploy the example above, named my-lambda.yaml, with the follwing:

helm install $LAMBDA_REL dgraph/dgraph-lambda \
  --namespace $NS \
  --values my-lambda.yaml \
  --set env[0].name=DGRAPH_URL \
  --set env[0].value=http://$DGRAPH_REL-dgraph-alpha-headless.$NS.svc:8080

The DGRAPH_URL environment variable will point to Dgraph Alpha service deployed in the previous step. The format Dgraph Alpha domain name is formatted as the following:

http://<helm-chart-release-name>-dgraph-alpha-headless.<namespace>.svc:8080

Add GraphQL schema

After deploying both services with the lambda script, upload a schema:

## create schema file
cat <<-EOF > my-schema.graphql
type Author {
    id: ID!
    name: String! @search(by: [hash, trigram])
    dob: DateTime
    reputation: Float
}

type Query {
    authorsByName(name: String!): [Author] @lambda
}

type Mutation {
    newAuthor(name: String!): ID! @lambda
}
EOF

## port-forward Dgraph Alpha
kubectl port-forward --namespace $NS $DGRAPH_REL-dgraph-alpha-0 8080:8080

## upload schema file
curl http://localhost:8080/admin/schema --upload-file my-schema.graphql

Configuration

The following table lists the configurable parameters of the dgraph chart and their default values.

Parameter	Description	Default
replicaCount	number of Kubernetes replicas	1
image.repository	Container repository name	dgraph/dgraph-lambda
image.pullPolicy	Container image pull policy	IfNotPresent
image.tag	Container image tag	v20.11.0
imagePullSecrets	Image pull secrets auth tokens used to access a private registry	[]
nameOverride	Name override of the default chart name	""
fullnameOverride	Full Name override of the release name + chart name	""
script.enabled	Enable adding a lambda script	false
script.script	Embedded lambda script stored in a config map	""
env	Environment variables	see values.yaml
serviceAccount.create	Specifies if service account should be created	true
serviceAccount.annotations	Service Account annotations	{}
serviceAccount.name	Service Account name	""
podAnnotations	Additional pod annotations	{}
podSecurityContext	Pod Security context to define privilege and access control	{}
securityContext	Container Security context to define privilege and access control	{}
service.type	Service type (ClusterIP, NodePort, LoadBalancer)	ClusterIP
service.port	Service inbound port	80
service.targetPort	Service targetPort of dgraph-lambda service	8686
ingress.enabled	Ingress enabled	false
ingress.annotations	Ingress annotations	{}
ingress.hosts	Ingress hosts list to configure virtual hosts + routes to the service	see values.yaml
ingress.tls	Ingress tls configuration	[]
resources	Resource limites and requests	{}
nodeSelector	Node selection constraints	{}
tolerations	Allow scheduling pods onto nodes matching specified taints	[]
affinity	Affinity configuration to allow nodes to scheduled on desired nodes	{}