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Remote GraphQL resolution

Explore remote GraphQL resolution with an example GraphQL server upstream.

In the previous section, you used local execution to resolve GraphQL queries to an upstream service. In this example, you deploy an example GraphQL server upstream, which uses remote execution. With remote execution, Envoy proxies the requests to the GraphQL server without executing the request first, and the GraphQL upstream both executes the query and provides the requested data. Additionally, Envoy validates the schema of the GraphQL server.

Deploy the following todos sample application to the default namespace, which you expose behind a GraphQL server embedded in Envoy.

kubectl apply -f - <<EOF
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: todos
  name: todos
spec:
  replicas: 1
  selector:
    matchLabels:
      app: todos
  template:
    metadata:
      labels:
        app: todos
    spec:
      containers:
        # If your system uses an arm64 or M1 processor, use `gcr.io/solo-public/graphql-todo:0.0.3-arm64` as the image name instead.
      - image: gcr.io/solo-public/graphql-todo:0.0.3-amd64
        imagePullPolicy: Always
        name: todos
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File     
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: todos
  name: todos
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 8080
  selector:
    app: todos
EOF

After the deployment is ready, verify that Gloo Gateway created a graphqlapi resource for the upstream.
```
kubectl get graphqlapis -n gloo-system
```
Example output:
```
NAME                                AGE
default-todos-80   2m58s
```

Optional: Check out the generated GraphQL schema.

kubectl get graphqlapis default-todos-80 -o yaml -n gloo-system

Update the default virtual service that you previously created to route traffic to /graphql to the new default-todos-80 GraphQL API.

kubectl apply -f - << EOF
apiVersion: gateway.solo.io/v1
kind: VirtualService
metadata:
  name: default
  namespace: gloo-system
spec:
  virtualHost:
    domains:
    - '*'
    routes:
    - graphqlApiRef:
        name: default-todos-80
        namespace: gloo-system
      matchers:
      - prefix: /graphql
      options:
        prefixRewrite: "/graphql"
EOF

Send a request to the GraphQL endpoint to verify that the request is successfully resolved by the upstream.
```
curl -X POST -d '{"query":"{todo(id:\"b\"){id,text,done}}"}' "$(glooctl proxy url)/graphql"
```
In the JSON response, note that only the information you queried is returned:
```
{"data":{"todo":{"done":false,"id":"b","text":"This is the most important"}}}
```

To see other example of data filtering, you can optionally send other queries to the GraphQL server, such as the following.

curl -X POST -d '{"query":"mutation _{updateTodo(id:\"b\",done:true){id,text,done}}", "operationName":"Mutation"}' "$(glooctl proxy url)/graphql"
curl -X POST -d '{"query":"mutation _{createTodo(text:\"My new todo\"){id,text,done}}", "operationName":"Mutation"}' "$(glooctl proxy url)/graphql"
curl -X POST -d '{"query":"{todo(id:\"b\"){id,text,done}}"}' "$(glooctl proxy url)/graphql"
curl -X POST -d '{"query":"{todoList{id,text,done}}"}' "$(glooctl proxy url)/graphql"

Up next: Protect the GraphQL API that you created in the previous sections by using an API key.