[federation] update federation example and enable tests (#1599)

Update Apollo Federation example to match [Federation JVM Spring Example](https://github.com/apollographql/federation-jvm-spring-example) schemas. DGS and GraphQL Java Kickstart also implement the same example schemas.

Changes:

* Updated base-app/extend-app to match products-subgraph/reviews-subgraph schemas
* Added integration tests to both subgraph (start app and run query)
* Updated to use new [Rust Router](https://www.apollographql.com/docs/router/).
* Added CI that builds the composition, starts the supergraph and runs federated query

Related:

Resolves #390

Author: dariuszkuc

.github/workflows/continuous-integration.yml

@@ -16,6 +16,10 @@ jobs:
     needs: build-libraries
     uses: ./.github/workflows/build-examples.yml
 
+  federation-composition:
+    needs: build-libraries
+    uses: ./.github/workflows/federation-composition.yml
+
   release-notes:
     timeout-minutes: 10
     runs-on: ubuntu-latest

.github/workflows/federation-composition.yml

@@ -0,0 +1,65 @@
+name: Federation Composition Test
+
+on:
+  workflow_call:
+
+jobs:
+  federation-composition-test:
+    timeout-minutes: 30
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: examples/federation
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Java 11
+        uses: actions/setup-java@v3
+        with:
+          java-version: 11
+          distribution: 'zulu'
+
+      - name: Set up Gradle cache
+        uses: gradle/gradle-build-action@v2
+
+      - name: Build Subgraphs
+        working-directory: examples
+        run: ./gradlew :federation-products-subgraph:build :federation-reviews-subgraph:build
+
+      - name: Setup rover CLI
+        run: |
+          curl -sSL https://rover.apollo.dev/nix/latest | sh -s -- --elv2-license accept
+          echo "$HOME/.rover/bin" >> ${GITHUB_PATH}
+
+      - name: Compose Supergraph
+        run: APOLLO_ELV2_LICENSE=accept rover supergraph compose --config supergraph.yaml > supergraph.graphql
+
+      - name: Start router
+        run: docker compose up --build --detach --wait
+
+      - name: Federation Tests
+        run: |
+          set -x
+          echo "verify router is up"
+          curl --verbose http://localhost:8088/health
+
+          echo "sending a test query"
+          curl --request POST \
+            --verbose \
+            --header 'content-type: application/json' \
+            --url http://localhost:3000/ \
+            --data '{"query":"query($productId: ID!) {\n  product(id: $productId) {\n    id\n    reviews {\n      id\n      text\n      starRating\n    }\n    name\n    description\n  }\n}","variables":{"productId":"5"}}' \
+            > response.json
+
+          echo "received GraphQL response"
+          cat response.json
+
+          echo "verifying response"
+          jq -e '.data.product?.id == "5" and .data.product?.name == "Dragon" and (.data.product?.reviews | length == 2) and (.data.product?.reviews[0]?.text | length > 0)' response.json
+      - name: Error Logs
+        if: ${{ failure() }}
+        run: docker-compose logs
+      - name: Stop Supergraph
+        if: ${{ always() }}
+        run: docker compose down --remove-orphans

.github/workflows/pr-check.yml

@@ -16,3 +16,7 @@ jobs:
   build-examples:
     needs: build-libraries
     uses: ./.github/workflows/build-examples.yml
+
+  federation-composition:
+    needs: build-libraries
+    uses: ./.github/workflows/federation-composition.yml

examples/federation/.gitignore

@@ -0,0 +1 @@
+supergraph.graphql

examples/federation/README.md

@@ -1,7 +1,61 @@
 # Federation Example
 
-This example is two Spring applications `base-app` and `extend-app` that use `graphql-kotlin-federation` to generate the schema.
-These apps run on different ports (`8080`, `8081`) so they can run simultaniously.
+[Apollo Federation](https://www.apollographql.com/docs/federation/) example using GraphQL Kotlin and [Apollo Router](https://www.apollographql.com/docs/router/).
+
+The repository contains two separate projects:
+
+1. `products-subgraph`: A Java GraphQL service providing the federated `Product` type
+2. `reviews-subgraph`: A Java GraphQL service that extends the `Product` type with `reviews`
+
+See individual projects READMEs for detailed instructions on how to run them.
+
+## Running example locally
+
+1. Start `products-subgraph` by running the Spring Boot app from the IDE or by running `gradle bootRun` from `products-subgraph` project
+2. Start `reviews-subgraph` by running the Spring Boot app from the IDE or `gradle bootRun` from `reviews-subgraph` project
+3. Start Federated Router
+    1. Install [rover CLI](https://www.apollographql.com/docs/rover/getting-started)
+    2. Start router and compose products schema using [rover dev command](https://www.apollographql.com/docs/rover/commands/dev)
+
+    ```shell
+    # start up router and compose products schema
+    rover dev --name products --url http://localhost:8080/graphql
+    ```
+
+    3. In **another** shell run `rover dev` to compose reviews schema
+
+    ```shell
+    rover dev --name reviews --url http://localhost:8081/graphql
+    ```
+
+4. Open http://localhost:3000 for the query editor
+
+Example federated query
+
+```graphql
+query ExampleQuery {
+    products {
+        id
+        name
+        description
+        reviews {
+            id
+            text
+            starRating
+        }
+    }
+}
+```
+
+
+
+
+
+
+
+
+is two Spring applications `base-app` and `extend-app` that use `graphql-kotlin-federation` to generate the schema.
+These apps run on different ports (`8080`, `8081`) so they can run simultaneously.
 
 The `gateway` is a Node.js app running Apollo Gateway on port `4000` and connects to the two Spring apps.
 You can make queries against the Spring apps directly or run combined queries from the gateway.
@@ -35,3 +89,41 @@ Once the app has started you can explore the example schema by opening the Playg
 ### Gateway
 
 See the instructions in the gateway [README](./gateway/README.md)
+
+
+
+1. Start `products-subgraph` by running the Spring Boot app from the IDE or by running `./gradlew bootRun` from `products-subgraph` project
+2. Start `reviews-subgraph` by running the Spring Boot app from the IDE or `./gradlew bootRun` from `reviews-subgraph` project
+3. Start Federated Router
+    1. Install [rover CLI](https://www.apollographql.com/docs/rover/getting-started)
+    2. Start router and compose products schema using [rover dev command](https://www.apollographql.com/docs/rover/commands/dev)
+
+    ```shell
+    # start up router and compose products schema
+    rover dev --name products --schema ./products-subgraph/src/main/resources/graphql/schema.graphqls --url http://localhost:8080/graphql
+    ```
+
+    3. In **another** shell run `rover dev` to compose reviews schema
+
+    ```shell
+    rover dev --name reviews --schema ./reviews-subgraph/src/main/resources/graphql/schema.graphqls --url http://localhost:8080/graphql
+    ```
+
+4. Open http://localhost:3000 for the query editor
+
+Example federated query
+
+```graphql
+query ExampleQuery {
+    products {
+        id
+        name
+        description
+        reviews {
+            id
+            text
+            starRating
+        }
+    }
+}
+```