Feat/allow multi federation

examples/README.md

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+Example of serveral federated services
+======================================
+This example shows 2 postgraphile services federated with a appolo-server service all federated through @apollo-gateway.
+
+
+Setup
+-----
+1) Create the databses: 
+`$> createdb accountsdb`
+`$> createdb productsdb`
+
+2) run the database creation scripts - THIS WILL CREATE ROLES ON YOUR SERVER
+`$> cat ./accounts/database.sql > psql -d accountsdb`
+`$> cat ./products/database.sql > psql -d products`
+
+3) Setup project (make sure you have built federation package):
+`$> yarn install`
+`$> yarn start`
+
+4) Navigate to https://localhost:3001
+
+Example Query:
+```graphql
+query {
+  purchase(purchaseId: 2) {
+    account {
+      firstName,
+      purchases {
+        purchaseId,
+				product {
+          reviews {
+            body
+          }
+        }
+      }
+    }
+  }
+}
+```

examples/accounts/database.sql

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+CREATE TABLE account (
+    account_id SERIAL PRIMARY KEY,
+    first_name VARCHAR NOT NULL,
+    last_name VARCHAR NOT NULL
+);
+
+INSERT INTO account (first_name, last_name) VALUES 
+    ('Charlotte', 'Williams'),
+    ('Jessica', 'Rodriguez'),
+    ('Emily', 'Davis'),
+    ('Jan', 'Mata'),
+    ('Michael', 'Williams'),
+    ('Jules', 'Michael');
+
+CREATE ROLE accountsuser WITH LOGIN ENCRYPTED PASSWORD 'jw8s0F4';
+GRANT ALL ON ALL TABLES IN SCHEMA public TO accountsuser;
+

examples/accounts/index.js

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+const express = require("express");
+const { postgraphile } = require("postgraphile");
+const FederationPlugin = require("@graphile/federation").default;
+const PgSimplifyInflectorPlugin = require("@graphile-contrib/pg-simplify-inflector");
+const { NodePlugin } = require("graphile-build");
+
+const DATABASE_URL =
+  "postgresql://accountsuser:jw8s0F4@localhost:5432/accountsdb";
+
+const app = express();
+app.use(
+  postgraphile(DATABASE_URL, "public", {
+    appendPlugins: [PgSimplifyInflectorPlugin, FederationPlugin],
+    graphiql: true,
+    watchPg: true,
+    skipPlugins: [NodePlugin],
+    graphileBuildOptions: {
+      pgOmitListSuffix: true,
+      pgShortPk: true,
+    },
+  })
+);
+
+app.listen(process.env.PORT || 3002);

examples/gateway/index.js

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+const { ApolloGateway, RemoteGraphQLDataSource } = require("@apollo/gateway");
+const { ApolloServer } = require("apollo-server");
+var waitOn = require("wait-on");
+
+class AuthenticatedDataSource extends RemoteGraphQLDataSource {
+  constructor(config) {
+    super(config);
+  }
+
+  willSendRequest({ request, context }) {
+    request.http.headers.set("x-account-id", context.account);
+    request.http.headers.set("x-organization-id", context.organization);
+  }
+}
+
+async function main() {
+  await waitOn({
+    resources: [
+      "http://localhost:3002/graphiql",
+      "http://localhost:3003/graphiql",
+      "http://localhost:3004/.well-known/apollo/server-health",
+    ],
+  });
+
+  const gateway = new ApolloGateway({
+    serviceList: [
+      { name: "accounts", url: "http://localhost:3002/graphql" },
+      { name: "products", url: "http://localhost:3003/graphql" },
+      { name: "reviews", url: "http://localhost:3004/" },
+    ],
+    buildService({ url }) {
+      return new AuthenticatedDataSource({ url });
+    },
+  });
+
+  const server = new ApolloServer({
+    gateway,
+    subscriptions: false,
+    context: ({ req }) => {
+      return {
+        account: req.headers["x-account-id"],
+        organization: req.headers["x-organization-id"],
+      };
+    },
+  });
+
+  server.listen(3001).then(({ url }) => {
+    console.log(`🚀 Server ready at ${url}`);
+  });
+}
+
+main();

examples/package.json

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+{
+  "name": "examples",
+  "version": "1.0.0",
+  "main": "index.js",
+  "license": "MIT",
+  "private": true,
+  "dependencies": {
+    "@apollo/federation": "^0.10.2",
+    "@apollo/gateway": "^0.10.8",
+    "@graphile-contrib/pg-simplify-inflector": "^5.0.0-beta.1",
+    "@graphile/federation": "../",
+    "apollo-server": "^2.9.7",
+    "express": "^4.17.1",
+    "graphile-build": "^4.4.5",
+    "graphile-build-pg": "^4.4.5",
+    "graphile-utils": "^4.4.5",
+    "graphql": "14.5.8",
+    "pg": "^7.12.1",
+    "postgraphile": "^4.4.4",
+    "wait-on": "^3.3.0"
+  },
+  "devDependencies": {
+    "concurrently": "^5.0.0"
+  },
+  "resolutions": {
+    "graphql": "14.5.8"
+  },
+  "scripts": {
+    "start": "concurrently yarn:start-*",
+    "start-accounts": "node ./accounts/index.js",
+    "start-products": "node ./products/index.js",
+    "start-gateway": "node ./gateway/index.js",
+    "start-reviews": "node ./reviews/index.js"
+  }
+}

examples/products/database.sql

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+CREATE TABLE product (
+    product_id SERIAL PRIMARY KEY,
+    product_name VARCHAR NOT NULL,
+    price VARCHAR NOT NULL
+);
+
+CREATE TABLE purchase (
+    purchase_id SERIAL PRIMARY KEY,
+    product_id INT REFERENCES product(product_id),
+    account_id INT NOT NULL,
+    date_purchased TIMESTAMP NOT NULL
+);
+
+COMMENT ON COLUMN purchase.account_id IS E'@name account\n@federated Account(accountId)';
+
+INSERT INTO product (product_name, price) VALUES
+('Book 1', '2.99'),
+('Book 2', '3.99'),
+('Book 3', '7.99'),
+('Book 4', '12.49'),
+('Toy Car 1', '2.49'),
+('Toy Car 2', '2.79');
+
+INSERT INTO purchase (product_id, account_id, date_purchased) VALUES 
+(2, 1, '2019-10-01 09:45:00'),
+(2, 2, '2019-10-01 12:22:00'),
+(3, 2, '2019-10-02 11:48:00'),
+(3, 3, '2019-10-02 20:39:00'),
+(3, 5, '2019-10-02 22:12:00'),
+(4, 2, '2019-10-04 12:34:00'),
+(4, 3, '2019-10-04 14:25:00'),
+(5, 3, '2019-10-04 21:42:00'),
+(5, 3, '2019-10-09 07:25:00'),
+(5, 4, '2019-10-09 09:11:00'),
+(5, 5, '2019-10-09 11:26:00'),
+(6, 3, '2019-10-09 14:53:00');
+
+CREATE ROLE productsuser WITH LOGIN ENCRYPTED PASSWORD 'jw8s0F4';
+GRANT ALL ON ALL TABLES IN SCHEMA public TO productsuser;

examples/products/index.js

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+const express = require("express");
+const { postgraphile } = require("postgraphile");
+const FederationPlugin = require("@graphile/federation").default;
+const PgSimplifyInflectorPlugin = require("@graphile-contrib/pg-simplify-inflector");
+const { makeExtendSchemaPlugin, gql } = require("graphile-utils");
+const { NodePlugin } = require("graphile-build");
+
+const ExtensionPlugin = makeExtendSchemaPlugin(build => {
+  const { pgSql: sql } = build;
+  return {
+    typeDefs: gql`
+      type Account @key(fields: "accountId") @extends {
+        accountId: Int! @external
+        purchases: [Purchase!]
+      }
+    `,
+    resolvers: {
+      Query: {},
+      Account: {
+        purchases: async (parent, args, context, resolveInfo) => {
+          return resolveInfo.graphile.selectGraphQLResultFromTable(
+            sql.fragment`public.purchase`,
+            (tableAlias, queryBuilder) => {
+              queryBuilder.where(
+                sql.fragment`${tableAlias}.account_id=${sql.value(
+                  parent.accountId
+                )}`
+              );
+            }
+          );
+        },
+      },
+    },
+  };
+});
+
+const DATABASE_URL =
+  "postgresql://productsuser:jw8s0F4@localhost:5432/productsdb";
+
+const app = express();
+app.use(
+  postgraphile(DATABASE_URL, "public", {
+    appendPlugins: [
+      ExtensionPlugin,
+      PgSimplifyInflectorPlugin,
+      FederationPlugin,
+    ],
+    graphiql: true,
+    watchPg: true,
+    skipPlugins: [NodePlugin],
+    graphileBuildOptions: {
+      pgOmitListSuffix: true,
+      pgShortPk: true,
+    },
+  })
+);
+
+app.listen(process.env.PORT || 3003);

examples/reviews/index.js

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+const { ApolloServer, gql } = require("apollo-server");
+const { buildFederatedSchema } = require("@apollo/federation");
+
+const typeDefs = gql`
+  type Review {
+    reviewId: Int!
+    body: String!
+    author: Account!
+    product: Product!
+  }
+
+  extend type Account @key(fields: "accountId") {
+    accountId: Int! @external
+    reviews: [Review!]
+  }
+
+  extend type Product @key(fields: "productId") {
+    productId: Int! @external
+    reviews: [Review!]
+  }
+`;
+
+const reviews = [
+  { productId: 2, accountId: 1, body: "Great Purchase" },
+  { productId: 3, accountId: 3, body: "Very Happy" },
+  { productId: 3, accountId: 5, body: "Could Be Better" },
+  { productId: 4, accountId: 2, body: "Fabulous" },
+  { productId: 5, accountId: 3, body: "Awful" },
+  { productId: 6, accountId: 3, body: "Perfect" },
+];
+
+const resolvers = {
+  Query: {},
+  Review: {
+    __resolveReference(review) {
+      return reviews[review.reviewId];
+    },
+  },
+  Account: {
+    reviews: account => {
+      return reviews.filter(x => x.accountId === account.accountId);
+    },
+  },
+  Product: {
+    reviews: product => {
+      return reviews.filter(x => x.productId === product.productId);
+    },
+  },
+};
+
+const server = new ApolloServer({
+  schema: buildFederatedSchema([{ typeDefs, resolvers }]),
+});
+
+server.listen(3004).then(({ url }) => {
+  console.log(`🚀 Server ready at ${url}`);
+});