@envelop/apollo-federation/esm/index.js

This plugin integrates Apollo Federation Gateway into Envelop.

import { getOperationAST, print, printSchema, Source } from 'graphql';
import { InMemoryLRUCache } from 'apollo-server-caching';
import { newCachePolicy } from './new-cache-policy.js';
export const useApolloFederation = (options) => {
    const { gateway, cache = new InMemoryLRUCache(), logger = console, metrics = Object.create(null), overallCachePolicy = newCachePolicy(), } = options;
    let schemaHash;
    const documentSourceMap = new WeakMap();
    return {
        onPluginInit({ setSchema }) {
            if (gateway.schema) {
                setSchema(gateway.schema);
            }
            else {
                logger.warn(`ApolloGateway doesn't have the schema loaded. Please make sure ApolloGateway is loaded with .load() method. Otherwise this plugin might not work consistently, especially if you are using ApolloServer.`);
                gateway.load();
            }
            gateway.onSchemaLoadOrUpdate(({ apiSchema, coreSupergraphSdl = printSchema(apiSchema) }) => {
                setSchema(apiSchema);
                schemaHash = (coreSupergraphSdl || printSchema(apiSchema));
            });
        },
        onParse({ params: { source } }) {
            const key = source instanceof Source ? source.body : source;
            return ({ result }) => {
                if (!result || result instanceof Error)
                    return;
                documentSourceMap.set(result, key);
            };
        },
        onExecute({ args, setExecuteFn }) {
            let documentStr = documentSourceMap.get(args.document);
            if (documentStr == null) {
                documentStr = print(args.document);
                documentSourceMap.set(args.document, documentStr);
            }
            const operation = getOperationAST(args.document, args.operationName ?? undefined);
            if (!operation) {
                throw new Error(`Operation ${args.operationName || ''} cannot be found in ${documentStr}`);
            }
            setExecuteFn(function federationExecutor() {
                return gateway.executor({
                    document: args.document,
                    request: {
                        query: documentStr,
                        operationName: args.operationName ?? undefined,
                        variables: args.variableValues ?? undefined,
                    },
                    overallCachePolicy,
                    operationName: args.operationName ?? null,
                    cache,
                    context: args.contextValue,
                    queryHash: documentStr,
                    logger,
                    metrics,
                    source: documentStr,
                    operation,
                    schema: args.schema,
                    schemaHash,
                });
            });
        },
    };
};