Serverless Appsync Offline

Serverless Plugin to run AWS AppSync GraphQL API localy with dynamoDB and lambda resolvers

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npm version License: MIT

This is a wrapper for the excellent AppSync Emulator.

This Plugin Requires


  • Emulate Appsync with AppSync Emulator and depends on Serverless-AppSync-Plugin
  • Connect to any DynamoDB or install DynamoDB Local
  • Start DynamoDB Local with all the parameters supported (e.g port, inMemory, sharedDb)
  • Table Creation for DynamoDB Local

This plugin is updated by its users, I just do maintenance and ensure that PRs are relevant to the community. In other words, if you find a bug or want a new feature, please help us by becoming one of the contributors.

Install Plugin

npm install --save serverless-appsync-offline

Then in serverless.yml add following entry to the plugins array: serverless-appsync-offline

  - serverless-appsync-offline

Using the Plugin

  1. Add Appsync Resource definitions to your Serverless configuration, as defined here:

Start appsync-offline

sls appsync-offline start

All CLI options are optional:

--port  		  -p  Port to provide the graphgl api. Default: dynamic
--dynamoDbPort            -d  Port to access the dynamoDB. Default: dynamic
--inMemory                -i  DynamoDB; will run in memory, instead of using a database file. When you stop DynamoDB;, none of the data will be saved. Note that you cannot specify both -dbPath and -inMemory at once.
--dbPath                  -b  The directory where DynamoDB will write its database file. If you do not specify this option, the file will be written to the current directory. Note that you cannot specify both -dbPath and -inMemory at once. For the path, current working directory is <projectroot>/node_modules/serverless-appsync-offline/dynamob. For example to create <projectroot>/node_modules/serverless-appsync-offline/dynamob/<mypath> you should specify -d <mypath>/ or --dbPath <mypath>/ with a forwardslash at the end.
--sharedDb                -h  DynamoDB will use a single database file, instead of using separate files for each credential and region. If you specify -sharedDb, all DynamoDB clients will interact with the same set of tables regardless of their region and credential configuration.
--delayTransientStatuses  -t  Causes DynamoDB to introduce delays for certain operations. DynamoDB can perform some tasks almost instantaneously, such as create/update/delete operations on tables and indexes; however, the actual DynamoDB service requires more time for these tasks. Setting this parameter helps DynamoDB simulate the behavior of the Amazon DynamoDB web service more closely. (Currently, this parameter introduces delays only for global secondary indexes that are in either CREATING or DELETING status.)
--optimizeDbBeforeStartup -o  Optimizes the underlying database tables before starting up DynamoDB on your computer. You must also specify -dbPath when you use this parameter.

All the above options can be added to serverless.yml to set default configuration: e.g.

Minimum Options:

    port: 62222
        port: 8000

All Options:

    port: 62222
        # if endpoint is provided, no local database server is started and and appsync connects to the endpoint - e.g. serverless-dynamodb-local
        endpoint: "http://localhost:8000"
        region: localhost
        accessKeyId: a
        secretAccessKey: a
        port: 8000
        dbPath: "./.dynamodb"
        inMemory: false,
        sharedDb: false,
        delayTransientStatuses: false,
        optimizeDbBeforeStartup: false,

How to Query:

curl -X POST \
  http://localhost:62222/graphql \
  -H 'Content-Type: application/json' \
  -H 'x-api-key: APIKEY' \
  -d '{
	"query": "{ hello { world } }"

Note: If you're using API_KEY as your authenticationType, then a x-api-key header has to be present in the request. The value of the key doesn't really matter.

Using DynamoDB Local in your code

You need to add the following parameters to the AWS NODE SDK dynamodb constructor

e.g. for dynamodb document client sdk

var AWS = require('aws-sdk');
new AWS.DynamoDB.DocumentClient({
    region: 'localhost',
    endpoint: 'http://localhost:8000'

e.g. for dynamodb document client sdk

new AWS.DynamoDB({
    region: 'localhost',
    endpoint: 'http://localhost:8000'

Using with serverless-offline plugin

When using this plugin with serverless-offline, it is difficult to use above syntax since the code should use DynamoDB Local for development, and use DynamoDB Online after provisioning in AWS. Therefore we suggest you to use serverless-dynamodb-client plugin in your code.

The serverless appsync-offline start command can be triggered automatically when using serverless-offline plugin.

Add both plugins to your serverless.yml file:

  - serverless-appsync-offline
  - serverless-offline

Make sure that serverless-appsync-offline is above serverless-offline so it will be loaded earlier.

Now your local Appsync and the DynamoDB database will be automatically started before running serverless offline.


SLS_DEBUG=* NODE_DEBUG=appsync-* yarn offline


SLS_DEBUG=* NODE_DEBUG=appsync-* yarn sls appsync-offline start

Using with serverless-offline and serverless-webpack plugin

Run serverless offline start. In comparison with serverless offline, the start command will fire an init and a end lifecycle hook which is needed for serverless-offline and serverless-appsync-offline to switch off both resources.

Add plugins to your serverless.yml file:

  - serverless-webpack
  - serverless-appsync-offline
  - serverless-offline #serverless-offline needs to be last in the list

    # when using serverless-webpack it (by default) outputs all the build assets to `<projectRoot>/.webpack/service`
    # this will let appsync-offline know where to find those compiled files
    buildPrefix: .webpack/service


The AppSync Emulator does not support CloudFormation syntax (e.g. tableName: { Ref: UsersTable }) in dataSources.