Jolt is a framework for developing, deploying, and maintaining JAMstack applications with serverless functions.

For an in-depth look at JAMstack + Serverless and to learn how we built Jolt, read our whitepaper here.

Table of Contents

• Jolt Commands
• Prerequisites
• Getting Started
• Working With Functions
• Local Development Server
• Deploying
• Updating
• Performing a Rollback
• Teardown

Jolt Commands

Command	Description
jolt init	Initializes an application for use with Jolt: Prompts the user to answer a series of questions about the application. Answers are stored in a local configuration file that Jolt references while running other commands.
jolt dev	Spins up the user’s front end development server + Lambda development server in order to allow the full application to be run locally.
jolt functions	Spins up the Lambda development server by itself.
jolt deploy	Deploys the application on AWS.
jolt update	Builds and deploys the latest version of a previously deployed application. The underlying infrastructure is reused wherever possible.
jolt rollback	Prompts the user to select from a list of versions associated with the current application. Once a version is selected, the front end and Lambdas are reverted to that version.
jolt destroy	Removes an application and all of its associated AWS infrastructure
jolt lambda [function_name]	Creates a Lambda template in the functions folder with the specified function_name

Prerequisites

• AWS Account
• AWS credentials saved locally. Can be done:
  • Via the AWS CLI:
    1. Run aws configure and follow the prompts
  • Manually without AWS CLI
    1. Run the following: mkdir ~/.aws && touch ~/.aws/credentials
    2. Open ~/.aws/credentials and set it up in the following format:

     [default]
     
     aws_access_key_id = [access_key]
     aws_secret_access_key = [secret_access_key]
    

Getting Started

1. Install Jolt

npm i -g jolt-framework

Note: All Jolt commands should be run from the route of the application

Demo: Each "Example" below will guide you through building a simple demo app that interfaces with a single serverless function. Once set up, this app can be deployed with Jolt.

2. Create an application.

Example:

npx create-react-app jolt-first-project
cd jolt-first-project

• Replace the contents of src/App.js with:

function App() {
	fetch(".functions/hello/jolt")
		.then(res => res.json()
			.then(data => alert(JSON.stringify(data))
		)
	)
    
	return <h1>Hello From Jolt!</h1>;
}

export default App;

3. Create the Functions Folder

• This is the directory where serverless functions will be defined

Example:

mkdir functions

4. Initialize the application with Jolt

Example:

jolt init
# For the simple demo app, all of the default options can be used

• Guides you through a series of questions to gather the information Jolt needs to manage and deploy your application

Working With Functions

Creating Serverless Functions

• Define all serverless function files within the functions directory that lives in the root of your application
• Functions are defined as .js files
• The URL path that the function will be deployed at is the relative path the function has within your functions folder
• For instance:
  • To create a function that will become a Lambda at the relative path /hello-jolt define the function in functions/hello-jolt.js
  • To create a function with the relative path /hello/jolt, define the function in functions/hello/jolt.js
• Any environment variables the function needs should be listed in a .env file that lives in the same directory as the function

Invoking Serverless Functions

• Functions can be invoked in your front-end application with the .functions path prefix
• ie: The /hello/jolt function can be invoked with fetch('/.functions/hello/jolt')

Function Templates

• Use jolt lambda [path/to/function/name.js] to automatically create a function and any needed directories inside your functions folder

Example:

jolt lambda hello/jolt

Local Development Server

Example:

jolt dev
# The application can be viewed at `localhost:3000`

1. Spins up a React development server on port 3000
2. Spins up a local Lambda server on port 3001
3. Front-end requests to functions will be proxied to the appropriate Lambda
4. The local Lambda server can also be spun up by itself

Example:

jolt functions

Deploying

• Once you've verified that the application works as intended, it's time to deploy it.

Example:

jolt deploy

• You will be prompted for a description that can be used to identify this version of the application should you need to rollback to it in the future.
• Deployment may take up to 10 minutes to finish propagating to all CDN servers.
• Once the application has finished being deployed, the link to the application on CloudFront will be displayed in the terminal.

Updating

• Under the hood, a different process is used to update the application, but from a user's perspective, updating works just like deployment.

Example:

# For the demo: Add some additional text to `App.js` to see the update take effect.
jolt update

Performing a Rollback

• Reverts the application to a different version
• The selected version can be any version of the application, forwards or backwards.

Example:

jolt rollback

1. Select from a list of all applications deployed with Jolt on the current AWS account
2. Select a version for the chosen application
3. Confirm to begin the rollback (this may take a while)

Teardown

• If you're certain that you no longer want the application, a teardown will deprovision all resources on AWS
• Warning: This is permanent. The application and all prior versions of it will be lost

Example:

jolt teardown