serverless/docs/understanding-serverless/services-and-functions.md

Services

A Serverless service is a group of one or multiple functions and any resources they require. By grouping related functions together, it's easier to share code and resources between those functions. Services are also designed to be completely independent, which helps teams develop more quickly without waiting for others.

Each Serverless service contains two configuration files:

serverless.yaml

• Declares a Serverless service
• Defines one or multiple functions in the service
• Defines the provider the service will be deployed to
• Defines custom plugins to be used
• Defines events that trigger each function to execute (e.g. HTTP requests)
• Defines one set of resources (e.g. 1 AWS CloudFormation stack) required by the functions in this service
• Events listed in the events section may automatically create the resources required for the event upon deployment

serverless.env.yaml

• Defines stages for this service
• Defines regions for each stage
• Defines Serverless variables

Example

Let's take a look at a service example to see how everything works together.

Service Structure

users
  |__ lib                   // contains logic
  |__ users.js              // single handler file, requires lib
  |__ serverless.yaml
  |__ serverless.env.yaml
  |__ node_modules
  |__ package.json

serverless.yaml

service: users
provider: aws
defaults: # overwrite defaults
    memory: ${memoryVariable} # reference a Serverless variable
functions:
    create:
        handler: users.create

serverless.env.yaml

vars:
    memoryVar: 512
stages:
    dev:
        vars:
        regions:
            us-east-1:
                vars: