Serverless Framework Services
A service, aka a project, is the Framework's unit of organization.
A service is configured via a
serverless.yml file where you define your functions, the events that trigger them, and the AWS resources to deploy. For example:
service: users provider: # Configuration of the cloud provider name: aws functions: # The functions to deploy usersCreate: events: - httpApi: 'POST /users/create' usersDelete: events: - httpApi: 'DELETE /users/delete' plugins: # Plugins to enable resources: # Additional AWS resources to deploy
To create a new service, run the
serverless command and check out the Getting started guide.
In the beginning of an application, many people use a single service to define all functions, events and resources for that project. This is what we recommend in the beginning.
my-service/ # Contains all functions and infrastructure resources serverless.yml
However, as an application grows, you can break it out into multiple services. A lot of people organize their services by workflows or data models, and group the functions related to those workflows and data models together in the service.
users/ # Contains 4 functions that do Users CRUD operations and the Users database serverless.yml posts/ # Contains 4 functions that do Posts CRUD operations and the Posts database serverless.yml comments/ # Contains 4 functions that do Comments CRUD operations and the Comments database serverless.yml
This makes sense since related functions usually use common infrastructure resources, and you want to keep those functions and resources together as a single unit of deployment, for better organization and separation of concerns.
To orchestrate and deploy multiple services, check out the "Composing services" documentation.
You'll see the following files in your working directory:
service configuration is managed in the
serverless.yml file. The main responsibilities of this file are:
- Declare a serverless service
- Define the cloud provider the service will be deployed to
- Define one or more functions
- Define the events that trigger each function (e.g. HTTP requests)
- Define any plugin to use
- Define a set of AWS resources to create
- Allow events listed in the
eventssection to automatically create the resources required for the event upon deployment
- Allow flexible configuration using variables
You can see the name of the service, the provider configuration and the first function inside the
functions definition which points to the
handler.js file. Any further service configuration will be done in this file.
# serverless.yml service: users provider: name: aws runtime: nodejs14.x stage: dev # Set the default stage used. Default is dev region: us-east-1 # Overwrite the default region used. Default is us-east-1 profile: production # The default profile to use with this service memorySize: 512 # Overwrite the default memory size. Default is 1024 functions: usersCreate: # A function handler: users.create events: # The events that trigger this function - httpApi: 'POST /users/create' usersDelete: # A function handler: users.delete events: # The events that trigger this function - httpApi: 'DELETE /users/delete' # The "Resources" your "Functions" use. Raw AWS CloudFormation goes in here. resources: Resources: usersTable: Type: AWS::DynamoDB::Table Properties: TableName: usersTable AttributeDefinitions: - AttributeName: email AttributeType: S KeySchema: - AttributeName: email KeyType: HASH BillingMode: PAY_PER_REQUEST
When you deploy a service, all functions, events and resources in
serverless.yml are translated to an AWS CloudFormation template and deployed as a single CloudFormation stack.
To deploy a service, run the
deploy command in the same directory as
Deployment defaults to
dev stage and
us-east-1 region on AWS. You can deploy to a different stage or region via CLI options:
serverless deploy --stage prod --region us-east-1
Check out the deployment guide to learn more about deployments and how they work. Or, check out the
deploy command reference to see all the options available.
To easily remove your service from your AWS account, you can use the
serverless remove command.
The removal process will only remove the service on your provider's infrastructure (including all the resources mentioned in
serverless.yml). The service directory will still remain on your local machine, so you can still modify and (re)deploy it to another stage, region or provider later on.
The Serverless Framework is usually installed globally via
npm install -g serverless. This way you have the Serverless CLI available for all your services.
Installing tools globally has the downside that the version can't be pinned inside package.json. This can lead to issues if you upgrade Serverless, but your colleagues or CI system don't. You can now use a new feature in your serverless.yml which is available only in the latest version without worrying that your CI system will deploy with an old version of Serverless.
Pinning a Version
To configure version pinning define a
frameworkVersion property in your serverless.yaml. Whenever you run a Serverless command from the CLI it checks if your current Serverless version is matching the
frameworkVersion range. The CLI uses Semantic Versioning so you can pin it to an exact version or provide a range. In general we recommend to pin to an exact version to ensure everybody in your team has the exact same setup and no unexpected problems happen.
# serverless.yml frameworkVersion: '2.1.0' service: users provider: name: aws runtime: nodejs14.x memorySize: 512 …
# serverless.yml frameworkVersion: "^2.1.0" # >=2.1.0 && <3.0.0 service: users provider: name: aws runtime: nodejs14.x memorySize: 512 …
Installing Serverless in an existing service
If you already have a Serverless service, and would prefer to lock down the framework version using
package.json, then you can install Serverless as follows:
# from within a service npm install serverless --save-dev
Invoking Serverless locally
To execute the locally installed Serverless executable you have to reference the binary out of the node modules directory.
npx serverless deploy
node ./node_modules/serverless/bin/serverless deploy