BETA: This repository contains a beta version of a new Serverless Framework feature.

Deploy and orchestrate multiple Serverless Framework services in monorepositories.

• Deploy multiple services in parallel
• Deploy dependent services in a specific order
• Share outputs from one service to another
• Run commands across multiple services

name: myapp

services:
  subscriptions:
    path: subscriptions

  users:
    path: users

  ...

You can also check out and deploy the example.

Beta version

This repository contains a beta version of Serverless Framework Compose: a new feature providing multi-service deployments.

While in beta, this feature is in a separate repository and NPM package. Eventually, it will be merged in the main serverless CLI and project.

We use GitHub issues to discuss ideas and features. We encourage you to:

• watch the GitHub repository to be notified of releases and discussions
• get involved in GitHub issues

Installation

While in beta, the feature ships as a separate package and CLI. Install it via NPM:

npm -g i @serverless/compose-beta

The CLI can now be used via the following command:

serverless-compose

or for short:

slsc

Note: while in beta, the feature is available via the serverless-compose command, not the main serverless CLI.

Usage

The multi-service deployment feature is designed for monorepositories.

Assuming you have an application containing multiple Serverless Framework services, for example:

my-app/
  service-a/
    src/
      ...
    serverless.yml
  service-b/
    src/
      ...
    serverless.yml

You can now create a serverless-compose.yml configuration file at the root of your monorepository.

In that new file, you can reference existing Serverless Framework projects by their relative paths:

# Name of the application
name: myapp

services:
  service-a:
    # Relative path to the Serverless Framework service
    path: service-a

  service-b:
    # Relative path to the Serverless Framework service
    path: service-b
    # If the file is not named "serverless.yml" it is possible to configure that:
    # config: serverless.api.yml

To deploy all services, instead of running serverless deploy in each service, you can now deploy all services at once via:

$ serverless-compose deploy

Deploying myapp to stage dev

    ✔  service-a › deployed › 15s
    ✔  service-b › deployed › 31s

⚠️ Warning: The deployment will run serverless deploy in each service directory. If Serverless Framework is installed locally (in node_modules/) in some services, you need to make sure Serverless Framework v3.3.0 or greater is installed.

Service dependencies and variables

Service variables let us:

• order deployments
• inject outputs from one service into another

This is possible via the ${service.output} syntax. For example:

services:
  service-a:
    path: service-a

  service-b:
    path: service-b
    params:
      queueUrl: ${service-a.queueUrl}

Let's break down the example above into 3 steps:

1. ${service-a.queueUrl} will resolve to the queueUrl output of the service-a service.

   The outputs of a Serverless Framework service are resolved from its CloudFormation outputs. Here is how we can expose the queueUrl output in the service-a/serverless.yml config:

   # service-a/serverless.yml
   # ...
   
   resources:
     Resources:
       MyQueue:
         Type: AWS::SQS::Queue
         # ...
     Outputs:
       queueUrl:
         Value: !Ref MyQueue

2. Because of the dependency introduced by the variable, serverless-compose deploy will automatically deploy service-a first, and then service-b.

3. The value will be passed to service-b as a parameter named queueUrl. Parameters can be referenced in Serverless Framework configuration via the ${param:xxx} syntax:

   # service-b/serverless.yml
   provider:
     ...
     environment:
       # Here we inject the queue URL as a Lambda environment variable
       SERVICE_A_QUEUE_URL: ${param:queueUrl}

Cross-services variables are a great way to share API URLs, queue URLs, database table names, and more, without having to hardcode resource names or use SSM.

Alternatively, you can also specify explicit dependencies without passing any variables between services by setting dependsOn to a name of service in configuration. For example:

services:
  service-a:
    path: service-a

  service-b:
    path: service-b
    dependsOn: service-a

  service-c:
    path: service-c

  service-d:
    path: service-d
    dependsOn:
      - service-a
      - service-c

As seen in the above example, it is possible to configure more than one dependency by providing dependsOn as a list.

Global commands

On top of serverless-compose deploy, the following commands can be run globally across all services:

• serverless-compose info to view all services outputs
• serverless-compose remove to remove all services
• serverless-compose refresh-outputs to refresh outputs of all services
• serverless-compose logs to fetch logs from all functions across all services
• serverless-compose outputs to view all services outputs

For example, it is possible to tail logs for all functions at once:

$ serverless-compose logs --tail

service-a › users › START
service-a › users › 2021-12-31 16:54:14  INFO  New user created
service-a › users › END Duration: 13 ms ...
service-b › subscriptions › START
service-b › subscriptions › 2021-12-31 16:54:14  INFO  New subscription enabled
service-b › subscriptions › END Duration: 7 ms ...

    ⠴  service-a › logs › 2s
    ⠦  service-a › logs › 2s

Service-specific commands

It is possible to run commands for a specific service only. For example to deploy only a specific service:

serverless-compose deploy --service=service-a

# Shortcut alternative
serverless-compose service-a:deploy

Or tail logs of a single function:

serverless-compose logs --service=service-a --function=index

# Shortcut alternative
serverless-compose service-a:logs --function=index

All Serverless Framework commands are supported via service-specific commands, including custom commands from plugins.

Service-specific commands when using parameters

The serverless-compose service-a:deploy command is the equivalent of running serverless deploy in service-a's directory. Both approaches can be used.

However, if "service-a" uses ${param:xxx} to reference serverless-compose.yml parameters, then serverless deploy will not work. Indeed, ${param:xxx} cannot be resolved outside of Serverless Framework compose.

In these cases, you must run all commands from the root: serverless-compose service-a:deploy.

Differences with serverless.yml

Unless documented here, expect any serverless.yml feature to not be supported in serverless-compose.yml. For example, it is not possible to include plugins or use serverless.yml variables (like ${env:, ${opt:, etc.) inside serverless-compose.yml.

Feel free to open an issue if you need a feature that isn't supported at the moment.

Refreshing outputs of already deployed services

If you need to refresh outputs of services that you already deployed previously, e.g. from different development machine, you can do it with the following command:

serverless-compose refresh-outputs

Removing services

To delete the whole project (and all its services), run serverless-compose remove. This will run serverless remove in each service.

To delete only one service:

1. run serverless-compose <component>:remove
2. then remove the service from serverless-compose.yml

If you remove the service from serverless-compose.yml without doing step 1 first the service will still be deployed in your AWS account.

Remember to do this for every stage you may have previously deployed.