serverless/docs/providers/knative/guide/services.md

Serverless Framework - Build web, mobile and IoT applications with serverless architectures using AWS Lambda, Azure Functions, Google CloudFunctions & more

<!--
title: Knative - Knative - Services | Serverless Framework
menuText: Services
menuOrder: 5
description: How to manage and configure Serverless services, which contain your Knative Serving services and their events
layout: Doc
-->

<!-- DOCS-SITE-LINK:START automatically generated  -->

### [Read this on the main serverless docs site](https://www.serverless.com/framework/docs/providers/knative/guide/services/)

<!-- DOCS-SITE-LINK:END -->

# Knative - Services

A `service` is like a project. It's where you define your [Knative Serving](https://knative.dev/docs/serving) services and the `events` that trigger them, all in a file called `serverless.yml`.

To get started building your first Serverless Framework project, create a `service`.

## Organization

In the beginning of an application, many people use a single service to define all of the functions and events for that project. This is what we recommend in the beginning.

```bash
myService/
  serverless.yml  # Contains all functions and infrastructure resources
```

However, as your 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.

```bash
users/
  serverless.yml # Contains 4 functions that do Users CRUD operations and the Users database
posts/
  serverless.yml # Contains 4 functions that do Posts CRUD operations and the Posts database
comments/
  serverless.yml # Contains 4 functions that do Comments CRUD operations and the Comments database
```

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.

## Creation

To create a service, use the `create` command. You can also pass in a path to create a directory and auto-name your service:

```bash
# Create service with Node.js template in the folder ./my-service
serverless create --template knative-docker --path my-service
```

Here are the available runtimes for Knative:

- knative-docker

Check out the [create command docs](../cli-reference/create) for all the details and options.

## Contents

You'll see the following files in your working directory:

- `serverless.yml`
- `code/hello-world.dockerfile`
- `code/app.py`

### serverless.yml

Each `service` configuration is managed in the `serverless.yml` file. The main responsibilities of this file are:

- Declare a Serverless service
- Define one or more functions in the service
  - Define the provider the service will be deployed to
  - Define any custom plugins to be used
  - Define events that trigger each function to execute (e.g. custom events)
  - Allow events listed in the `events` section to automatically create the resources required for the event upon deployment
  - Allow flexible configuration using Serverless Variables

You can see the name of the service, the provider configuration and the first function inside the `functions` definition. Any further service configuration will be done in this file.

```yaml
service: my-service # service name

provider: # provider information
  name: knative

plugins:
  - serverless-knative

functions:
  functionOne:
    handler: function-one.dockerfile
    events:
      - cron:
          schedule: '* * * * *'
          data: '{"message": "Hello world from a Cron event source!"}'
```

### hello-world.dockerfile

The `hello-world.dockerfile` contains the container image description which defines how the service is containerized.

### app.py

The `app.py` file contains an example Python service which exposes an HTTP server and is therefore deployable as a [Knative Serving](https://knative.dev/docs/serving) service.

## Deployment

When you deploy a service, all of the functions and events in your `serverless.yml` are translated into calls to the Kubernetes API to dynamically define those resources.

To deploy a service, use the `deploy` command:

```bash
serverless deploy
```

Check out the [deployment guide](./deploying.md) to learn more about deployments and how they work. Or, check out the [deploy command docs](../cli-reference/deploy.md) for all the details and options.

## Removal

To easily remove your service from Knative, you can use the `remove` command.

Run `serverless remove` to trigger the removal process.

Serverless will start the removal and informs you about it's process on the console. A success message is printed once the whole service is removed.

The removal process will only remove the service on your Knative installation and optionally the Docker image on your local machine. The service directory will still remain on your local machine so you can still modify and (re)deploy it to another stage later on.

## Version Pinning

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 use a feature in your `serverless.yml` 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](http://semver.org/) 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.

### Examples

#### Exact Version

```yaml
frameworkVersion: '2.1.0'
```

#### Version Range

```yaml
frameworkVersion: ^2.1.0 # >=2.1.0 && <3.0.0
```

## 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:

```bash
# from within a service
npm install serverless --save-dev
```