Run serverless workloads on Kubernetes using [Knative](https://cloud.google.com/knative/).
## Overview
Knative extends Kubernetes to provide a set of middleware components that are useful to build modern, source-centric, container-based applications. Knative brings some significant benefits out of the box through its main components:
1.**`serverless.yml`** (for [functions only](#deploying-functions)): When using serverless to deploy functions, the `serverless.yml` file
will contain the information for all the functions being hosted in the repository as well as a reference to the
runtime being used.
1.**`Dockerfile`** (for [applications only](#deploying-serverless-applications): Knative requires a `Dockerfile` in order to build your application. It should be included
at the root of your project's repo and expose port `8080`.
You can find all the files referenced in this doc in the [functions example project](https://gitlab.com/knative-examples/functions).
Follow these steps to deploy a function using the Node.js runtime to your Knative instance:
1. Create a directory that will house the function. In this example we will create a directory called `echo` at the root of the project.
1. Create the file that will contain the function code. In this example, our file is called `echo.js` and is located inside the `echo` directory. If your project is:
- Public, continue to the next step.
- Private, you will need to [create a GitLab deploy token](../../deploy_tokens/index.md#creating-a-deploy-token) with `gitlab-deploy-token` as the name and the `read_registry` scope.
such as name, runtime, and environment. It must be included at the root of your repository. The following is a sample `echo` function which shows the required structure for the file. You can find the relevant files for this project in the [functions example project](https://gitlab.com/knative-examples/functions).
| `service` | Name for the Knative service which will serve the function. |
| `description` | A short description of the `service`. |
### `provider`
| Parameter | Description |
|-----------|-------------|
| `name` | Indicates which provider is used to execute the `serverless.yml` file. In this case, the TriggerMesh `tm` CLI. |
| `registry-secret` | Indicates which registry will be used to store docker images. The sample function is using the GitLab Registry (`gitlab-registry`). A different registry host may be specified using `registry` key in the `provider` object. If changing the default, update the permission and the secret value on the `gitlab-ci.yml` file |
| `environment` | Includes the environment variables to be passed as part of function execution for **all** functions in the file, where `FOO` is the variable name and `BAR` are he variable contents. You may replace this with you own variables. |
### `functions`
In the `serverless.yml` example above, the function name is `echo` and the subsequent lines contain the function attributes.
| Parameter | Description |
|-----------|-------------|
| `handler` | The function's file name. In the example above, both the function name and the handler are the same. |
| `runtime` | The runtime to be used to execute the function. |
| `description` | A short description of the function. |
| `buildargs` | Pointer to the function file in the repo. In the sample the function is located in the `echo` directory. |
| `environment` | Sets an environment variable for the specific function only. |
Alternatively, use the CI/CD deployment job output to obtain the deployment URL. Once all the stages of the pipeline finish, click the **deploy** stage.
Using docker image sha256:6b3f6590a9b30bd7aafb9573f047d930c70066e43955b4beb18a1eee175f6de1 for gcr.io/triggermesh/tm@sha256:e3ee74db94d215bd297738d93577481f3e4db38013326c90d57f873df7ab41d5 ...
Running on runner-72989761-project-4342902-concurrent-0 via runner-72989761-stg-srm-1541795796-27929c96...
