Overview
Knative
Prerequisites
Configuring Knative
Supported runtimes
- GitLab-managed runtimes
- OpenFaaS runtimes
Deploying functions
Deploying Serverless applications
Configuring logging
Enabling TLS for Knative services
Using an older version of gitlabktl

Serverless

Introduced in GitLab 11.5.

Serverless is currently in alpha.

Overview

Serverless architectures offer Operators and Developers the ability write highly scalable applications without provisioning a single server.

GitLab supports several ways deploy Serverless applications in both Kubernetes Environments and also major cloud Function as a Service (FaaS) environments.

Currently we support:

Knative: Build Knative applications with Knative and gitlabktl on GKE and EKS.
AWS Lambda: Create serverless applications via the Serverless Framework and GitLab CI/CD.

Knative

Run serverless workloads on Kubernetes using Knative.

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:

Serving: Request-driven compute that can scale to zero.
Eventing: Management and delivery of events.

For more information on Knative, visit the Knative docs repository.

With GitLab Serverless, you can deploy both FaaS and serverless applications.

Prerequisites

To run Knative on GitLab, you need:

Existing GitLab project: You need a GitLab project to associate all resources. The simplest way to get started:
- If you are planning on deploying functions, clone the functions example project to get started.
- If you are planning on deploying a serverless application, clone the sample Knative Ruby App to get started.
Kubernetes Cluster: An RBAC-enabled Kubernetes cluster is required to deploy Knative. The simplest way to get started is to add a cluster using the GitLab GKE integration. The set of minimum recommended cluster specifications to run Knative is 3 nodes, 6 vCPUs, and 22.50 GB memory.
GitLab Runner: A runner is required to run the CI jobs that deploy serverless applications or functions onto your cluster. You can install GitLab Runner onto the existing Kubernetes cluster.
Domain Name: Knative provides its own load balancer using Istio, and an external IP address or hostname for all the applications served by Knative. Enter a wildcard domain to serve your applications. Configure your DNS server to use the external IP address or hostname for that domain.
.gitlab-ci.yml: GitLab uses Kaniko to build the application. We also use GitLab Knative tool CLI to simplify the deployment of services and functions to Knative.
serverless.yml (for functions only): When using serverless to deploy functions, the serverless.yml file contains the information for all the functions being hosted in the repository as well as a reference to the runtime being used.
Dockerfile (for applications only): Knative requires a Dockerfile in order to build your applications. It should be included at the root of your project’s repository and expose port 8080. Dockerfile is not require if you plan to build serverless functions using our runtimes.
Prometheus (optional): The Prometheus cluster integration allows you to monitor the scale and traffic of your serverless function/application.
Logging (optional): Configuring logging allows you to view and search request logs for your serverless function/application. See Configuring logging for more information.

Configuring Knative

Introduced in GitLab 12.0.

Follow the steps to add a Kubernetes cluster.
Ensure GitLab can manage Knative:
- For a non-GitLab managed cluster, ensure that the service account for the token provided can manage resources in the serving.knative.dev API group.
- For a GitLab managed cluster, if you added the cluster in GitLab 12.1 or later, then GitLab already has the required access and you can proceed to the next step.
  Otherwise, you need to manually grant the GitLab service account the ability to manage resources in the serving.knative.dev API group. Since every GitLab service account has the edit cluster role, the simplest way to do this is with an aggregated ClusterRole adding rules to the default edit cluster role: First, save the following YAML as knative-serving-only-role.yaml:
```
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: knative-serving-only-role
  labels:
    rbac.authorization.k8s.io/aggregate-to-edit: "true"
rules:
  - apiGroups:
      - serving.knative.dev
    resources:
      - configurations
      - configurationgenerations
      - routes
      - revisions
      - revisionuids
      - autoscalers
      - services
    verbs:
      - get
      - list
      - create
      - update
      - delete
      - patch
      - watch
```
  Then run the following command:
```
kubectl apply -f knative-serving-only-role.yaml
```
  Alternatively, permissions can be granted on a per-service account basis using Roles and RoleBindings (see the Kubernetes RBAC documentation for more information).
Follow the steps to deploy functions or serverless applications onto your cluster.
Optional: For invocation metrics to show in GitLab, additional Istio metrics need to be configured in your cluster. For example, with Knative v0.9.0, you can use this manifest.

Supported runtimes

Serverless functions for GitLab can be run using:

GitLab-managed runtimes.
OpenFaaS runtimes.

If a runtime is not available for the required programming language, consider deploying a serverless application.

GitLab-managed runtimes

The following GitLab-managed runtimes are available:

go (proof of concept)
nodejs
ruby

You must provide a Dockerfile to run serverless functions if no runtime is specified.

OpenFaaS runtimes

Introduced in GitLab 12.5.

OpenFaaS classic runtimes can be used with GitLab serverless.

OpenFaas runtimes are available for the following languages:

C#
Go
NodeJS
PHP
Python
Ruby

Runtimes are specified using the pattern: openfaas/classic/<template_name>. The following example shows how to define a function in serverless.yml using an OpenFaaS runtime:

hello:
  source: ./hello
  runtime: openfaas/classic/ruby
  description: "Ruby function using OpenFaaS classic runtime"

handler is not needed for OpenFaaS functions. The location of the handler is defined by the conventions of the runtime.

See the ruby-openfaas-function project for an example of a function using an OpenFaaS runtime.

Deploying functions

Introduced in GitLab 11.6.

You can find and import all the files referenced in this doc in the functions example project.

Follow these steps to deploy a function using the Node.js runtime to your Knative instance (you can skip these steps if you’ve cloned the example project):

Create a directory to house the function. In this example we will create a directory called echo at the root of the project.
Create the file to 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 must create a GitLab deploy token with gitlab-deploy-token as the name and the read_registry scope.
.gitlab-ci.yml: this defines a pipeline used to deploy your functions. It must be included at the root of your repository:
```
include:
  - template: Serverless.gitlab-ci.yml

functions:build:
  extends: .serverless:build:functions
  environment: production

functions:deploy:
  extends: .serverless:deploy:functions
  environment: production
```
This .gitlab-ci.yml creates jobs that invoke some predefined commands to build and deploy your functions to your cluster.
Serverless.gitlab-ci.yml is a template that allows customization. You can either import it with include parameter and use extends to customize your jobs, or you can inline the entire template by choosing it from Apply a template dropdown when editing the .gitlab-ci.yml file through the user interface.

serverless.yml: this file contains the metadata for your functions, 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.

service: functions
description: "GitLab Serverless functions using Knative"

provider:
  name: triggermesh
  envs:
    FOO: value
  secrets:
    - my-secrets

functions:
  echo-js:
    handler: echo-js
    source: ./echo-js
    runtime: gitlab/runtimes/nodejs
    description: "node.js runtime function"
    envs:
      MY_FUNCTION: echo-js
    secrets:
      - my-secrets

Explanation of the fields used above:

`service`

Parameter	Description
`service`	Name for the Knative service which serves 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 middleware.
`envs`	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 the variable contents. You may replace this with your own variables.
`secrets`	Includes the contents of the Kubernetes secret as environment variables accessible to be passed as part of function execution for all functions in the file. The secrets are expected in INI format.

`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 name.
`source`	Directory with sources of a functions.
`runtime` (optional)	The runtime to be used to execute the function. This can be a runtime alias (see Runtime aliases), or it can be a full URL to a custom runtime repository. When the runtime is not specified, we assume that `Dockerfile` is present in the function directory specified by `source`.
`description`	A short description of the function.
`envs`	Sets an environment variable for the specific function only.
`secrets`	Includes the contents of the Kubernetes secret as environment variables accessible to be passed as part of function execution for the specific function only. The secrets are expected in INI format.

Deployment

Runtime aliases

The optional runtime parameter can refer to one of the following runtime aliases (also see Supported runtimes):

Runtime alias	Maintained by
`gitlab/runtimes/go`	GitLab
`gitlab/runtimes/nodejs`	GitLab
`gitlab/runtimes/ruby`	GitLab
`openfaas/classic/csharp`	OpenFaaS
`openfaas/classic/go`	OpenFaaS
`openfaas/classic/node`	OpenFaaS
`openfaas/classic/php7`	OpenFaaS
`openfaas/classic/python`	OpenFaaS
`openfaas/classic/python3`	OpenFaaS
`openfaas/classic/ruby`	OpenFaaS

After the gitlab-ci.yml template has been added and the serverless.yml file has been created, pushing a commit to your project results in a CI pipeline being executed which deploys each function as a Knative service. After the deploy stage has finished, additional details for the function display under Infrastructure > Serverless platform.

This page contains all functions available for the project, the description for accessing the function, and, if available, the function’s runtime information. The details are derived from the Knative installation inside each of the project’s Kubernetes cluster. Click on each function to obtain detailed scale and invocation data.

The function details can be retrieved directly from Knative on the cluster:

kubectl -n "$KUBE_NAMESPACE" get services.serving.knative.dev

The sample function can now be triggered from any HTTP client using a simple POST call:

Using curl (replace the URL on the last line with the URL of your application):

curl \
--header "Content-Type: application/json" \
--request POST \
--data '{"GitLab":"FaaS"}' \
"http://functions-echo.functions-1.functions.example.com/"

Using a web-based tool (such as Postman or Restlet)

Secrets

To access your Kubernetes secrets from within your function, the secrets should be created under the namespace of your serverless deployment and specified in your serverless.yml file as above. You can create secrets in several ways. The following sections show some examples.

CLI example

kubectl create secret generic my-secrets -n "$KUBE_NAMESPACE" --from-literal MY_SECRET=imverysecure

Part of deployment job

You can extend your .gitlab-ci.yml to create the secrets during deployment using the CI/CD variables stored securely under your GitLab project.

deploy:function:
  stage: deploy
  environment: production
  extends: .serverless:deploy:functions
  before_script:
    - kubectl create secret generic my-secret
        --from-literal MY_SECRET="$GITLAB_SECRET_VARIABLE"
        --namespace "$KUBE_NAMESPACE"
        --dry-run -o yaml | kubectl apply -f -

Running functions locally

Running a function locally is a good way to quickly verify behavior during development.

Running functions locally requires:

Go 1.12 or newer installed.
Docker Engine installed and running.

gitlabktl installed using the Go package manager:

GO111MODULE=on go get gitlab.com/gitlab-org/gitlabktl

To run a function locally:

Navigate to the root of your GitLab serverless project.
Build your function into a Docker image:
```
gitlabktl serverless build
```

Run your function in Docker:

docker run -itp 8080:8080 <your_function_name>

Invoke your function:
```
curl "http://localhost:8080"
```

Deploying Serverless applications

Introduced in GitLab 11.5.

Serverless applications are an alternative to serverless functions. They’re useful in scenarios where an existing runtime does not meet the needs of an application, such as one written in a language that has no runtime available. Note though that serverless applications should be stateless.

You can reference and import the sample Knative Ruby App to get started. Add the following .gitlab-ci.yml to the root of your repository (you may skip this step if you’ve previously cloned the previously mentioned, sample Knative Ruby App):

include:
  - template: Serverless.gitlab-ci.yml

build:
  extends: .serverless:build:image

deploy:
  extends: .serverless:deploy:image

Serverless.gitlab-ci.yml is a template that allows customization. You can either import it with include parameter and use extends to customize your jobs, or you can inline the entire template by choosing it from Apply a template dropdown when editing the .gitlab-ci.yml file through the user interface.

A serverless.yml file is not required when deploying serverless applications.

Deploy the application with Knative

With all the pieces in place, the next time a CI pipeline runs the Knative application deploys. Navigate to CI/CD > Pipelines and click the most recent pipeline.

Function details

Go to the Infrastructure > Serverless platform page to see the final URL of your functions.

Invocation metrics

On the same page as above, click on one of the function rows to bring up the function details page.

The pod count gives you the number of pods running the serverless function instances on a given cluster.

For the Knative function invocations to appear, the Prometheus cluster integration must be enabled.

Once Prometheus is enabled, a message may appear indicating that the metrics data is loading or is not available at this time. It appears upon the first access of the page, but should go away after a few seconds. If the message does not disappear, then it is possible that GitLab is unable to connect to the Prometheus instance running on the cluster.

Configuring logging

Introduced in GitLab 12.5.

Prerequisites

A GitLab-managed cluster.
kubectl installed and working.

Running kubectl commands on your cluster requires setting up access to the cluster first. For clusters created on:

GKE, see GKE Cluster Access
Other platforms, see Install and Set Up kubectl.

Enable request log template

Run the following command to enable request logs:

kubectl edit cm -n knative-serving config-observability

Copy the logging.request-log-template from the data._example field to the data field one level up in the hierarchy.

Enable request logs

Run the following commands to install Elasticsearch, Kibana, and Filebeat into a kube-logging namespace and configure all nodes to forward logs using Filebeat:

kubectl apply -f https://gitlab.com/gitlab-org/serverless/configurations/knative/raw/v0.7.0/kube-logging-filebeat.yaml
kubectl label nodes --all beta.kubernetes.io/filebeat-ready="true"

Viewing request logs

To view request logs:

Run kubectl proxy.
Navigate to Kibana UI.

Or:

Open the Kibana UI.
Click on Discover, then select filebeat-* from the dropdown on the left.
Enter kubernetes.container.name:"queue-proxy" AND message:/httpRequest/ into the search box.

Enabling TLS for Knative services

By default, a GitLab serverless deployment is served over http. To serve over https, you must manually obtain and install TLS certificates.

The simplest way to accomplish this is to use Certbot to manually obtain Let’s Encrypt certificates. Certbot is a free, open source software tool for automatically using Let’s Encrypt certificates on manually-administered websites to enable HTTPS.

The following instructions relate to installing and running Certbot on a Linux server that has Python 3 installed, and may not work on other operating systems or with other versions of Python.

Install Certbot by running the certbot-auto wrapper script. On the command line of your server, run the following commands:

wget https://dl.eff.org/certbot-auto
sudo mv certbot-auto /usr/local/bin/certbot-auto
sudo chown root /usr/local/bin/certbot-auto
sudo chmod 0755 /usr/local/bin/certbot-auto
/usr/local/bin/certbot-auto --help

To check the integrity of the certbot-auto script, run:

wget -N https://dl.eff.org/certbot-auto.asc
gpg2 --keyserver ipv4.pool.sks-keyservers.net --recv-key A2CFB51FA275A7286234E7B24D17C995CD9775F2
gpg2 --trusted-key 4D17C995CD9775F2 --verify certbot-auto.asc /usr/local/bin/certbot-auto

The output of the last command should look something like:

gpg: Signature made Mon 10 Jun 2019 06:24:40 PM EDT
gpg:                using RSA key A2CFB51FA275A7286234E7B24D17C995CD9775F2
gpg: key 4D17C995CD9775F2 marked as ultimately trusted
gpg: checking the trustdb
gpg: marginals needed: 3  completes needed: 1  trust model: pgp
gpg: depth: 0  valid:   1  signed:   0  trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: next trustdb check due at 2027-11-22
gpg: Good signature from "Let's Encrypt Client Team <letsencrypt-client@eff.org>" [ultimate]

Run the following command to use Certbot to request a certificate using DNS challenge during authorization:

/usr/local/bin/certbot-auto certonly --manual --preferred-challenges dns -d '*.<namespace>.example.com'

Where <namespace> is the namespace created by GitLab for your serverless project (composed of <project_name>-<project_id>-<environment>) and example.com is the domain being used for your project. If you are unsure what the namespace of your project is, navigate to the Infrastructure > Serverless platform page of your project and inspect the endpoint provided for your function/app.

In the above image, the namespace for the project is node-function-11909507 and the domain is knative.info, thus certificate request line would look like this:

./certbot-auto certonly --manual --preferred-challenges dns -d '*.node-function-11909507.knative.info'

The Certbot tool walks you through the steps of validating that you own each domain that you specify by creating TXT records in those domains. After this process is complete, the output should look something like this:

IMPORTANT NOTES:
- Congratulations! Your certificate and chain have been saved at:
  /etc/letsencrypt/live/namespace.example.com/fullchain.pem
  Your key file has been saved at:
  /etc/letsencrypt/live/namespace.example/privkey.pem
  Your cert will expire on 2019-09-19. To obtain a new or tweaked
  version of this certificate in the future, simply run certbot-auto
  again. To non-interactively renew *all* of your certificates, run
  "certbot-auto renew"
-----BEGIN PRIVATE KEY-----
- Your account credentials have been saved in your Certbot
  configuration directory at /etc/letsencrypt. You should make a
  secure backup of this folder now. This configuration directory will
  also contain certificates and private keys obtained by Certbot so
  making regular backups of this folder is ideal.

Create certificate and private key files. Using the contents of the files returned by Certbot, create two files in order to create the Kubernetes secret:

Run the following command to see the contents of fullchain.pem:

sudo cat /etc/letsencrypt/live/node-function-11909507.knative.info/fullchain.pem

Output should look like this:

Create a file with the name cert.pem with the contents of the entire output.

Once cert.pem is created, run the following command to see the contents of privkey.pem:

sudo cat /etc/letsencrypt/live/namespace.example/privkey.pem

Output should look like this:

Create a new file with the name cert.pk with the contents of the entire output.

Create a Kubernetes secret to hold your TLS certificate, cert.pem, and the private key cert.pk:
Running kubectl commands on your cluster requires setting up access to the cluster first. For clusters created on GKE, see GKE Cluster Access. For other platforms, install kubectl.
```
kubectl create --namespace istio-system secret tls istio-ingressgateway-certs \
--key cert.pk \
--cert cert.pem
```
Where cert.pem and cert.pk are your certificate and private key files. Note that the istio-ingressgateway-certs secret name is required.

Configure Knative to use the new secret that you created for HTTPS connections. Run the following command to open the Knative shared gateway in edit mode:

kubectl edit gateway knative-ingress-gateway --namespace knative-serving

Update the gateway to include the following tls: section and configuration:

tls:
  mode: SIMPLE
  privateKey: /etc/istio/ingressgateway-certs/tls.key
  serverCertificate: /etc/istio/ingressgateway-certs/tls.crt

Example:

apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  # ... skipped ...
spec:
  selector:
    istio: ingressgateway
  servers:
    - hosts:
        - "*"
      port:
        name: http
        number: 80
        protocol: HTTP
    - hosts:
        - "*"
      port:
        name: https
        number: 443
        protocol: HTTPS
      tls:
        mode: SIMPLE
        privateKey: /etc/istio/ingressgateway-certs/tls.key
        serverCertificate: /etc/istio/ingressgateway-certs/tls.crt

After your changes are running on your Knative cluster, you can begin using the HTTPS protocol for secure access your deployed Knative services. In the event a mistake is made during this process and you need to update the cert, you must edit the gateway knative-ingress-gateway to switch back to PASSTHROUGH mode. Once corrections are made, edit the file again so the gateway uses the new certificates.

Using an older version of `gitlabktl`

There may be situations where you want to run an older version of gitlabktl. This requires setting an older version of the gitlabktl image in the .gitlab-ci.yml file.

To set an older version, add image: to the functions:deploy block. For example:

functions:deploy:
  extends: .serverless:deploy:functions
  environment: production
  image: registry.gitlab.com/gitlab-org/gitlabktl:0.5.0

Different versions are available by changing the version tag at the end of the registry URL in the format registry.gitlab.com/gitlab-org/gitlabktl:<version>.

For a full inventory of available gitlabktl versions, see the gitlabktl project’s container registry.

Serverless

Overview

Knative

Prerequisites

Configuring Knative

Supported runtimes

GitLab-managed runtimes

OpenFaaS runtimes

Deploying functions

service

provider

functions

Deployment

Runtime aliases

Secrets

CLI example

Part of deployment job

Running functions locally

Deploying Serverless applications

Deploy the application with Knative

Function details

Invocation metrics

Configuring logging

Prerequisites

Enable request log template

Enable request logs

Viewing request logs

Enabling TLS for Knative services

Using an older version of gitlabktl

`service`

`provider`

`functions`

Using an older version of `gitlabktl`