Screwdriver.CD with Minikube

Prerequisites

Minikube
ksonnet v0.11.0
jsonnet v0.10.0

As a forewarning, this readme assumes your minikube is configured to the default settings.

Usage

In order to deploy

Starting minikube
Connect Screwdriver API with minikube API
Configuring the API secrets
Optional: modify your /etc/hosts file for convenient CNAME use

Starting Minikube

# start minikube if it's not already running
$ minikube start

# enable ingress for a simplified ingress solution
$ minikube addons enable ingress

Connect Screwdriver API with Minikube API

# get the minikube ip
$ minikube ip
192.168.99.xxx

# in the environments/default/params.libsonnet file
...
  components +: {
    api+: {
      k8sHostname: "192.168.99.xxx:8443",
    },
  }
...

Configure Secrets

At a minimum, you will need a JWT private-public key pair and a configured SCM strategy.

These secrets can be created in a secrets.libsonnet file at the root of the repository. As an example, you may review the example.secrets.libsonnet file to see a more concrete example.

JWT Keys

# generating a private jwt private-public pair on a mac

# creates a private key
$ openssl genrsa -out jwt.pem 4096

# creates the related public key
$ openssl rsa -in jwt.pem -pubout -out jwt.pub

# inclue the values in your secrets.libsonnet file
{
    "publicJwtKey": "...",
    "privateJwtKey": "..."
}

SCM Configurations

Depending on the SCM Services, creating an OAuth application will be different. For example, this page describes how to provision one with Github.com

It is highly recommended to read up on the Configuring Screwdriver API documentation.

Here is a sample of what values to include in the secrets.libsonnet file.

# include the values in your secrets.libsonnet file
{
    scmSettings: {
        "scm_strategy_name": {
            plugin: "github",
            config: {
                "oauthClientId": "replace_with_your_oauth_client_id",
                "oauthClientSecret": "replace_with_your_oauth_client_secret",
                "username": "github.com_username",
                "email": "email_address",
                "secret": "secret_for_github.com_webhook_auth",
            }
        },
        "scm_strategy_name_2": {
            ...
        }
    }
}

Optional: Edit /etc/hosts

Although Kubernetes allows you to define a localized DNS server, doing so may be too cumbersome for some to attempt. As an alternative, you may edit your /etc/hosts file so that you can have a similar workflow.

# get the local IP address of minikube
$ minikube ip
192.168.99.xxx

# append the ip address to your /etc/hosts file
$ echo '192.168.99.xxx my.sd api.my.sd' >> /etc/hosts

# open your browser and go to http://my.sd

Deploy

Ensure that your kubectl configuration is pointing to your minikube cluster. Once that's confirmed, you can simly run the ks apply default command.

# deploy it to the minikube cluster
$ ks apply default

Limitations

Minikube runs a single-node Kubernetes cluster inside a VM on your laptop. Since it's an incredibly simplified cluster, it is a great way to get familiar with a Kubernetes environment.

Since it's running a single-node cluster, there are some limitations that should be called out that may not be obvious.

Build Resources

By default, a build will run with a Low CPU/Low Memory resource requirement. As of writing, this requires 2 CPU cores & 2GB of RAM. If your minikube cluster isn't allocated enough resources, builds will not dequeue until the cluster has enough capacity to allow the builds to run.

There are 3 ways to resolving this:

Increase the size of your minikube cluster. This may be difficult if your local workstation does not have the hardware capacity for it.
Explicitly define your builds with a Micro CPU/Micro Memory annotation. See Annotations page for specific details.
Override the default values for K8S_CPU_LOW/K8S_MEMORY_LOW resource definitions. See Executor Plugin section.

FenrirUnbound/minikube-sdcd