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Version: v0.2

Advanced Installation

This guide explains how to perform a full manual installation of Furiko, and also serves as a full explainer for the recommended YAML method of installation.

The following walkthrough assumes a sufficient understanding of various Kubernetes concepts and knowledge to administer a Kubernetes cluster. In addition, it also assumes that you have understood the architecture of Furiko and its various components.

Manually Installing Furiko

To start, first download furiko-execution.yaml from the relevant version on the GitHub Releases page.

There are two services that will need to be installed as part of Furiko Execution:

Create Namespace

Create a namespace for Furiko's control plane components. In the YAML, this is furiko-system, which is meant to be shared across all Furiko components.

Install CRDs

Copy and install the CustomResourceDefinition resources specified in the YAML.

The following CRDs will be needed by Furiko Execution:

  • jobconfigs.execution.furiko.io
  • jobs.execution.furiko.io

Setup RBAC

We need to set up RBAC for the execution-controller and execution-webhook services.

  1. Create the correct ClusterRole and Role resources. The RBAC manifests in the YAML can serve as a guide for the minimum permissions needed.
  2. Create ServiceAccount(s) for the two components, and bind the RBAC with ClusterRoleBinding and RoleBinding respectively.

Refer to the YAML for the full list of minimum required permissions.

Build Custom Container Images (optional)

This step can be skipped if you are alright with using the images released on Docker Hub.

If you wish to customize the container image, you can download the binaries directly from the GitHub Releases page to be bundled in your own Docker image.

Setup Deployments

We can set up the Deployment for execution-controller and execution-webhook now. The Deployment manifests in the YAML can serve as a guide for reference.

Bootstrap Configuration

Both execution-controller and execution-webhook requires Bootstrap Configuration loaded from a YAML or JSON file at startup, using the --config command-line flag. For example, this can be loaded via a configMap volume mount. Refer to the following configuration pages for each of the above binaries:

Container Configuration

Use the custom container images from the previous step if you built your own images. You can customize other configuration for the Deployment, including the command, args and securityContext. By default, images on Docker Hub are rootless and thus runAsNonRoot is enabled. If using a custom Docker image you may need to disable it.

The liveness and readiness probes default to the HTTP server at port 8080 for both execution-controller and execution-webhook. To customize the port and paths, refer to the Bootstrap Configuration.

You can also increase or update the resource limits for the containers if needed.

Setup Services

Once created, you can create the corresponding Service resources as well. Only execution-webhook requires a Service, since it will be used as an admission webhook server that extends the Kubernetes API server.

info

The YAML method uses a ClusterIP service type, which requires a Container Network Interface (CNI) network add-on to be installed in your cluster.

It may be possible to run execution-webhook using LoadBalancer, which could potentially route traffic from kube-apiserver to execution-controller over WAN, incurring high latency and greater network instability in general. Another method may be to use hostNetwork and run execution-controller on the same machines as kube-apiserver itself.

Both of the alternative methods mentioned are not officially supported by Furiko.

By default, execution-webhook listens on port 8443 (can be changed via bootstrap configuration). The server listens on HTTPS, which is required in order to be used by the Kubernetes API server for webhooks. Refer to the following section on further HTTPS setup.

Provisioning Webhook Certificates

Traffic between the Kubernetes API server and admission webhook servers must be using HTTPS, so we will need to provision TLS certificates that will be served by execution-webhook.

In the YAML installation method, a Job is used to automatically provision a self-signed certificate (valid for 100 years), store it in a Secret, and patch the webhook configurations with the certificate's public key. This functionality is provided by jet/kube-webhook-certgen, and is the recommended approach taken by Furiko since no external add-ons are required.

Alternative methods include using a static TLS certificate, or utilizing cluster add-ons such as cert-manager.

Setup Webhook Configuration

We can now create webhook configuration resources for execution-webhook. Both ValidatingWebhookConfiguration and MutatingWebhookConfiguration resources will need to be installed. Refer to the YAML for an example.

The webhook server expects to receive webhook requests at well-defined paths, that include the canonical name of the CustomResourceDefinition. For example, to validate a Job, the following path is used:

/validating/jobs.execution.furiko.io

On the other hand, to mutate a JobConfig, the following path is used:

/mutating/jobconfigs.execution.furiko.io

Refer to the official Kubernetes documentation on admission webhooks to manually configure the caBundle of the webhook configuration if needed.

Additional Setup

Prometheus Metrics

All components, including execution-controller and execution-webhook, expose Prometheus metrics that provide insight into the status of the service.

In the YAML installation method, kube-rbac-proxy is used as a sidecar to restrict access to the /metrics endpoint for enhanced security. An additional Service is also created to expose the metrics using ClusterIP.

More information on the setup can be found in the bootstrap configuration.

Customize Dynamic Configuration

Furiko also offers a dynamic configuration mechanism to configure components without requiring a restart. This is typically loaded from a ConfigMap, such that any changes to the configuration can take effect immediately.

More information can be found on the dynamic configuration section of the documentation.