Browser Controller

Browser Controller is a Kubernetes controller for the Selenosis ecosystem.
It manages Browser and BrowserConfig custom resources and is responsible for creating, monitoring, and cleaning up ephemeral browser Pods.

The controller is designed for deterministic browser provisioning with strict lifecycle management.

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Overview

• Browser — runtime resource representing a single browser instance.
• BrowserConfig — configuration resource defining browser images and pod templates.
• Controller — resolves configuration, creates Pods, tracks their lifecycle, and updates status.

Each Browser resource results in exactly one Pod with the same name.

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What the Controller Does

• Registers Browser and BrowserConfig CRDs
• Reconciles Browser resources into Pods
• Resolves configuration using BrowserConfig (template + overrides)
• Updates Browser.status with runtime information
• Ensures proper cleanup via finalizers
• Exposes health, readiness, and metrics endpoints

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Requirements & RBAC

• Runs inside a Kubernetes cluster (in-cluster config)
• Uses a ServiceAccount with ClusterRole / ClusterRoleBinding
• RBAC manifests are located in config/rbac
• Examples assume the default namespace

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Quickstart

Apply CRDs, RBAC, and deploy the controller:

kubectl apply -f config/crd
kubectl apply -f config/rbac
kubectl apply -f config/controller

BrowserConfig examples config/examples

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Browser CRD

Browser is a namespaced CustomResource that defines a desired browser session (browser type and version) and exposes the actual runtime state of the underlying Kubernetes Pod (phase, IP, container details). It is used by the browser-controller to manage the full lifecycle of browser pods.

API Overview

• Group/Version: selenosis.io/v1 (adjust if your API group differs)
• Kind: Browser
• Scope: Namespaced
• Resource: browsers
• Short name: brw
• Categories: selenosis
• Status subresource: enabled (/status)

The CRD defines additional printer columns for quick inspection:

• Browser: .spec.browserName
• Version: .spec.browserVersion
• Phase: .status.phase
• PodIP: .status.podIP
• StartTime: .status.startTime
• Age: .metadata.creationTimestamp

Example:

kubectl get browsers
kubectl get brw

Spec

spec describes the desired browser configuration:

• browserName (string, required, minLength=1)
  Name of the browser to run (for example: chrome, firefox).

• browserVersion (string, required, minLength=1)
  Browser version to use (for example: 91.0, 120.0, or latest if supported by the controller).

Status

status is populated by the controller and reflects the observed state of the browser pod:

• podIP (string, optional)
  IP address assigned to the pod.

• phase (PodPhase, optional)
  Current lifecycle phase of the pod (Pending, Running, Succeeded, Failed, Unknown).

• message (string, optional)
  Human-readable description of the current condition.

• reason (string, optional)
  Short, machine-friendly reason (for example: Evicted).

• startTime (Time, optional)
  Timestamp when the pod was started.

• containerStatuses (array, optional)
  Detailed status for each container:

  • name — container name
  • state — current container state (Pending, Running, Failed)
  • image — container image
  • restartCount — number of restarts
  • ports — exposed ports (container/host, protocol, name)

Minimal Manifest Example

apiVersion: selenosis.io/v1 
kind: Browser
metadata:
  name: d568aeff-a91a-449b-834b-d79bf2d6d623
  namespace: default
spec:
  browserName: chrome
  browserVersion: "120.0"

Apply and inspect:

kubectl apply -f browser.yaml
kubectl get brw 
kubectl describe brw d568aeff-a91a-449b-834b-d79bf2d6d623
kubectl get brw d568aeff-a91a-449b-834b-d79bf2d6d623 -o yaml

Expected Controller Behavior

• Based on spec.browserName and spec.browserVersion, the controller creates and manages a dedicated browser pod.
• Runtime details (IP, phase, start time, container statuses) are continuously published to .status, allowing UIs and clients to quickly determine browser availability and health.

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BrowserConfig CRD

BrowserConfig is a namespaced CustomResource that defines browser images and pod-level configuration templates used by the browser-controller when creating browser pods.
It allows you to centrally manage defaults (template) and override them per browser name and browser version.

This CRD does not create pods by itself. Instead, it acts as a configuration source consumed by the browser-controller.

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API Overview

• Group/Version: selenosis.io/v1 (adjust if your API group differs)
• Kind: BrowserConfig
• Scope: Namespaced
• Status subresource: enabled (/status)

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Purpose

BrowserConfig provides:

• A global pod template applied to all browsers and versions
• Per-browser and per-version override capabilities
• A deterministic merge strategy (version → browser → template)
• Centralized control over:
  • Browser images
  • Resources
  • Environment variables
  • Volumes and mounts
  • Sidecars and init containers
  • Scheduling and security settings

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Spec

Template

spec.template defines a base pod configuration applied to all browsers and versions unless explicitly overridden.

Supported fields include:

• labels, annotations
• env
• resources
• volumes, volumeMounts
• nodeSelector, affinity, tolerations
• hostAliases
• initContainers
• sidecars
• privileged
• imagePullSecrets
• dnsConfig
• securityContext
• workingDir

All fields are optional.

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Browsers

spec.browsers is a required map that defines browser-specific and version-specific configuration.

Structure:

browsers:
  <browserName>:
    <browserVersion>:
      image: <container-image>
      ...

Example:

browsers:
  chrome:
    "120.0":
      image: selenium/standalone-chrome:120.0
    "121.0":
      image: selenium/standalone-chrome:121.0
  firefox:
    "118.0":
      image: selenium/standalone-firefox:118.0

Each browser version supports the same override fields as the template.

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Merge Semantics

Configuration is merged in the following order (later overrides earlier):

1. Template
2. Browser-level version config
3. Explicit version overrides

Rules:

• nil fields inherit values from the template
• Maps and lists are merged, not replaced
• Sidecars and init containers are merged by name
• Environment variables are merged by variable name

This ensures predictable and reusable configuration without duplication.

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Status

status reflects metadata about the effective configuration:

• version (string) — current configuration version identifier
• lastUpdated (timestamp) — last update time

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Minimal Example

apiVersion: selenosis.io/v1
kind: BrowserConfig
metadata:
  name: default-browser-config
  namespace: default
spec:
  template:
    resources:
      requests:
        cpu: "500m"
        memory: "1Gi"
    env:
      - name: TZ
        value: UTC

  browsers:
    chrome:
      "120.0":
        image: selenium/standalone-chrome:120.0

Apply and inspect:

kubectl apply -f browserconfig.yaml
kubectl get browserconfig -n
kubectl describe browserconfig default-browser-config 
kubectl get browserconfig default-browser-config -o yaml

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Reconciliation Model (Summary)

• BrowserConfig is loaded and cached by the controller
• Browser reconciliation:
  • resolves configuration
  • creates a Pod with the same name
  • tracks Pod lifecycle
  • updates Browser.status
• Pods are non-restarting and treated as ephemeral
• Failures are terminal and reflected in Browser.status

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Build & Generate

This project uses make to generate code, manifests, and build the controller image.

Install tools

make install-tools

Generate code and manifests

make generate
make manifests

Or run everything:

make all

Build and push image

make docker-build
make docker-push

Or combined:

make deploy