README.md

file-monitor-kube-controller

A Kubernetes controller that monitors file system changes and updates Custom Resource Definitions (CRDs) with file information such as inode, file name, size, and modification time.

Features

• Queries Kubernetes CRDs using the k8s.io/client-go library
• Monitors file system changes in specified paths
• Updates CRD status with file information (inode, name, size, modification time)
• Supports both in-cluster and out-of-cluster configurations
• Namespace-aware file monitoring

Prerequisites

• Go 1.24 or later
• Kubernetes cluster (for deployment)
• kubectl configured to access your cluster

Installation

1. Install the CRD:

   kubectl apply -f filemonitor-crd.yaml

2. Deploy the controller:

   kubectl apply -f deployment.yaml

3. Create a FileMonitor resource:

   kubectl apply -f example-filemonitor.yaml

Usage

Running locally (development)

1. Build the application:

   go build -o file-monitor-controller

2. Run the controller:

   ./file-monitor-controller

Running in Kubernetes

1. Build and push Docker image:

   docker build -t your-registry/file-monitor-controller:latest .
   docker push your-registry/file-monitor-controller:latest

2. Update the deployment image:

   # Edit deployment.yaml to use your image
   kubectl apply -f deployment.yaml

CRD Structure

The FileMonitor CRD has the following structure:

apiVersion: sentinalfs.io/v1
kind: FileMonitor
metadata:
  name: example-file-monitor
  namespace: default
spec:
  path: "/tmp"           # Path to monitor
  namespace: "default"   # Target namespace
status:
  files:                 # Updated by controller
  - name: "example.txt"
    inode: 12345
    size: 1024
    modTime: "2025-01-13T10:00:00Z"
    path: "/tmp/example.txt"
    isDir: false

Controller Functionality

The controller performs the following operations in a continuous loop:

1. Query CRDs: Lists all FileMonitor resources across namespaces
2. Namespace-specific queries: Queries CRDs in specific namespaces
3. File information updates: Updates CRD status with current file information
4. Error handling: Gracefully handles missing CRDs and API errors

Key Functions

• queryCRDs(): Queries all CRDs across all namespaces
• queryCRDsInNamespace(): Queries CRDs in a specific namespace
• updateCRDWithFileInfo(): Updates CRD status with file information
• initKubernetesClients(): Initializes both regular and dynamic K8s clients

Configuration

The controller automatically detects the runtime environment:

• In-cluster: Uses service account credentials
• Local development: Uses kubeconfig from ~/.kube/config

RBAC Permissions

The controller requires the following permissions:

• Get, list, watch, create, update, patch, delete on filemonitors resources
• Get, update, patch on filemonitors/status
• Create, patch on events for logging

Monitoring

The controller logs its operations including:

• CRD discovery and enumeration
• File system monitoring events
• Error conditions and retries
• Status updates

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test thoroughly
5. Submit a pull request