kluster-compare

kluster-compare

Compare Kubernetes resources between two clusters. Interactive TUI or plain CLI output.

Built to debug drift during Pulumi-to-ArgoCD migrations, but works for any cluster-to-cluster comparison.

Install

From source (Go)

go install github.com/ramsrib/kluster-compare@latest

Clone and build

git clone https://github.com/ramsrib/kluster-compare.git
cd kluster-compare
make install

Usage

# Interactive TUI (default)
kluster-compare ctx-a ctx-b

# Non-interactive summary
kluster-compare ctx-a ctx-b -s

# Specific resource diff (kubectl-style)
kluster-compare ctx-a ctx-b deployment/api-deployment -n app-namespace
kluster-compare ctx-a ctx-b namespace/kube-system

# Diff resources with different names on each cluster (left:right)
kluster-compare ctx-a ctx-b hpa/daily-proxy-hpa-a75e5255:daily-proxy-hpa -n app-namespace

# Filter by types or namespaces
kluster-compare ctx-a ctx-b -t deployments,services -n app-namespace

# List available contexts
kluster-compare contexts

# List supported resource types
kluster-compare types

Flags

TUI

Navigation

Resource type list

Resource list

Diff view

Side-by-side diff with color-coded changes. Left column shows the first cluster, right column shows the second.

Resource types

By default, kluster-compare loads 19 built-in K8s resource types for fast startup:

Core: Namespaces, Deployments, Services, DaemonSets, StatefulSets, ConfigMaps, ServiceAccounts

RBAC: ClusterRoles, ClusterRoleBindings, Roles, RoleBindings

Autoscaling: HPA

Policy: PDB, PriorityClasses

Networking: Ingresses, NetworkPolicies, IngressClasses

Batch: Jobs, CronJobs

Press d in the TUI to auto-discover all additional resource types (CRDs) from both clusters. This finds everything installed on either cluster -- Karpenter, KEDA, cert-manager, Gateway API, Prometheus, ArgoCD, and any custom CRDs.

Adding a static resource type

Add one entry to internal/model/registry.go:

{Name: "MyResource", Group: "example.io", Version: "v1", Resource: "myresources", Namespaced: true},

No other code changes needed -- the dynamic client handles everything.

How it works

• Connects to both clusters using kubeconfig contexts
• Fetches resources progressively in parallel via the Kubernetes dynamic client
• Matches resources by exact name first, then fuzzy-matches by stripping hex hash suffixes (e.g. app-19e0eebb-backplane and app-23b5ac0a-backplane are paired automatically)
• Normalizes resources by stripping runtime fields (status, uid, managedFields, etc.) and migration annotations (pulumi.com/*, argocd.argoproj.io/*)
• Computes unified diffs on the normalized YAML
• Presents results in an interactive TUI with side-by-side diff or prints to stdout
• For CLI diff mode, use type/left:right to compare resources with different names

Local development

# Build
make build

# Run
./kluster-compare ctx-a ctx-b

# Run tests
make test

# Format code
make fmt

# Lint (requires golangci-lint)
make lint

# Install to $GOPATH/bin
make install

# Clean build artifacts
make clean

Requirements

• Go 1.21+
• Access to two Kubernetes clusters via kubeconfig