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CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+This is the OpenShift Dedicated Custom Domain Operator, a Kubernetes operator that creates custom ingress controllers with TLS certificates for custom domains. The operator watches for `CustomDomain` custom resources and creates corresponding `IngressController` resources in the `openshift-ingress-operator` namespace.
+
+**Key Architecture Pattern**: CustomDomain CR → IngressController → Router pods
+- Custom resources are cluster-scoped and trigger the creation of ingress controllers
+- The operator creates managed ingress controllers with custom certificates
+- External DNS can create CNAME records pointing to the custom domain endpoints
+
+## Development Commands
+
+### Building and Testing
+```bash
+# Build the operator binary
+make go-build
+
+# Run unit tests
+make go-test
+
+# Run unit tests with coverage for customdomain controller specifically
+go test ./controller/ -coverprofile /tmp/cp.out && go tool cover -html /tmp/cp.out
+
+# Run linting and static analysis
+make go-check
+
+# Generate CRDs and manifests
+make generate
+
+# Validate that generated files are up-to-date
+make generate-check
+
+# Run all checks (lint + test + build)
+make default
+```
+
+### Container Operations
+```bash
+# Build container image
+make docker-build
+
+# Build and push container image (requires REGISTRY_USER and REGISTRY_TOKEN)
+make docker-push
+
+# Build and push in one step
+make build-push
+```
+
+### Local Development
+```bash
+# Apply CRDs to cluster
+oc apply -f deploy/crds/managed.openshift.io_customdomains_crd.yaml
+
+# Run operator locally (outside cluster)
+operator-sdk run --local --namespace ''
+
+# Deploy to cluster
+oc apply -f deploy/
+```
+
+## Code Architecture
+
+### Core Components
+
+- **`api/v1alpha1/`**: Custom Resource Definitions
+  - `customdomain_types.go`: Defines the CustomDomain CRD spec and status
+  - Key types: `CustomDomainSpec`, `CustomDomainStatus`, `CustomDomainCondition`
+
+- **`controller/`**: Controller logic
+  - `customdomain_controller.go`: Main reconciliation logic for CustomDomain resources
+  - `customdomain_utils.go`: Utility functions for controller operations
+  - Uses controller-runtime pattern with Reconcile() method
+
+- **`main.go`**: Operator entry point
+  - Sets up manager, registers schemes, and starts controller
+
+### Key Constants and Validation
+- Restricted ingress names: `["default", "apps2", "apps"]`
+- Valid object names must match DNS-1035 label format: `^[a-z]([-a-z0-9]*[a-z0-9])?$`
+- Default scope: "External" (can be "Internal")
+- Supports AWS load balancer types: "Classic" and "NLB"
+
+### Important Namespaces
+- `openshift-ingress`: Where router pods are created
+- `openshift-ingress-operator`: Where IngressController resources are managed
+- Custom domain operator typically runs in `openshift-custom-domains-operator`
+
+## Build System
+
+This project uses a sophisticated build system based on boilerplate makefiles:
+
+- **Main Makefile**: Includes boilerplate and delegates to generated targets
+- **Boilerplate system**: Provides standardized targets via `boilerplate/generated-includes.mk`
+- **FIPS support**: Enabled by default (`FIPS_ENABLED=true`)
+- **Konflux builds**: Enabled for CI/CD integration
+
+### Environment Variables
+- `FIPS_ENABLED=true`: Enables FIPS mode with `GOEXPERIMENT=boringcrypto`
+- `ALLOW_DIRTY_CHECKOUT=false`: Prevents building with uncommitted changes
+- `GOLANGCI_LINT_CACHE=/tmp/golangci-cache`: Lint cache directory
+
+## Testing Strategy
+
+### Unit Testing
+- Tests located in `controller/` alongside source files
+- Use `make go-test` for standard testing
+- Coverage reports available with `go tool cover`
+
+### E2E Testing
+- E2E tests in `test/e2e/` directory
+- Integration with osde2e framework for OpenShift testing
+- See `TESTING.md` for detailed testing procedures
+
+### Live Testing Requirements
+- Requires SRE setup with elevated privileges
+- Need valid TLS certificates (can use Let's Encrypt for wildcards)
+- External DNS configuration for CNAME records
+
+## Deprecation Notice
+
+On OSD/ROSA clusters > v4.14 (or v4.13 with legacy ingress support flag), this operator transitions CustomDomain objects to native OpenShift IngressController resources. The operator maintains backward compatibility during this transition.