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Merge pull request #2623 from danielmellado/add_debug_flag
MON-4318: Add debug image manifest to CMO
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‎Documentation/debug-container.md‎

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# Debug Container for Cluster Monitoring Operator
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## Overview
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The Cluster Monitoring Operator (CMO) supports an optional debug container that can be deployed as a sidecar alongside the main operator. This debug container provides additional tooling capabilities for troubleshooting monitoring stack issues without requiring separate pod deployments or complex debugging setups.
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## Enabling the Debug Container
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### For Existing Clusters (Immediate Use)
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Create a patch file to add the debug container to the running deployment:
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```bash
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# Create debug container patch
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cat > debug-enable-patch.yaml << 'EOF'
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spec:
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template:
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spec:
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containers:
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- name: debug-tools
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image: registry.redhat.io/ubi9/ubi:latest
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command: ["/bin/bash", "-c", "dnf swap -y libcurl-minimal libcurl && sleep infinity"]
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resources:
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requests:
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cpu: 10m
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memory: 32Mi
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limits:
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cpu: 50m
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memory: 128Mi
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securityContext:
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allowPrivilegeEscalation: false
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capabilities:
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drop: ["ALL"]
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runAsNonRoot: true
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terminationMessagePolicy: FallbackToLogsOnError
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EOF
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# Apply the patch
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kubectl patch deployment cluster-monitoring-operator \
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-n openshift-monitoring \
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--patch-file debug-enable-patch.yaml
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# Verify the rollout
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kubectl rollout status deployment/cluster-monitoring-operator -n openshift-monitoring
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```
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### Option 2: Edit Deployment Directly
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```bash
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# Edit the deployment manifest
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kubectl edit deployment cluster-monitoring-operator -n openshift-monitoring
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# Find the commented debug container section and uncomment it:
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# Look for the section starting with "# DEBUG TOOLS SIDECAR (OPTIONAL)"
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# Remove the '#' from the container definition lines
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```
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## Using the Debug Container
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### Basic Access
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Once enabled, access the debug container using kubectl exec:
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```bash
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# Access the debug container
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kubectl exec -n openshift-monitoring \
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deployment/cluster-monitoring-operator \
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-c debug-tools -- /bin/bash
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# Or target a specific pod
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kubectl exec -n openshift-monitoring \
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pod/cluster-monitoring-operator-xyz \
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-c debug-tools -- /bin/bash
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```
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## Common Use Cases and Examples
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### 1. Network Connectivity Testing
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```bash
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# Exec into debug container
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kubectl exec -n openshift-monitoring deployment/cluster-monitoring-operator -c debug-tools -- /bin/bash
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# Test connectivity to Prometheus
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curl -I http://prometheus-k8s.openshift-monitoring:9090/metrics
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# Test connectivity to Alertmanager
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curl -I http://alertmanager-main.openshift-monitoring:9093/api/v1/status
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# DNS resolution testing
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nslookup prometheus-k8s.openshift-monitoring
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nslookup alertmanager-main.openshift-monitoring
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# Network port testing (if netcat is available)
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nc -zv prometheus-k8s.openshift-monitoring 9090
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```
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### 2. Kubernetes API Debugging
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```bash
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# Use the mounted service account token
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TOKEN=$(cat /var/run/secrets/kubernetes.io/serviceaccount/token)
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CA_CERT=/var/run/secrets/kubernetes.io/serviceaccount/ca.crt
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# Test API access with same permissions as operator
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curl -H "Authorization: Bearer $TOKEN" \
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--cacert $CA_CERT \
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https://kubernetes.default.svc/api/v1/namespaces/openshift-monitoring/pods
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# Check RBAC permissions
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curl -H "Authorization: Bearer $TOKEN" \
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--cacert $CA_CERT \
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https://kubernetes.default.svc/apis/authorization.k8s.io/v1/selfsubjectaccessreviews \
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-X POST -H "Content-Type: application/json" -d '{
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"kind": "SelfSubjectAccessReview",
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"apiVersion": "authorization.k8s.io/v1",
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"spec": {
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"resourceAttributes": {
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"namespace": "openshift-monitoring",
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"verb": "get",
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"resource": "pods"
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}
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}
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}'
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```
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### 3. Resource and Environment Investigation
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```bash
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# Check process information
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ps aux
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# Monitor resource usage
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top
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# Check mounted volumes
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mount | grep -E "(configmap|secret)"
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# Examine environment variables
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env | sort
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# Check disk usage
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df -h
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# Network interface information
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ip addr show
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# Process network connections
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ss -tuln
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```
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### 4. Configuration Analysis
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```bash
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# Examine mounted ConfigMaps
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find /etc -name "*.yaml" -o -name "*.yml" | head -10
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cat /etc/cluster-monitoring-operator/telemetry/metrics.yaml
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# Check mounted secrets
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ls -la /etc/ssl/certs/
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ls -la /var/run/secrets/
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# Validate configuration files
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find /etc -type f -exec file {} \; | grep -i yaml
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```
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### 5. Log Analysis
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```bash
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# Check operator logs from inside the pod
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# (Note: This shows logs from the main container, not the debug container)
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tail -f /proc/1/fd/1
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# Or check specific log files if they exist
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find /var/log -type f 2>/dev/null
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```
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## Custom Debug Images
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For enhanced debugging capabilities, you can create a custom debug image with additional tools:
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### Creating a Custom Debug Image
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```dockerfile
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# Example Dockerfile for custom debug image
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FROM registry.redhat.io/ubi9/ubi:latest
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# Install common debugging tools and swap to full curl
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RUN dnf update -y && \
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dnf swap -y libcurl-minimal libcurl && \
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dnf install -y \
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wget \
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bind-utils \
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procps-ng \
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&& dnf clean all
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USER 1001
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CMD ["/bin/sleep", "infinity"]
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```
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### Using a Custom Image
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Update the image reference in your debug container patch:
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```yaml
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spec:
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template:
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spec:
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containers:
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- name: debug-tools
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image: quay.io/your-org/debug-tools:latest # Your custom image
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command: ["/bin/sleep", "infinity"]
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# ... rest of container spec
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```
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## Security Considerations
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The debug container runs with a restricted security context:
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- **No privilege escalation** - `allowPrivilegeEscalation: false`
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- **Dropped capabilities** - All Linux capabilities are dropped
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- **Non-root user** - Runs as non-root user (UID 1001)
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- **Same permissions** - Uses the same ServiceAccount as the operator
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- **Network isolation** - Shares the pod network namespace
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## Troubleshooting
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### Debug Container Won't Start
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```bash
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# Check pod events
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kubectl describe pod -n openshift-monitoring -l app.kubernetes.io/name=cluster-monitoring-operator
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# Check container status
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kubectl get pods -n openshift-monitoring -l app.kubernetes.io/name=cluster-monitoring-operator -o jsonpath='{.items[0].status.containerStatuses}'
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# Verify image pull
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kubectl get events -n openshift-monitoring --field-selector reason=Failed
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```
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### Cannot Access Debug Container
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```bash
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# Verify container is running
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kubectl get pods -n openshift-monitoring -l app.kubernetes.io/name=cluster-monitoring-operator
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# Check if debug container exists
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kubectl get pods -n openshift-monitoring -l app.kubernetes.io/name=cluster-monitoring-operator -o jsonpath='{.items[0].spec.containers[*].name}'
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# Try accessing by pod name instead of deployment
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kubectl get pods -n openshift-monitoring -l app.kubernetes.io/name=cluster-monitoring-operator
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kubectl exec -n openshift-monitoring pod/cluster-monitoring-operator-abc123 -c debug-tools -- /bin/bash
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```

‎manifests/0000_50_cluster-monitoring-operator_05-deployment.yaml‎

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- mountPath: /etc/cluster-monitoring-operator/telemetry
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name: telemetry-config
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readOnly: true
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# DEBUG TOOLS SIDECAR (OPTIONAL)
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# Uncomment the debug-tools container below to enable debugging capabilities
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#
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# To enable:
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# 1. Uncomment the debug-tools container below
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# 2. Replace the image with your debug tools image (optional - UBI minimal works)
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# 3. Apply the updated deployment
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#
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# Usage: kubectl exec -n openshift-monitoring deployment/cluster-monitoring-operator -c debug-tools -- /bin/bash
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#
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# - name: debug-tools
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# # TODO: Replace with your debug tools image at quay.io/openshift/[debug-image-name]:latest
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# # UBI9 includes dnf and more packages. Can upgrade curl and install debugging tools.
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# image: registry.redhat.io/ubi9/ubi:latest # Full UBI9 with dnf package manager
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# command: ["/bin/bash", "-c", "dnf swap -y libcurl-minimal libcurl && sleep infinity"]
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# resources:
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# requests:
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# cpu: 10m
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# memory: 32Mi
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# limits:
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# cpu: 50m
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# memory: 128Mi
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# securityContext:
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# allowPrivilegeEscalation: false
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# capabilities:
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# drop: ["ALL"]
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# runAsNonRoot: true
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# terminationMessagePolicy: FallbackToLogsOnError

‎manifests/image-references‎

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from:
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kind: DockerImage
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name: quay.io/openshift/origin-monitoring-plugin:latest
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- name: kube-metrics-server
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from:
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kind: DockerImage

‎pkg/manifests/config.go‎

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TelemeterClient string
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Thanos string
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MonitoringPlugin string
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DebugTools string
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}
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type HTTPConfig struct {
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c.Images.OpenShiftStateMetrics = images["openshift-state-metrics"]
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c.Images.Thanos = images["thanos"]
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c.Images.MonitoringPlugin = images["monitoring-plugin"]
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c.Images.DebugTools = images["debug-tools"]
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}
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func (c *Config) SetTelemetryMatches(matches []string) {

‎pkg/operator/operator.go‎

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configMapName: configMapName,
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userWorkloadConfigMapName: userWorkloadConfigMapName,
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remoteWrite: remoteWrite,
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CollectionProfilesEnabled: false,
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namespace: namespace,
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namespaceUserWorkload: namespaceUserWorkload,
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client: c,

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