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debug-network

Diagnose OpenShift service connectivity issues including DNS resolution, service endpoints, route ingress, and network policies. Automates multi-step diagnosis: service endpoint verification, pod selector matching, route status, and network policy analysis. Use this skill when services can't communicate, routes return 503/502 errors, or external access fails. Triggers on /debug-network command or phrases like "can't reach service", "route returning 503", "pods can't communicate", "no endpoints".

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SKILL.md
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/debug-network Skill

Diagnose OpenShift service connectivity issues by automatically checking endpoints, routes, network policies, and pod readiness.

Prerequisites

Before running this skill:

  1. User is logged into OpenShift cluster
  2. User has access to the target namespace
  3. Service, Route, or application name is known

When to Use This Skill

Use this skill when services cannot communicate, routes return 503/502 errors, or external access fails. It automates checking service endpoints, pod selector matching, route status, and network policy analysis to pinpoint connectivity issues.

Critical: Human-in-the-Loop Requirements

See Human-in-the-Loop Requirements for mandatory checkpoint behavior.

Workflow

Step 1: Identify Target Service

## Network Debugging

**Current OpenShift Context:**
- Cluster: [cluster]
- Namespace: [namespace]

What connectivity issue would you like me to debug?

1. **Service connectivity** - Internal service-to-service communication
2. **Route/Ingress** - External access to application
3. **Specify service name** - Debug a specific service
4. **List services** - Show services in current namespace

Select an option or enter a service name:

WAIT for user response. Do NOT proceed until user identifies the target.

If user selects "List services": Use kubernetes MCP resources_list for services:

## Services in [namespace]

| Service | Type | Cluster IP | Ports | Endpoints |
|---------|------|------------|-------|-----------|
| [app-service] | ClusterIP | [ip] | [8080/TCP] | [2 ready] |
| [db-service] | ClusterIP | [ip] | [5432/TCP] | [0 - no endpoints!] |
| [api-service] | ClusterIP | [ip] | [3000/TCP] | [1 ready] |

Which service would you like me to debug?

WAIT for user to select a service.

Step 2: Check Service and Endpoints

Use kubernetes MCP resources_get for Service and Endpoints:

## Service Analysis: [service-name]

**Service Configuration:**
| Field | Value |
|-------|-------|
| Type | [ClusterIP/NodePort/LoadBalancer] |
| Cluster IP | [ip] |
| Ports | [port-mappings] |
| Selector | [label-selector] |

**Endpoints:**
| Subset | Addresses | Ports | Status |
|--------|-----------|-------|--------|
| [subset] | [pod-ip-1, pod-ip-2] | [port] | [Ready] |

[If no endpoints:]
**WARNING: Service has NO endpoints!**

This means no pods match the service selector, or matching pods are not ready.

**Service Selector:** `app=[value], tier=[value]`

**Quick Assessment:**
[Based on endpoints status, provide initial assessment]

Continue with pod analysis? (yes/no)

WAIT for user confirmation before proceeding.

Step 3: Verify Backend Pods

Use kubernetes MCP pods_list with label selector matching service:

## Backend Pods for Service: [service-name]

**Service Selector:** `[selector-labels]`

**Matching Pods:**
| Pod | Status | Ready | IP | Node |
|-----|--------|-------|-----|------|
| [pod-1] | Running | 1/1 | [ip] | [node] |
| [pod-2] | Running | 0/1 | [ip] | [node] |
| [pod-3] | CrashLoopBackOff | 0/1 | [ip] | [node] |

**Readiness Analysis:**
| Pod | Readiness Probe | Last Check | Status |
|-----|-----------------|------------|--------|
| [pod-1] | HTTP GET :8080/ | [time] | Passing |
| [pod-2] | HTTP GET :8080/ | [time] | Failing - Connection refused |
| [pod-3] | HTTP GET :8080/ | [time] | Failing - Container not running |

[If selector mismatch:]
**WARNING: Label Mismatch Detected!**

Service selector: `app=myapp`
Pod labels: `app=my-app` (hyphen difference!)

**Issues Found:**
- [Issue 1 - e.g., "Pod [pod-2] failing readiness probe - application not listening on port 8080"]
- [Issue 2 - e.g., "Pod [pod-3] is in CrashLoopBackOff - run /debug-pod for details"]

Continue to check Route? (yes/no/skip)

WAIT for user confirmation before proceeding.

Step 4: Check Route Status

Use kubernetes MCP resources_get for Route:

## Route Analysis: [route-name]

**Route Configuration:**
| Field | Value |
|-------|-------|
| Host | [hostname] |
| Path | [path or "/"] |
| TLS Termination | [edge/passthrough/reencrypt/none] |
| Insecure Policy | [Redirect/Allow/None] |
| Target Service | [service-name] |
| Target Port | [port-name or port-number] |
| Weight | [100] |

**Route Status:**
| Condition | Status | Reason | Message |
|-----------|--------|--------|---------|
| Admitted | [True/False] | [reason] | [message] |

[If not admitted:]
**WARNING: Route NOT admitted by router!**

**Ingress Status:**
| Router | Admitted | Host | Conditions |
|--------|----------|------|------------|
| [default] | [True/False] | [host] | [conditions] |

**TLS Configuration:**
| Setting | Value |
|---------|-------|
| Certificate | [Provided/Default/None] |
| Key | [Provided/None] |
| CA Certificate | [Provided/None] |
| Destination CA | [Provided/None] (for reencrypt) |

**Issues Found:**
- [Issue 1 - e.g., "Route not admitted - hostname conflicts with existing route"]
- [Issue 2 - e.g., "TLS termination is 'passthrough' but backend is HTTP only"]

Continue to check Network Policies? (yes/no/skip)

WAIT for user confirmation before proceeding.

Step 5: Analyze Network Policies

Use kubernetes MCP resources_list for NetworkPolicy:

## Network Policy Analysis

**NetworkPolicies in [namespace]:**
| Policy | Pod Selector | Ingress Rules | Egress Rules |
|--------|--------------|---------------|--------------|
| [policy-1] | app=myapp | [2 rules] | [Allow all] |
| [policy-2] | tier=backend | [1 rule] | [1 rule] |
| [default-deny] | {} (all pods) | [Deny all] | [Allow all] |

**Policies Affecting [service-name] Pods:**

**Policy: [policy-name]**
```yaml
ingress:
- from:
  - podSelector:
      matchLabels:
        app: frontend
  ports:
  - port: 8080
    protocol: TCP

Analysis:

  • Pods with app=myapp only accept traffic from pods with app=frontend
  • Traffic from other namespaces is BLOCKED
  • Traffic on ports other than 8080 is BLOCKED

Potential Blocking:

  • [Issue 1 - e.g., "Source pods have label 'app=web' but policy requires 'app=frontend'"]
  • [Issue 2 - e.g., "Cross-namespace traffic blocked - no namespaceSelector in policy"]

Continue to diagnosis summary? (yes/no)

**WAIT for user confirmation before proceeding.**

### Step 6: Present Diagnosis Summary

```markdown
## Network Diagnosis Summary: [service-name]

### Connectivity Path

[Source] → [Service] → [Endpoints] → [Pod] OK → OK → [STATUS] → [STATUS]

[External] → [Route] → [Router] → [Service] → [Pod] OK → OK → OK → OK → [STATUS]

### Root Cause

**Primary Issue:** [Categorized root cause]

| Component | Status | Details |
|-----------|--------|---------|
| Service | [OK/FAIL] | [details] |
| Endpoints | [OK/FAIL] | [count] ready |
| Pod Readiness | [OK/FAIL] | [X/Y] pods ready |
| Route | [OK/FAIL] | [details] |
| Network Policy | [OK/WARN] | [details] |
| DNS | [OK/FAIL] | [details] |

### Detailed Findings

**[Category 1: e.g., No Endpoints]**
- Problem: [specific problem - e.g., "Service selector doesn't match any pods"]
- Evidence: [selector vs pod labels]
- Impact: [all traffic to service fails]

**[Category 2: e.g., Readiness Probe Failing]**
- Problem: [specific problem]
- Evidence: [probe configuration and failure reason]
- Impact: [pod removed from endpoints]

### Recommended Actions

1. **[Action 1]** - [description]
   ```bash
   [command to fix - e.g., oc label pod myapp-xxx app=myapp --overwrite]

  1. [Action 2] - [description]

    [command to fix - e.g., oc patch svc myapp -p '{"spec":{"selector":{"app":"my-app"}}}']

  2. [Action 3] - [description]

Test Connectivity

After fixing, verify with:

# Test internal connectivity from another pod
oc run test-curl --rm -i --tty --image=curlimages/curl -- \
  curl -v http://[service-name].[namespace].svc.cluster.local:[port]

# Test route externally
curl -v https://[route-host]

# Check endpoints
oc get endpoints [service-name] -n [namespace]

Would you like me to:

  1. Execute one of the recommended fixes
  2. Test connectivity from a debug pod
  3. Debug specific pods (/debug-pod)
  4. Check DNS resolution
  5. Exit debugging

Select an option:

**WAIT for user to select next action.**

## Common Connectivity Issues

For detailed diagnosis and fix tables covering service, route, and network policy issues, see [references/debugging-patterns.md](references/debugging-patterns.md).

## Dependencies

### Required MCP Servers
- `openshift` - Kubernetes/OpenShift resource access for services, routes, endpoints, and network policies

### Related Skills
- `/debug-pod` - To debug specific backend pods
- `/deploy` - To fix and redeploy the service

### Reference Documentation
- [references/debugging-patterns.md](references/debugging-patterns.md) - Common error patterns
- [references/prerequisites.md](references/prerequisites.md) - Required tools (oc), cluster access verification
Repository

RHEcosystemAppEng/agentic-plugins

Path

rh-developer/skills/debug-network/SKILL.md

Revision

df1d156

Last updated
First committed

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