generating-ovn-topology

Quick Start - OVN Topology Generation

IMMEDIATE ACTIONS (follow these steps in order):

1. Detect Cluster: Find the OVN-Kubernetes cluster kubeconfig

   Run: scripts/detect-cluster.sh 2>/dev/null

   The script discovers OVN-Kubernetes clusters:

   • Scans all kubeconfig files: current KUBECONFIG env, ~/.kube/kind-config, ~/ovn.conf, ~/.kube/config
   • Tests ALL contexts in each kubeconfig (not just current-context)
   • Returns parseable list to stdout: index|kubeconfig|cluster_name|node_count|namespace
   • Diagnostics go to stderr
   • Exit code: 0=success, 1=no clusters found

   How to handle the output:

   The script returns pipe-delimited lines to stdout, one per cluster found, e.g.:

   1|/home/user/.kube/kind-config|kind-ovn|3|ovn-kubernetes
   2|/home/user/.kube/config|prod-cluster|12|openshift-ovn-kubernetes
   

   Decision logic:

   • If one cluster found → automatically use it (extract kubeconfig path from column 2)
   • If multiple clusters found → show the list to user and ask them to choose by number
   • After selection, extract the kubeconfig path from column 2 of the chosen line
   • Store the selected kubeconfig path in variable KC for use in subsequent steps

   Example output format parsing:

   • Column 1: Index number (for user selection)
   • Column 2: Kubeconfig file path (this is what you need for $KC)
   • Column 3: Cluster display name
   • Column 4: Number of nodes
   • Column 5: OVN namespace name

   Important: Parse the output using standard text processing. The exact implementation is up to you - use whatever approach works best (awk, Python, inline parsing, etc.).

2. Check Permissions: Verify user's Kubernetes access level and inform about write permissions

   Run: scripts/check_permissions.py "$KC"

   The script returns:

   • Exit 0: Read-only access or user confirmed → proceed
   • Exit 1: Error or user cancelled → stop
   • Exit 2: Write permissions detected → AI must ask user for confirmation

   When exit code 2 is returned:

   1. Parse the stdout to get the list of write permissions
   2. Display the permissions clearly to the user using a formatted message
   3. Explain that:
      • This skill performs ONLY read-only operations
      • No cluster modifications will be made
      • The warning is for transparency about their access level
      • List read-only operations: kubectl get, kubectl exec (ovn-nbctl list), local file writes
      • List forbidden operations: kubectl create/delete/patch, ovn-nbctl modifications
   4. Ask the user explicitly: "You have cluster admin permissions. This command will only perform read-only operations. Do you want to proceed?"
   5. If user says yes → continue, if no → stop

   Example of proper user communication:

   ⚠️  WARNING: Write Permissions Detected
   
   Your kubeconfig has cluster admin permissions:
     • Delete pods, deployments, services
     • Create and modify resources
     • Full cluster access
   
   📋 IMPORTANT:
   This command will ONLY perform read-only operations:
     ✅ kubectl get (pods, nodes)
     ✅ kubectl exec (to run read-only ovn-nbctl list commands)
     ✅ Local file writes (topology diagram)
   
   Operations that will NEVER be performed:
     ❌ kubectl create/delete/patch/apply
     ❌ ovn-nbctl modifications
     ❌ Any cluster state changes
   
   Do you want to proceed with read-only topology generation?
   

   Security Note: This step ensures informed consent. The user must be explicitly aware that their cluster admin credentials are accessible to the AI agent (acting on their behalf), even though only read-only operations will be performed. This transparency is critical for security and trust.

3. Check Output File: Ask user if ovn-topology-diagram.md exists:

   • (1) Overwrite, (2) Custom path, (3) Timestamp, (4) Cancel

4. Create Private Temp Directory: Create a private temporary directory using mkdtemp and use it for all temporary files.

   TMPDIR=$(mktemp -d)
   

5. Collect OVN Data: Get full topology data from the cluster

   Run: scripts/collect_ovn_data.py "$KC" "$TMPDIR"

   Detail files written to $TMPDIR:

   • ovn_switches_detail.txt - node|uuid|name|other_config
   • ovn_routers_detail.txt - node|uuid|name|external_ids|options
   • ovn_lsps_detail.txt - node|name|addresses|type|options
   • ovn_lrps_detail.txt - node|name|mac|networks|options
   • ovn_pods_detail.txt - namespace|name|ip|node

6. Analyze Placement: Determine per-node vs cluster-wide components

   Run: scripts/analyze_placement.py "$TMPDIR"

   Placement results written to $TMPDIR:

   • ovn_switch_placement.txt - name|placement (per-node|cluster-wide|cluster-wide-visual)
   • ovn_router_placement.txt - name|placement (per-node|cluster-wide|cluster-wide-visual)

7. Generate Diagram: Create Mermaid graph BT diagram

   • Read $TMPDIR/ovn_switch_placement.txt to determine where each switch goes
   • Read $TMPDIR/ovn_router_placement.txt to determine where each router goes
   • Read detail files directly (ovn_switches_detail.txt, ovn_routers_detail.txt, etc.)
   • Skip UUID column when parsing switches/routers detail files
   • If placement is per-node → put inside node subgraph
   • If placement is cluster-wide or cluster-wide-visual → put outside subgraphs

8. Save & Report: Write diagram to file, show summary, clean up temporary files

CRITICAL RULES:

• ❌ NO codebase searching for IPs/MACs
• ❌ NO synthetic/example data
• ❌ NO inline multi-line bash (use helper scripts)
• ❌ NO direct kubectl commands (must use helper scripts only)
• ✅ Use helper scripts for all kubectl interactions and architecture discovery
• ✅ For helper scripts only: If kubectl is required, use KUBECONFIG="$KC" kubectl --kubeconfig="$KC"
• ✅ SECURITY: Create private temp directory with TMPDIR=$(mktemp -d) - never use /tmp directly
• ✅ Temporary files use $TMPDIR (private directory created with mkdtemp)
• ✅ Clean up temporary files when done: rm -rf "$TMPDIR"

Safety & Security Guarantees

🔒 Read-Only Operations

This skill performs ONLY read-only operations against your Kubernetes cluster. No cluster state is modified.

Allowed Operations:

• ✅ kubectl get - Query resources
• ✅ kubectl exec ... ovn-nbctl list - Query OVN database (read-only)
• ✅ Local file writes (temporary files in $TMPDIR, output diagram)

Forbidden Operations (NEVER used):

• ❌ kubectl create/apply/delete/patch - No resource modifications
• ❌ kubectl scale/drain/cordon - No cluster operations
• ❌ ovn-nbctl create/set/add/remove/destroy - No OVN modifications
• ❌ No pod restarts or service disruptions

Privacy Consideration: The generated diagram contains network topology information. Control sharing based on your organization's security policies and data classification requirements.

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Architecture Concepts

Interconnect Mode (Distributed NBDB)

In interconnect mode, each node runs its own NBDB with local copies of components:

Per-Node Components (different UUIDs on each node):

• ovn_cluster_router - Each node has its own cluster router instance
• join switch - Each node has its own join switch instance
• transit_switch - Each node has its own transit switch instance
• Node switches (e.g., ovn-control-plane, ovn-worker)
• External switches (e.g., ext_ovn-control-plane)
• Gateway routers (e.g., GR_ovn-control-plane)

Visualization Overrides:

• transit_switch: PER-NODE in reality → shown CLUSTER-WIDE for visualization clarity
• join: PER-NODE → kept PER-NODE (no override)

Helper Scripts

All helper scripts are in the scripts/ directory.

Script	Purpose	Input	Output
detect-cluster.sh	Find OVN cluster kubeconfig across all contexts. Scans multiple kubeconfig files and all their contexts. Returns parseable list.	None	Parseable list to stdout: index|kubeconfig|cluster|nodes|namespace. Exit: 0=success, 1=none found
check_permissions.py	Check user permissions and warn if write access detected.	KUBECONFIG path	Exit: 0=proceed, 1=cancelled/error, 2=write perms (needs user confirmation)
collect_ovn_data.py	Data collector: Queries each node for all data, with graceful degradation (continues on node failures). Writes detail files.	KUBECONFIG path, TMPDIR	Detail files: ovn_switches_detail.txt, ovn_routers_detail.txt, ovn_lsps_detail.txt, ovn_lrps_detail.txt, ovn_pods_detail.txt
analyze_placement.py	Placement analyzer: Analyzes UUID patterns from detail files to determine per-node vs cluster-wide placement.	TMPDIR (reads detail files)	Placement files: ovn_switch_placement.txt, ovn_router_placement.txt

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Diagram Generation Rules

Structure

graph BT
    subgraph node1["<b style='color:black'>Node: name (node_ip)</b>"]
        direction BT

        %% LAYER 1 (Bottom): Pods and Management Ports
        POD_example["Pod: pod-name<br/>Namespace: ns<br/>IP: x.x.x.x"]
        MGMT["Management Port: k8s-node<br/>IP: x.x.x.x"]

        %% LAYER 2: Pod LSPs
        LSP_pod["LSP: namespace_pod-name<br/>MAC: xx:xx:xx:xx:xx:xx<br/>IP: x.x.x.x"]
        LSP_mgmt["LSP: k8s-node<br/>MAC: xx:xx:xx:xx:xx:xx<br/>IP: x.x.x.x"]

        %% LAYER 3: Node Switch
        LS_node["Logical Switch: node-name<br/>Subnet: x.x.x.x/24"]

        %% LAYER 4: Node Switch LSPs
        LSP_stor["LSP: stor-node<br/>Type: router"]

        %% LAYER 5: Cluster Router
        LR_cluster["Logical Router: ovn_cluster_router"]
        LRP_rtos["LRP: rtos-node<br/>MAC: xx:xx<br/>IP: x.x.x.x/24"]
        LRP_rtoj["LRP: rtoj-ovn_cluster_router<br/>IP: x.x.x.x/16"]
        LRP_rtots["LRP: rtots-node<br/>IP: x.x.x.x/16"]

        %% LAYER 6: Join Switch
        LS_join["Logical Switch: join"]
        LSP_jtor_cr["LSP: jtor-ovn_cluster_router<br/>Type: router"]
        LSP_jtor_gr["LSP: jtor-GR_node<br/>Type: router"]

        %% LAYER 7: Gateway Router
        LR_gr["Gateway Router: GR_node"]
        LRP_rtoj_gr["LRP: rtoj-GR_node<br/>IP: x.x.x.x/16"]
        LRP_rtoe["LRP: rtoe-GR_node<br/>IP: x.x.x.x/24"]

        %% LAYER 8: External Switch
        LS_ext["Logical Switch: ext_node"]
        LSP_etor["LSP: etor-GR_node<br/>Type: router"]
        LSP_breth0["LSP: breth0_node<br/>Type: localnet"]

        %% LAYER 9 (Top): External Network
        EXT_NET["External Network<br/>Physical bridge: breth0<br/>Node IP: x.x.x.x"]

        %% Connections (bottom-to-top flow)
        POD_example --> LSP_pod --> LS_node
        MGMT --> LSP_mgmt --> LS_node
        LS_node --> LSP_stor
        LSP_stor -.->|peer| LRP_rtos --> LR_cluster
        LR_cluster --> LRP_rtoj -.->|peer| LSP_jtor_cr --> LS_join
        LS_join --> LSP_jtor_gr -.->|peer| LRP_rtoj_gr --> LR_gr
        LR_gr --> LRP_rtoe -.->|peer| LSP_etor --> LS_ext
        LS_ext --> LSP_breth0 -.->|physical| EXT_NET
        LR_cluster --> LRP_rtots
    end

    %% Cluster-wide components (AFTER nodes to appear on top)
    %% Only include components with placement=cluster-wide or cluster-wide-visual
    %% Example: transit_switch in interconnect mode
    LS_cluster_component["Component Name<br/>Details"]

    %% Connections from nodes to cluster-wide components
    LRP_from_node -.->|connects to| LSP_cluster_port --> LS_cluster_component

Key Requirements

1. Graph Direction: Always graph BT (bottom-to-top)

2. Component Placement: Determined by $TMPDIR/ovn_*_placement.txt

   • per-node → INSIDE node subgraph
   • cluster-wide or cluster-wide-visual → OUTSIDE all subgraphs, defined AFTER all node subgraphs
   • CRITICAL: Define ALL cluster-wide components AFTER all nodes to position them at the TOP
     • Prevents connection lines from overlapping with node subgraphs
     • Applies to ANY component with cluster-wide or cluster-wide-visual placement

3. Node Subgraphs: Each physical node gets a subgraph with direction BT

   • Node Ordering: ALWAYS order nodes as: control-plane node first, then worker nodes sorted alphabetically by name
   • Title format: "<b style='color:black'>Node: {node_name} ({external_ip})</b>"
   • Get external IP from rtoe-GR_{node} router port network field
   • Use different background colors for each node for visual distinction
   • CRITICAL: Define components in BOTTOM-TO-TOP order (matches packet flow):
     1. Bottom Layer: Pods and Management Ports (traffic originates here)
     2. Layer 2: Pod LSPs
     3. Layer 3: Node Switch (where pods connect)
     4. Layer 4: Node Switch LSPs (stor, breth0)
     5. Layer 5: Cluster Router + Router Ports (rtos, rtoj, rtots)
     6. Layer 6: Join Switch + Join LSPs
     7. Layer 7: Gateway Router + Router Ports (rtoj, rtoe)
     8. Layer 8: External Switch + External LSPs (etor, breth0)
     9. Top Layer: External Network (physical bridge)

4. Pod Representation:

   • CRITICAL: Show ALL pods from $TMPDIR/ovn_pods_detail.txt as SEPARATE entities
   • DO NOT discover pods from LSPs - many pods (host-network) don't have individual LSPs
   • Pod format: POD_{id}["Pod: {name}<br/>Namespace: {ns}<br/>IP: {ip}"]
   • Connect pods to their respective LSPs:
     • Host-network pods (IP == node IP): POD_{id} --> MGMT_{node} --> LSP_k8s_{node}
     • Pod-network pods (IP in 10.244.x.x): POD_{id} --> LSP_{namespace}_{podname}

5. Physical Network Layer:

   • Show explicit external network entities per node
   • Format: EXT_NET_{node}["External Network<br/>Physical bridge: breth0<br/>Node IP: {external_ip}"]
   • Connect localnet LSPs to external network: LSP_breth0_{node} -.->|physical| EXT_NET_{node}

6. Colors (apply using classDef with color:#000 for black text):

   • Pods: fill:#e8f5e9,stroke:#2e7d32,stroke-width:2px,color:#000
   • Switches: fill:#fff3e0,stroke:#e65100,stroke-width:2px,color:#000
   • Routers: fill:#fff9c4,stroke:#f57f17,stroke-width:2px,color:#000
   • LSPs (ALL types): fill:#e3f2fd,stroke:#1565c0,stroke-width:2px,color:#000
   • LRPs: fill:#f3e5f5,stroke:#6a1b9a,stroke-width:2px,color:#000
   • External Network: fill:#e0e0e0,stroke:#424242,stroke-width:2px,color:#000
   • Management Ports (MGMT entities only, not LSPs): fill:#fff8e1,stroke:#f57c00,stroke-width:2px,color:#000
   • Node Subgraph Backgrounds (use style statements, NOT classDef): Apply at END of diagram after all class assignments. Rotate through these 3 colors:
     • Node 1 (index 0): style node1 fill:#e8f5e9,stroke:#2e7d32,stroke-width:3px,stroke-dasharray: 5 5,color:#000 (green)
     • Node 2 (index 1): style node2 fill:#e1f5fe,stroke:#0277bd,stroke-width:3px,stroke-dasharray: 5 5,color:#000 (blue)
     • Node 3 (index 2): style node3 fill:#fff3e0,stroke:#ef6c00,stroke-width:3px,stroke-dasharray: 5 5,color:#000 (orange)
     • Node 4+ repeats: Use index % 3 to rotate colors (0=green, 1=blue, 2=orange)

7. Required Info:

   • Pods: Name, Namespace, IP
   • Switches: Name, Subnet (from other_config), Gateway (optional)
   • LSPs: Name, MAC, IP (or Type + Router Port for router ports)
   • LRPs: Name, MAC, Network (IP/CIDR)
   • Routers: Name, Description
   • External Network: Physical bridge name (breth0), Node IP

8. Connections:

   • Solid arrows: Layer connections
   • Dashed arrows with |peer|: Peer port relationships

Pod Discovery

CRITICAL: Discover pods from $TMPDIR/ovn_pods_detail.txt, NOT from LSPs

The file $TMPDIR/ovn_pods_detail.txt contains ALL running pods in the cluster (populated by collect_ovn_data.py). Format: namespace|pod_name|pod_ip|node_name

Pod-to-LSP Mapping Logic:

1. Read ALL pods from $TMPDIR/ovn_pods_detail.txt

2. For each pod, determine which LSP it connects to:

   a. Host-Network Pods (pod IP == node IP, e.g., 10.89.0.10):

   • Connect to management port LSP: k8s-{node}
   • These pods share the management port's IP address
   • MUST be included in diagram despite not having individual LSPs

   b. Pod-Network Pods (pod IP in pod network range, e.g., 10.244.x.x):

   • Connect to individual LSP: {namespace}_{pod-name-with-hash}
   • LSP name format: kube-system_coredns-674b8bbfcf-qhfrq
   • Filter LSPs where type="" (empty string)
   • Extract MAC and IP from LSP addresses field

3. Diagram representation:

   POD_id["Pod: {name}<br/>Namespace: {ns}<br/>IP: {ip}"]
   POD_id --> LSP_id
   

Special LSPs (NOT pods, treat as infrastructure):

• k8s-{node}: Management port LSP (multiple host-network pods connect to this)
• stor-{node}: Router port (type="router")
• breth0_{node}: LocalNet port (type="localnet")
• jtor-*, etor-*, tstor-*: Router ports (type="router")

Example: Control Plane Node with Host-Network Pods

%% 8 host-network pods sharing management port
POD_etcd["Pod: etcd-ovn-control-plane<br/>Namespace: kube-system<br/>IP: 10.89.0.10"]
POD_apiserver["Pod: kube-apiserver-ovn-control-plane<br/>Namespace: kube-system<br/>IP: 10.89.0.10"]
POD_controller["Pod: kube-controller-manager-ovn-control-plane<br/>Namespace: kube-system<br/>IP: 10.89.0.10"]
POD_scheduler["Pod: kube-scheduler-ovn-control-plane<br/>Namespace: kube-system<br/>IP: 10.89.0.10"]
POD_ovnkube_cp["Pod: ovnkube-control-plane-ovn-control-plane<br/>Namespace: ovn-kubernetes<br/>IP: 10.89.0.10"]
POD_ovnkube_id["Pod: ovnkube-identity-ovn-control-plane<br/>Namespace: ovn-kubernetes<br/>IP: 10.89.0.10"]
POD_ovnkube_node["Pod: ovnkube-node-xyz<br/>Namespace: ovn-kubernetes<br/>IP: 10.89.0.10"]
POD_ovs_node["Pod: ovs-node-xyz<br/>Namespace: ovn-kubernetes<br/>IP: 10.89.0.10"]

%% Management port LSP (shared by all host-network pods)
MGMT_cp["Management Port: k8s-ovn-control-plane<br/>IP: 10.89.0.10"]
LSP_mgmt["LSP: k8s-ovn-control-plane<br/>MAC: xx:xx:xx:xx:xx:xx<br/>IP: 10.244.0.2"]

%% All host-network pods connect to same management port
POD_etcd --> MGMT_cp
POD_apiserver --> MGMT_cp
POD_controller --> MGMT_cp
POD_scheduler --> MGMT_cp
POD_ovnkube_cp --> MGMT_cp
POD_ovnkube_id --> MGMT_cp
POD_ovnkube_node --> MGMT_cp
POD_ovs_node --> MGMT_cp

MGMT_cp --> LSP_mgmt --> LS_node

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Final Steps

1. Generate complete Mermaid diagram following structure above
2. Save to file chosen by user
3. Show summary: nodes, switches, routers, ports, mode
4. Clean up temporary directory:

   rm -rf "$TMPDIR"
   

5. Tell user to open file in IDE to view rendered diagram