managing-linkerd-deep

name	managing-linkerd-deep
description	Use when working with Linkerd Deep — advanced Linkerd service mesh management covering proxy diagnostics, multi-cluster linking, policy resources, HTTPRoute configuration, server authorization, retry budgets, and advanced observability. Use for deep Linkerd troubleshooting, multi-cluster traffic management, policy-based authorization, or advanced proxy debugging.
connection_type	linkerd
preload	false

Linkerd Deep Skill

Advanced Linkerd management including proxy diagnostics, multi-cluster, policy resources, and HTTPRoute configuration.

Core Helper Functions

#!/bin/bash

linkerd_cmd() {
    linkerd "$@" 2>/dev/null
}

linkerd_get() {
    local resource="$1" ns="${2:---all-namespaces}"
    if [ "$ns" = "--all-namespaces" ]; then
        kubectl get "$resource" -A -o json 2>/dev/null
    else
        kubectl get "$resource" -n "$ns" -o json 2>/dev/null
    fi
}

MANDATORY: Discovery-First Pattern

Phase 1: Discovery

#!/bin/bash

echo "=== Linkerd Version & Channel ==="
linkerd version 2>/dev/null
linkerd check --pre 2>/dev/null | grep -E "linkerd-version" | head -3

echo ""
echo "=== Control Plane Components ==="
kubectl get pods -n linkerd -o json 2>/dev/null | jq -r '
    .items[] | "\(.metadata.name)\t\(.status.phase)\tRestarts: \(.status.containerStatuses[0].restartCount // 0)\tImage: \(.spec.containers[0].image | split(":") | last)"
' | column -t

echo ""
echo "=== Extensions Installed ==="
kubectl get namespaces -o json 2>/dev/null | jq -r '
    .items[] | select(.metadata.name | startswith("linkerd-")) | .metadata.name
'
kubectl get pods -n linkerd-viz -o json 2>/dev/null | jq -r '.items[].metadata.name' | head -5
kubectl get pods -n linkerd-multicluster -o json 2>/dev/null | jq -r '.items[].metadata.name' | head -5

echo ""
echo "=== Policy Resources ==="
for res in servers serverauthorizations httproutes authorizationpolicies meshtlsauthentications networkauthentications; do
    COUNT=$(kubectl get "$res" -A --no-headers 2>/dev/null | wc -l | tr -d ' ')
    [ "$COUNT" -gt 0 ] && echo "$res: $COUNT"
done

echo ""
echo "=== Multi-Cluster Links ==="
kubectl get links -A -o json 2>/dev/null | jq -r  | column -t |  -10

Phase 2: Analysis

#!/bin/bash
NS="${1:-default}"

echo "=== Proxy Diagnostics ==="
for pod in $(kubectl get pods -n "$NS" -o jsonpath='{.items[*].metadata.name}' 2>/dev/null | tr ' ' '\n' | head -5); do
    PROXY_VER=$(kubectl get pod "$pod" -n "$NS" -o json 2>/dev/null | jq -r '.spec.containers[] | select(.name == "linkerd-proxy") | .image | split(":") | last')
    if [ -n "$PROXY_VER" ] && [ "$PROXY_VER" != "null" ]; then
        echo "$pod: proxy=$PROXY_VER"
    fi
done

echo ""
echo "=== Server Resources ==="
linkerd_get servers "$NS" | jq '
    .items[]? | {
        name: .metadata.name, port: .spec.port,
        proxyProtocol: .spec.proxyProtocol,
        podSelector: .spec.podSelector
    }' | head -20

echo ""
echo "=== Authorization Policies ==="
linkerd_get authorizationpolicies "$NS" | jq '
    .items[]? | {
        name: .metadata.name,
        targetRef: .spec.targetRef,
        requiredAuthenticationRefs: .spec.requiredAuthenticationRefs
    }' |  -20

 
 
linkerd_get httproutes  | jq  |  -20

 
 
linkerd routes deploy -n  2>/dev/null |  -20

Output Rules

• TOKEN EFFICIENCY: Target <=50 lines per output
• Use linkerd diagnostics for advanced proxy inspection
• Show policy resource relationships clearly

Safety Rules

• Read-only by default: Use check, stat, diagnostics for inspection
• Policy changes can break authorization immediately -- test in permissive mode first
• Multi-cluster link changes affect cross-cluster traffic routing
• Never remove proxy injection from production namespaces without confirmation

Output Format

Present results as a structured report:

Managing Linkerd Deep Report
════════════════════════════
Resources discovered: [count]

Resource       Status    Key Metric    Issues
──────────────────────────────────────────────
[name]         [ok/warn] [value]       [findings]

Summary: [total] resources | [ok] healthy | [warn] warnings | [crit] critical
Action Items: [list of prioritized findings]

Target ≤50 lines of output. Use tables for multi-resource comparisons.

Anti-Hallucination Rules

1. NEVER assume resource names — always discover via CLI/API in Phase 1 before referencing in Phase 2.
2. NEVER fabricate metric names or dimensions — verify against the service documentation or --help output.
3. NEVER mix CLI commands between service versions — confirm which version/API you are targeting.
4. ALWAYS use the discovery → verify → analyze chain — every resource referenced must have been discovered first.
5. ALWAYS handle empty results gracefully — an empty response is valid data, not an error to retry.

Counter-Rationalizations

Shortcut	Counter	Why
"I'll skip discovery and check known resources"	Always run Phase 1 discovery first	Resource names change, new resources appear — assumed names cause errors
"The user only asked for a quick check"	Follow the full discovery → analysis flow	Quick checks miss critical issues; structured analysis catches silent failures
"Default configuration is probably fine"	Audit configuration explicitly	Defaults often leave logging, security, and optimization features disabled
"Metrics aren't needed for this"	Always check relevant metrics when available	API/CLI responses show current state; metrics reveal trends and intermittent issues
"I don't have access to that"	Try the command and report the actual error	Assumed permission failures prevent useful investigation; actual errors are informative

Common Pitfalls

• Policy vs default: Without Server resources, traffic is allowed by default; adding a Server makes it deny-by-default
• HTTPRoute vs ServiceProfile: HTTPRoute is the newer API; ServiceProfile is legacy
• Multi-cluster mirroring: Mirrored services must have matching ports and protocols
• Proxy version skew: Control plane and proxy versions should match within one minor version
• Opaque ports: Protocols that can't be detected need explicit opaque port annotation