---
name: mtls-configuration
description: "mTLS Configuration workflow skill. Use this skill when the user needs Configure mutual TLS (mTLS) for zero-trust service-to-service communication. Use when implementing zero-trust networking, certificate management, or securing internal service communication and the operator should preserve the upstream workflow, copied support files, and provenance before merging or handing off."
version: "0.0.1"
category: development
tags: ["mtls-configuration", "configure", "mutual", "tls", "mtls", "for", "zero-trust", "service-to-service"]
complexity: advanced
risk: caution
tools: ["codex-cli", "claude-code", "cursor", "gemini-cli", "opencode"]
source: community
author: "sickn33"
date_added: "2026-04-15"
date_updated: "2026-04-25"
---

# mTLS Configuration

## Overview

This public intake copy packages `plugins/antigravity-awesome-skills-claude/skills/mtls-configuration` from `https://github.com/sickn33/antigravity-awesome-skills` into the native Omni Skills editorial shape without hiding its origin.

Use it when the operator needs the upstream workflow, support files, and repository context to stay intact while the public validator and private enhancer continue their normal downstream flow.

This intake keeps the copied upstream files intact and uses the `external_source` block in `metadata.json` plus `ORIGIN.md` as the provenance anchor for review.

# mTLS Configuration Comprehensive guide to implementing mutual TLS for zero-trust service mesh communication.

Imported source sections that did not map cleanly to the public headings are still preserved below or in the support files. Notable imported sections: Core Concepts, Templates, Certificate Rotation, Debugging mTLS Issues, Limitations.

## When to Use This Skill

Use this section as the trigger filter. It should make the activation boundary explicit before the operator loads files, runs commands, or opens a pull request.

- The task is unrelated to mtls configuration
- You need a different domain or tool outside this scope
- Implementing zero-trust networking
- Securing service-to-service communication
- Certificate rotation and management
- Debugging TLS handshake issues

## Operating Table

| Situation | Start here | Why it matters |
| --- | --- | --- |
| First-time use | `metadata.json` | Confirms repository, branch, commit, and imported path through the `external_source` block before touching the copied workflow |
| Provenance review | `ORIGIN.md` | Gives reviewers a plain-language audit trail for the imported source |
| Workflow execution | `SKILL.md` | Starts with the smallest copied file that materially changes execution |
| Supporting context | `SKILL.md` | Adds the next most relevant copied source file without loading the entire package |
| Handoff decision | `## Related Skills` | Helps the operator switch to a stronger native skill when the task drifts |

## Workflow

This workflow is intentionally editorial and operational at the same time. It keeps the imported source useful to the operator while still satisfying the public intake standards that feed the downstream enhancer flow.

1. Clarify goals, constraints, and required inputs.
2. Apply relevant best practices and validate outcomes.
3. Provide actionable steps and verification.
4. If detailed examples are required, open resources/implementation-playbook.md.
5. Confirm the user goal, the scope of the imported workflow, and whether this skill is still the right router for the task.
6. Read the overview and provenance files before loading any copied upstream support files.
7. Load only the references, examples, prompts, or scripts that materially change the outcome for the current request.

### Imported Workflow Notes

#### Imported: Instructions

- Clarify goals, constraints, and required inputs.
- Apply relevant best practices and validate outcomes.
- Provide actionable steps and verification.
- If detailed examples are required, open `resources/implementation-playbook.md`.

#### Imported: Core Concepts

### 1. mTLS Flow

```
┌─────────┐                              ┌─────────┐
│ Service │                              │ Service │
│    A    │                              │    B    │
└────┬────┘                              └────┬────┘
     │                                        │
┌────┴────┐      TLS Handshake          ┌────┴────┐
│  Proxy  │◄───────────────────────────►│  Proxy  │
│(Sidecar)│  1. ClientHello             │(Sidecar)│
│         │  2. ServerHello + Cert      │         │
│         │  3. Client Cert             │         │
│         │  4. Verify Both Certs       │         │
│         │  5. Encrypted Channel       │         │
└─────────┘                              └─────────┘
```

### 2. Certificate Hierarchy

```
Root CA (Self-signed, long-lived)
    │
    ├── Intermediate CA (Cluster-level)
    │       │
    │       ├── Workload Cert (Service A)
    │       └── Workload Cert (Service B)
    │
    └── Intermediate CA (Multi-cluster)
            │
            └── Cross-cluster certs
```

## Examples

### Example 1: Ask for the upstream workflow directly

```text
Use @mtls-configuration to handle <task>. Start from the copied upstream workflow, load only the files that change the outcome, and keep provenance visible in the answer.
```

**Explanation:** This is the safest starting point when the operator needs the imported workflow, but not the entire repository.

### Example 2: Ask for a provenance-grounded review

```text
Review @mtls-configuration against metadata.json and ORIGIN.md, then explain which copied upstream files you would load first and why.
```

**Explanation:** Use this before review or troubleshooting when you need a precise, auditable explanation of origin and file selection.

### Example 3: Narrow the copied support files before execution

```text
Use @mtls-configuration for <task>. Load only the copied references, examples, or scripts that change the outcome, and name the files explicitly before proceeding.
```

**Explanation:** This keeps the skill aligned with progressive disclosure instead of loading the whole copied package by default.

### Example 4: Build a reviewer packet

```text
Review @mtls-configuration using the copied upstream files plus provenance, then summarize any gaps before merge.
```

**Explanation:** This is useful when the PR is waiting for human review and you want a repeatable audit packet.



## Best Practices

Treat the generated public skill as a reviewable packaging layer around the upstream repository. The goal is to keep provenance explicit and load only the copied source material that materially improves execution.

- Start with PERMISSIVE - Migrate gradually to STRICT
- Monitor certificate expiry - Set up alerts
- Use short-lived certs - 24h or less for workloads
- Rotate CA periodically - Plan for CA rotation
- Log TLS errors - For debugging and audit
- Don't disable mTLS - For convenience in production
- Don't ignore cert expiry - Automate rotation

### Imported Operating Notes

#### Imported: Best Practices

### Do's
- **Start with PERMISSIVE** - Migrate gradually to STRICT
- **Monitor certificate expiry** - Set up alerts
- **Use short-lived certs** - 24h or less for workloads
- **Rotate CA periodically** - Plan for CA rotation
- **Log TLS errors** - For debugging and audit

### Don'ts
- **Don't disable mTLS** - For convenience in production
- **Don't ignore cert expiry** - Automate rotation
- **Don't use self-signed certs** - Use proper CA hierarchy
- **Don't skip verification** - Verify the full chain

## Troubleshooting

### Problem: The operator skipped the imported context and answered too generically

**Symptoms:** The result ignores the upstream workflow in `plugins/antigravity-awesome-skills-claude/skills/mtls-configuration`, fails to mention provenance, or does not use any copied source files at all.
**Solution:** Re-open `metadata.json`, `ORIGIN.md`, and the most relevant copied upstream files. Check the `external_source` block first, then restate the provenance before continuing.

### Problem: The imported workflow feels incomplete during review

**Symptoms:** Reviewers can see the generated `SKILL.md`, but they cannot quickly tell which references, examples, or scripts matter for the current task.
**Solution:** Point at the exact copied references, examples, scripts, or assets that justify the path you took. If the gap is still real, record it in the PR instead of hiding it.

### Problem: The task drifted into a different specialization

**Symptoms:** The imported skill starts in the right place, but the work turns into debugging, architecture, design, security, or release orchestration that a native skill handles better.
**Solution:** Use the related skills section to hand off deliberately. Keep the imported provenance visible so the next skill inherits the right context instead of starting blind.



## Related Skills

- `@00-andruia-consultant` - Use when the work is better handled by that native specialization after this imported skill establishes context.
- `@00-andruia-consultant-v2` - Use when the work is better handled by that native specialization after this imported skill establishes context.
- `@10-andruia-skill-smith` - Use when the work is better handled by that native specialization after this imported skill establishes context.
- `@10-andruia-skill-smith-v2` - Use when the work is better handled by that native specialization after this imported skill establishes context.

## Additional Resources

Use this support matrix and the linked files below as the operator packet for this imported skill. They should reflect real copied source material, not generic scaffolding.

| Resource family | What it gives the reviewer | Example path |
| --- | --- | --- |
| `references` | copied reference notes, guides, or background material from upstream | `references/n/a` |
| `examples` | worked examples or reusable prompts copied from upstream | `examples/n/a` |
| `scripts` | upstream helper scripts that change execution or validation | `scripts/n/a` |
| `agents` | routing or delegation notes that are genuinely part of the imported package | `agents/n/a` |
| `assets` | supporting assets or schemas copied from the source package | `assets/n/a` |



### Imported Reference Notes

#### Imported: Resources

- [Istio Security](https://istio.io/latest/docs/concepts/security/)
- [SPIFFE/SPIRE](https://spiffe.io/)
- [cert-manager](https://cert-manager.io/)
- [Zero Trust Architecture (NIST)](https://www.nist.gov/publications/zero-trust-architecture)

#### Imported: Templates

### Template 1: Istio mTLS (Strict Mode)

```yaml
# Enable strict mTLS mesh-wide
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: default
  namespace: istio-system
spec:
  mtls:
    mode: STRICT
---
# Namespace-level override (permissive for migration)
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: default
  namespace: legacy-namespace
spec:
  mtls:
    mode: PERMISSIVE
---
# Workload-specific policy
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: payment-service
  namespace: production
spec:
  selector:
    matchLabels:
      app: payment-service
  mtls:
    mode: STRICT
  portLevelMtls:
    8080:
      mode: STRICT
    9090:
      mode: DISABLE  # Metrics port, no mTLS
```

### Template 2: Istio Destination Rule for mTLS

```yaml
apiVersion: networking.istio.io/v1beta1
kind: DestinationRule
metadata:
  name: default
  namespace: istio-system
spec:
  host: "*.local"
  trafficPolicy:
    tls:
      mode: ISTIO_MUTUAL
---
# TLS to external service
apiVersion: networking.istio.io/v1beta1
kind: DestinationRule
metadata:
  name: external-api
spec:
  host: api.external.com
  trafficPolicy:
    tls:
      mode: SIMPLE
      caCertificates: /etc/certs/external-ca.pem
---
# Mutual TLS to external service
apiVersion: networking.istio.io/v1beta1
kind: DestinationRule
metadata:
  name: partner-api
spec:
  host: api.partner.com
  trafficPolicy:
    tls:
      mode: MUTUAL
      clientCertificate: /etc/certs/client.pem
      privateKey: /etc/certs/client-key.pem
      caCertificates: /etc/certs/partner-ca.pem
```

### Template 3: Cert-Manager with Istio

```yaml
# Install cert-manager issuer for Istio
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: istio-ca
spec:
  ca:
    secretName: istio-ca-secret
---
# Create Istio CA secret
apiVersion: v1
kind: Secret
metadata:
  name: istio-ca-secret
  namespace: cert-manager
type: kubernetes.io/tls
data:
  tls.crt: <base64-encoded-ca-cert>
  tls.key: <base64-encoded-ca-key>
---
# Certificate for workload
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: my-service-cert
  namespace: my-namespace
spec:
  secretName: my-service-tls
  duration: 24h
  renewBefore: 8h
  issuerRef:
    name: istio-ca
    kind: ClusterIssuer
  commonName: my-service.my-namespace.svc.cluster.local
  dnsNames:
    - my-service
    - my-service.my-namespace
    - my-service.my-namespace.svc
    - my-service.my-namespace.svc.cluster.local
  usages:
    - server auth
    - client auth
```

### Template 4: SPIFFE/SPIRE Integration

```yaml
# SPIRE Server configuration
apiVersion: v1
kind: ConfigMap
metadata:
  name: spire-server
  namespace: spire
data:
  server.conf: |
    server {
      bind_address = "0.0.0.0"
      bind_port = "8081"
      trust_domain = "example.org"
      data_dir = "/run/spire/data"
      log_level = "INFO"
      ca_ttl = "168h"
      default_x509_svid_ttl = "1h"
    }

    plugins {
      DataStore "sql" {
        plugin_data {
          database_type = "sqlite3"
          connection_string = "/run/spire/data/datastore.sqlite3"
        }
      }

      NodeAttestor "k8s_psat" {
        plugin_data {
          clusters = {
            "demo-cluster" = {
              service_account_allow_list = ["spire:spire-agent"]
            }
          }
        }
      }

      KeyManager "memory" {
        plugin_data {}
      }

      UpstreamAuthority "disk" {
        plugin_data {
          key_file_path = "/run/spire/secrets/bootstrap.key"
          cert_file_path = "/run/spire/secrets/bootstrap.crt"
        }
      }
    }
---
# SPIRE Agent DaemonSet (abbreviated)
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: spire-agent
  namespace: spire
spec:
  selector:
    matchLabels:
      app: spire-agent
  template:
    spec:
      containers:
        - name: spire-agent
          image: ghcr.io/spiffe/spire-agent:1.8.0
          volumeMounts:
            - name: spire-agent-socket
              mountPath: /run/spire/sockets
      volumes:
        - name: spire-agent-socket
          hostPath:
            path: /run/spire/sockets
            type: DirectoryOrCreate
```

### Template 5: Linkerd mTLS (Automatic)

```yaml
# Linkerd enables mTLS automatically
# Verify with:
# linkerd viz edges deployment -n my-namespace

# For external services without mTLS
apiVersion: policy.linkerd.io/v1beta1
kind: Server
metadata:
  name: external-api
  namespace: my-namespace
spec:
  podSelector:
    matchLabels:
      app: my-app
  port: external-api
  proxyProtocol: HTTP/1  # or TLS for passthrough
---
# Skip TLS for specific port
apiVersion: v1
kind: Service
metadata:
  name: my-service
  annotations:
    config.linkerd.io/skip-outbound-ports: "3306"  # MySQL
```

#### Imported: Certificate Rotation

```bash
# Istio - Check certificate expiry
istioctl proxy-config secret deploy/my-app -o json | \
  jq '.dynamicActiveSecrets[0].secret.tlsCertificate.certificateChain.inlineBytes' | \
  tr -d '"' | base64 -d | openssl x509 -text -noout

# Force certificate rotation
kubectl rollout restart deployment/my-app

# Check Linkerd identity
linkerd identity -n my-namespace
```

#### Imported: Debugging mTLS Issues

```bash
# Istio - Check if mTLS is enabled
istioctl authn tls-check my-service.my-namespace.svc.cluster.local

# Verify peer authentication
kubectl get peerauthentication --all-namespaces

# Check destination rules
kubectl get destinationrule --all-namespaces

# Debug TLS handshake
istioctl proxy-config log deploy/my-app --level debug
kubectl logs deploy/my-app -c istio-proxy | grep -i tls

# Linkerd - Check mTLS status
linkerd viz edges deployment -n my-namespace
linkerd viz tap deploy/my-app --to deploy/my-backend
```

#### Imported: Limitations

- Use this skill only when the task clearly matches the scope described above.
- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.