Agent skill

sealed-secrets

Create sealed secrets for Kubernetes using kubeseal

View SKILL.md on GitHub Repository
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Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/devops/sealed-secrets

SKILL.md

Sealed Secrets

Create encrypted sealed secrets for storing sensitive data in Git repositories.

Prerequisites

  • kubeseal CLI installed
  • Access to Kubernetes cluster with sealed-secrets-controller
  • kubectl configured with cluster access

Workaround for Network Issues

The sealed-secrets-controller may not be directly reachable due to network policies. Use port-forwarding as a workaround:

bash
# Start port-forward in background
kubectl port-forward -n flux-system svc/sealed-secrets-controller 8080:8080 &
PF_PID=$!
sleep 3

# Fetch the certificate
CERT=$(curl -s http://localhost:8080/v1/cert.pem)

# Create and seal the secret using the certificate
cat <<EOF | kubeseal --cert <(echo "$CERT") --format yaml > sealed-secret.yaml
apiVersion: v1
kind: Secret
metadata:
  name: my-secret
  namespace: my-namespace
type: Opaque
stringData:
  key1: "value1"
  key2: "value2"
EOF

# Clean up port-forward
kill $PF_PID 2>/dev/null || true

Process

1. Prepare the secret manifest

Create a standard Kubernetes Secret manifest with your sensitive data:

yaml
apiVersion: v1
kind: Secret
metadata:
  name: my-secret
  namespace: target-namespace
type: Opaque
stringData:
  api-key: "your-api-key"
  password: "your-password"

For docker registry secrets:

yaml
apiVersion: v1
kind: Secret
metadata:
  name: registry-secret
  namespace: target-namespace
type: kubernetes.io/dockerconfigjson
data:
  .dockerconfigjson: <base64-encoded-docker-config>

2. Seal the secret

Using port-forward (recommended for our environment):

bash
kubectl port-forward -n flux-system svc/sealed-secrets-controller 8080:8080 &
PF_PID=$!
sleep 3
CERT=$(curl -s http://localhost:8080/v1/cert.pem)

cat secret.yaml | kubeseal --cert <(echo "$CERT") --format yaml > sealed-secret.yaml

kill $PF_PID 2>/dev/null || true

3. Apply or commit the sealed secret

The sealed secret can be safely committed to Git:

yaml
apiVersion: bitnami.com/v1alpha1
kind: SealedSecret
metadata:
  name: my-secret
  namespace: target-namespace
spec:
  encryptedData:
    api-key: AgB...encrypted...
    password: AgC...encrypted...
  template:
    metadata:
      name: my-secret
      namespace: target-namespace
    type: Opaque

Common Secret Types

API Credentials

yaml
stringData:
  api-key: "${API_KEY}"
  private-key: |
    ${PRIVATE_KEY_CONTENT}

Docker Registry (GHCR)

bash
# Get existing secret from another namespace
kubectl get secret ghcr-secret -n source-namespace -o jsonpath='{.data.\.dockerconfigjson}'

TLS Certificates

yaml
type: kubernetes.io/tls
data:
  tls.crt: <base64-cert>
  tls.key: <base64-key>

Troubleshooting

"Resource already exists and is not managed by SealedSecret"

Delete the existing secret first:

bash
kubectl delete secret my-secret -n target-namespace

"illegal base64 data"

Ensure the encrypted data has no line breaks or extra whitespace. The sealed secret YAML should have the encrypted values on single lines.

Controller not reachable (502 Bad Gateway)

Use the port-forward workaround described above.

Notes

  • Sealed secrets are namespace-scoped by default
  • The encryption key is stored in the sealed-secrets-controller
  • If the controller key rotates, old sealed secrets still work but you should re-seal with new key
  • Always verify the sealed secret syncs correctly: kubectl get sealedsecrets -n namespace

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