A Week-Long Journey Through Deployment Errors and RBAC Implementation

How It Started

Last month, my manager dropped a folder on my desk. “The dev team deployed our new ETL pipeline on AKS. It works, but security is wide open. Lock it down with Kubernetes RBAC. No Azure AD, pure Kubernetes only.”

I nodded confidently. “I’ll have it done by Friday.”

It was Tuesday. I didn’t finish until the following Tuesday. Here’s what went wrong, and what I learned.

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Part 1: The Setup (The Easy Part)

Setting up the infrastructure was straightforward:

export RESOURCE_GROUP="CloudWave-RG"
export LOCATION="eastus"
export ACR_NAME="cloudwaveacr$RANDOM"
export AKS_CLUSTER_NAME="CloudWaveAKS"

# Create everything
az group create --name $RESOURCE_GROUP --location $LOCATION
az acr create --resource-group $RESOURCE_GROUP --name $ACR_NAME --sku Basic
az aks create \
  --resource-group $RESOURCE_GROUP \
  --name $AKS_CLUSTER_NAME \
  --node-count 1 \
  --node-vm-size Standard_D2s_v3 \
  --enable-managed-identity \
  --generate-ssh-keys

# Connect AKS to ACR and get credentials
az aks update -n $AKS_CLUSTER_NAME -g $RESOURCE_GROUP --attach-acr $ACR_NAME
az aks get-credentials --resource-group $RESOURCE_GROUP --name $AKS_CLUSTER_NAME

Pro tip: Always use $RANDOM ACR names. I once wasted 30 minutes because “mycompanyacr” was already taken by someone in Europe. ACR names are globally unique.

The ETL script was straightforward: it fetched data from an API and stored it in PostgreSQL. It had retry logic for database connections:

retries = 5
while retries > 0:
    try:
        conn = psycopg2.connect(host=db_host, dbname=db_name, ...)
        return conn
    except:
        retries -= 1
        time.sleep(5)

I containerized it and pushed it to ACR. By Wednesday morning, I was feeling good.

That didn’t last long.

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Part 2: The Three Disasters 💥

Creating Namespaces

I created separate namespaces for isolation:

kubectl create namespace db
kubectl create namespace etl

Think of namespaces like apartments in a building: shared infrastructure, but you can’t walk into someone else’s place without permission.

Error #1: PostgreSQL Won’t Start

I deployed the database:

kubectl apply -f db-setup.yaml
kubectl get statefulset -n db

Output: ` 0/1 READY` 😱

I checked the logs:

kubectl logs postgres-statefulset-0 -n db

The error:

initdb: error: directory "/var/lib/postgresql/data" exists but is not empty
It contains a lost+found directory

What I learned: Azure persistent disks automatically include a lost+found system directory. PostgreSQL refuses to initialize if it finds anything in its data directory.

The fix: Tell PostgreSQL to use a subdirectory:

env:
- name: PGDATA
  value: /var/lib/postgresql/data/pgdata

But here’s the catch: I had to delete the old persistent volume claim first.

kubectl delete -f db-setup.yaml
kubectl delete pvc postgres-storage-postgres-statefulset-0 -n db
kubectl apply -f db-setup.yaml

Key insight: Kubernetes doesn’t auto-delete PVCs. This protects your data, but you need to clean up manually when troubleshooting.

✅ Database finally started!

Error #2: Image Not Found

I deployed the ETL job:

kubectl apply -f etl-cronjob.yaml
kubectl create job --from=cronjob/data-fetcher-cronjob test-run -n etl

Result: ErrImagePull - no such host

The problem: My YAML had a placeholder image name from a tutorial. I needed my actual ACR name:

az acr list --resource-group $RESOURCE_GROUP --output table

Updated the YAML with the correct registry (cloudwaveacr26077.azurecr.io/etl-script:v1) and redeployed.

Lesson: Never use placeholder values. Always double-check your image paths.

Error #3: Secret Not Found (The Eye-Opener)

The pod started but immediately failed. The logs showed:

But I HAD created the secret! I checked:

kubectl get secrets -n db

There it was, in the db namespace, but not in etl. Then it hit me.

Secrets are namespace-scoped. My ETL pod in the etl` `` namespace couldn't access a secret in the db` `` namespace. This isn’t a bug; it’s intentional isolation!

The fix: Copy the secret to the ETL namespace:

apiVersion: v1
kind: Secret
metadata:
  name: postgres-secret
  namespace: etl  # Different namespace!
type: Opaque
data:
  POSTGRES_PASSWORD: bXlTdXBlclNlY3JldFBhc3N3b3Jk
kubectl apply -f etl-secret.yaml

✅ Finally, the ETL job completed successfully!

This namespace isolation moment was crucial, it showed me how Kubernetes enforces boundaries, which would become the foundation of our RBAC security.

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Part 3: Implementing RBAC (The Real Mission) 🔒

By Friday, the app was working. Now for the security lockdown.

Understanding RBAC

I explained it to myself like a nightclub VIP system:

• Role = The VIP list (what you’re allowed to do)
• ServiceAccount = Your ID card (who you are)
• RoleBinding = The bouncer (connects your ID to the VIP list)

Creating the Roles

Database Admin Role:

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  namespace: db
  name: db-admin-role
rules:
- apiGroups: ["", "apps"]
  resources: ["statefulsets", "services", "secrets", "persistentvolumeclaims", "pods"]
  verbs: ["get", "list", "watch", "create", "update", "patch", "delete"]

ETL Admin Role:

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  namespace: etl
  name: etl-admin-role
rules:
- apiGroups: ["batch", "", "apps"]
  resources: ["cronjobs", "jobs", "pods"]
  verbs: ["get", "list", "watch", "create", "update", "patch", "delete"]

Key differences:

• Different namespaces
• Different resources (databases vs. jobs)
• ETL role includes the batch API group for CronJobs

Creating ServiceAccounts and Bindings

# ETL Manager Identity
apiVersion: v1
kind: ServiceAccount
metadata:
  name: etl-manager-sa
  namespace: etl
---
# Link identity to permissions
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: bind-etl-manager
  namespace: etl
subjects:
- kind: ServiceAccount
  name: etl-manager-sa
  namespace: etl
roleRef:
  kind: Role
  name: etl-admin-role
  apiGroup: rbac.authorization.k8s.io

Repeated the same pattern for db-manager-sa in the database namespace.

Applied everything:

kubectl apply -f db-role.yaml
kubectl apply -f etl-role.yaml
kubectl apply -f rbac-setup.yaml

Part 4: The Proof (Testing Security) ✅

This was the moment of truth. I used the --as flag to impersonate ServiceAccounts:

Test 1: ETL Manager accessing ETL resources (should work)

kubectl get cronjobs -n etl --as=system:serviceaccount:etl:etl-manager-sa

✅ Success! Shows the CronJob.

Test 2: ETL Manager trying to access DB resources (should fail)

kubectl get pods -n db --as=system:serviceaccount:etl:etl-manager-sa

✅ Perfect failure! This is exactly what we want.

Tests 3 & 4: DB Manager

# Can access DB namespace ✅
kubectl get statefulsets -n db --as=system:serviceaccount:db:db-manager-sa

# Cannot access ETL namespace ❌
kubectl get cronjobs -n etl --as=system:serviceaccount:db:db-manager-sa

Perfect isolation achieved! Each manager can only access their designated namespace.

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What I Learned

1. Namespaces Provide Organizational Isolation, Not Network Isolation

Namespaces separate resources for RBAC and organization, but pods can still talk across namespaces. The ETL pod connects to the database using postgres-db-service.db.svc.cluster.local. For network isolation, you need NetworkPolicies.

2. Secrets Don’t Cross Namespaces

This seemed annoying at first, but it’s excellent security. It forces explicit sharing. Copying the database password to the ETL namespace was the right call; the job legitimately needs it.

3. PVCs Are Sticky By Design

Kubernetes protects your data by not auto-deleting persistent volumes. This felt annoying during debugging, but would be a lifesaver in production.

4. Application Retry Logic Is Essential

Even with init containers and readiness probes, application-level retries are crucial. Databases restart, networks hiccup, and distributed systems are inherently unreliable.

5. The --as Flag Is Your Testing Superpower

Impersonating ServiceAccounts makes testing RBAC painless. No tokens, no kubeconfig gymnastics, just pretend to be the user and see what happens.

6. Error Messages Are Helpful

• CrashLoopBackOff → Check logs
• ErrImagePull → Check image path
• Secret not found → Check namespace
• Forbidden → RBAC working correctly!

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Real-World Applications

After presenting this at our team meeting, people immediately saw uses:

• Multi-tenant SaaS: One namespace per customer with isolated permissions
• Compliance: SOC2 auditors love the separation of duties
• Team boundaries: Dev teams manage their namespaces without breaking production
• CI/CD: Build jobs can’t touch production resources

The Bottom Line

It took me a week and three major errors to secure our Kubernetes cluster, but I learned more from those failures than any tutorial could teach.

What I wish I’d known on day one:

1. Start with working apps, then add security
2. Expect failures; they’re learning opportunities
3. Test thoroughly with --as a flag.
4. Document everything
5. Security is iterative, not a one-time task

The key lesson: Security isn’t about building a perfect fortress on the first try. It’s about understanding tools, learning from mistakes, and continuously improving.

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Clean Up

Don’t forget to delete resources if you’re following along:

az group delete --name $RESOURCE_GROUP --yes --no-wait

Your cloud bill will thank you! 💰