first commit
This commit is contained in:
sttlab
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kafka-ca.crt
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*.p12
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*.jks
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*.pem
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# Kafka on Kubernetes (Strimzi)
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Single-broker Kafka cluster for dev/test, deployed via the [Strimzi](https://strimzi.io/) operator on a single-node k3s cluster.
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---
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## Architecture
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```
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kafka namespace
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├── strimzi-cluster-operator Strimzi operator — reconciles Kafka/KafkaUser/KafkaTopic CRs
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├── kafka-dual-role-0 Kafka 4.1.0 broker (KRaft, controller + broker in one pod)
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└── kafka-entity-operator Topic Operator + User Operator (manages topics and users)
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```
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### Key design decisions
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| Choice | Rationale |
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|---|---|
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| **KRaft mode** | No ZooKeeper dependency — simpler, fewer pods |
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| **Single node pool** `dual-role` | One pod acts as both controller and broker, suitable for dev/test |
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| **SASL_SSL + SCRAM-SHA-512** | Authenticated and encrypted connections; TLS managed by Strimzi CA |
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| **Simple authorization** | ACLs enforced per user; `kafka-admin` is declared super user |
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| **`local-path` storage (10 Gi)** | Default k3s storage class; PVC deleted on cluster teardown |
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### Listeners
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| Name | Port | Protocol | Auth |
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|---|---|---|---|
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| `tls` | 9093 | SASL_SSL | SCRAM-SHA-512 |
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Bootstrap address (cluster-internal):
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```
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kafka-kafka-bootstrap.kafka.svc.cluster.local:9093
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```
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### Users
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| KafkaUser | Secret | Role |
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|---|---|---|
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| `kafka-admin` | `kafka-admin` | Super user — unrestricted access |
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| `kafka-client` | `kafka-client` | Application user — Read/Write all topics and groups |
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Strimzi stores credentials in Kubernetes secrets. Each secret contains two keys:
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- `password` — the SCRAM password
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- `sasl.jaas.config` — the ready-to-use JAAS config string
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### TLS
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Strimzi generates and manages its own internal CA. The cluster CA certificate is stored in:
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```
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secret/kafka-cluster-ca-cert (key: ca.crt)
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```
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This certificate must be trusted by any Kafka client connecting over TLS.
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---
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## Prerequisites
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- `kubectl` configured against the target cluster
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- `helm` v3
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- `cert-manager` is **not** required — Strimzi manages its own CA
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---
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## Installation
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```bash
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./deploy.sh
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```
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The script performs the following steps:
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1. Creates the `kafka` namespace
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2. Installs the Strimzi operator via Helm (scoped to the `kafka` namespace)
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3. Waits for the Strimzi CRDs to be fully established
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4. Applies `kafka.yaml` (KafkaNodePool + Kafka CRs) and waits for `Ready`
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5. Applies `kafka-users.yaml` (KafkaUser CRs) and waits for `Ready`
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Expected duration: **4–6 minutes** on a single-node k3s cluster.
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### Verify the installation
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```bash
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kubectl get kafka,kafkanodepool,kafkauser,pods -n kafka
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```
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Expected output:
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```
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NAME READY KAFKA VERSION METADATA VERSION
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kafka.kafka.strimzi.io/kafka True 4.1.0 4.1-IV0
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NAME DESIRED REPLICAS ROLES NODEIDS
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kafkanodepool.kafka.strimzi.io/dual-role 1 ["controller","broker"] [0]
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NAME CLUSTER AUTHENTICATION AUTHORIZATION READY
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kafkauser.kafka.strimzi.io/kafka-admin kafka scram-sha-512 True
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kafkauser.kafka.strimzi.io/kafka-client kafka scram-sha-512 simple True
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```
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---
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## Client configuration
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### Get the CA certificate
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```bash
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kubectl -n kafka get secret kafka-cluster-ca-cert \
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-o jsonpath='{.data.ca\.crt}' | base64 -d > kafka-ca.crt
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```
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### Get user credentials
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```bash
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# Admin password
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kubectl -n kafka get secret kafka-admin \
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-o jsonpath='{.data.password}' | base64 -d
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# Client password
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kubectl -n kafka get secret kafka-client \
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-o jsonpath='{.data.password}' | base64 -d
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# Ready-to-use JAAS config (includes username and password)
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kubectl -n kafka get secret kafka-client \
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-o jsonpath='{.data.sasl\.jaas\.config}' | base64 -d
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```
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### Sample `client.properties`
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```properties
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bootstrap.servers=kafka-kafka-bootstrap.kafka.svc.cluster.local:9093
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security.protocol=SASL_SSL
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ssl.truststore.type=PEM
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ssl.truststore.location=/path/to/kafka-ca.crt
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sasl.mechanism=SCRAM-SHA-512
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sasl.jaas.config=org.apache.kafka.common.security.scram.ScramLoginModule required \
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username="kafka-client" password="<password>";
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```
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---
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## Testing
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A smoke test job is provided that validates the full produce/consume cycle over SASL_SSL.
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### Run the smoke test
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```bash
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kubectl apply -f kafka-smoke-test.yaml
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kubectl logs -n kafka -l job-name=kafka-smoke-test -f
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```
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### Re-run
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```bash
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kubectl delete job kafka-smoke-test -n kafka
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kubectl apply -f kafka-smoke-test.yaml
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kubectl logs -n kafka -l job-name=kafka-smoke-test -f
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```
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### What the test does
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1. **Topic creation** — creates topic `smoke-test` with `--if-not-exists` (idempotent)
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2. **Produce** — sends 5 messages (`message-1` … `message-5`) via `kafka-console-producer`
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3. **Consume** — reads 5 messages from the beginning via `kafka-console-consumer` and asserts count
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Expected output:
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```
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==> [1/3] Creating topic 'smoke-test' (idempotent)
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Topic ready.
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==> [2/3] Producing 5 messages
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5 messages produced.
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==> [3/3] Consuming (from-beginning, max 5)
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message-1
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message-2
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message-3
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message-4
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message-5
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==> SMOKE TEST PASSED (5/5 messages)
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```
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The job is cleaned up automatically after 10 minutes (`ttlSecondsAfterFinished: 600`).
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---
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## Adding a new user
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Create a new `KafkaUser` manifest following the `kafka-client` pattern in `kafka-users.yaml`, then apply it:
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```bash
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kubectl apply -f kafka-users.yaml
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```
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Strimzi will create the corresponding secret in the `kafka` namespace within seconds.
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---
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## Upgrade
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### Upgrade the Kafka version
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Supported versions are dictated by the installed Strimzi operator. Check available versions:
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```bash
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kubectl get kafka kafka -n kafka \
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-o jsonpath='{.status.kafkaVersion}'
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helm show chart strimzi/strimzi-kafka-operator | grep appVersion
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```
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To upgrade Kafka from e.g. `4.1.0` to `4.1.1`:
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1. Update `spec.kafka.version` in `kafka.yaml`
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2. Update `spec.kafka.metadataVersion` if the new version introduces a new metadata version
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3. Apply the change:
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```bash
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kubectl apply -f kafka.yaml
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kubectl wait kafka/kafka --for=condition=Ready --timeout=10m -n kafka
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```
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Strimzi performs a rolling restart of the broker pod automatically.
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### Upgrade the Strimzi operator
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```bash
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helm repo update strimzi
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helm upgrade strimzi-kafka-operator strimzi/strimzi-kafka-operator \
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--namespace kafka \
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--set watchAnyNamespace=false \
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--wait --timeout 5m
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```
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> **Note:** always upgrade the operator before upgrading the Kafka version. Check the [Strimzi upgrade guide](https://strimzi.io/docs/operators/latest/deploying.html#assembly-upgrade-str) for supported upgrade paths.
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---
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## Uninstallation
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```bash
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# Delete Kafka cluster and users (PVC is deleted because deleteClaim: true)
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kubectl delete -f kafka-users.yaml
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kubectl delete -f kafka.yaml
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# Wait for pods to terminate
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kubectl wait --for=delete pod -l strimzi.io/cluster=kafka -n kafka --timeout=120s
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# Uninstall Strimzi operator
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helm uninstall strimzi-kafka-operator -n kafka
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# Delete namespace (removes all remaining secrets and CRDs bindings)
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kubectl delete namespace kafka
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```
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> The `deleteClaim: true` flag in `kafka.yaml` ensures the 10 Gi PVC is deleted together with the KafkaNodePool, leaving no orphaned volumes.
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@@ -0,0 +1,85 @@
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#!/usr/bin/env bash
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set -euo pipefail
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NAMESPACE="kafka"
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KAFKA_NAME="kafka"
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SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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echo "==> Checking prerequisites"
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command -v kubectl >/dev/null || { echo "kubectl not found"; exit 1; }
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command -v helm >/dev/null || { echo "helm not found"; exit 1; }
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echo "==> Verifying cluster reachable"
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kubectl cluster-info --request-timeout=5s >/dev/null
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echo "==> Step 1/5 : Create namespace"
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kubectl create namespace "${NAMESPACE}" --dry-run=client -o yaml | kubectl apply -f -
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echo "==> Step 2/5 : Install Strimzi operator"
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helm repo add strimzi https://strimzi.io/charts/ 2>/dev/null || true
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helm repo update strimzi
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helm upgrade --install strimzi-kafka-operator strimzi/strimzi-kafka-operator \
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--namespace "${NAMESPACE}" \
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--set watchAnyNamespace=false \
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--wait --timeout 5m
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echo "==> Waiting for Strimzi Cluster Operator to be ready"
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kubectl rollout status deployment/strimzi-cluster-operator -n "${NAMESPACE}" --timeout=120s
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echo "==> Waiting for Strimzi CRDs to be fully established"
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for crd in kafkas.kafka.strimzi.io kafkanodepools.kafka.strimzi.io kafkausers.kafka.strimzi.io; do
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until kubectl get crd "${crd}" -o jsonpath='{.status.conditions[?(@.type=="Established")].status}' 2>/dev/null | grep -q "True"; do
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sleep 2
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done
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echo " - ${crd} established"
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done
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echo "==> Step 3/5 : Apply Kafka cluster (KRaft, TLS, SCRAM-SHA-512)"
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kubectl apply -f "${SCRIPT_DIR}/kafka.yaml"
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echo "==> Waiting for Kafka cluster to be Ready (3-5 min)"
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kubectl wait kafka/"${KAFKA_NAME}" \
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--for=condition=Ready \
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--timeout=10m \
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-n "${NAMESPACE}"
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echo "==> Step 4/5 : Apply KafkaUsers"
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kubectl apply -f "${SCRIPT_DIR}/kafka-users.yaml"
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echo "==> Waiting for KafkaUsers to be Ready"
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for user in kafka-admin kafka-client; do
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echo " - waiting for ${user}"
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kubectl wait kafkauser/"${user}" \
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--for=condition=Ready \
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--timeout=120s \
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-n "${NAMESPACE}"
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done
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echo ""
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echo "==> Step 5/5 : Deployment complete"
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echo ""
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kubectl get pods -n "${NAMESPACE}"
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echo ""
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echo "Bootstrap (TLS + SCRAM-SHA-512, cluster-internal):"
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echo " kafka-kafka-bootstrap.${NAMESPACE}.svc.cluster.local:9093"
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echo ""
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echo "Get CA cert (import on client side):"
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echo " kubectl -n ${NAMESPACE} get secret kafka-cluster-ca-cert \\"
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echo " -o jsonpath='{.data.ca\\.crt}' | base64 -d > kafka-ca.crt"
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echo ""
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echo "Get SCRAM credentials:"
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echo " # Admin"
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echo " kubectl -n ${NAMESPACE} get secret kafka-admin -o jsonpath='{.data.password}' | base64 -d"
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echo " # Client"
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echo " kubectl -n ${NAMESPACE} get secret kafka-client -o jsonpath='{.data.password}' | base64 -d"
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echo ""
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echo "Sample client config (properties):"
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echo " bootstrap.servers=kafka-kafka-bootstrap.${NAMESPACE}.svc.cluster.local:9093"
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echo " security.protocol=SASL_SSL"
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echo " ssl.truststore.type=PEM"
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echo " ssl.truststore.certificates=<contents of kafka-ca.crt>"
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echo " sasl.mechanism=SCRAM-SHA-512"
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echo " sasl.jaas.config=org.apache.kafka.common.security.scram.ScramLoginModule required \\"
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echo " username=\"kafka-client\" password=\"<password>\";"
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echo ""
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@@ -0,0 +1,91 @@
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apiVersion: batch/v1
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kind: Job
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metadata:
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name: kafka-smoke-test
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namespace: kafka
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spec:
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ttlSecondsAfterFinished: 600
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backoffLimit: 3
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template:
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spec:
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restartPolicy: Never
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volumes:
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- name: ca-cert
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secret:
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secretName: kafka-cluster-ca-cert
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items:
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- key: ca.crt
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path: ca.crt
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containers:
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- name: smoke-test
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image: apache/kafka:4.1.0
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command: ["/bin/bash", "-c"]
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args:
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- |
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set -euo pipefail
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BOOTSTRAP="kafka-kafka-bootstrap.kafka.svc.cluster.local:9093"
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TOPIC="smoke-test"
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# Build client.properties injecting sasl.jaas.config from the Strimzi-managed secret
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cat > /tmp/client.properties <<EOF
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security.protocol=SASL_SSL
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ssl.truststore.type=PEM
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ssl.truststore.location=/ca/ca.crt
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sasl.mechanism=SCRAM-SHA-512
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sasl.jaas.config=${SASL_JAAS_CONFIG}
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EOF
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echo "==> [1/3] Creating topic '${TOPIC}' (idempotent)"
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/opt/kafka/bin/kafka-topics.sh \
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--bootstrap-server "${BOOTSTRAP}" \
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--command-config /tmp/client.properties \
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--create \
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--topic "${TOPIC}" \
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||||
--partitions 1 \
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||||
--replication-factor 1 \
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||||
--if-not-exists
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echo " Topic ready."
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||||
|
||||
echo "==> [2/3] Producing 5 messages"
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printf 'message-%s\n' 1 2 3 4 5 | \
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/opt/kafka/bin/kafka-console-producer.sh \
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--bootstrap-server "${BOOTSTRAP}" \
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--producer.config /tmp/client.properties \
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--topic "${TOPIC}"
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echo " 5 messages produced."
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||||
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||||
echo "==> [3/3] Consuming (from-beginning, max 5)"
|
||||
MESSAGES=$(/opt/kafka/bin/kafka-console-consumer.sh \
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--bootstrap-server "${BOOTSTRAP}" \
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||||
--consumer.config /tmp/client.properties \
|
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--topic "${TOPIC}" \
|
||||
--from-beginning \
|
||||
--max-messages 5 \
|
||||
--timeout-ms 30000 2>/dev/null || true)
|
||||
|
||||
echo "${MESSAGES}"
|
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COUNT=$(echo "${MESSAGES}" | grep -c '^message-' || true)
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||||
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||||
if [ "${COUNT}" -eq 5 ]; then
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||||
echo "==> SMOKE TEST PASSED (${COUNT}/5 messages)"
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||||
else
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||||
echo "==> SMOKE TEST FAILED: expected 5, got ${COUNT}"
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||||
exit 1
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||||
fi
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env:
|
||||
- name: SASL_JAAS_CONFIG
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||||
valueFrom:
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||||
secretKeyRef:
|
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name: kafka-client
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||||
key: sasl.jaas.config
|
||||
volumeMounts:
|
||||
- name: ca-cert
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mountPath: /ca
|
||||
readOnly: true
|
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resources:
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||||
requests:
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||||
memory: 256Mi
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||||
cpu: "100m"
|
||||
limits:
|
||||
memory: 512Mi
|
||||
cpu: "500m"
|
||||
@@ -0,0 +1,53 @@
|
||||
---
|
||||
# Admin account: super user (declared in Kafka CR → authorization.superUsers).
|
||||
# Strimzi-generated secret: kubectl -n kafka get secret kafka-admin
|
||||
apiVersion: kafka.strimzi.io/v1
|
||||
kind: KafkaUser
|
||||
metadata:
|
||||
name: kafka-admin
|
||||
namespace: kafka
|
||||
labels:
|
||||
strimzi.io/cluster: kafka
|
||||
spec:
|
||||
authentication:
|
||||
type: scram-sha-512
|
||||
---
|
||||
# Application account with explicit ACLs — duplicate per application.
|
||||
# Strimzi-generated secret: kubectl -n kafka get secret kafka-client
|
||||
apiVersion: kafka.strimzi.io/v1
|
||||
kind: KafkaUser
|
||||
metadata:
|
||||
name: kafka-client
|
||||
namespace: kafka
|
||||
labels:
|
||||
strimzi.io/cluster: kafka
|
||||
spec:
|
||||
authentication:
|
||||
type: scram-sha-512
|
||||
authorization:
|
||||
type: simple
|
||||
acls:
|
||||
- resource:
|
||||
type: topic
|
||||
name: "*"
|
||||
patternType: literal
|
||||
operations:
|
||||
- Read
|
||||
- Write
|
||||
- Create
|
||||
- Describe
|
||||
- DescribeConfigs
|
||||
- resource:
|
||||
type: group
|
||||
name: "*"
|
||||
patternType: literal
|
||||
operations:
|
||||
- Read
|
||||
- Describe
|
||||
- resource:
|
||||
type: transactionalId
|
||||
name: "*"
|
||||
patternType: literal
|
||||
operations:
|
||||
- Describe
|
||||
- Write
|
||||
+60
@@ -0,0 +1,60 @@
|
||||
---
|
||||
# KRaft mode: single pod acting as both controller and broker.
|
||||
# Storage is defined here (not in the Kafka CR) because node pools are enabled.
|
||||
apiVersion: kafka.strimzi.io/v1
|
||||
kind: KafkaNodePool
|
||||
metadata:
|
||||
name: dual-role
|
||||
namespace: kafka
|
||||
labels:
|
||||
strimzi.io/cluster: kafka
|
||||
spec:
|
||||
replicas: 1
|
||||
roles:
|
||||
- controller
|
||||
- broker
|
||||
storage:
|
||||
type: persistent-claim
|
||||
size: 10Gi
|
||||
deleteClaim: true
|
||||
class: local-path
|
||||
resources:
|
||||
requests:
|
||||
memory: 1Gi
|
||||
cpu: "250m"
|
||||
limits:
|
||||
memory: 2Gi
|
||||
cpu: "1000m"
|
||||
---
|
||||
apiVersion: kafka.strimzi.io/v1
|
||||
kind: Kafka
|
||||
metadata:
|
||||
name: kafka
|
||||
namespace: kafka
|
||||
annotations:
|
||||
strimzi.io/node-pools: enabled
|
||||
strimzi.io/kraft: enabled
|
||||
spec:
|
||||
kafka:
|
||||
version: 4.1.0
|
||||
metadataVersion: "4.1-IV0"
|
||||
listeners:
|
||||
- name: tls
|
||||
port: 9093
|
||||
type: internal
|
||||
tls: true
|
||||
authentication:
|
||||
type: scram-sha-512
|
||||
authorization:
|
||||
type: simple
|
||||
superUsers:
|
||||
- kafka-admin
|
||||
config:
|
||||
offsets.topic.replication.factor: "1"
|
||||
transaction.state.log.replication.factor: "1"
|
||||
transaction.state.log.min.isr: "1"
|
||||
default.replication.factor: "1"
|
||||
min.insync.replicas: "1"
|
||||
entityOperator:
|
||||
topicOperator: {}
|
||||
userOperator: {}
|
||||
Reference in New Issue
Block a user