http.kafka.crud

http.kafka.crud

This simple http.kafka.crud example illustrates how to configure zilla to expose a REST API that just creates, updates, deletes and reads messages in items-snapshots log-compacted Kafka topic acting as a table.

Requirements

• bash, jq, nc
• Kubernetes (e.g. Docker Desktop with Kubernetes enabled)
• kubectl
• helm 3.0+

Setup

The setup.sh script:

• installs Zilla and Kafka to the Kubernetes cluster with helm and waits for the pods to start up
• creates the items-snapshots topic in Kafka with the cleanup.policy=compact topic configuration
• starts port forwarding

./setup.sh

output:

+ ZILLA_CHART=oci://ghcr.io/aklivity/charts/zilla
+ helm upgrade --install zilla-http-kafka-crud oci://ghcr.io/aklivity/charts/zilla --namespace zilla-http-kafka-crud --create-namespace --wait [...]
NAME: zilla-http-kafka-crud
LAST DEPLOYED: [...]
NAMESPACE: zilla-http-kafka-crud
STATUS: deployed
REVISION: 1
NOTES:
Zilla has been installed.
[...]
+ helm upgrade --install zilla-http-kafka-crud-kafka chart --namespace zilla-http-kafka-crud --create-namespace --wait
NAME: zilla-http-kafka-crud-kafka
LAST DEPLOYED: [...]
NAMESPACE: zilla-http-kafka-crud
STATUS: deployed
REVISION: 1
TEST SUITE: None
++ kubectl get pods --namespace zilla-http-kafka-crud --selector app.kubernetes.io/instance=kafka -o name
+ KAFKA_POD=pod/kafka-1234567890-abcde
+ kubectl exec --namespace zilla-http-kafka-crud pod/kafka-1234567890-abcde -- /opt/bitnami/kafka/bin/kafka-topics.sh --bootstrap-server localhost:9092 --create --topic items-snapshots --config cleanup.policy=compact --if-not-exists
Created topic items-snapshots.
+ kubectl port-forward --namespace zilla-http-kafka-crud service/zilla 7114 7143
+ nc -z localhost 7114
+ kubectl port-forward --namespace zilla-http-kafka-crud service/kafka 9092 29092
+ sleep 1
+ nc -z localhost 7114
Connection to localhost port 7114 [tcp/http-alt] succeeded!
+ nc -z localhost 9092
Connection to localhost port 9092 [tcp/XmlIpcRegSvc] succeeded!

Endpoints

Protocol	Method	Endpoint	Topic	Description
HTTP	POST	/items	items-snapshots	Create an item.
HTTP	PUT	/items/{id}	items-snapshots	Update item by the key.
HTTP	DELETE	/items/{id}	items-snapshots	Delete item by the key.
HTTP	GET	/items	items-snapshots	Fetch all items.
HTTP	GET	/items/{id}	items-snapshots	Fetch item by the key.

Verify behavior

POST request.

Note: You can remove -H 'Idempotency-Key: 1' to generate random key.

curl -k -v -X POST https://localhost:7143/items -H 'Idempotency-Key: 1'  -H 'Content-Type: application/json' -d '{"greeting":"Hello, world1"}'

output:

...
POST /items HTTP/2
Host: localhost:7143
user-agent: curl/7.85.0
accept: */*
idempotency-key: 2
content-type: application/json
content-length: 28
* We are completely uploaded and fine
* Connection state changed (MAX_CONCURRENT_STREAMS == 2147483647)!
HTTP/2 204

GET request to fetch specific item.

curl -k -v https://localhost:7143/items/1

output:

...
* Connection state changed (MAX_CONCURRENT_STREAMS == 2147483647)!
< HTTP/2 200
< content-length: 27
< content-type: application/json
< etag: AQIACA==
<
* Connection #0 to host localhost left intact
{"greeting":"Hello, world1"}%

PUT request to update specific item.

curl -k -v -X PUT https://localhost:7143/items/1 -H 'Content-Type: application/json' -d '{"greeting":"Hello, world2"}'

output:

...
PUT /items/1 HTTP/2
Host: localhost:7143
user-agent: curl/7.85.0
accept: */*
idempotency-key: 2
content-type: application/json
content-length: 28
* We are completely uploaded and fine
* Connection state changed (MAX_CONCURRENT_STREAMS == 2147483647)!
HTTP/2 204

DELETE request to delete specific item.

curl -k -v -X DELETE https://localhost:7143/items/1

output:

...
> DELETE /items/1 HTTP/2
> Host: localhost:7143
> user-agent: curl/7.85.0
> accept: */*
>
* Connection state changed (MAX_CONCURRENT_STREAMS == 2147483647)!
< HTTP/2 204

Teardown

The teardown.sh script stops port forwarding, uninstalls Zilla and Kafka and deletes the namespace.

./teardown.sh

output:

+ pgrep kubectl
99998
99999
+ killall kubectl
+ helm uninstall zilla-http-kafka-crud --namespace zilla-http-kafka-crud
release "zilla-http-kafka-crud" uninstalled
release "zilla-http-kafka-crud-kafka" uninstalled
+ kubectl delete namespace zilla-http-kafka-crud-kafka
namespace "zilla-http-kafka-crud" deleted