asyncapi.mqtt.proxy

asyncapi.mqtt.proxy

Listens on mqtt port 7183 and will forward mqtt publish messages and proxies subscribes to mosquitto MQTT broker listening on 1883 for topic smartylighting/streetlights/1/0/event/+/lighting/measured.

Requirements

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

Setup

The setup.sh script:

• installs Zilla to the Kubernetes cluster with helm and waits for the pod to start up
• installs mosquitto MQTT broker to the Kubernetes cluster with helm and waits for the pod to start up
• starts port forwarding

./setup.sh

+ ZILLA_CHART=oci://ghcr.io/aklivity/charts/zilla
+ helm upgrade --install asyncapi-mqtt-proxy oci://ghcr.io/aklivity/charts/zilla --namespace asyncapi-mqtt-proxy --create-namespace --wait --values values.yaml --set-file 'zilla\.yaml=zilla.yaml'
NAME: asyncapi-mqtt-proxy
LAST DEPLOYED: [...]
NAMESPACE: asyncapi-mqtt-proxy
STATUS: deployed
REVISION: 1
NOTES:
Zilla has been installed.
+ helm upgrade --install zilla-mqtt-kafka-reflect-kafka chart --namespace zilla-mqtt-kafka-reflect --create-namespace --wait
NAME: zilla-mqtt-kafka-reflect-kafka
LAST DEPLOYED: [...]
NAMESPACE: zilla-mqtt-kafka-reflect
STATUS: deployed
REVISION: 1
TEST SUITE: None
+ helm upgrade --install asyncapi-mqtt-proxy-mosquitto chart --namespace asyncapi-mqtt-proxy --create-namespace --wait
NAME: asyncapi-mqtt-proxy-mosquitto
LAST DEPLOYED: Tue Sep 19 18:15:07 2023
NAMESPACE: asyncapi-mqtt-proxy
STATUS: deployed
REVISION: 1
TEST SUITE: None
+ kubectl port-forward --namespace asyncapi-mqtt-proxy service/asyncapi-mqtt-proxy-zilla 7183
+ nc -z localhost 7183
+ kubectl port-forward --namespace asyncapi-mqtt-proxy service/mosquitto 1883
+ sleep 1
+ nc -z localhost 7183
Connection to localhost port 7183 [tcp/ibm-mqisdp] succeeded!
+ nc -z localhost 1883
Connection to localhost port 1883 [tcp/idmaps] succeeded!

Install mqtt client

Requires MQTT 5.0 client, such as Mosquitto clients.

brew install mosquitto

Verify behavior

Connect a subscribing client to mosquitto broker to port 1883. Using mosquitto_pub client publish {"id":"1","status":"on"} to Zilla on port 7183. Verify that the message arrived to on the first client.

mosquitto_sub -V '5' -t 'smartylighting/streetlights/1/0/event/+/lighting/measured' -d

output:

Client null sending CONNECT
Client auto-5A1C0A41-0D16-497D-6C3B-527A93E421E6 received CONNACK (0)
Client auto-5A1C0A41-0D16-497D-6C3B-527A93E421E6 sending SUBSCRIBE (Mid: 1, Topic: smartylighting/streetlights/1/0/event/+/lighting/measured, QoS: 0, Options: 0x00)
Client auto-5A1C0A41-0D16-497D-6C3B-527A93E421E6 received SUBACK
Subscribed (mid: 1): 0
{"id":"1","status":"on"}

mosquitto_pub -V '5' -t 'smartylighting/streetlights/1/0/event/1/lighting/measured' -m '{"id":"1","status":"on"}' -d -p 7183

output:

Client null sending CONNECT
Client 244684c7-fbaf-4e08-b382-a1a2329cf9ec received CONNACK (0)
Client 244684c7-fbaf-4e08-b382-a1a2329cf9ec sending PUBLISH (d0, q0, r0, m1, 'smartylighting/streetlights/1/0/event/1/lighting/measured', ... (24 bytes))
Client 244684c7-fbaf-4e08-b382-a1a2329cf9ec sending DISCONNECT

Now attempt to publish an invalid message, with property stat instead of status.

mosquitto_pub -V '5' -t 'smartylighting/streetlights/1/0/event/1/lighting/measured' -m '{"id":"1","stat":"off"}' -d -p 7183 --repeat 2 --repeat-delay 3

output:

Client null sending CONNECT
Client e7e9ddb0-f8c9-43a0-840f-dab9981a9de3 received CONNACK (0)
Client e7e9ddb0-f8c9-43a0-840f-dab9981a9de3 sending PUBLISH (d0, q0, r0, m1, 'smartylighting/streetlights/1/0/event/1/lighting/measured', ... (23 bytes))
Received DISCONNECT (153)
Error: The client is not currently connected.

Note that the invalid message is rejected with error code 153 payload format invalid, and therefore not received by the subscriber.

Teardown

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

./teardown.sh

output:

+ + pgrep kubectl
99998
99999
+ killall kubectl
+ helm uninstall asyncapi-mqtt-proxy asyncapi-mqtt-proxy-mosquitto --namespace asyncapi-mqtt-proxy
release "asyncapi-mqtt-proxy" uninstalled
release "asyncapi-mqtt-proxy-mosquitto" uninstalled
+ kubectl delete namespace asyncapi-mqtt-proxy
namespace "asyncapi-mqtt-proxy" deleted