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Examples

Addition (Host Runtime)

Addition example using external wasmtime runtime

This is a simple addition example. It takes two numbers as inputs and returns their sum. For this example since we want to use the external wasmtime runtime we need to specify the runtime when starting proplet. For the proplet docker image the wasmtime runtime is already included. It is found in /usr/local/bin/wasmtime. To enable proplet to use this runtime we need to set the WASMTIME_RUNTIME environment variable to /usr/local/bin/wasmtime.

export PROPLET_EXTERNAL_WASM_RUNTIME="/usr/local/bin/wasmtime"
make start-proplet

The logs from the proplet should look like this.

2026-02-13T11:47:58.203643Z  INFO Proplet configuration: PropletConfig { log_level: "debug", instance_id: "9f428638-d8f4-4fe4-9249-4b3dcdb59f14", mqtt_address: "tcp://mqtt-adapter:1883", mqtt_timeout: 30, mqtt_qos: 2, mqtt_keep_alive: 30, mqtt_max_packet_size: 10485760, mqtt_inflight: 10, mqtt_request_channel_capacity: 128, liveliness_interval: 10, metrics_interval: 10, domain_id: "002cbbc7-0834-4ce7-be9e-d57b5fe6cd85", channel_id: "bda8692b-35fa-4d4d-88a7-dc412edfda63", client_id: "a95517f9-5655-4cf5-a7c8-aa00290b3895", client_key: "ea812299-b561-494d-80aa-0f636142f147", k8s_namespace: Some("default"), external_wasm_runtime: Some("/usr/local/bin/wasmtime"), enable_monitoring: true, tee_enabled: false, kbs_uri: None, aa_config_path: None, layer_store_path: "/tmp/proplet/layers", pull_concurrent_limit: 4 }
2026-02-13T11:47:58.203664Z  INFO Starting Proplet (Rust) - Instance ID: 9f428638-d8f4-4fe4-9249-4b3dcdb59f14
2026-02-13T11:47:58.203722Z  INFO MQTT client created (TLS: false)
2026-02-13T11:47:58.203774Z  INFO Using external Wasm runtime: /usr/local/bin/wasmtime
2026-02-13T11:47:58.203846Z  INFO Starting MQTT event loop
2026-02-13T11:47:58.208623Z DEBUG Received MQTT packet: ConnAck(ConnAck { session_present: false, code: Success })
2026-02-13T11:47:58.277561Z  INFO Starting PropletService
2026-02-13T11:47:58.277597Z DEBUG Published to topic: m/002cbbc7-0834-4ce7-be9e-d57b5fe6cd85/c/bda8692b-35fa-4d4d-88a7-dc412edfda63/control/proplet/create
2026-02-13T11:47:58.277603Z  INFO Published discovery message
2026-02-13T11:47:58.277609Z  INFO Subscribed to topic: m/002cbbc7-0834-4ce7-be9e-d57b5fe6cd85/c/bda8692b-35fa-4d4d-88a7-dc412edfda63/control/manager/start
2026-02-13T11:47:58.277620Z  INFO Subscribed to topic: m/002cbbc7-0834-4ce7-be9e-d57b5fe6cd85/c/bda8692b-35fa-4d4d-88a7-dc412edfda63/control/manager/stop
2026-02-13T11:47:58.277626Z  INFO Subscribed to topic: m/002cbbc7-0834-4ce7-be9e-d57b5fe6cd85/c/bda8692b-35fa-4d4d-88a7-dc412edfda63/registry/server
2026-02-13T11:47:58.278883Z DEBUG Published to topic: m/002cbbc7-0834-4ce7-be9e-d57b5fe6cd85/c/bda8692b-35fa-4d4d-88a7-dc412edfda63/control/proplet/alive
2026-02-13T11:47:58.278910Z DEBUG Published liveliness update
2026-02-13T11:47:58.280534Z DEBUG Published to topic: m/002cbbc7-0834-4ce7-be9e-d57b5fe6cd85/c/bda8692b-35fa-4d4d-88a7-dc412edfda63/control/proplet/metrics
2026-02-13T11:47:58.280571Z DEBUG Published proplet metrics
2026-02-13T11:47:58.281366Z DEBUG Received MQTT packet: PubAck(PubAck { pkid: 1 })
2026-02-13T11:47:58.300338Z DEBUG Received MQTT packet: SubAck(SubAck { pkid: 2, return_codes: [Success(AtLeastOnce)] })
2026-02-13T11:47:58.306389Z DEBUG Received MQTT packet: SubAck(SubAck { pkid: 3, return_codes: [Success(AtLeastOnce)] })
2026-02-13T11:47:58.312443Z DEBUG Received MQTT packet: SubAck(SubAck { pkid: 4, return_codes: [Success(AtLeastOnce)] })
2026-02-13T11:47:58.312704Z DEBUG Received MQTT packet: PubAck(PubAck { pkid: 5 })
2026-02-13T11:47:58.312774Z DEBUG Received MQTT packet: PubAck(PubAck { pkid: 6 })

Source Code

The source code is available in the examples/addition directory.

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Create Task

To create a task for this example, we need to build the example to wasm and then create a task with the wasm file.

cd propeller
make addition

Your output should look like this:

GOOS=js GOARCH=wasm tinygo build -buildmode=c-shared -o build/addition.wasm -target wasip1 examples/addition/addition.go

Now we can create a task with the wasm file:

curl -X POST "http://localhost:7070/tasks" \
-H "Content-Type: application/json" \
-d '{"name": "add", "cli_args": ["--invoke", "add"], "inputs": [10, 20]}'

Your output should look like this:

{
  "id": "dc5e4109-5677-4fc0-b12a-6f7dcf216be7",
  "name": "add",
  "kind": "standard",
  "state": 0,
  "cli_args": ["--invoke", "add"],
  "inputs": [10, 20],
  "daemon": false,
  "encrypted": false,
  "start_time": "0001-01-01T00:00:00Z",
  "finish_time": "0001-01-01T00:00:00Z",
  "created_at": "2026-02-13T12:41:28.911748133Z",
  "updated_at": "0001-01-01T00:00:00Z",
  "next_run": "0001-01-01T00:00:00Z",
  "priority": 50
}

Upload Wasm

Now we need to upload the wasm file:

curl -X PUT "http://localhost:7070/tasks/dc5e4109-5677-4fc0-b12a-6f7dcf216be7/upload" \
-F "file=@$(pwd)/build/addition.wasm"

Your output should look like this:

{
  "id": "dc5e4109-5677-4fc0-b12a-6f7dcf216be7",
  "name": "add",
  "kind": "standard",
  "state": 0,
  "file": "...<redacted>...",
  "cli_args": ["--invoke", "add"],
  "inputs": [10, 20],
  "daemon": false,
  "encrypted": false,
  "start_time": "0001-01-01T00:00:00Z",
  "finish_time": "0001-01-01T00:00:00Z",
  "created_at": "2026-02-13T12:41:28.911748133Z",
  "updated_at": "2026-02-13T12:42:01.174016764Z",
  "next_run": "0001-01-01T00:00:00Z",
  "priority": 50
}

Start Task

Now we can start the task:

curl -X POST "http://localhost:7070/tasks/dc5e4109-5677-4fc0-b12a-6f7dcf216be7/start"

Your output should look like this:

{ "started": true }

The results of the task will be something like this.

curl -X GET "http://localhost:7070/tasks/dc5e4109-5677-4fc0-b12a-6f7dcf216be7"

Your output should look like this:

{
  "id": "dc5e4109-5677-4fc0-b12a-6f7dcf216be7",
  "name": "add",
  "kind": "standard",
  "state": 3,
  "file": "...<redacted>...",
  "cli_args": ["--invoke", "add"],
  "inputs": [10, 20],
  "daemon": false,
  "encrypted": false,
  "proplet_id": "a95517f9-5655-4cf5-a7c8-aa00290b3895",
  "results": "30",
  "start_time": "2026-02-13T12:42:24.021570599Z",
  "finish_time": "2026-02-13T12:42:24.157970897Z",
  "created_at": "2026-02-13T12:41:28.911748133Z",
  "updated_at": "2026-02-13T12:42:24.157970797Z",
  "next_run": "0001-01-01T00:00:00Z",
  "priority": 50
}

Invoking Using WasmTime

wasmtime --invoke add ./build/addition.wasm 10 20

The results of the task will be something like this.

warning: using `--invoke` with a function that takes arguments is experimental and may break in the future
warning: using `--invoke` with a function that returns values is experimental and may break in the future
30

Addition WAT

Addition WAT example

Addition (Embedded Proplet)

Addition example on the Embedded Proplet running Zephyr RTOS and WAMR

On this page

Source CodeCreate TaskUpload WasmStart TaskInvoking Using WasmTime