sdks/go/examples/wasm/README.md

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# Overview

wasm is an **_EXPERIMENTAL_** simple example that loads and executes a wasm file function.
greet.wasm, Cargo.toml and greet.rs were copied from the example provided by the wazero library:
https://github.com/tetratelabs/wazero/blob/v1.0.0-pre.3/examples/allocation/rust/greet.go

# Usage

To run this example in various runners, the following assumes:

```
OUTPUT=<path to output i.e. /tmp/example/output>
git clone https://github.com/apache/beam
BEAM_HOME=$(pwd)/beam
cd $BEAM_HOME/sdks
```

## Local Runner execution

To execute this example on the local runner:

```shell
go run ./go/examples/wasm --output=$OUTPUT
```

## Flink Portable Runner

The following describes how to execute this example on the flink portable runner.

### REQUIREMENTS:

- [Docker](https://docker.io); MacOS users may consider alternative: https://github.com/abiosoft/colima
- Google Cloud Storage (https://cloud.google.com/storage) or S3 (https://aws.amazon.com/s3/) bucket;
NOTE this example was only tested on Google Cloud Storage

#### 0. Set OUTPUT to a Cloud storage bucket path

The example below shows Google Cloud Storage.
```
OUTPUT=gs://<my bucket>/greet
```

#### 1. Find the latest flink runner version

```shell
cd $BEAM_HOME
./gradlew :runners:flink:properties --property flink_versions
```

Expected output should include the following, from which you acquire the latest flink runner version.

```shell
'flink_versions: 1.17,1.18,1.19'
```

#### 2. Set to the latest flink runner version i.e. 1.16

```shell
FLINK_VERSION=1.16
```

#### 3. In a separate terminal, start the flink runner (It should take a few minutes on the first execution)
```shell
cd $BEAM_HOME
./gradlew :runners:flink:$FLINK_VERSION:job-server:runShadow
```

Note the JobService host and port from the output, similar to:

```shell
INFO: JobService started on localhost:8099
```

#### 4. Set the JOB_SERVICE variable from the aforementioned output

```shell
JOB_SERVICE=localhost:8099
```

#### 5. Execute this example using the portable flink runner

```shell
cd $BEAM_HOME/sdks
go run ./go/examples/wasm --runner=universal --endpoint=$JOB_SERVICE --output=$OUTPUT --environment_config=apache/beam_go_sdk:latest
```

## Dataflow Runner

The following describes how to execute this example on Dataflow.

### REQUIREMENTS:

- Google Cloud Storage (https://cloud.google.com/storage) bucket

#### 1. Set OUTPUT to a Cloud storage bucket path

The example below shows Google Cloud Storage.

```shell
OUTPUT=gs://<my bucket>/greet
```

#### 2. Set additional variables

```shell
PROJECT=<project id>
REGION=<region>
STAGING=gs://<my bucket>/staging
NETWORK=<network>
SUBNETWORK=regions/$REGION/subnetworks/<subnetwork>
```

#### 3. Execute this example using Dataflow

```
cd $BEAM_HOME/sdks
go run ./go/examples/wasm --runner=dataflow --output=$OUTPUT --environment_config=apache/beam_go_sdk:latest \
    --project=$PROJECT --region=$REGION --network=$NETWORK --subnetwork=$SUBNETWORK --staging_location=$STAGING
```