Actism

Run Extism plug-ins as a pipeline on GitHub Actions.

Example

name: test action

on:
  push:
  pull_request:

jobs:
  ci_example_pipelines:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: dylibso/actism@main
        id: actism-image
        with:
          wasi: true
          input: "this is a test"
          output_type: text
          steps: |- # line-delimited set of named plugin calls, where "step()" export is ran
            count vowels | https://github.com/extism/plugins/releases/latest/download/count_vowels.wasm | count_vowels
            convert output to image data | https://cdn.modsurfer.dylibso.com/api/v1/module/271d6599df5fc1c54ddc33c266840123636d2c886e5064a739324f92ae8fc5ac.wasm
            generate png | https://cdn.modsurfer.dylibso.com/api/v1/module/2c9eb901052b1e6397d2414bdb796975407cc87085e6b5fe9564932538d8af51.wasm | handle
      - name: check output
        run: |
          echo '${{steps.actism-image.outputs.output}}' | jq '.value' | base64 -d -i > out.png
      - uses: actions/upload-artifact@v4
        with:
          name: out.png
          path: ./out.png

      - uses: dylibso/actism@main
        id: actism-text
        with:
          wasi: true
          input: "this is a test"
          output_type: text
          steps: |- # line-delimited set of named plugin calls, where "step()" export is ran
            count vowels | https://github.com/extism/plugins/releases/latest/download/count_vowels.wasm | count_vowels
      - name: check output
        run: |
          echo '${{steps.actism-text.outputs.output}}' | grep '"count":4'

The above step with id "actism-image" will count the vowels in the input, convert that to a known format for the image generator, and then use the total count from the first plugin to generate an image with the value encoded. Then the output (out.png) will be uploaded to the summary artifacts on the Action run.

You can combine Extism plug-ins and arbitrary GitHub Action steps to execute pipelines to do anything.

Usage

Within the steps key, you write the pipeline. This must be a line-delimited, "|"-segmented list of Extism plug-ins to run in a pipeline. Components are: name | source (url or path) | function (optional export to call, default = run).

  with:
    wasi: true # enable WASI access to all plugins
    input: '{"some": "data"}' # or `$(cat file.data)` etc. to be used as input to first plugin
    output_type: text # or `bytes` used to tell the runner how to encode the final plugin's output
    steps: |-
      this is plugin 1 | https://.../plugin.wasm
      this is plugin 2 | ./path/to/local.wasm | override_function_name_to_call
      ...

Note: checkout https://modsurfer.dylibso.com for plug-in hosting!

There is no known limit to the number of plug-ins you can call in a single pipeline.

Next Steps

The Extism plug-ins should get host functions that wrap the convenient @actions/core and @actions/github JavaScript package functions, so a plug-in could interact with GitHub Actions more directly.