Use conda-presto in GitHub Actions

The jezdez/conda-presto composite Action can run the checked-out conda-presto CLI on a runner or call an existing HTTP deployment.

Pin the Action to a released tag. The examples use the latest released version at the time this page was written.

Resolve a checked-in environment file

Check out the repository before passing a file to local mode:

name: Resolve environment

on:
  pull_request:
    paths:
      - environment.yml

jobs:
  solve:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: jezdez/conda-presto@v0.8.0
        with:
          file: environment.yml
          platforms: linux-64,osx-arm64

Local mode is the default. The Action uses a commit-pinned setup-pixi action to install Pixi 0.70.1 and runs conda-presto from the pinned Action checkout. It does not require a running server.

Write and upload a lockfile

Set format and output, then use the written file in later steps:

jobs:
  lock:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: jezdez/conda-presto@v0.8.0
        id: solve
        with:
          file: environment.yml
          platforms: linux-64,osx-arm64
          format: pixi-lock-v6
          output: pixi.lock

      - uses: actions/upload-artifact@v4
        if: steps.solve.outputs.solved == 'true'
        with:
          name: pixi-lock
          path: pixi.lock

The solved output is false when native JSON contains a platform error. A request that exits unsuccessfully fails the Action step.

Resolve inline specs

Pass comma-separated specs, channels, and platforms:

- uses: jezdez/conda-presto@v0.8.0
  with:
    specs: python=3.13,numpy,pandas
    channels: conda-forge
    platforms: linux-64,osx-arm64

The Action has no command input. Resolving is its only operation.

Call a hosted deployment

Remote mode sends a JSON request to the deployment’s /resolve endpoint:

- uses: actions/checkout@v4

- uses: jezdez/conda-presto@v0.8.0
  with:
    mode: remote
    endpoint: ${{ vars.CONDA_PRESTO_URL }}
    file: environment.yml
    platforms: linux-64,osx-arm64
    format: conda-lock-v1
    output: conda-lock.yml

Store the base URL without a trailing slash in the repository or organization variable CONDA_PRESTO_URL. Use a secret instead if the URL itself contains sensitive information.

Remote mode requires jq and curl on the runner. GitHub-hosted Ubuntu runners provide both tools. It sends the complete environment file and channel configuration to the endpoint. Use only a trusted HTTPS deployment whose operators are permitted to read that data.

The Action rejects plain HTTP except for localhost, 127.0.0.1, and ::1. It disables curl’s default curlrc configuration, accepts only HTTP 2xx, and validates the native JSON result shape when no exporter format is selected. It does not print response bodies automatically. Use output to write the body to a workspace file, or read the bounded result output in a later step.

Read outputs in another step

Give the solve step an ID, then use its solved and result outputs:

- uses: jezdez/conda-presto@v0.8.0
  id: solve
  with:
    specs: python=3.13,numpy
    platforms: linux-64

- name: Report result
  if: always()
  env:
    SOLVED: ${{ steps.solve.outputs.solved }}
  run: echo "solved=${SOLVED}"

Large response bodies are not copied into result. Set output when another step needs a large solve or lockfile result.

At least one of file or specs must normally provide solve input. Do not add spaces around comma-separated values because the Action passes each value through without trimming it.

Use GitHub Action reference for the complete input, output, and failure contract. Use Output format reference to choose a format and Call the HTTP API to inspect the remote request contract.