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Qt6 CMake CI Docker Action – Reproducible Builds on GitHub Actions

Learn why, what, and how to use the Qt6 CMake CI Docker Action for consistent, cross‑platform builds on GitHub Actions.
1 February 2026 by
Suraj Barman

Why Use a Docker‑Based Approach?

Building Qt6 projects in CI often suffers from environment drift: different runner OS versions, varying aqtinstall outputs, and inconsistent CMake/Ninja installations. Docker eliminates these variables by providing a single, immutable Ubuntu image for every run.

  • Identical toolchain on Ubuntu, Windows, and macOS runners
  • No hidden dependency differences
  • Fully reproducible builds across commits
  • Reduced maintenance of platform‑specific scripts

What the Qt6 CMake CI Action Does

The action automates the entire build pipeline inside a Docker container:

  • Installs the requested Qt6 version using aqtinstall
  • Sets up CMake and Ninja (pre‑installed in the image)
  • Executes the CMake configuration and Ninja build steps
  • Runs on any GitHub‑hosted runner while the actual build runs in Linux

How to Use the Action

Add a step to your workflow that references the action and supplies the required inputs.

  • qt-version – The exact Qt6 version (e.g., 6.6.1) – required
  • source-dir – Path to the directory containing CMakeLists.txt; defaults to repository root
  • modules – Space‑separated list of additional Qt add‑on modules (e.g., qtimageformats qtshadertools)

Example Workflow

A minimal GitHub Actions workflow that builds a Qt6 project:

  • name: Build Qt6 Project
  • on: [push, pull_request]
  • jobs:
  • build:
  • runs-on: ubuntu-latest
  • steps:
  • - uses: actions/checkout@v4
  • - name: Install Qt6 and build
  • uses: acc-vcc/qt6-cmake-ci-action@v1
  • with:
  • qt-version: "6.6.1"
  • # modules: "qtimageformats qtshadertools"
  • - name: Upload artifacts
  • uses: actions/upload-artifact@v4
  • with:
  • name: build
  • path: build/

Supported Environments

The action runs on all GitHub‑hosted runners (Ubuntu, Windows, macOS) because the actual build occurs inside a Linux Docker container.

  • Ubuntu‑latest, windows‑latest, macos‑latest runners
  • CMake ≥ 3.24 and Ninja preinstalled in the image
  • All core Qt6 modules (Core, GUI, Widgets, QML) are available by default

Benefits of the Docker‑Based Action

Using this action provides several long‑term advantages for Qt6 developers:

  • Consistent build results regardless of host OS
  • Simplified CI configuration – only the Qt version is required
  • Easy addition of optional Qt modules via the modules input
  • Potential for build caching and faster subsequent runs
  • Extensible for GUI testing (Xvfb/noVNC) and Qt Installer Framework automation