[snap] GUI-less snap Launchpad integration

.github/workflows/lint.yml

@@ -91,3 +91,9 @@ jobs:
             echo "Run '3rd-party/flutter/bin/dart format' to fix formatting."
             exit 1
           fi
+
+      - name: Check gui-less snapcraft.yaml is up to date
+        shell: bash
+        run: |
+          pip install --quiet -r git-hooks/requirements.txt
+          packaging/gui-less/generate-snapcraft.py --check

CMakePresets.json

@@ -76,6 +76,19 @@
                 }
             }
         },
+        {
+            "name": "snap-gui-less",
+            "description": "Preset for snap builds without the GUI.",
+            "inherits": [
+                "snap"
+            ],
+            "cacheVariables": {
+                "MULTIPASS_ENABLE_FLUTTER_GUI": {
+                    "type": "BOOL",
+                    "value": "OFF"
+                }
+            }
+        },
         {
             "name": "snap-debug",
             "description": "Preset for snap builds in CI for test runs (debug).",

CONTRIBUTING.md

@@ -230,6 +230,9 @@ code injection (now or in the future).
     * `git config --local commit.template .gitmessage`
 - Consider adding the `commit-msg` file in the repository root as a git hook (in `.git/hooks`)
     * `ln -s ../../git-hooks/commit-msg.py .git/hooks/commit-msg`
+- Consider adding the `pre-commit` hook to automatically regenerate
+`packaging/gui-less/snap/snapcraft.yaml` when `snap/snapcraft.yaml` changes
+    * `ln -s ../../git-hooks/pre-commit .git/hooks/pre-commit`
 
 ### Dependencies (DEP)
 

git-hooks/pre-commit

@@ -0,0 +1,12 @@
+#!/bin/bash
+# Regenerates packaging/gui-less/snap/snapcraft.yaml when snap/snapcraft.yaml is staged.
+# Install: ln -s ../../git-hooks/pre-commit .git/hooks/pre-commit
+
+set -euo pipefail
+
+if git diff --cached --name-only | grep -q "^snap/snapcraft\.yaml$"; then
+    REPO_ROOT="$(git rev-parse --show-toplevel)"
+    echo "snap/snapcraft.yaml staged — regenerating gui-less variant..."
+    python3 "${REPO_ROOT}/packaging/gui-less/generate-snapcraft.py"
+    git add "${REPO_ROOT}/packaging/gui-less/snap/snapcraft.yaml"
+fi

git-hooks/requirements.txt

@@ -1 +1,2 @@
 pytest
+ruamel.yaml

packaging/gui-less/generate-snapcraft.py

@@ -0,0 +1,92 @@
+#!/usr/bin/env python3
+"""Generates packaging/gui-less/snap/snapcraft.yaml from snap/snapcraft.yaml.
+The transformations here are the authoritative definition of how the gui-less
+variant differs from the main snap.
+
+Usage:
+    ./generate-snapcraft.py          # regenerate packaging/gui-less/snap/snapcraft.yaml
+    ./generate-snapcraft.py --check  # verify it's up to date (for CI)
+"""
+
+import argparse
+import re
+import subprocess
+import sys
+from pathlib import Path
+
+from ruamel.yaml import YAML
+from ruamel.yaml.scalarstring import LiteralScalarString
+
+SCRIPT_DIR = Path(__file__).parent
+INPUT = SCRIPT_DIR / "../../snap/snapcraft.yaml"
+OUTPUT = SCRIPT_DIR / "snap/snapcraft.yaml"
+
+MULTIPASS_SOURCE = "https://github.com/canonical/multipass.git"
+HEADER = (
+    "Generated by packaging/gui-less/generate-snapcraft.py — do not edit directly.\n"
+    "# Edit snap/snapcraft.yaml and re-run the script."
+)
+
+
+def generate(input_path: Path, output_path: Path) -> None:
+    yaml = YAML()
+    yaml.preserve_quotes = True
+    yaml.width = 4096
+
+    data = yaml.load(input_path)
+
+    # Add architectures for gui-less snap
+    data["platforms"]["s390x"] = None
+    data["platforms"]["ppc64el"] = None
+
+    # Remove the GUI app
+    del data["apps"]["gui"]
+
+    # Change multipass part to use remote git source
+    data["parts"]["multipass"]["source"] = MULTIPASS_SOURCE
+
+    # Use a CMake preset to turn off the GUI
+    data["parts"]["multipass"]["build-environment"].append(
+        {"CMAKE_PRESET": "snap-gui-less"}
+    )
+
+    # Change glue part to clone snap-wrappers from remote git source
+    glue = data["parts"]["glue"]
+    glue["source"] = MULTIPASS_SOURCE
+    glue["source-type"] = "git"
+    glue["source-subdir"] = "snap-wrappers"
+
+    data.yaml_set_start_comment(HEADER)
+
+    with output_path.open("w") as f:
+        yaml.dump(data, f)
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--check", action="store_true", help="verify the output is up to date (for CI)")
+    args = parser.parse_args()
+
+    if not INPUT.exists():
+        print(f"ERROR: source file not found: {INPUT}", file=sys.stderr)
+        sys.exit(1)
+
+    generate(INPUT.resolve(), OUTPUT.resolve())
+
+    if args.check:
+        result = subprocess.run(
+            ["git", "diff", "--exit-code", "snap/snapcraft.yaml"],
+            cwd=SCRIPT_DIR,
+        )
+        if result.returncode != 0:
+            print(
+                "ERROR: packaging/gui-less/snap/snapcraft.yaml is out of date.\n"
+                "Run packaging/gui-less/generate-snapcraft.py to update it.",
+                file=sys.stderr,
+            )
+            sys.exit(1)
+        print("packaging/gui-less/snap/snapcraft.yaml is up to date.")
+
+
+if __name__ == "__main__":
+    main()