Add Discover logging patch and Firefox to vnc-desktop image

Adds a discover-logging/ build step that fetches the plasma-discover
source, instruments PKTransaction.cpp with qWarning calls at key points
(trigger, statusChanged, progressChanged, cleanup, errorFound,
installFile) to diagnose hanging .deb installs, then rebuilds and
reinstalls the patched packagekit-backend.so.

Also installs Firefox via the Mozilla apt repo (Ubuntu 24.04 ships
Firefox as a snap which doesn't work in the container).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

nixos/vnc-desktop/Dockerfile

@@ -22,6 +22,21 @@ RUN apt-get purge -y --auto-remove bluez bluez-obexd 2>/dev/null || true; \
     rm -f /usr/share/dbus-1/services/org.bluez.obex.service \
           /usr/share/dbus-1/system-services/org.bluez.service
 
+# Firefox via Mozilla apt repo (Ubuntu 24.04 ships Firefox as snap by default)
+RUN apt-get install -y --no-install-recommends wget ca-certificates gnupg \
+    && wget -qO- https://packages.mozilla.org/apt/repo-signing-key.gpg \
+       | gpg --dearmor > /usr/share/keyrings/packages.mozilla.org.gpg \
+    && echo "deb [signed-by=/usr/share/keyrings/packages.mozilla.org.gpg] https://packages.mozilla.org/apt mozilla main" \
+       > /etc/apt/sources.list.d/mozilla.list \
+    && printf 'Package: *\nPin: origin packages.mozilla.org\nPin-Priority: 1000\n' \
+       > /etc/apt/preferences.d/mozilla \
+    && apt-get update \
+    && apt-get install -y --no-install-recommends firefox \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY discover-logging/ /discover-logging/
+RUN chmod +x /discover-logging/build.sh && /discover-logging/build.sh
+
 COPY start.sh /start.sh
 RUN chmod +x /start.sh
 

nixos/vnc-desktop/discover-logging/build.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Enable deb-src so apt-get source works
+sed -i 's/^Types: deb$/Types: deb deb-src/' /etc/apt/sources.list.d/ubuntu.sources
+
+apt-get update -qq
+
+apt-get install -y --no-install-recommends \
+    dpkg-dev \
+    build-essential \
+    devscripts \
+    python3
+
+apt-get build-dep -y plasma-discover
+
+cd /tmp
+apt-get source plasma-discover
+
+SRC_DIR=$(ls -d /tmp/plasma-discover-*/)
+
+# Apply logging patch
+python3 /discover-logging/patch.py "$SRC_DIR/libdiscover/backends/PackageKitBackend/PKTransaction.cpp"
+
+cd "$SRC_DIR"
+DEB_BUILD_OPTIONS=nocheck dpkg-buildpackage -b -uc -us -j"$(nproc)"
+
+# Install the rebuilt packages (packagekit-backend.so lives in plasma-discover_*.deb)
+dpkg -i /tmp/plasma-discover_*.deb
+
+# Clean up to keep image lean
+rm -rf /tmp/plasma-discover-* /tmp/*.deb /tmp/*.dsc /tmp/*.tar.*

nixos/vnc-desktop/discover-logging/patch.py

@@ -0,0 +1,84 @@
+#!/usr/bin/env python3
+"""
+Patch PKTransaction.cpp to add verbose logging so we can diagnose
+why installs hang on "Installing..." status.
+"""
+import sys
+
+def replace_once(src, old, new, label):
+    count = src.count(old)
+    if count != 1:
+        print(f"ERROR: '{label}' matched {count} times (expected 1)", file=sys.stderr)
+        sys.exit(1)
+    return src.replace(old, new)
+
+path = sys.argv[1]
+with open(path) as f:
+    src = f.read()
+
+# 1. trigger(): log what phase we're entering and with what flags
+src = replace_once(src,
+    'void PKTransaction::trigger(PackageKit::Transaction::TransactionFlags flags)\n{',
+    'void PKTransaction::trigger(PackageKit::Transaction::TransactionFlags flags)\n{\n'
+    '    qWarning() << "[DISCOVER] trigger(): flags=" << flags << "role=" << role();',
+    'trigger() header'
+)
+
+# 2. statusChanged(): log the raw PK status instead of the collapsed UI status
+src = replace_once(src,
+    'void PKTransaction::statusChanged()\n{'
+    '\n    setStatus(m_trans->status() == PackageKit::Transaction::StatusDownload ? Transaction::DownloadingStatus : Transaction::CommittingStatus);',
+    'void PKTransaction::statusChanged()\n{'
+    '\n    qWarning() << "[DISCOVER] statusChanged(): pk_status=" << m_trans->status()'
+    ' << "percentage=" << m_trans->percentage()'
+    ' << "lastPackage=" << m_trans->lastPackage();'
+    '\n    setStatus(m_trans->status() == PackageKit::Transaction::StatusDownload ? Transaction::DownloadingStatus : Transaction::CommittingStatus);',
+    'statusChanged() body'
+)
+
+# 3. progressChanged(): log when percentage updates (or fails to)
+src = replace_once(src,
+    '    auto percent = m_trans->percentage();\n    if (percent == 101) {\n        qWarning() << "percentage cannot be calculated";',
+    '    auto percent = m_trans->percentage();\n'
+    '    qWarning() << "[DISCOVER] progressChanged(): raw_pct=" << percent << "pk_status=" << m_trans->status();\n'
+    '    if (percent == 101) {\n        qWarning() << "percentage cannot be calculated";',
+    'progressChanged() body'
+)
+
+# 4. cleanup(): log the exit/cancel/failed/simulate flags
+src = replace_once(src,
+    'void PKTransaction::cleanup(PackageKit::Transaction::Exit exit, uint runtime)\n{',
+    'void PKTransaction::cleanup(PackageKit::Transaction::Exit exit, uint runtime)\n{\n'
+    '    const bool _simulate_flag = m_trans && (m_trans->transactionFlags() & PackageKit::Transaction::TransactionFlagSimulate);\n'
+    '    qWarning() << "[DISCOVER] cleanup(): exit=" << exit << "runtime=" << runtime'
+    ' << "simulate=" << _simulate_flag'
+    ' << "proceedFunctions=" << m_proceedFunctions.size();',
+    'cleanup() header'
+)
+
+# 5. errorFound(): log every error, including ones currently silently swallowed
+src = replace_once(src,
+    'void PKTransaction::errorFound(PackageKit::Transaction::Error err, const QString &error)\n{'
+    '\n    if (err == PackageKit::Transaction::ErrorNoLicenseAgreement || err == PackageKit::Transaction::ErrorTransactionCancelled'
+    '\n        || err == PackageKit::Transaction::ErrorNotAuthorized) {'
+    '\n        return;\n    }',
+    'void PKTransaction::errorFound(PackageKit::Transaction::Error err, const QString &error)\n{'
+    '\n    qWarning() << "[DISCOVER] errorFound(): err=" << err << "detail=" << error;'
+    '\n    if (err == PackageKit::Transaction::ErrorNoLicenseAgreement || err == PackageKit::Transaction::ErrorTransactionCancelled'
+    '\n        || err == PackageKit::Transaction::ErrorNotAuthorized) {'
+    '\n        return;\n    }',
+    'errorFound() body'
+)
+
+# 6. LocalFilePKResource path: log the .deb path being installed
+src = replace_once(src,
+    '        m_trans = PackageKit::Daemon::installFile(QUrl(app->packageName()).toLocalFile(), flags);',
+    '        qWarning() << "[DISCOVER] installFile():" << QUrl(app->packageName()).toLocalFile() << "flags=" << flags;\n'
+    '        m_trans = PackageKit::Daemon::installFile(QUrl(app->packageName()).toLocalFile(), flags);',
+    'installFile() call'
+)
+
+with open(path, 'w') as f:
+    f.write(src)
+
+print(f"Patched {path}")