fix(viewer): send Accept-Language from system locale - #2878
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vpetersson merged 4 commits intoMay 12, 2026
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The Qt WebEngine in AnthiasWebview never set an Accept-Language header, so multi-language URL assets served their default (typically English) regardless of how the Pi's locale was configured. Plumb the host's locale through: bind-mount /etc/default/locale into the viewer container, source it in start_viewer.sh, and have the C++ webview build an RFC 7231 header from QLocale::system().uiLanguages(). A Pi configured with LANG=nl_NL.UTF-8 now advertises nl-NL,nl;q=0.9,en-US;q=0.8,en;q=0.7 to origin servers. Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>
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Pull request overview
This PR addresses multi-language URL assets rendering in the wrong language by propagating the host locale into the viewer/webview process and using it to set an Accept-Language header in QtWebEngine (fixes issue #480).
Changes:
- Build an RFC 7231
Accept-Languagevalue fromQLocale::system().uiLanguages()and apply it to the sharedQWebEngineProfile. - Source
/etc/default/localein the viewer startup script and preserve locale env vars across thesudo -u viewerboundary. - Bind-mount
/etc/default/localeinto the viewer container viadocker-compose.yml.tmpl.
Reviewed changes
Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
webview/src/view.cpp |
Derives Accept-Language from system UI languages and sets it on the default QtWebEngine profile. |
bin/start_viewer.sh |
Loads locale env from /etc/default/locale and preserves LANG/LANGUAGE/LC_ALL into the viewer process. |
docker-compose.yml.tmpl |
Mounts /etc/default/locale into the viewer container to surface host locale settings. |
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Bind-mounting /etc/default/locale was risky: when the file is missing on the host (some minimal RPi OS / x86 images), Docker silently creates an empty *directory* at the mount path on the host, then maps it into the container — where the start_viewer.sh source would fail. Drop the bind mount and forward LANG/LANGUAGE through compose envsubst instead: upgrade_containers.sh sources /etc/default/locale before templating, so docker-compose.yml ends up with the host's locale baked into the viewer service's environment block. No host filesystem mutation, no compose-time bind dependency. Same change extends the fix to balena: the balena supervisor injects Device / Service Variables as env vars into the running container, so setting LANG=nl_NL.UTF-8 in the balena dashboard now reaches AnthiasWebview without any compose mount. Add discoverability comments in both balena compose templates. Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>
Document how to override the device locale on Raspberry Pi OS (via update-locale) and on balena (via Device Variable) so multi-language URL assets serve the right language. Companion to the Accept-Language plumbing in the viewer. Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>
Two Copilot review follow-ups on the locale plumbing:
* `LC_ALL` was missing from the envsubst forwarding — some operators
configure their locale via `LC_ALL` rather than `LANG`/`LANGUAGE`.
Add it to the viewer service's environment block and the sudo
--preserve-env allowlist (the latter was already in place).
* `envsubst` substitutes `${LANG}` to an empty string when LANG is
unset on the host, which means the viewer container starts with
`LANG=""` — semantically different from "unset" and capable of
overriding image defaults that downstream consumers (Python's
`locale`, libc helpers) rely on. Strip empty locale vars in
`start_viewer.sh` before launch so an unconfigured host leaves the
container's image defaults in place.
Reword the comment block so "issue 480" doesn't visually collide with
the YAML `#` comment marker.
Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>
|
vpetersson
added a commit
that referenced
this pull request
May 12, 2026
* Master's #2881 (e2e-test findings) added an `installer_venv` persistent venv provisioned by `bin/install.sh::provision_host_agent_venv` and kept the systemd unit ExecStart pointed at that stable path. Drops the duplicate ansible-side `.anthias-venv` task and reverts the unit-template path I'd introduced — master's approach is upstream and avoids rewriting the unit path on devices installed pre-refactor. * Master's #2880 replaced the gum UI with whiptail. The auto-merge took whiptail's wiring; my arm64-aware INTRO_MESSAGE / set_device_type / Pi-tag-skip branches survived alongside it. * Master's #2878 viewer locale changes auto-merged with my arm64 start_viewer.sh conditional. Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>
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Issues Fixed
Closes #480.
Description
AnthiasWebview(the Qt WebEngine binary that renders URL assets) never set anAccept-LanguageHTTP header, so multi-language sites always served their default — typically English — regardless of how the device's locale was configured.Plumb the host locale through to the viewer container:
webview/src/view.cpp— build an RFC 7231Accept-Languagevalue fromQLocale::system().uiLanguages()(which honorsLANGUAGE/LC_ALL/LANGper the GNU gettext convention) and set it on the sharedQWebEngineProfile. A Pi withLANG=nl_NL.UTF-8now advertisesnl-NL,nl;q=0.9,en-US;q=0.8,en;q=0.7. SkipsC/POSIXso a misconfigured device falls back to QtWebEngine's default rather than to "C".bin/upgrade_containers.sh— source/etc/default/localebeforeenvsubstruns, so the host's configuredLANG/LANGUAGEend up baked into the generateddocker-compose.yml.docker-compose.yml.tmpl— declareLANG=${LANG}/LANGUAGE=${LANGUAGE}in the viewer service'senvironment:block; envsubst fills them in at compose-generation time. No host bind mount, so there's no risk of Docker silently creating an empty directory at the mount path when/etc/default/localedoesn't exist.bin/start_viewer.sh— addLANG/LANGUAGE/LC_ALLtosudo --preserve-envso the env vars survive the drop from root to thevieweruser on both Pi and x86 (cage) paths.docker-compose.balena.yml.tmpl/docker-compose.balena.dev.yml.tmpl— comment explaining that balena operators setLANGas a Device or Service Variable in the dashboard; the balena supervisor injects dashboard variables as container env vars at runtime, so no compose entry is needed.website/data/faq.yaml— FAQ entry walking the operator through setting the locale on Raspberry Pi OS (sudo update-locale) and balena (Device Variable).Checklist