Enable web-based configuration updates

Dockerfile

@@ -33,7 +33,7 @@ RUN --mount=type=cache,target=/root/.cache/pip \
 FROM debian:trixie-slim AS runtime
 
 RUN apt-get update \
-    && apt-get install -y --no-install-recommends ca-certificates iproute2 \
+    && apt-get install -y --no-install-recommends ca-certificates gosu iproute2 \
     && rm -rf /var/lib/apt/lists/* \
     && groupadd --system --gid 10001 drivershub \
     && useradd --system --uid 10001 --gid drivershub --home-dir /app drivershub
@@ -44,7 +44,6 @@ COPY --from=builder --chown=drivershub:drivershub /build/dist/ ./
 COPY --from=builder --chown=drivershub:drivershub /build/src/external_plugins/ ./external_plugins/
 COPY --chown=root:root docker/entrypoint.sh /usr/local/bin/drivershub-entrypoint
 
-USER drivershub
 EXPOSE 7777 8700
 
 ENTRYPOINT ["drivershub-entrypoint"]

README.md

@@ -107,16 +107,35 @@ configure it as follows:
 2. Copy the application ID to `discord_client_id` in
    `config/config.json`.
 3. Create a client secret and copy it to `discord_client_secret`.
-4. Add a bot to the application and copy its token to `discord_bot_token`.
-5. Copy the ID of the Discord server to `discord_guild_id`.
-6. Install the bot in that server.
 
 The callback URL points to the frontend. Do not add `/api` to it. The frontend
 requests the `identify`, `email`, and `role_connections.write` OAuth scopes.
 
-Give the bot only the permissions that your configuration needs. It needs
-access to channels where it sends messages. Give it **Manage Roles** if the Hub
-must change roles. Put the bot role above every role that it must manage. The
+This configuration is sufficient for Discord sign-in and account connections.
+A Discord bot is optional. Create and install a bot only if the Hub must check
+server membership, use server nicknames, manage roles, or send messages and
+direct notifications. For these functions:
+
+1. Add a bot to the Discord application and copy its token to
+   `discord_bot_token`.
+2. Copy the ID of the Discord server to `discord_guild_id`.
+3. Install the bot in that server.
+
+Give the bot only the permissions that these functions need. It needs access to
+channels where it sends messages. Give it **Manage Roles** if the Hub must
+change roles. Put the bot role above every role that it must manage.
+
+If you do not install a bot, use these settings:
+
+```json
+"must_join_guild": false,
+"use_server_nickname": false,
+"discord_guild_id": "",
+"discord_bot_token": ""
+```
+
+The external `discord-member` plugin also requires the bot, but the built-in
+functions listed above do not depend on that plugin. The
 [Discord OAuth2 documentation](https://docs.discord.com/developers/topics/oauth2)
 explains application installation and OAuth2 settings.
 
@@ -164,6 +183,24 @@ connect. Add `truckersmp` if a TruckersMP connection is mandatory. For example:
 Restart the backend after you change these settings. You do not have to rebuild
 an image for changes in `config/config.json`.
 
+## Edit the configuration in the Hub
+
+The administration interface can save and apply application configuration
+changes. The container sets the owner of the bind-mounted `config/` directory
+to its internal user, UID and GID `10001`, when it starts. It then runs the
+backend as that unprivileged user. This lets the backend create
+`config.json.saved` and replace `config.json`. Both files stay in the project
+directory on the host.
+
+The administrator needs the `update_config` permission to save changes and the
+`reload_config` permission to apply them. The default `administrator`
+permission also grants access to these operations. The administrator must
+enable MFA before applying a saved configuration.
+
+The start process can change the numeric owner of files in `config/` to
+`10001:10001` on the host. Use an account with sufficient permissions when you
+edit these files directly. Do not make the directory writable by all users.
+
 ## Start the deployment
 
 ```bash

docker/entrypoint.sh

@@ -2,6 +2,10 @@
 # Start a compiled program.
 set -eu
 
+if [ "$(id -u)" = "0" ] && [ -d /app/config ]; then
+    chown -R drivershub:drivershub /app/config
+fi
+
 if [ "${TRUST_HOST_PROXY:-0}" = "1" ]; then
     proxy_ip="$(ip -4 route show default | sed -n 's/^default via \([^ ]*\).*/\1/p' | head -n 1)"
     if [ -z "$proxy_ip" ]; then
@@ -13,12 +17,12 @@ fi
 
 if [ "${1:-}" = "drivershub" ]; then
     shift
-    exec /app/drivershub "$@"
+    exec gosu drivershub /app/drivershub "$@"
 fi
 
 if [ "${1:-}" = "bannergen" ]; then
     shift
-    exec /app/bannergen "$@"
+    exec gosu drivershub /app/bannergen "$@"
 fi
 
-exec "$@"
+exec gosu drivershub "$@"