A Discord bot written in Rust for sending file previews of GitHub URLs and for juxtaposing images.
You can invite the official instance of this bot to your server.
Provides an HTTP API for detailed views of juxtaposed images on the web. The source code of the website used for the official instance of this bot is available here.
A container image can be built by using the provided Dockerfile. It supports fast multi-architecture builds for amd64, aarch64 and arm/v7 using cross compilation instead of emulation. The produced binaries are fully statically-linked using musl and mold. As such, the image is derived from the empty scratch base image and only contains the binary.
Running the bot with the --reload-commands argument will register all slash commands after connecting to the Discord API. This is only necessary on new accounts or after changes to the structure of slash commands.
All environment variables without a default value must be specified, otherwise the application will panic (usually during startup). If a .env file exists within the working directory, the location of the file is logged and it will be parsed and loaded while keeping the values of already existing environment variables.
| Name | Default Value | Description |
|---|---|---|
| BOT_TOKEN | NONE | Secret token for the bot account created in the Discord Developer Portal. |
| BLAKE3_KEY_MATERIAL | NONE | Master secret key for deriving other keys using the BLAKE3 KDF, e.g. the key for creating and validating the HMAC in Juxtapose URLs. |
| JUXTAPOSE_BASE_URL | http://localhost |
Base URL used for viewing juxtaposed images, used for generating URLs for the "Open" button. |
| REDIS_URL | redis://127.0.0.1/ |
URL used for connecting to Redis. Can be either a TCP connection (redis:// or rediss://), or an IPC/UNIX connection (redis+unix://). |
| PORT | NONE | Port number that the HTTP API runs on. |
| SOCKET_PATH | NONE | UNIX Domain Socket path that the HTTP API runs on. Only supported on UNIX systems, takes precendence over PORT. |
| CORS_ORIGIN | * |
Allowed origin domains for CORS. Allows all domains by default, but is highly recommended to be set to a specific domain in production (typically JUXTAPOSE_BASE_URL). |
You can run the provided image using rootless Podman. This section describes how you can use the systemd integration, Quadlets, to setup user-space systemd services for Redis and previewBOT with persistent storage and communication via Unix Domain Sockets.
After creating the .container files at the bottom of this section, run systemctl --user daemon-reload to generate the systemd service files. The configuration makes a few assumptions about the user's home directory.
- All of the folders and files mentioned below are owned and writable by the current user.
~/production/previewbot/previewbot.envis an existing file that contains the environment variables described in the section above. Among other things, it must containREDIS_URL=redis+unix:///run/redis/redis.sock.~/production/redis/datais an existing folder used to store RDB dumps for persistent storage.~/production/redis/conf/redis.confis an existing file with the following content for configuring the Unix Domain Socket.
unixsocket /run/redis/redis.sock
unixsocketperm 666
port 0
Then, run previewBOT using systemctl --user start previewbot.service. previewBOT will be started automatically after rebooting.
~/.config/containers/systemd/previewbot.container
[Unit]
Description=previewBOT container
After=network-online.target
[Container]
Image=ghcr.io/kneemund/previewbot:latest
Volume=redis-unix-socket:/run/redis
EnvironmentFile=%h/production/previewbot/previewbot.env
Network=host
AutoUpdate=registry
[Install]
WantedBy=default.target~/.config/containers/systemd/redis.container
[Unit]
Description=Redis container
After=network-online.target
[Container]
Image=docker.io/redis:alpine
Volume=%h/production/redis/data:/data
Volume=%h/production/redis/conf:/usr/local/etc/redis
Volume=redis-unix-socket:/run/redis
UserNS=keep-id:uid=999,gid=1000
Network=none
AutoUpdate=registry
Exec=redis-server /usr/local/etc/redis/redis.conf
[Install]
WantedBy=previewbot.service