Configuration Reference¶

Every Selkies based container is configured through environment variables. This page collects all of them in one place. They fall into three groups:

1. Container variables: standard LinuxServer.io conventions plus Selkies baseimage options (ports, auth, GPU, language).
2. Selkies application settings (SELKIES_*): transport, stream, client UI, and feature toggles, with a locking syntax.
3. Hardening variables: lockdown options covered in detail on the Security page.

Standard LinuxServer variables¶

These work in every LinuxServer.io container:

Baseimage variables¶

WATERMARK_LOCATION values: 1 top left, 2 top right, 3 bottom left, 4 bottom right, 5 centered, 6 animated.

How the baseimage feeds Selkies¶

The Selkies server reads its own SELKIES_* variables, and the baseimage's init scripts translate the container level variables above into them. A few of those translations are worth knowing because they change the defaults you would otherwise read off the upstream project:

Everything the container does not translate keeps its upstream default. Two of those are worth knowing: SELKIES_CONGESTION_CONTROL is on, and only acts once a session runs under CBR, and SELKIES_USE_PAINT_OVER_QUALITY is on because Turbo mode is off.

HARDEN_DESKTOP=true also sets SELKIES_FILE_TRANSFERS to empty, turns SELKIES_PRINTING_ENABLED off, and hides the files and apps sidebar sections unless you set those variables yourself. Anything you pass explicitly always wins over these defaults.

Selkies application settings¶

Every facet of the streaming application can be configured with SELKIES_* variables. These also drive what the user can change in the sidebar UI: the server sends the resolved settings schema to the client, so a locked or single valued setting simply has no control to change.

Each setting is also a CLI flag with the same name, SELKIES_VIDEO_CRF is --video-crf. Precedence is CLI flag, then the SELKIES_* variable, then the legacy container variable where one exists (PASSWORD, DRI_NODE, and so on), then the built in default. The upstream Settings Reference is generated from the server's own definitions and is the authoritative list; this page describes the same settings as the containers ship them.

Value syntax¶

• Booleans and locking. true or 1 (case insensitive) is on, anything else is off. Append |locked to prevent the user changing the setting in the UI: -e SELKIES_USE_CPU="true|locked"
• Enums and lists. Comma separated values, the first item is the default and the full list is what the user may pick from. A single item hides the UI dropdown entirely: -e SELKIES_ENCODER="jpeg". Matching is case insensitive and invalid items are dropped; if nothing valid is left the built in menu is kept.
• Ranges. Three forms. min-max restricts the allowed span and keeps the built in initial value: SELKIES_FRAMERATE="8-120". A bare value sets the initial value and keeps the built in span, widening it when the value falls outside: SELKIES_FRAMERATE="60". Both at once: SELKIES_FRAMERATE="60,8-120". A degenerate span such as "60-60" locks the setting.
• Empty means default. Setting a variable to "" means "use the built in default", except for list type settings where "" or none means disabled (for example SELKIES_FILE_TRANSFERS).
• Manual resolution. Setting SELKIES_MANUAL_WIDTH or SELKIES_MANUAL_HEIGHT to a positive value forces manual resolution mode.
• Per user overrides. Some settings say "users may override unless locked": the browser keeps the user's choice for that setting and applies it on later visits, so the variable sets the starting position rather than a fixed value. Append |locked to pin it.

Legacy variables¶

These names are no longer Selkies settings, but the containers still accept them. At startup the init script copies a legacy value into its current equivalent when you have not set the current name yourself, so existing compose files keep working. Prefer the current names for anything new.

Transport¶

Video encoders¶

SELKIES_ENCODER is a comma separated menu of the values below. The first item is the default and the whole list is what the sidebar offers. Every full frame codec is encoded on the GPU when the encoding device has an engine for it, and by the software encoder in the pixelflux build otherwise, so the same menu works on a CPU only host, an Intel or AMD card, and an Nvidia card. The container default is h264enc,h265enc,vp8enc,vp9enc,av1enc,jpeg.

Nvidia has no VP8 or VP9 encode engine, so those two codecs are software on every Nvidia card. AMD has no VP8 or VP9 engine either, and AV1 starts with RDNA 3. Intel carries VP9 and, on Arc and newer integrated graphics, AV1. Run vainfo inside the container to see the encode entry points your card exposes. The same pixelflux wheels also carry a Jetson's Tegra encoder and V4L2 memory to memory engines; this guide covers the three desktop GPU vendors.

How the menu behaves at runtime:

• The host trims the menu. At startup Selkies probes the encoding device once and drops every encoder that neither the GPU nor the pixelflux software build can serve, logging Encoders not served on this host are left off the menu. If the default itself is not served the session starts on the next encoder down the ladder below. The wheels in the containers carry a software encoder for all five codecs, so on a CPU only host the full menu still appears, all of it in software.
• The browser greys out what it cannot decode. Encoders the browser has no decoder for stay in the menu disabled and labelled (Unsupported Browser). A browser that cannot decode the server default steps down one ladder: the codecs this host encodes in hardware, most efficient first (AV1, H.265, VP9, H.264, VP8), then the ones it encodes in software in order of encode time (H.264, AV1, VP8, H.265, VP9), then h264enc-striped, and jpeg last. Only encoders in the allowed menu are stepped to, so a browser facing a single valued locked encoder it cannot play gets an on page error instead.
• Only H.264 and JPEG are striped. H.265, VP8, VP9, and AV1 always encode the whole frame, so they never get the per core parallelism or the dirty stripe savings of the H.264 and JPEG paths. In software they also cost several times the CPU of x264. On a machine whose GPU lacks the engine, keep h264enc first and treat the other codecs as options for GPU hosts.
• Software encoding toggle. The sidebar's CPU encoding switch only appears for a codec the host serves both ways, since it moves the session between the GPU and the software encoder and would be a no-op otherwise. SELKIES_USE_CPU still applies to every full frame codec. While a session encodes in software the sidebar also shows the multithreading switch behind SELKIES_CPU_ENCODE_THREADING.
• Demotion. If pixelflux still cannot serve the codec once capture starts it walks the same ladder itself, the other codecs the host serves in hardware first, then software, then striped H.264, then JPEG, and Selkies rewrites the encoder setting to match, logging no encoder served. Trust the encoder shown in the sidebar over the one you configured.
• 10-bit. SELKIES_VIDEO_10BIT asks for 10 bits per sample where the codec and encoder carry it. The desktop is an 8-bit source, so the extra bits add precision to the color conversion rather than new shades, and a software encoder pays for them in CPU. It is only worth pairing with FullColor 4:4:4, and the sidebar offers it only where the browser's decoder returns a 10-bit picture for that codec.
• Colors. VP8 cannot signal BT.709, so it is encoded and declared BT.601 and looks very slightly different from the other codecs. Firefox before 157 paints AV1 received over WebRTC as BT.601 for the same reason.

Video encoding¶

Audio¶

Display and input¶

Feature toggles and session start state¶

The *_ENABLED variables decide what the server offers at all. The *_ON_START variables decide whether a feature is already running when a client connects, or waits for the user to press its sidebar button. Whatever starts off is not captured at all until it is turned on.

Clipboard, files, and apps¶

A copy a password manager marks as sensitive is kept out of the sidebar's clipboard view and off the local clipboard, and formatted content travels with its plain text so a terminal paste gets text rather than markup.

Webcam¶

The containers create a virtual /dev/video0 and preload a V4L2 interposer so ordinary applications see the browser's camera as a normal webcam. Set NO_WEBCAM to skip all of it.

Gamepads¶

Inside the containers the interposer serves four slots as js0 to js3 and event1000 to event1003. A game's rumble is mixed per slot and played on the controller of the browser driving it; each browser can turn that off in its gamepad section.

Printing and audit¶

The session has a printer named Selkies. Selkies runs the CUPS queue itself as the session user, the containers ship cups-daemon and cups-filters and point CUPS_SERVER at it, and every printed document is turned into a PDF and handed to the browser, which opens its own print dialog. Documents also collect in the sidebar's printing section for reprinting or saving. The queue prints on A4 unless PAPERSIZE names another size such as letter.

Selkies can also post an audit event for each clipboard transfer, file transfer, print, connect, disconnect, recording, and demand camera or microphone request, plus an audit.dropped count once an overflowed queue drains.

Sharing¶

Without a master token the sharing section hands out view only and player links, and a second page opened on the session's own address joins as a controller beside the first rather than taking it over. With a master token the session is in secure mode: every page presents a provisioned token that carries its role, and the fragments are ignored. See Security.

Client UI visibility¶

Server and diagnostics¶

The container's built in Nginx owns the listening ports, TLS, basic auth, and the SUBFOLDER prefix, and the init scripts hand the matching values to Selkies. Use the container variables (CUSTOM_PORT, CUSTOM_HTTPS_PORT, CUSTOM_WS_PORT, CUSTOM_USER, PASSWORD, SUBFOLDER) rather than the Selkies server's own listener (SELKIES_ADDR, SELKIES_PORT, SELKIES_UNIX_SOCKET), HTTPS, and basic auth settings, which exist for running the selkies binary outside these containers.

Display backend¶

Lifecycle hooks¶

Watermark¶

WebRTC networking, STUN, and TURN¶

Setting any of these switches the container into WebRTC mode with the transport switch enabled. They are only meaningful for WebRTC; the WebRTC Transport page explains when you need which.

Optional run configurations¶

Internationalization¶

Set LC_ALL to launch the session in another language:

• -e LC_ALL=zh_CN.UTF-8 Chinese
• -e LC_ALL=ja_JP.UTF-8 Japanese
• -e LC_ALL=ko_KR.UTF-8 Korean
• -e LC_ALL=ar_AE.UTF-8 Arabic
• -e LC_ALL=ru_RU.UTF-8 Russian
• -e LC_ALL=es_MX.UTF-8 Spanish (Latin America)
• -e LC_ALL=de_DE.UTF-8 German
• -e LC_ALL=fr_FR.UTF-8 French
• -e LC_ALL=nl_NL.UTF-8 Dutch
• -e LC_ALL=it_IT.UTF-8 Italian

Hardening variables¶

HARDEN_DESKTOP, HARDEN_OPENBOX, DISABLE_SUDO, DISABLE_TERMINALS, RESTART_APP, and friends are documented with context on the Security and Hardening page.