bluebluesoda
ef5be89643
- drop the four on-screen arrow buttons: a physical keyboard already sends them, and the app-cursor mode that made them awkward is handled by keySequence - add a Paste button that reads the clipboard and hands the text to the shell the same way a browser paste does, bracketed paste included - report a refusal (no secure context or permission) instead of looking dead, and fall back to Ctrl+V
82 lines
4.0 KiB
Markdown
82 lines
4.0 KiB
Markdown
# Web SSH
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A terminal in the browser: a shell inside the user's own container, opened from
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the Machine card (next to Start / Stop / Restart) in the user panel.
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It is not an SSH client. The container runs on the panel host, so the panel
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talks to it through the Incus exec API over the daemon's unix socket, with a
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PTY. Nothing listens on the container side, there are no keys to hand out, and
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there is no extra network path to arrange.
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## Shape of it
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- **Its own window.** The button opens a separate browser window rather than a
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dialog, so it can be dragged to any size, moved to another screen or
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maximised. It remembers the size it was last dragged to and reopens that way.
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- **Root shell.** The shell runs as root inside the account's own container,
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which is the same access the user already has over SSH. The container is
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always taken from the session: a client cannot name a container it does not
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own.
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- **One account, two shells.** A third connection is offered the option to close
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the others instead of being refused, which is also how a slot held by a closed
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window is reclaimed.
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## Surviving a bad connection
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The panel is often reached from far away, so the browser side is built to
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survive the link rather than to be torn down by it.
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- **Liveness.** The server pings every 20 seconds and treats 60 seconds of
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silence as gone. The browser answers pings from its network stack, so this
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works in a backgrounded tab too, and a connection that disappears without
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saying so is noticed in about a minute.
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- **Reconnect.** The page hears a small heartbeat the server sends alongside the
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protocol pings; hearing nothing for 45 seconds means the socket is dead even
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though it has not said so. It then reconnects with exponential backoff and
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jitter, up to eight attempts, after which a manual *Reconnect* is offered.
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- **Resume.** The shell outlives the socket: when the client goes away the PTY
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keeps running for 120 seconds and its output goes into a bounded buffer
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(256 KiB, with a notice if anything is dropped). A client that comes back with
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its session token resumes the *same* shell — a running build, an open editor
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and the shell's variables are all still there.
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- **Redraw.** A resumed terminal starts blank and is rebuilt from the buffered
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output, so a full-screen program is asked to repaint itself; if one does not,
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`Ctrl+L` forces it.
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- **Token.** The resume token lives in `sessionStorage`, so reloading the page
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comes back to the shell and closing the window lets it go.
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## Keys and the mouse
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Typing works as it does in any terminal: arrows, Home/End, PageUp/PageDown,
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Insert/Delete, Tab, Escape and the function keys all send what a terminal sends,
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and the arrows follow the mode a full-screen program asks for.
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A small bar above the terminal carries the few keys a browser keeps for itself
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(Ctrl+C, Ctrl+Z, Ctrl+D, Escape, Tab), so they are never out of reach, plus a
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**Paste** button. It reads the clipboard through the browser's clipboard API,
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so it needs a secure context and permission; if either is missing the bar says
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so, and Ctrl+V still works.
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Selecting text is left to the browser, so it works like text anywhere: drag
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across the terminal to select, double-click a word, and the selection survives
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output arriving underneath it — a repaint puts the highlight back. **Ctrl+C**
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(or **Cmd+C**) copies a selection, and interrupts the running command when
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there is none, which is the rule a desktop terminal follows; the right-click
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menu offers Copy too.
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Pasting uses the platform's shortcuts — Cmd+V/Ctrl+V, Shift+Insert — and a
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block of several lines is handed to the shell exactly as the shell asked for
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it: a shell with bracketed paste enabled shows the text in its edit buffer
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first.
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## Turning it off
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```
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vps config set panel.web_ssh false
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```
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The panel restarts and the feature is off: the button is not rendered, and the
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terminal page, its script and the terminal connection all refuse. `true` (the
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default) turns it back on. A configuration written before this feature existed
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comes out enabled.
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