update_site_environment

Send the whole list every time, in the order the lines run. Each line is one of:

Line	Shape	What it does
Install packages	{ "type": "packages", "packages": ["ffmpeg"] }	Installs Debian 12 packages with apt. A line holds at most 50 packages.
Run command	{ "type": "command", "command": "..." }	Runs one shell command as root while the machine image is built. A command holds at most 2,000 characters and fails as soon as any part of it fails.

An empty list puts the site back on the standard environment, and undo_site_environment goes back to the last environment that worked.

Every line is built twice, once for the preview and once for the live site and its publish build. Both start with the same tools: Python 3, curl, make and g++, but not pip or gnupg. Install whatever a command uses in a packages line above it, for example python3-pip before pip install --break-system-packages pandas. A line cannot use or install git, because the preview keeps it turned off. For a headless browser, install chromium and launch it from /usr/bin/chromium with playwright-core or puppeteer-core, since their own browser downloads land where the site cannot read them.

Modulify's own base comes first and its own setup comes last, and neither can change. A command cannot change /app, Node.js, npm, setpriv, git or the appuser account, setuid permissions are removed, and the preview and the live site both run as appuser.

A build takes a few minutes. Read how it went with get_site_environment. A build that fails changes nothing, because the machines keep the last build that worked, and the preview only moves to a build it starts on. Saving the same lines again does nothing while they are queued, building or built, and builds them again after a failure. The lines can add at most 2 GB on top of the base, and a build is stopped after 20 minutes. On a paid plan a site holds 20 lines and can be saved 20 times a day. See Environment.

Pass linesHash, the LinesHash that get_site_environment returned, and a save made after the lines changed, in the Environment tab, from chat or from another client, is refused with a 409 reading The environment changed since it was read, so nothing was saved. Read it again and save your change on top of the lines it holds now! instead of overwriting that change.

Inputs

Input	Type	Required	Description
projectId	string	Yes	The site id.
lines	array of objects	Yes	Every line of the environment, in the order they run. Each one is a packages line with its packages list or a command line with its command. Send an empty list to go back to the standard environment.
linesHash	string	No	The LinesHash from get_site_environment for the lines this change starts from. When the saved lines changed since, nothing is saved and the call is refused with a 409. Leave it out to save regardless.