`BASE_PATH=/mail` mounts the whole app under a prefix, for a host that is not
ihasmail's alone. Unset -- every deployment that exists -- is the domain root
and is byte-for-byte what it was: the canonical form of the setting is the
empty string, and `""` concatenated onto `/api/health` is `/api/health`.
That choice of canonical form is the whole design. A trailing slash would have
been the obvious alternative, and it fails quietly in exactly one place: at the
root it makes `//api/health`, which is not a path on this host but a
protocol-relative URL to a host called `api`. One call site forgetting to
branch is a request leaving the origin. So the empty string, one leading slash,
no trailing one, worked out once in `scripts/basePath.mjs` -- plain JS, next to
`version.mjs`, because the web build and the server both have to reach the same
answer and two implementations of "what does /mail/ mean" is precisely the bug
where the server serves an app whose script tags point somewhere else.
`/mail`, `mail`, `/mail/` and `//mail//` all mean the same mount; a deployment
should not fail over a trailing slash.
Unlike everything else ihasmail is told, this one cannot wait for the process
to start. The bundle writes its own asset URLs into index.html, so `BASE_PATH`
is read at build time for Vite's `base` as well as at run time for the routes,
and the Dockerfile carries one value into both. Get them out of step and the
page comes up blank with a 404 in a console nobody has open -- so the static
handler, which is reading index.html anyway, checks what it asks for and says
so in the log once per build.
Everything moves together. The API mounts at `${base}/api`; the router is
given the base once, so every `<Route path>` and `<Link href>` stays written
root-absolute and wouter does the rest; `apiFetch` adds the prefix in one place
rather than at forty call sites; the session cookie's Path narrows to the mount
so two instances on one host cannot sign each other out.
Two things need no prefix at all, and it is worth saying why they were not
given one. A manifest's members resolve against the manifest's own address, so
relative URLs there follow the mount with nothing substituted at build time --
which is also why `public/` needed no template step. The service worker is the
same trick: it is served from the mount, so `new URL("./", self.location)`
tells it where that is, and a worker that derives the value cannot disagree
with the page that registered it.
Anything outside the mount is a 404 rather than the app shell, and
`stripBasePath` does not use `startsWith` -- under `/mail` this process shares
a hostname, and answering `/mailbox` with our index would shadow a neighbour
instead of letting it 404 honestly. For the same reason the notification-click
handler now checks the path as well as the origin: `includeUncontrolled` widens
`matchAll` to the whole origin, which off the root would have navigated a
stranger's tab to our inbox.
Inline images in a draft were the one silent trap. They are matched by their
blob URL on the way out, once unanchored and once anchored, and a bare
`/api/blob/` still appears inside `/mail/api/blob/...` -- so one pattern would
have replaced the tail and left `/mail` in front of a `cid:`, and the other
would have missed and sent the message linking to the sender's own webmail.
Both patterns are built from the base now.
Checking only on a 401 was not automatic, just deferred. It needs the tab to
make a request, so one left open and idle went on running the old build until
somebody touched it -- which is exactly the thing that cannot be relied on.
The obvious signal turned out to be the wrong one, and testing is what showed
it. A deploy kills the EventSource behind /api/events, which looks like the
perfect cue, except it arrives while the container is still being replaced: the
check that follows cannot reach the server, fails, and is never retried.
Waiting for the stream to come back instead does not work either, because the
session died with the old container, so the reconnect is answered with a 401
and never reaches "connected" at all. The drop is still watched, since it costs
nothing and sometimes lands late enough to be useful, but nothing depends on it.
What the guarantee rests on is a slow poll while the tab is visible, plus a
check when it becomes visible again. Neither cares what the stream is doing or
whether anyone is at the keyboard. /api/health touches nothing upstream, so a
minute between checks costs one small request per open tab.
Reloading is now something that happens to people rather than something they
ask for, which makes it able to destroy work. A compose window holds text that
has not reached the server, and after a deploy it cannot be saved at all --
the session went with the container. Reloading would be the difference between
signing in again and pressing send, and losing what was written. So anything
holding such state can say so, and compose does; the tab stays on the old build
until the draft is dealt with, and catches up on the next check afterwards.
jcoffey-dev