Drop the separate Alpine bootstrap, install.func already covers it

Alpine had its own in-container bootstrap, lxc/alpine-install.func: 266 lines
holding thinner copies of eleven functions install.func also defines. Both
backends picked between them on var_os, so install.func's own Alpine support
-- detect_os setting apk and openrc, seven apk branches, the OpenRC service
and inittab handling -- was written, maintained and never executed for LXC.

Two copies of the same eight functions is not free. The hostname -I failure
on BusyBox came out of it, and the /dev/tty prompt fix earlier today had to
be written twice into two copies of network_check. Deleting the thin one
means Alpine now gets what everything else gets: the conditional testing
banner instead of a hardcoded "DEV Repository (ProxmoxVED)" that every
Alpine container on ProxmoxVE was shown, the IPv6 leg of network_check, the
proxy and telemetry handling, and mirror fallback that shuffles.

Two things really were only in the Alpine copy and are ported rather than
lost:

- util-linux. Alpine ships BusyBox getty, not agetty, and the inittab rewrite
  names /sbin/agetty explicitly. The host installs bash, curl and friends
  into Alpine containers but not util-linux, so without this the new inittab
  line would point at a binary that does not exist and the console would not
  come back. The rewrite is now skipped entirely if agetty is still missing.
- The bootstrap probe. alpine-install.func checked each download before
  sourcing it; install.func used `source <(...)`, which hides the exit code,
  so a failed fetch sourced an empty script and surfaced as "command not
  found" somewhere later. _bootstrap_source now names the file that could not
  be fetched, and catches a truncated response that parses but is missing
  what we asked for.

The apk mirror loop also shuffles with shuf, which BusyBox may not provide.
It now falls back to the fixed order -- an empty list there would have
reported "all mirrors failed" without trying a single one.

Not ported: the /etc/local.d/autologin.start boot hook. install.func writes
the same change directly to /etc/inittab, which persists, and reloads it more
thoroughly (telinit q plus a targeted pkill) than the kill -HUP 1 it replaces.

Checked locally: every engine file parses, both prefetch lists still cover
the tree, and the three loader API snapshots are unchanged. The inittab
regexes were run against real Alpine and Gentoo inittab formats -- both
rewrite tty1 and console and leave tty2 alone. What this cannot cover is a
real Alpine container; those code paths go from dead to load-bearing here.

Author: MickLesk

core/build.func

@@ -245,7 +245,7 @@ _cs_source_func() {
 # so a new .func cannot be forgotten here. A file missing from it would still
 # work — _cs_local_path falls through to the network — just slower.
 _CS_ENGINE_FILES=(
-  lxc/alpine-install.func lib/alpine.func api/api.func
+  lib/alpine.func api/api.func
   api/errorlog.func api/exitcodes.func api/sysinfo.func
   api/telemetry.func
   ui/build-ui.func ui/advanced.func ui/defaults.func

docs/README.md

@@ -67,8 +67,7 @@ engine and ProxmoxVE, which has not moved over yet.
 | [`lib/db.func`](../lib/db.func) | Databases and search engines |
 | [`lib/hwaccel.func`](../lib/hwaccel.func) | GPU detection and hardware acceleration |
 | [`lib/alpine.func`](../lib/alpine.func) | The Alpine helper library, loaded instead of the above |
-| [`lxc/install.func`](../lxc/install.func) | In-container bootstrap, multi-distro |
-| [`lxc/alpine-install.func`](../lxc/alpine-install.func) | In-container bootstrap for Alpine |
+| [`lxc/install.func`](../lxc/install.func) | In-container bootstrap, every distro including Alpine |
 | [`lxc/platform.func`](../lxc/platform.func) | Proxmox VE / Incus / in-container detection |
 | [`host/preflight.func`](../host/preflight.func) | Optional host readiness checks, off by default |
 | [`host/validate.func`](../host/validate.func) | MAC, VLAN and MTU checks shared by both platforms |

docs/lxc.md

@@ -20,15 +20,10 @@ folder-qualified paths, the same as on the host.
 Which helper library gets loaded is decided here: `lib/alpine.func` for Alpine,
 `lib/tools.func` otherwise.
 
-## [`alpine-install.func`](../lxc/alpine-install.func)
-
-The Alpine bootstrap. Separate because Alpine uses `apk` and `ash`, and because
-a freshly booted Alpine container may not have `curl` yet — the first thing this
-file does is install it if missing.
-
-It also sets `TELEMETRY_CONTEXT=container`, so the error handler writes failure
-artifacts instead of calling the API, and it checks each download before
-sourcing it rather than sourcing an empty stream on a failed fetch.
+Alpine used to get its own bootstrap, `alpine-install.func`. It was a second,
+thinner copy of the same eight functions, so every fix had to be made twice and
+`install.func`'s own apk and OpenRC branches never ran. Both backends now hand
+`install.func` to every container and `detect_os` decides the rest.
 
 ## [`platform.func`](../lxc/platform.func)
 

incus/backend.func

@@ -198,11 +198,9 @@ validate_storage_space() {
 }
 
 _incus_prepare_install_exports() {
-  if [[ "${var_os:-debian}" == "alpine" ]]; then
-    export FUNCTIONS_FILE_PATH="$(_cs_fetch_text "lxc/alpine-install.func")"
-  else
-    export FUNCTIONS_FILE_PATH="$(_cs_fetch_text "lxc/install.func")"
-  fi
+  # One bootstrap for every OS — see pve/backend.func for why the Alpine split
+  # went away.
+  export FUNCTIONS_FILE_PATH="$(_cs_fetch_text "lxc/install.func")"
 
   export DIAGNOSTICS="${DIAGNOSTICS:-yes}"
   export RANDOM_UUID="${RANDOM_UUID}"