pastilhasandClaude Opus 5
716a6e2750
Four things the original got wrong, all of which only show up on a machine that is not this one: It detected swap with `swapon --show | grep -q '/'` — a test for a swap FILE. A machine using zram or a swap partition reports no swap at all, and the step would add a swapfile beside working swap. Reads SwapTotal from /proc/meminfo now, which covers every kind. It never looked at free disk. On a VPS with 4G free and 16G of RAM it would fallocate 8G, fail, and take the run down under `set -e`. The recommendation is now capped by what is actually there, keeping 5G back, and refuses rather than shrinking to something useless. fallocate was assumed to work. It produces a file that btrfs and zfs will not swap on, so dd is the fallback — slow, but it always works. swappiness was written by sed'ing /etc/sysctl.conf in place, tangling it with whatever else lives there. It is a drop-in at /etc/sysctl.d now, so what this script set is visible as its own file. Role-dependent, which is the first use of MACHINE_ROLE: swappiness 10 on a server, where swapping is the emergency valve and a page fault on a request path is latency somebody is waiting for; the kernel default of 60 on dev, where swapping out an application nobody has touched in an hour is exactly what you want. WSL is left alone entirely — WSL2 runs its own managed swap inside the VM, and a swapfile written here is wasted disk the kernel will not use. Sizes are reported rounded rather than floored. A 4 GiB swapfile is 4194300 kB, which floors to 3 and reads as though a gigabyte went missing. Free disk stays floored, deliberately: it decides how much to allocate, and rounding up invents space. Verified on this host — 4G RAM, 4G existing swap correctly detected and left alone — and with the disk check stubbed at 6G free (caps to 1G) and 3G free (refuses). Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
221 lines
8.5 KiB
Bash
221 lines
8.5 KiB
Bash
#!/bin/bash
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# =============================================================================
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# machine-setup — system configuration
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# =============================================================================
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#
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# Definitions only, like the other lib/ files. Locale, and the system-level
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# settings that follow it.
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[[ -n "${MACHINE_SETUP_SYSTEM_LOADED:-}" ]] && return 0
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MACHINE_SETUP_SYSTEM_LOADED=1
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# -----------------------------------------------------------------------------
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# Locale
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# -----------------------------------------------------------------------------
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#
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# Two separate facts, and the original only handled one of them:
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#
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# what a new login shell is told to use — LANG in /etc/default/locale
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# whether that locale actually exists — whether it has been generated
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#
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# Setting LANG to a locale that was never generated is the state that produces
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# "setlocale: LC_ALL: cannot change locale" on every ssh login and every perl
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# invocation. Both are checked, so the step can say which one is missing.
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# What a new login shell will be handed, or empty if nothing is configured.
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locale_current() {
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if [[ -r /etc/default/locale ]]; then
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awk -F= '/^LANG=/ { gsub(/"/, "", $2); print $2 }' /etc/default/locale
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elif [[ -r /etc/locale.conf ]]; then
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awk -F= '/^LANG=/ { gsub(/"/, "", $2); print $2 }' /etc/locale.conf
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fi
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}
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# Has this locale actually been built?
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#
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# `locale -a` prints en_US.utf8 where the configuration spells it en_US.UTF-8,
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# so both sides are folded to lower case with the dashes removed before
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# comparing. A literal match here would report a perfectly good locale missing.
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locale_is_generated() {
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local want="${1,,}"
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want="${want//-/}"
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locale -a 2>/dev/null | tr '[:upper:]' '[:lower:]' | tr -d '-' | grep -qx "$want"
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}
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locale_set() {
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local want="$1"
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local escaped="${want//./\\.}"
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case "$PM" in
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apt)
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# locale-gen comes from the `locales` package, which minimal images and
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# most cloud base images do not ship. Without this the step fails with
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# "locale-gen: command not found" halfway through.
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if ! pkg_is_installed locales; then
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info " installing locales, which provides locale-gen"
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pkg_install_now locales
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fi
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# Uncomment it if it is there commented out, add it if it is absent.
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# Editing the file rather than passing the name to locale-gen is what makes
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# it survive: a locale generated by argument alone is lost the next time
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# anything regenerates from /etc/locale.gen.
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if grep -qE "^#[[:space:]]*${escaped}[[:space:]]" /etc/locale.gen 2>/dev/null; then
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sed -i "s/^#[[:space:]]*\(${escaped}[[:space:]]\)/\1/" /etc/locale.gen
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elif ! grep -qE "^${escaped}[[:space:]]" /etc/locale.gen 2>/dev/null; then
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# The charset is the part after the dot: en_US.UTF-8 -> UTF-8
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echo "${want} ${want##*.}" >>/etc/locale.gen
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fi
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locale-gen
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update-locale LANG="$want"
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;;
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pacman)
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if grep -qE "^#[[:space:]]*${escaped}[[:space:]]" /etc/locale.gen 2>/dev/null; then
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sed -i "s/^#[[:space:]]*\(${escaped}[[:space:]]\)/\1/" /etc/locale.gen
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fi
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locale-gen
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echo "LANG=${want}" >/etc/locale.conf
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;;
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dnf)
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# No locale.gen here — the locales come prebuilt in langpack packages.
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pkg_install_now "glibc-langpack-${want%%_*}"
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localectl set-locale "LANG=${want}"
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;;
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brew)
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warn "macOS has no system locale to set — it is per-user, from the terminal's settings"
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return 1
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;;
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esac
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}
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# -----------------------------------------------------------------------------
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# Swap
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# -----------------------------------------------------------------------------
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SWAPFILE=/swapfile
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# Rounded to nearest, not floored: a 4 GiB swapfile is 4194300 kB, which floors
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# to 3 and reads as though a gigabyte went missing. Same for RAM, where 3.7 GiB
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# reporting as "3G" makes the sizing tiers look wrong.
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kb_to_gb_rounded() { echo $((($1 + 524288) / 1048576)); }
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# Total active swap in GiB, 0 if there is none.
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#
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# From /proc/meminfo rather than by grepping swapon's output for a slash, which
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# is what the original did to spot a swap FILE — that test reports no swap at all
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# on a machine using zram or a swap partition, and the step would then add a
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# swapfile beside perfectly good swap.
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swap_active_gb() { kb_to_gb_rounded "$(awk '/^SwapTotal:/ { print $2 }' /proc/meminfo)"; }
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ram_gb() { kb_to_gb_rounded "$(awk '/^MemTotal:/ { print $2 }' /proc/meminfo)"; }
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# Free space on the filesystem that would hold the swapfile, in GiB. Floored
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# rather than rounded, deliberately: this one decides how much to allocate, and
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# rounding up invents space that is not there.
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disk_free_gb() { echo $(($(df -Pk "$(dirname "$SWAPFILE")" | awk 'NR == 2 { print $4 }') / 1024 / 1024)); }
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# How much swap this machine should have.
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#
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# The tiers are the original's. What is new is that the answer is capped by what
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# is actually on the disk — the original would try to fallocate 8G on a VPS with
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# 4G free, fail, and take the run down with it.
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swap_recommended_gb() {
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local ram size
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ram="$(ram_gb)"
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if ((ram <= 2)); then
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size=2
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elif ((ram <= 8)); then
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size=4
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else
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size=8
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fi
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# Leave a few gigabytes behind. A swapfile that fills the disk is a worse
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# problem than no swapfile.
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local room=$(($(disk_free_gb) - 5))
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((room < size)) && size="$room"
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((size < 1)) && size=0
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echo "$size"
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}
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# How eagerly the kernel swaps, by role.
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#
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# 10 on a server: swapping is the emergency valve, not a routine, and the cost of
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# a page fault on a request path is latency somebody is waiting for. A desktop is
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# the opposite case — swapping out an application nobody has touched in an hour
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# is exactly what you want — so dev keeps the kernel default of 60.
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swappiness_for_role() { if is_server; then echo 10; else echo 60; fi; }
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swap_create() {
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local gb="$1"
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# fallocate is instant but produces a file some filesystems refuse to swap on
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# (btrfs without the right attributes, zfs at all). dd is slow and always
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# works, so it is the fallback rather than the default.
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if ! fallocate -l "${gb}G" "$SWAPFILE" 2>/dev/null; then
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info " fallocate is not usable here — writing the file with dd, which is slower"
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dd if=/dev/zero of="$SWAPFILE" bs=1M count=$((gb * 1024)) status=none
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fi
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chmod 600 "$SWAPFILE"
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mkswap "$SWAPFILE" >/dev/null
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swapon "$SWAPFILE"
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grep -qs "^${SWAPFILE}[[:space:]]" /etc/fstab || echo "${SWAPFILE} none swap sw 0 0" >>/etc/fstab
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}
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# Written as a drop-in rather than by rewriting /etc/sysctl.conf in place. The
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# original sed'd that file, which means the setting is tangled up with whatever
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# else lives there and is invisible to anyone looking for what this script did.
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swappiness_set() {
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echo "vm.swappiness=$1" >/etc/sysctl.d/99-machine-setup-swappiness.conf
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sysctl -q -w "vm.swappiness=$1"
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}
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# -----------------------------------------------------------------------------
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# Timezone
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# -----------------------------------------------------------------------------
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# The shortlist offered at the prompt. Any zone name can be typed instead, so
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# this is a convenience rather than a limit.
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TZ_OPTIONS=(UTC Europe/Lisbon Europe/London Europe/Berlin Europe/Stockholm US/Eastern US/Pacific Asia/Tokyo)
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# What the machine is set to now.
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#
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# Three sources because they disagree about availability rather than about the
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# answer: timedatectl is absent without systemd (containers, WSL), /etc/timezone
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# is Debian-specific, and the /etc/localtime symlink is the one thing that is
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# always true when any of them are.
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timezone_current() {
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if command -v timedatectl &>/dev/null && timedatectl show -p Timezone --value 2>/dev/null | grep -q .; then
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timedatectl show -p Timezone --value 2>/dev/null
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elif [[ -r /etc/timezone ]]; then
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tr -d '[:space:]' </etc/timezone
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elif [[ -L /etc/localtime ]]; then
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readlink -f /etc/localtime | sed 's|.*/zoneinfo/||'
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fi
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}
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# Checked against the zoneinfo database before it is used. `timedatectl
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# set-timezone` on a name that does not exist fails, and under `set -e` that
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# takes the whole run down over a typo.
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timezone_is_valid() { [[ -f "/usr/share/zoneinfo/$1" ]]; }
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timezone_set() {
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local tz="$1"
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case "$PM" in
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brew) systemsetup -settimezone "$tz" >/dev/null ;;
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*)
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# timedatectl where there is a systemd to talk to; the files directly
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# otherwise, which is the same thing it would have written.
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if command -v timedatectl &>/dev/null && [[ "$IS_WSL" != true ]]; then
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timedatectl set-timezone "$tz"
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else
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ln -sf "/usr/share/zoneinfo/${tz}" /etc/localtime
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echo "$tz" >/etc/timezone
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fi
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;;
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esac
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}
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