71 lines
2.5 KiB
Bash
71 lines
2.5 KiB
Bash
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#!/usr/bin/env bash
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# =============================================================================
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# lib/init/nomad/lib-systemd.sh — Shared idempotent systemd-unit installer
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#
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# Sourced by lib/init/nomad/systemd-nomad.sh and lib/init/nomad/systemd-vault.sh
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# (and any future sibling) to collapse the "write unit if content differs,
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# daemon-reload, enable (never start)" boilerplate.
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#
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# Install-but-don't-start is the invariant this helper enforces — mid-migration
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# installers land files and enable units; the orchestrator (S0.4) starts them.
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#
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# Public API (sourced into caller scope):
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#
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# systemd_require_preconditions UNIT_PATH
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# Asserts the caller is uid 0 and `systemctl` is on $PATH. Calls the
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# caller's die() with a UNIT_PATH-scoped message on failure.
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#
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# systemd_install_unit UNIT_PATH UNIT_NAME UNIT_CONTENT
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# Writes UNIT_CONTENT to UNIT_PATH (0644 root:root) only if on-disk
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# content differs. If written, runs `systemctl daemon-reload`. Then
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# enables UNIT_NAME (no-op if already enabled). Never starts the unit.
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#
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# Caller contract:
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# - Callers MUST define `log()` and `die()` before sourcing this file (we
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# call log() for status chatter and rely on the caller's error-handling
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# stance; `set -e` propagates install/cmp/systemctl failures).
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# =============================================================================
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# systemd_require_preconditions UNIT_PATH
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systemd_require_preconditions() {
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local unit_path="$1"
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if [ "$(id -u)" -ne 0 ]; then
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die "must run as root (needs write access to ${unit_path})"
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fi
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command -v systemctl >/dev/null 2>&1 \
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|| die "systemctl not found (systemd is required)"
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}
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# systemd_install_unit UNIT_PATH UNIT_NAME UNIT_CONTENT
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systemd_install_unit() {
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local unit_path="$1"
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local unit_name="$2"
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local unit_content="$3"
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local needs_reload=0
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if [ ! -f "$unit_path" ] \
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|| ! printf '%s\n' "$unit_content" | cmp -s - "$unit_path"; then
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log "writing unit → ${unit_path}"
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local tmp
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tmp="$(mktemp)"
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printf '%s\n' "$unit_content" > "$tmp"
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install -m 0644 -o root -g root "$tmp" "$unit_path"
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rm -f "$tmp"
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needs_reload=1
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else
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log "unit file already up to date"
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fi
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if [ "$needs_reload" -eq 1 ]; then
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log "systemctl daemon-reload"
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systemctl daemon-reload
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fi
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if systemctl is-enabled --quiet "$unit_name" 2>/dev/null; then
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log "${unit_name} already enabled"
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else
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log "systemctl enable ${unit_name}"
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systemctl enable "$unit_name" >/dev/null
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fi
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}
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