Archived
Add scripts/backup-admin-key.sh to back up the local sops admin key
Companion to rotate-admin-key.sh: copies whatever age identity sops/age itself would resolve (or an explicit --key-file) to a given destination path with 0600 perms, validating it's a real identity and round-tripping the derived public key before/after the write so a corrupted copy is caught immediately rather than discovered later during a restore. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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@@ -116,6 +116,16 @@ Beyond `codex-setup.sh`/`codex-maintenance.sh` above, `scripts/` also has:
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for the manual steps `sync-host-keys.sh`/`create-proxmox-resource.sh`
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print when they bootstrap a brand-new, not-yet-trusted key on a machine
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with no prior admin access.
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- `scripts/backup-admin-key.sh <dest-path> [--key-file <path>] [--force]
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[--dry-run]` — copies the local sops age key (source resolution matches
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sops/age itself: `$SOPS_AGE_KEY` inline, then `--key-file`, then
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`$SOPS_AGE_KEY_FILE`, then the XDG default) to an arbitrary destination
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path with `0600` permissions, validating it's a real age identity and
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round-tripping the public key before and after the write. Refuses to
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overwrite an existing `<dest-path>` without `--force`. Purely a local
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filesystem copy — never touches `.sops.yaml`/`secrets/*.yaml` or the
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repo at all. The resulting file is exactly what `rotate-admin-key.sh`
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expects as its backup-key argument.
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`sync-host-keys.sh`, `create-proxmox-resource.sh`, and
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`rotate-admin-key.sh` genuinely mutate real state when run for real (not
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@@ -124,6 +134,9 @@ containers, real revocation of decrypt access. They require the
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operator's own SSH/sops access, which an agent session doesn't have — but
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don't suggest running any of them non-dry-run without the operator's
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explicit go-ahead even if it becomes technically reachable.
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`backup-admin-key.sh` only writes a key copy to a path the operator gives
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it — lower-stakes than the others, but it still handles a real private
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key, so treat its destination path choice as the operator's call too.
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## Architecture
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Executable
+148
@@ -0,0 +1,148 @@
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#!/usr/bin/env bash
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# Backs up the local sops age key (the private key that decrypts
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# secrets/*.yaml -- normally the one trusted as &admin) to an arbitrary
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# destination path, e.g. a USB drive or other offline storage, so it can
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# later be restored and handed to rotate-admin-key.sh if this machine's
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# copy is ever lost, or to run either script from a different machine.
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#
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# Usage:
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# scripts/backup-admin-key.sh <dest-path> [--key-file <path>] [--force] [--dry-run]
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#
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# Source key resolution matches sops/age's own default order:
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# $SOPS_AGE_KEY (inline identity text) if set, else
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# --key-file if given, else
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# $SOPS_AGE_KEY_FILE if set, else
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# ${XDG_CONFIG_HOME:-$HOME/.config}/sops/age/keys.txt
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set -euo pipefail
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repo_root="$(cd "$(dirname "$0")/.." && pwd)"
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sops_yaml="${repo_root}/.sops.yaml"
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# shellcheck source=env.sh
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source "${repo_root}/scripts/env.sh"
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# Pin cwd for the same reason rotate-admin-key.sh does: age/sops calls
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# below should never depend on wherever the caller's shell happened to be.
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cd "$repo_root"
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usage() {
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cat <<EOF
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Usage: $0 <dest-path> [--key-file <path>] [--force] [--dry-run]
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<dest-path> Where to write the backup. Parent directories are
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created as needed. Written with 0600 permissions.
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--key-file <path> Read the key from here instead of the default
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sops/age resolution (\$SOPS_AGE_KEY_FILE, then
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\${XDG_CONFIG_HOME:-\$HOME/.config}/sops/age/keys.txt).
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Ignored if \$SOPS_AGE_KEY is set (that always wins,
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same precedence sops/age itself uses).
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--force Overwrite <dest-path> if it already exists.
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--dry-run Print what would happen; write nothing.
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EOF
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}
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dry_run=0
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force=0
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key_file="${SOPS_AGE_KEY_FILE:-${XDG_CONFIG_HOME:-$HOME/.config}/sops/age/keys.txt}"
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args=()
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while [[ $# -gt 0 ]]; do
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case "$1" in
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--dry-run)
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dry_run=1
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shift
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;;
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--force)
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force=1
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shift
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;;
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--key-file)
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key_file="${2:?--key-file requires a path}"
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shift 2
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;;
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-h | --help)
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usage
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exit 0
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;;
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--*)
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echo "Unknown option: $1" >&2
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usage >&2
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exit 1
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;;
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*)
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args+=("$1")
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shift
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;;
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esac
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done
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if [[ "${#args[@]}" -ne 1 ]]; then
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usage >&2
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exit 1
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fi
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dest="${args[0]}"
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nix_extra_opts
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if [[ -n "${SOPS_AGE_KEY:-}" ]]; then
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echo "==> Source: \$SOPS_AGE_KEY (inline identity from the environment)."
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src_content="$SOPS_AGE_KEY"
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else
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[[ -s "$key_file" ]] || {
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echo "ERROR: no key found. \$SOPS_AGE_KEY is unset and ${key_file} doesn't exist or is empty." >&2
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exit 1
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}
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echo "==> Source: ${key_file}"
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src_content="$(cat "$key_file")"
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fi
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# Round-trip through a private scratch file (rather than trusting the
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# source string as-is) so age-keygen -y validates it's a real identity
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# before anything is written to <dest-path>.
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scratch="$(mktemp)"
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trap 'rm -f "$scratch"' EXIT
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( umask 077; printf '%s\n' "$src_content" > "$scratch" )
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src_pub="$(nix-shell "${NIX_OPTS[@]}" -p age --run "age-keygen -y '$scratch'")" || {
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echo "ERROR: source doesn't look like a valid age identity (age-keygen -y failed)." >&2
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exit 1
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}
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echo " public key: ${src_pub}"
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current_admin_pub="$(grep -E '^ - &admin age1' "$sops_yaml" 2>/dev/null | awk '{print $NF}' || true)"
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if [[ -n "$current_admin_pub" && "$current_admin_pub" != "$src_pub" ]]; then
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echo "NOTE: this key does not match .sops.yaml's current &admin entry (${current_admin_pub})."
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echo " Backing it up anyway -- this script doesn't require it to be the admin key."
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fi
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if [[ -e "$dest" && "$force" -ne 1 ]]; then
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echo "ERROR: ${dest} already exists. Pass --force to overwrite." >&2
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exit 1
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fi
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if [[ "$dry_run" -eq 1 ]]; then
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echo
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echo "[dry-run] would write $(wc -c <"$scratch" | tr -d ' ') bytes to ${dest} (mode 0600)"
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[[ -e "$dest" ]] && echo "[dry-run] would overwrite existing file (--force given)"
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echo "[dry-run] Nothing was written. Re-run without --dry-run to apply this."
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exit 0
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fi
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mkdir -p "$(dirname "$dest")"
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install -m 600 "$scratch" "$dest"
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dest_pub="$(nix-shell "${NIX_OPTS[@]}" -p age --run "age-keygen -y '$dest'")"
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if [[ "$dest_pub" != "$src_pub" ]]; then
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echo "ERROR: ${dest} was written but its public key doesn't match the source -- investigate before relying on this backup." >&2
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exit 1
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fi
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cat <<EOF
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Done. Backed up to: ${dest}
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public key: ${dest_pub}
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This is a private key -- store it somewhere offline/secure, not in this
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repo or anywhere it'd get committed. Restore it with:
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scripts/rotate-admin-key.sh ${dest}
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EOF
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