restamp: new command to bump timestamp

Split out the `--timestamp-only` functionality from the `prune` command
since it feels awkward there, and put it in a new dedicated `restamp`
command instead.

coreos-assembler

@@ -34,7 +34,7 @@ if [ -e /sys/fs/selinux/status ]; then
 fi
 
 cmd=${1:-}
-build_commands="init fetch build buildextend-ec2 buildextend-openstack tag run prune clean"
+build_commands="init fetch build buildextend-ec2 buildextend-openstack tag restamp run prune clean"
 other_commands="shell"
 utility_commands="gf-oemid virt-install oscontainer"
 if [ -z "${cmd}" ]; then

src/cmd-prune

@@ -11,21 +11,17 @@ dn=$(dirname "$0")
 print_help() {
     cat 1>&2 <<'EOF'
 Usage: coreos-assembler prune --help
-       coreos-assembler prune [--keep=N] [--timestamp-only]
+       coreos-assembler prune [--keep=N]
 
   Delete older build artifacts. By default, only the last 3 builds are kept.
   This can be overridden with the `--keep` option.
-
-  The `--timestamp-only` option will just update the `timestamp` key of
-  `builds.json`
 EOF
 }
 
 # Parse options
 KEEP_LAST_N="3"
-TIMESTAMP=0
 rc=0
-options=$(getopt --options h --longoptions help,keep:,timestamp-only -- "$@") || rc=$?
+options=$(getopt --options h --longoptions help,keep: -- "$@") || rc=$?
 [ $rc -eq 0 ] || {
     print_help
     exit 1
@@ -41,9 +37,6 @@ while true; do
             shift
             KEEP_LAST_N="$1"
             ;;
-        --timestamp-only)
-            TIMESTAMP=1
-            ;;
         --)
             shift
             break
@@ -64,9 +57,4 @@ fi
 
 prepare_build
 
-if [ "${TIMESTAMP}" == 1 ]; then
-    "${dn}"/prune_builds --timestamp-only --workdir "${workdir:?}"
-    exit 0
-fi
-
 "${dn}"/prune_builds --keep-last-n "${KEEP_LAST_N}" --workdir "${workdir:?}"

src/cmd-restamp

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+dn=$(dirname "$0")
+# shellcheck source=src/cmdlib.sh
+. "${dn}"/cmdlib.sh
+
+print_help() {
+    cat 1>&2 <<'EOF'
+Usage: coreos-assembler restamp
+
+  Update the `timestamp` key of `builds.json`.
+EOF
+}
+
+if [ $# -ne 0 ]; then
+    print_help
+    fatal "ERROR: Too many arguments"
+    exit 1
+fi
+
+prepare_build
+
+"${dn}"/prune_builds --timestamp-only --workdir "${workdir:?}"