Add a script for rolling back k8s snapshots.

ansible/roles/mrmanager/files/k8s_rollback.bash

@@ -0,0 +1,84 @@
+#!/usr/bin/env bash
+#
+# Kill the virtual machines, take a snapshot, and start the virtual machines up again.
+set -euo pipefail
+IFS=$'\n\t'
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+: ${VMS:="poudriere controller0 controller1 controller2 worker0 worker1 worker2"}
+
+############## Setup #########################
+
+function die {
+    local status_code="$1"
+    shift
+    (>&2 echo "${@}")
+    exit "$status_code"
+}
+
+function log {
+    (>&2 echo "${@}")
+}
+
+############## Program #########################
+
+function main {
+    VMS=($(convert_ifs "$VMS" ' ' "$IFS"))
+    local snapshot_name="$1"
+
+    local rollback_targets=$(doas zfs list -t snapshot -p -o name | grep -E "@${snapshot_name}\$")
+    log "Rolling back to the following snapshots:"
+    while read target; do
+        log "    $target"
+    done<<<"$rollback_targets"
+    sanity_check_targets "$rollback_targets"
+
+    kill_all_bhyve
+    log "Rolling back to snapshot $1"
+    while read target; do
+        zfs rollback "$target"
+    done<<<"$rollback_targets"
+    launch_all_bhyve
+    log "Done."
+}
+
+function kill_all_bhyve {
+    log "Killing all virtual machines."
+    doas killall bhyve; while true; do tmux ls || break; sleep 2; done;
+}
+
+function launch_all_bhyve {
+    log "Launching all virtual machines."
+    for vm in $VMS[@]; do tmux new -d -s $vm doas bhyve_netgraph_bridge start $vm zdata/vm/$vm /vm/$vm; sleep 5; done
+}
+
+function sanity_check_targets {
+    local rollback_targets="$1"
+    local targets_length=$(wc -l <<<"$rollback_targets")
+    if [ $targets_length -ne 7 ]; then
+        die 1 "Expecting the snapshot to exist for each k8s vm and the k8s persistent storage space. Only found $targets_length targets."
+    fi
+    while read rollback_target; do
+        if [[ ! $rollback_target = "zdata/vm"[/@]* ]] && [[ ! $rollback_target = "zdata/k8spersistent"[/@]* ]]; then
+            die 1 "Rollback target not in k8s-vm-related zfs datasets: $rollback_target"
+        fi
+    done<<<"$rollback_targets"
+}
+
+function convert_ifs {
+    # Converts a string from one internal field separator to another. For example "foo bar baz" to "foo:bar:baz". This is useful for parsing a string as an array (for example, to read the value from environment variables like $PATH) while using a different IFS
+    #
+    # TODO: It would be a lot better if we could just convert from string to array directly using a temporarily different IFS variable without converting to a different string format first.
+    local string_to_convert="$1"
+    local ifs_in_string="$2"
+    local target_ifs="$3"
+    local current_ifs="$IFS"
+    IFS="$ifs_in_string"
+    local split_to_array=($string_to_convert)
+    local expanded_string=$(IFS="$target_ifs"; printf '%s' "${split_to_array[*]}")
+    # Restore IFS to the original value in case this function is not run inside a subshell
+    IFS="$current_ifs"
+    cat <<<"$expanded_string"
+}
+
+main "$@"

ansible/roles/mrmanager/tasks/freebsd.yaml

@@ -48,5 +48,7 @@
     owner: root
     group: wheel
   loop:
-    - src: "k8s_snapshot.bash"
+    - src: k8s_snapshot.bash
       dest: /usr/local/bin/k8s_snapshot
+    - src: k8s_rollback.bash
+      dest: /usr/local/bin/k8s_rollback