CP-46179 update metadata backup/restore to use deterministic UUID

We introduce deterministic UUID for backup VDIs to avoid searching for VDIs. Add this capability to the scripts that create and restore backups. In case the VDI with the expected UUID does not exist, let the user confirm probing for it. Signed-off-by: Christian Lindig <[email protected]>
minglumlu · Mar 25, 2024 · 65f152d · 65f152d
1 parent bbc5a1f
commit 65f152d
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Showing 2 changed files with 73 additions and 15 deletions.
diff --git a/scripts/xe-backup-metadata b/scripts/xe-backup-metadata
@@ -48,6 +48,29 @@ function usage {
     exit 1
 }
 
+function uuid5 {
+  # could use a modern uuidgen but it's not on XS 8
+  # should work with Python 2 and 3
+  python -c "import uuid; print (uuid.uuid5(uuid.UUID('$1'), '$2'))"
+}
+
+function validate_vdi_uuid {
+  # we check that vdi has the expected UUID which depends on the UUID of
+  # the SR. This is a deterministic hash of the SR UUID and the
+  # namespace UUID $NS. This UUID must match what Xapi's Uuidx module is using.
+  local NS="e93e0639-2bdb-4a59-8b46-352b3f408c19"
+  local sr="$1"
+  local vdi="$2"
+  local uuid
+
+  uuid=$(uuid5 "$NS" "$sr")
+  if [ "$vdi" != "$uuid" ]; then
+    return 1
+  else
+    return 0
+  fi
+}
+
 function test_sr {
   sr_uuid_found=$(${XE} sr-list uuid="$1" --minimal)
   if [ "${sr_uuid_found}" != "$1" ]; then
@@ -93,7 +116,7 @@ if [  -z "${sr_uuid}" ]; then
 fi
 test_sr "${sr_uuid}"
 
-sr_name=$(${XE} sr-param-get uuid=${sr_uuid} param-name=name-label)
+sr_name=$(${XE} sr-param-get uuid="${sr_uuid}" param-name=name-label)
 # see if a backup VDI already exists on the selected SR
 vdi_uuid=$(${XE} vdi-list other-config:ctxs-pool-backup=true sr-uuid=${sr_uuid} params=uuid --minimal)
 
@@ -134,11 +157,24 @@ function cleanup {
    fi
 }
 
-echo Using SR: ${sr_name}
+# if we can't validate the UUID of the VDI, prompt the user
+if [ -n "${vdi_uuid}" ]; then
+    if ! validate_vdi_uuid "${sr_uuid}" "${vdi_uuid}"; then
+        echo "Backup VDI $vdi_uuid was most likley create by an earlier"
+        echo "version of this code. Make sure this is a VDI that you"
+        echo "created as we can't validate it without mounting it."
+        read -p "Continue? [Y/N]" -n 1 -r; echo
+        if [[ ! $REPLY =~ ^[Yy]$ ]]; then exit 1; fi
+    fi
+fi
+
+echo "Using SR: ${sr_name}"
 if [ -z "${vdi_uuid}" ]; then
   if [ "${create_vdi}" -gt 0 ]; then
     echo -n "Creating new backup VDI: "
-    vdi_uuid=$(${XE} vdi-create virtual-size=500MiB sr-uuid=${sr_uuid} type=user name-label="Pool Metadata Backup")
+    label="Pool Metadata Backup"
+    # the label must match what xapi_vdi.ml is using for backup VDIs
+    vdi_uuid=$(${XE} vdi-create virtual-size=500MiB sr-uuid="${sr_uuid}" type=user name-label="${label}")
     init_fs=1
     if [ $? -ne 0 ]; then
        echo failed
@@ -225,7 +261,7 @@ if [ ${leave_mounted} -eq 0 ]; then
   usage=`cd ${mnt} && df . | sed -n "2p" | awk '{ print $5 }' | tr -d '%'`
   echo "Checking backup VDI space usage: $usage%"
   if [ $usage -gt $usage_alert ] && [ ${force_backup} -eq 0 ]; then
-    echo "Running out of space, you can use "-d" option to attach VDI and free more space, exit now."
+    echo "Running out of space, you can use '-d' option to attach VDI and free more space, exit now."
     cleanup
     exit 1
   fi

diff --git a/scripts/xe-restore-metadata b/scripts/xe-restore-metadata
@@ -52,6 +52,13 @@ function test_sr {
   fi
 }
 
+# name space to hash SRs for a deterministic VDI UUID
+NS="e93e0639-2bdb-4a59-8b46-352b3f408c19"
+function uuid5 {
+  # could use a modern uuidgen but it's not on XS 8
+  python -c "import uuid; print (uuid.uuid5(uuid.UUID('$1'), '$2'))"
+}
+
 dry_run=0
 sr_uuid=
 yes=0
@@ -100,9 +107,16 @@ test_sr "${sr_uuid}"
 
 sr_name=$(${XE} sr-param-get uuid=${sr_uuid} param-name=name-label)
 
+# probe first for a VDI with known UUID derived from the SR to avoid
+# scanning for a VDI
+backup_vdi=$(uuid5 "${NS}" "${sr_uuid}")
+if [ -z "${vdis}" ]; then
+  vdis=$(${XE} vdi-list uuid="${backup_vdi}" sr-uuid="${sr_uuid}" read-only=false --minimal)
+fi
+
 # get a list of all VDIs if an override has not been provided on the cmd line
 if [ -z "${vdis}" ]; then
-  vdis=$(${XE} vdi-list params=uuid sr-uuid=${sr_uuid} read-only=false --minimal)
+  vdis=$(${XE} vdi-list params=uuid sr-uuid="${sr_uuid}" read-only=false --minimal)
 fi
 
 mnt=
@@ -149,6 +163,14 @@ fi
 trap cleanup SIGINT ERR
 
 for vdi_uuid in ${vdis}; do
+   if [ "${vdi_uuid}" != "${backup_vdi}" ]; then
+      echo "Probing VDI ${vdi_uuid}."
+      echo "This VDI was created with a prior version of XenServer."
+      echo "Its validity can't be checked without mounting it first."
+      read -p "Continue? [Y/N]" -n 1 -r; echo
+      if [[ ! $REPLY =~ ^[Yy]$ ]]; then exit 1; fi
+   fi
+
    ${debug} echo -n "Creating VBD: " >&2
    vbd_uuid=$(${XE} vbd-create vm-uuid=${CONTROL_DOMAIN_UUID} vdi-uuid=${vdi_uuid} device=autodetect 2>/dev/null)
 
@@ -253,7 +275,7 @@ all)
     ;;
 esac
 
-if [ ! -d ${full_dir} ]; then
+if [ ! -d "${full_dir}" ]; then
     echo No VM metadata exports were found for the selected SR >&2
     cleanup
     exit 1
@@ -266,9 +288,9 @@ ${debug} echo "" >&2
 ${debug} echo Latest VM metadata found is: >&2
 ${debug} ls >&2
 
-if [ $yes -eq 0 ]; then
+if [ "$yes" -eq 0 ]; then
    echo "Do you wish to reimport all VM metadata?" 
-   echo "Please type in "yes" and <enter> to continue." 
+   echo "Please type in 'yes' and <enter> to continue."
    read response
    if [ "$response" != "yes" ]; then
      echo Aborting metadata restore.
@@ -297,30 +319,30 @@ else
 fi
 shopt -s nullglob
 for meta in *.vmmeta; do
-   echo xe vm-import filename=${meta} sr-uuid=${sr_uuid} --metadata --preserve${force_flag}${dry_run_flag}
-   "@OPTDIR@/bin/xe" vm-import filename="${full_dir}/${meta}" sr-uuid=${sr_uuid} --metadata --preserve${force_flag}${dry_run_flag}
+   echo xe vm-import filename="${meta}" sr-uuid="${sr_uuid}" --metadata --preserve"${force_flag}""${dry_run_flag}"
+   "@OPTDIR@/bin/xe" vm-import filename="${full_dir}/${meta}" sr-uuid="${sr_uuid}" --metadata --preserve"${force_flag}""${dry_run_flag}"
    if [ $? -gt 0 ]; then
       error_count=$(( $error_count + 1 ))
    else
       good_count=$(( $good_count + 1 ))
    fi
 done
 
-smmeta_file=${mnt}/metadata/${chosen_metadata_dir}/SRMETA.xml
+smmeta_file="${mnt}/metadata/${chosen_metadata_dir}/SRMETA.xml"
 if [ "$restore_mode" == "all" ]; then
    cmd="@LIBEXECDIR@/restore-sr-metadata.py -f ${smmeta_file}"
 else
    cmd="@LIBEXECDIR@/restore-sr-metadata.py -u ${sr_uuid} -f ${smmeta_file}"
 fi
 
-if [ -e ${smmeta_file} ]; then
-    if [ ${dry_run} -gt 0 ]; then
-        echo ${cmd}
+if [ -e "${smmeta_file}" ]; then
+    if [ "${dry_run}" -gt 0 ]; then
+        echo "${cmd}"
     else
         ${cmd}
     fi
 fi
 
 echo "Restored ${good_count} VM(s), and ${error_count} error(s)"
 cleanup
-exit ${error_count}
+exit "${error_count}"