Merge branch '13-allow-more-time-for-disk-operations' into 'master'

Resolve "Allow more time for disk operations"

Closes #13

See merge request !7

driver/src/driver.sh

@@ -114,6 +114,27 @@ ghostAction() {
     diskSlot=$(jq '."disk_slot"' <<<"$response")
 }
 
+waitForFile() {
+    local filePath=$1
+    local timeout=$2
+    local counter=0
+    while true
+    do
+        if [[ -e "$filePath" ]]
+        then
+            # File is found.
+            return 0
+        fi
+        sleep 1
+        ((++counter))
+        if [ $counter -ge $timeout ]
+        then
+            # Timeout has elapsed, giving up.
+            return 1
+        fi
+    done
+}
+
 domount() {
     debug "domount $@"
     local mountPath=$1
@@ -130,6 +151,12 @@ domount() {
     then
         exitWithFailure "$errorMessage"
     fi
+
+    # Wait a little while, so that if the disk is in fact reattached to the
+    # same VPS, the VPS kernel gets a chance to recognise that the disk is gone
+    # before it is reinserted again.
+    sleep 1
+
     # Now tell Cosmos2 to attach the disk to the right VPS.
     if ! ghostAction "attach" "$apiToken" "$diskID" "$vpsID"
     then
@@ -154,6 +181,16 @@ domount() {
     diskLetter=$(printf \\$(printf '%03o' $((97 + $diskSlot))))
     device="/dev/xvd${diskLetter}1"
     debug "device: $device"
+
+    # Wait for the device file to appear. It might take the VPS kernel some
+    # time to realise that a disk has been attached.
+    timeout=30
+    if ! waitForFile "$device" $timeout
+    then
+        errorMessage="Device $device did not appear in $timeout seconds."
+        exitWithFailure "$errorMessage"
+    fi
+
     # Use the `blkid` program to scan the device for an existing filesystem.
     if ! existingFileSystem=$(lsblk -n -o FSTYPE "$device" 2>&1)
     then