Unsupported storage and checking latest launcher create infinite loop

Product Support
9

Ayup. I searched the launcher script for prior art -

ag -o '[A-Z]{4,}' launcher | sort | uniq

There’s no existing pattern for this manner of knob. I propose the DANGER_ prefix. I think it communicates the need for the user to take on additional responsibility.

diff --git a/launcher b/launcher
index b629bfc..3aed081 100755
--- a/launcher
+++ b/launcher
@@ -154,14 +154,19 @@ check_prereqs() {
 
   # 2. running an approved storage driver?
   if ! $docker_path info 2> /dev/null | egrep -q '^Storage Driver: (aufs|btrfs|zfs|overlay|overlay2)$'; then
-    echo "Your Docker installation is not using a supported storage driver.  If we were to proceed you may have a broken install."
+    echo "Your Docker installation is not using a supported storage driver."
     echo "aufs is the recommended storage driver, although zfs/btrfs/overlay and overlay2 may work as well."
     echo "Other storage drivers are known to be problematic."
     echo "You can tell what filesystem you are using by running \"docker info\" and looking at the 'Storage Driver' line."
     echo
-    echo "If you wish to continue anyway using your existing unsupported storage driver,"
-    echo "read the source code of launcher and figure out how to bypass this check."
-    exit 1
+
+    if [[ -z "${DANGER_UNSUPPORTED_DOCKER_STORAGE_DRIVER:-}" ]]; then
+      echo "Aborting."
+      echo
+      echo "If you wish to continue anyway using your existing unsupported storage driver,"
+      echo "read the source code of launcher and figure out how to bypass this check."
+      exit 1
+    fi
   fi
 
   # 3. running recommended docker version