Add test for vfat formatted config drive

Dockerfile.dapper

@@ -24,6 +24,7 @@ RUN echo "Acquire::http { Proxy \"$APTPROXY\"; };" >> /etc/apt/apt.conf.d/01prox
         libselinux1-dev \
         locales \
         module-init-tools \
+        mtools \
         openssh-client \
         pkg-config \
         qemu \

scripts/run

@@ -250,8 +250,10 @@ if [ "$QIND" != "1" ]; then
                 CLOUD_CONFIG_DISK="-cdrom ${BASE}/state/configdrive.iso"
             ;;
             fat)
-                echo "TODO: implement a vfat formated qemu img & copy the config files into it"
-                exit 1
+                truncate --size 2M ${BASE}/state/configdrive.img
+                mkfs.vfat -n config-2 ${BASE}/state/configdrive.img
+                mcopy -osi ${BASE}/state/configdrive.img ${CCROOT}/* ::
+                CLOUD_CONFIG_DISK="-hdb ${BASE}/state/configdrive.img"
             ;;
             *)
                 CLOUD_CONFIG_DISK="-fsdev local,security_model=passthrough,readonly,id=fsdev0,path=${CCROOT} \

tests/cloud_init_test.go

@@ -28,3 +28,13 @@ func (s *QemuSuite) TestIsoCloudConfig(c *C) {
 
 	s.CheckCall(c, `ls .ssh/authorized_keys`)
 }
+
+func (s *QemuSuite) TestFatCloudConfig(c *C) {
+        runArgs := []string{
+                "--fresh",
+                "--cloud-config-fat",
+        }
+        s.RunQemuWith(c, runArgs...)
+
+        s.CheckCall(c, `ls .ssh/authorized_keys`)
+}