Use multiple locations for elements dir.

Using ELEMENTS_DIR env variable, you can specify multiple dirs containint your elements.
It must be a ":" separated elements list.

When an element is seen in one of those lists, it will be chosen and will continue with the next element.

Change-Id: I18eca27d943139cd6ca1ebd232b419e502d7b048

README.md

@@ -256,6 +256,11 @@ The scripts can generally just be run. Options can be set on the command line
 or by exporting variables to override those present in lib/img-defaults. -h to
 get help.
 
+
+Using the variable ELEMENTS_PATH will allow to specify multiple elements locations.
+It's a colon (:) separated path list, and it will work in a first path/element found,
+first served approach.
+
 Copyright
 =========
 

bin/disk-image-create

@@ -35,6 +35,8 @@ function show_options () {
     echo "    -c -- clear environment before starting work"
     echo "    -n skip the default inclusion of the 'base' element"
     echo "    -p package[,package,package] -- list of packages to install in the image"
+    echo
+    echo "ELEMENTS_PATH will allow you to specify multiple locations for the elements."
     exit 0
 }
 

diskimage_builder/elements.py

@@ -20,9 +20,9 @@ import sys
 
 
 def get_elements_dir():
-    if not os.environ.get('ELEMENTS_DIR'):
-        raise Exception("$ELEMENTS_DIR must be set.")
-    return os.environ['ELEMENTS_DIR']
+    if not os.environ.get('ELEMENTS_PATH'):
+        raise Exception("$ELEMENTS_PATH must be set.")
+    return os.environ['ELEMENTS_PATH']
 
 
 def dependencies(element, elements_dir=None):
@@ -37,16 +37,22 @@ def dependencies(element, elements_dir=None):
     if elements_dir is None:
         elements_dir = get_elements_dir()
 
-    element_deps_path = os.path.join(elements_dir, element, 'element-deps')
+    for path in elements_dir.split(':'):
+        element_deps_path = (os.path.join(path, element, 'element-deps'))
         try:
             with open(element_deps_path) as element_deps:
                 return set([line.strip() for line in element_deps])
         except IOError as e:
-        if e.errno == 2:
+            if os.path.exists(os.path.join(path, element)) and e.errno == 2:
                 return set()
+            if e.errno == 2:
+                continue
             else:
                 raise
 
+    sys.stderr.write("ERROR: Element %s doesn't exists\n" % (element, ))
+    exit(-1)
+
 
 def expand_dependencies(user_elements, elements_dir=None):
     """ Expand user requested elements using element-deps files.

diskimage_builder/test_elementdeps.py

@@ -77,9 +77,9 @@ class TestElementDeps(TestCase):
 
 class TestElements(TestCase):
     def test_depends_on_env(self):
-        self.useFixture(EnvironmentVariable('ELEMENTS_DIR', '/foo/bar'))
+        self.useFixture(EnvironmentVariable('ELEMENTS_PATH', '/foo/bar'))
         self.assertEquals('/foo/bar', get_elements_dir())
 
     def test_env_not_set(self):
-        self.useFixture(EnvironmentVariable('ELEMENTS_DIR', ''))
+        self.useFixture(EnvironmentVariable('ELEMENTS_PATH', ''))
         self.assertRaises(Exception, get_elements_dir, ())

lib/common-functions

@@ -39,8 +39,11 @@ function save_image () {
 function generate_hooks () {
   mkdir -p $TMP_HOOKS_PATH
   for _ELEMENT in $IMAGE_ELEMENT ; do
-    [ -d $ELEMENTS_DIR/$_ELEMENT ] || die "Element $_ELEMENT does not exist." ;
-    cp -t $TMP_HOOKS_PATH -a $ELEMENTS_DIR/$_ELEMENT/* ;
+    for dir in $(echo $ELEMENTS_PATH | tr ":" " ") ; do
+       [ -d $dir/$_ELEMENT ] || continue
+      cp -t $TMP_HOOKS_PATH -a $dir/$_ELEMENT/* ;
+      break
+    done
   done
 }
 

lib/img-defaults

@@ -22,4 +22,4 @@ IMAGE_NAME=${IMAGE_NAME:-image}
 export IMAGE_SIZE=${IMAGE_SIZE:-2} # N.B. This size is in GB
 # Set via the CLI normally.
 # IMAGE_ELEMENT=
-export ELEMENTS_DIR=$(dirname $0)/../elements
+export ELEMENTS_PATH=${ELEMENTS_PATH:-(dirname $0)/../elements}

lib/ramdisk-defaults

@@ -21,4 +21,4 @@ MODULE_ROOT=${MODULE_ROOT:-""}
 LIB_UDEV_ROOT=${LIB_UDEV_ROOT:-""}
 BUSYBOX=${BUSYBOX:-$(which busybox)}
 IMAGE_NAME=${IMAGE_NAME:-"ramdisk"}
-export ELEMENTS_DIR=$(dirname $0)/../elements
+export ELEMENTS_PATH=${ELEMENTS_PATH:-(dirname $0)/../elements}

lib/ramdisk-functions

@@ -31,12 +31,16 @@ function cleanup () {
 function ensure_binaries() {
   BINARY_DEPS="${BUSYBOX}"
   for _FLVR in ${RAMDISK_ELEMENT} ; do
-    _FILE="${ELEMENTS_DIR}/${_FLVR}/binary-deps"
+    for dir in $(echo $ELEMENTS_PATH | tr ":" " ") ; do
+      [ -d $dir/$_FLVR ] || continue
+      _FILE="${dir}/${_FLVR}/binary-deps"
       if [ -a $_FILE ]; then
         for _LINE in $(cat $_FILE) ; do
           BINARY_DEPS="${BINARY_DEPS} $_LINE"
         done
       fi
+      break
+    done
   done
 
   for _BIN in $BINARY_DEPS ; do
@@ -171,14 +175,17 @@ function populate_init () {
 
   # Append /init with any element fragments that are present
   for _FLVR in ${RAMDISK_ELEMENT} ; do
-    _FILE="${ELEMENTS_DIR}/${_FLVR}/init"
+    for dir in $(echo $ELEMENTS_PATH | tr ":" " ") ; do
+      [ -d $dir/$_FLVR ] || continue
+      _FILE="${dir}/${_FLVR}/init"
       if [ -a $_FILE ]; then
         cat >>$TMP_MOUNT_PATH/init <<EOF
-
 # init fragment from ${_FLVR}
 EOF
         cat <$_FILE >>$TMP_MOUNT_PATH/init
       fi
+      break
+    done
   done
 
   # Add our final steps to /init
@@ -194,10 +201,14 @@ function populate_udev () {
   echo "Installing udev rules"
 
   for _FLVR in ${RAMDISK_ELEMENT} ; do
-    _DIR="${ELEMENTS_DIR}/${_FLVR}/udev"
+    for dir in $(echo $ELEMENTS_PATH | tr ":" " ") ; do
+      [ -d $dir/$_FLVR ] || continue
+      _DIR="${dir}/${_FLVR}/udev"
       if [ -d $_DIR ]; then
         find $_DIR -type f -exec cp -v {} $TMP_MOUNT_PATH/lib/udev/rules.d/ \;
       fi
+      break
+    done
   done
 }