Load and use JSON schema definition always

The JSON schema as previously stored at the root directory of the
daliuge-translator package, making it unavailable to the package
runtime, and therefore limiting its usage to deployments where the file
would need to be manually copied to a known location.

This limitation is unnecessary if the file is stored as part of the
daliuge-translator package data. This commit implements that, moving
(and renaming) the file under dlg/dropmake/lg.graph.schema, declaring it
as part of the package data, and loading its contents unconditionally at
package import time. This means we can now run LG schema validation in
all cases, including during unit testing.

This work is part of YAN-899.

Signed-off-by: Rodrigo Tobar <rtobar@icrar.org>

daliuge-translator/MANIFEST.in

@@ -2,4 +2,5 @@ include dlg/dropmake/web/img/*
 include dlg/dropmake/web/*.css
 include dlg/dropmake/web/*.js
 include dlg/dropmake/web/*.html
+include dlg/dropmake/*.schema
 include dlg/dropmake/lib/*

daliuge-translator/dlg/dropmake/web/lg_web.py

@@ -69,8 +69,8 @@
 bottle.BaseRequest.MEMFILE_MAX = 1024 * 512
 
 
-def file_as_string(fname, enc="utf8"):
-    b = pkg_resources.resource_string(__name__, fname)  # @UndefinedVariable
+def file_as_string(fname, package=__name__, enc="utf8"):
+    b = pkg_resources.resource_string(package, fname)  # @UndefinedVariable
     return common.b2s(b, enc)
 
 
@@ -94,7 +94,8 @@ def file_as_string(fname, enc="utf8"):
     ("max_mem", int),
 ]  # max_mem is only relevant for the old editor, not used in EAGLE
 
-LG_SCHEMA_PATH = "/daliuge/dlg-lg.graph.schema"
+
+LG_SCHEMA = json.loads(file_as_string("lg.graph.schema", package="dlg.dropmake"))
 
 
 def lg_path(lg_name):
@@ -573,18 +574,12 @@ def gen_pgt_post():
         logical_graph = json.loads(json_string)
         error = None
 
-        # load LG schema
-        lg_schema = None
-        if os.path.exists(LG_SCHEMA_PATH):
-            with open(LG_SCHEMA_PATH, "r") as schema_file:
-                lg_schema = json.load(schema_file)
-
-        # validate JSON (if schema was found)
-        if lg_schema is not None:
-            try:
-                validate(logical_graph, lg_schema)
-            except ValidationError as ve:
-                error = "Validation Error {1}: {0}".format(str(ve), lg_name)
+        # validate LG against schema
+        try:
+            validate(logical_graph, LG_SCHEMA)
+        except ValidationError as ve:
+            error = "Validation Error {1}: {0}".format(str(ve), lg_name)
+
         logical_graph = prepare_lgt(logical_graph, rmode)
         # LG -> PGT
         pgt = unroll_and_partition_with_params(logical_graph, reqform)