slaps.request: don't fetch schema for frontend software release

The frontend software URL is a virtual URL that does not have a
corresponding schema, so fetching the schema is just a waste of time.

Generally speaking, fetching the schema impact performance a lot, so it
would be nice to cache them. In practice most of the requests made
during instantiation are frontend request, so this is a first easy step
to fix the performance impact of fetching the schema.

CHANGES.rst

@@ -4,6 +4,7 @@ Changes
 1.8.4 (unreleased)
 ------------------
  * service list, service info: output json
+ * request: don't fetch schema for frontend software release, speeding up slapos node instance
 
 1.8.3 (2022-10-17)
 ------------------

slapos/slap/slap.py

@@ -87,15 +87,24 @@ class SlapRequester(SlapDocument):
   """
   Abstract class that allow to factor method for subclasses that use "request()"
   """
+  def _validateRequestParameters(self, software_release, software_type, parameter_dict):
+    """Validate requests parameters.
 
-  def _requestComputerPartition(self, request_dict):
+    Default behavior is to fetch schema and warn using `warnings.warn` in case
+    of problems, with a special case for the magic git.erp5.org used as an alias
+    for frontend software release that does not have a software.cfg.json
+    """
+    if software_release in (
+      # no corresponding schema
+      'http://git.erp5.org/gitweb/slapos.git/blob_plain/HEAD:/software/apache-frontend/software.cfg',
+    ):
+      return
 
     try:
       SoftwareReleaseSchema(
-          request_dict['software_release'],
-          request_dict['software_type']
-      ).validateInstanceParameterDict(
-          loads(request_dict['partition_parameter_xml']))
+        software_release,
+        software_type,
+      ).validateInstanceParameterDict(parameter_dict)
     except jsonschema.ValidationError as e:
       warnings.warn(
         "Request parameters do not validate against schema definition:\n{e}".format(e=e),
@@ -115,6 +124,12 @@ class SlapRequester(SlapDocument):
         UserWarning,
       )
 
+  def _requestComputerPartition(self, request_dict):
+    self._validateRequestParameters(
+      request_dict['software_release'],
+      request_dict['software_type'],
+      loads(request_dict['partition_parameter_xml']),
+    )
     try:
       xml = self._connection_helper.POST('requestComputerPartition', data=request_dict)
     except ResourceNotReady: