workflow_run_manager: add code mount in dev mode

* Adds REANA code mounted to runtime pods (RWE_ and RJC) when
  FLASK_ENV is `development`. We assume that when REANA is installed
  in dev mode, minikube will have all REANA source code under `/code`
  this safe to assume since it is part of our Makefile procedures
  (we do not allow to run REANA in dev mode without the mount active).

reana_workflow_controller/config.py

@@ -85,9 +85,11 @@
 """Common to all workflow engines environment variables."""
 
 DEBUG_ENV_VARS = ({'name': 'WDB_SOCKET_SERVER',
-                   'value': 'wdb'},
+                   'value': 'reana-wdb'},
                   {'name': 'WDB_NO_BROWSER_AUTO_OPEN',
-                   'value': 'True'})
+                   'value': 'True'},
+                  {'name': 'FLASK_ENV',
+                   'value': 'development'})
 """Common to all workflow engines environment variables for debug mode."""
 
 TTL_SECONDS_AFTER_FINISHED = 60

reana_workflow_controller/workflow_run_manager.py

@@ -373,10 +373,6 @@ def _create_job_spec(self, name, command=None, image=None,
             args=self._create_job_controller_startup_cmd(user),
             ports=[])
 
-        if os.getenv('FLASK_ENV') == 'development':
-            job_controller_env_vars.extend(
-                current_app.config['DEBUG_ENV_VARS'])
-
         job_controller_env_vars.extend([
             {
                 'name': 'REANA_USER_ID',
@@ -425,6 +421,28 @@ def _create_job_spec(self, name, command=None, image=None,
             secrets_store.get_file_secrets_volume_as_k8s_specs(),
         ]
 
+        if os.getenv('FLASK_ENV') == 'development':
+            code_volume_name = 'reana-code'
+            code_mount_path = '/code'
+            k8s_code_volume = client.V1Volume(
+                name=code_volume_name
+            )
+            k8s_code_volume.host_path = client.V1HostPathVolumeSource(
+                code_mount_path
+            )
+            spec.template.spec.volumes.append(k8s_code_volume)
+
+            for container in spec.template.spec.containers:
+                container.env.extend(current_app.config['DEBUG_ENV_VARS'])
+                sub_path = f'reana-{container.name}'
+                if container.name == 'workflow-engine':
+                    sub_path += f'-{self.workflow.type_}'
+                container.volume_mounts.append({
+                    'name': code_volume_name,
+                    'mountPath': code_mount_path,
+                    'subPath': sub_path
+                })
+
         job.spec = spec
         job.spec.template.spec.restart_policy = 'Never'
         job.spec.ttl_seconds_after_finished = TTL_SECONDS_AFTER_FINISHED