Draft: Resolve "Cannot run multiple maestro applications on the same node under slurm with GNI (Aries) network"

Closes #86 (closed)

include/maestro/env.h

@@ -239,6 +239,27 @@
  **/
 #define MSTRO_ENV_MIO_CONFIG "MSTRO_MIO_CONFIG"
 
+
+/**
+ ** @brief Flag to enable higher network security on Cray GNI interfaces
+ **
+ ** By default, Cray GNI (Aries) networks allow only jobs of the same
+ ** job allocation to use the HSN between each other. Despite using
+ ** user-id based DRC credentials (which allows cross-talk for jobs on
+ ** different nodes if the user's UID matches), jobs running on the
+ ** same node of an allocation can not talk to each other unless we
+ ** use DRC_FLAGS_FLEX_CREDENTIAL.
+ **
+ ** By default we do set DRC_FLAGS_FLEX_CREDENTIAL, as that allows
+ ** users to schedule jobs of the same workflow on the same or
+ ** different nodes without worrying about this. If you are sure you
+ ** will only run one job per compute node, consider enabling @ref
+ ** MSTRO_ENV_DRC_NON_FLEX to disable flex-credential usage.
+ **
+ **/
+#define MSTRO_ENV_DRC_NON_FLEX "MSTRO_DRC_NON_FLEX"
+
+
 /**@} (end of group MSTRO_ENV) */
 
 #endif