[occ] Support environment variable for control port

Author: teo

occ/OccGlobals.h

@@ -22,10 +22,15 @@
  * Intergovernmental Organization or submit itself to any jurisdiction.
  */
 
+/** @file OccGlobals.h
+ * @brief Global constants for OCC library.
+ */
+
 #ifndef OCC_OCCGLOBALS_H
 #define OCC_OCCGLOBALS_H
 
-#define OCC_DEFAULT_PORT 47100
-#define OCC_CONTROL_PORT_ARG "control-port"
+#define OCC_DEFAULT_PORT 47100                  /// Fallback value for the control port
+#define OCC_CONTROL_PORT_ARG "control-port"     /// Name of the boost::program_option to use for the control port parameter
+#define OCC_CONTROL_PORT_ENV "OCC_CONTROL_PORT" /// Name of the env variable to query for the control port
 
 #endif //OCC_OCCGLOBALS_H

occ/occlib/OccInstance.cxx

@@ -34,6 +34,15 @@ using namespace std::literals;
 
 OccInstance::OccInstance(RuntimeControlledObject *rco, int controlPort)
 {
+    if (!controlPort) {
+        if (const char* env_controlPort = std::getenv(OCC_CONTROL_PORT_ENV)) {
+            controlPort = std::atoi(env_controlPort);
+        }
+        else {
+            controlPort = OCC_DEFAULT_PORT;
+            std::cout << "no control port configured, defaulting to " << OCC_DEFAULT_PORT;
+        }
+    }
     m_grpcThread = std::thread(&OccInstance::runServer, this, rco, controlPort);
 }
 

occ/occlib/OccInstance.h

@@ -39,7 +39,7 @@ class RuntimeControlledObject;
 class OCC_EXPORT OccInstance
 {
 public:
-    explicit OccInstance(RuntimeControlledObject *rco, int controlPort = OCC_DEFAULT_PORT);
+    explicit OccInstance(RuntimeControlledObject *rco, int controlPort = 0);
     explicit OccInstance(RuntimeControlledObject *rco, const boost::program_options::variables_map& vm);
     virtual ~OccInstance();