pcn-k8switch: fix bad initialization logic

Before 09356c4c033 ("services: remove generate_code and generate_code_vector")
the k8switch was created with a stub program and then reloaded with the initial
configuration.  That approach is far from optimal as the code is immediately
reloaded, then 09356c4c033 changed that to created the cube without any eBPF
program and then add it with the initial configuration.

However, the call to reload_program was still there, it fails because the
stub is not present anymore.  This commits fix that by calling add_program
when the cube is created.

Fixes: e09356c ("services: remove generate_code and generate_code_vector")

Signed-off-by: Mauricio Vasquez B <mauriciovasquezbernal@gmail.com>

Author: mauriciovasquezbernal

src/services/pcn-k8switch/src/K8switch.cpp

@@ -34,7 +34,7 @@ K8switch::K8switch(const std::string name, const K8switchJsonObject &conf)
   doSetVirtualClientSubnet(conf.getVirtualClientSubnet());
 
   // reload code a single time
-  reloadConfig();
+  add_program(getFlags() + k8switch_code, 0);
 
   addServiceList(conf.getService());
   addPortsList(conf.getPorts());
@@ -170,7 +170,7 @@ void K8switch::doSetVirtualClientSubnet(const std::string &value) {
   virtual_client_cidr_ = value;
 }
 
-void K8switch::reloadConfig() {
+std::string K8switch::getFlags() {
   std::string flags;
 
   // ports
@@ -197,6 +197,13 @@ void K8switch::reloadConfig() {
       "#define CLIENT_SUBNET " + std::to_string(htonl(client_subnet_)) + "\n";
   flags += "#define VIRTUAL_CLIENT_SUBNET " +
            std::to_string(htonl(virtual_client_subnet_)) + "\n";
+  logger()->debug("flags is {}", flags);
+
+  return flags;
+}
+
+void K8switch::reloadConfig() {
+  std::string flags(getFlags());
 
   logger()->debug("Reloading code with flags port: {}", flags);
 

src/services/pcn-k8switch/src/K8switch.h

@@ -143,6 +143,7 @@ class K8switch : public polycube::service::Cube<Ports>,
   void cleanupSessionTable();
   uint32_t timestampToAge(const uint64_t timestamp);
   void tick();
+  std::string getFlags();
 
   std::unique_ptr<std::thread> tick_thread;
   bool stop_;