Fix examples (#119)

Signed-off-by: Dmitriy Khaustov aka xDimon <khaustov.dm@gmail.com>

example/01-echo/libp2p_echo_client.cpp

@@ -25,7 +25,7 @@ groups:
   - name: main
     sink: console
     level: info
-    children
+    children:
       - name: libp2p
 # ----------------
   )");

example/01-echo/libp2p_echo_server.cpp

@@ -11,10 +11,29 @@
 #include <libp2p/common/literals.hpp>
 #include <libp2p/host/basic_host.hpp>
 #include <libp2p/injector/host_injector.hpp>
+#include <libp2p/log/configurator.hpp>
+#include <libp2p/log/logger.hpp>
 #include <libp2p/protocol/echo.hpp>
 #include <libp2p/security/noise.hpp>
 #include <libp2p/security/plaintext.hpp>
 
+namespace {
+  const std::string logger_config(R"(
+# ----------------
+sinks:
+  - name: console
+    type: console
+    color: true
+groups:
+  - name: main
+    sink: console
+    level: info
+    children:
+      - name: libp2p
+# ----------------
+  )");
+}  // namespace
+
 bool isInsecure(int argc, char **argv) {
   if (2 == argc) {
     const std::string insecure{"-insecure"};
@@ -56,6 +75,24 @@ int main(int argc, char **argv) {
   using libp2p::crypto::PublicKey;
   using libp2p::common::operator""_unhex;
 
+  // prepare log system
+  auto logging_system = std::make_shared<soralog::LoggingSystem>(
+      std::make_shared<libp2p::log::Configurator>(logger_config));
+  auto r = logging_system->configure();
+  if (not r.message.empty()) {
+    (r.has_error ? std::cerr : std::cout) << r.message << std::endl;
+  }
+  if (r.has_error) {
+    exit(EXIT_FAILURE);
+  }
+
+  libp2p::log::setLoggingSystem(logging_system);
+  if (std::getenv("TRACE_DEBUG") != nullptr) {
+    libp2p::log::setLevelOfGroup("*", soralog::Level::TRACE);
+  } else {
+    libp2p::log::setLevelOfGroup("*", soralog::Level::ERROR);
+  }
+
   // resulting PeerId should be
   // 12D3KooWEgUjBV5FJAuBSoNMRYFRHjV7PjZwRQ7b43EKX9g7D6xV
   KeyPair keypair{PublicKey{{Key::Type::Ed25519,

example/03-gossip/gossip_chat_example.cpp

@@ -43,7 +43,7 @@ groups:
   - name: main
     sink: console
     level: info
-    children
+    children:
       - name: libp2p
 # ----------------
   )");

example/04-dnstxt/ares_resolver.cpp

@@ -23,7 +23,7 @@ groups:
   - name: main
     sink: console
     level: info
-    children
+    children:
       - name: libp2p
 # ----------------
   )");