logging-meeting

Example code to present logging and tracing in the Barcelona C++ Meetup group.

The code shows basic concepts and includes inefficient code, questionable constructions and repetitions.

The example has three services:

• apigateway: calls the internal services. Has a single GET end point /forecasting/{SYMBOL}
• pricereader: returns the price of a ticker symbol. GET end point /value/{SYMBOL}
• forecaster: calculates the forecasting of a ticker symbol. GET end point /forecasting?symbol={SYMBOL}&value={VALUE}

The apigateway will receive the request, call the pricereader to get the last value and pass it to the forecaster. It wil return to the user the forecasted value.

Building

Use CMake to build the project.

Dependencies

Header only libraries found in the include folder:

• cxxopts: A lightweight C++ option parser library, supporting the standard GNU style syntax for options.

Libraries installed by the user:

• spdlog: Very fast, header only, C++ logging library
• fmt: {fmt} is an open-source formatting library for C++.
• boost: Boost provides free peer-reviewed portable C++ source libraries.
• C++ REST SDK: The C++ REST SDK is a Microsoft project for cloud-based client-server communication in native code using a modern asynchronous C++ API design.
• OpenTracing API for C++: C++ implementation of the OpenTracing API
• jaeger-client-cpp: C++ OpenTracing binding for Jaeger.
• openssl: OpenSSL is a robust, commercial-grade, and full-featured toolkit for the Transport Layer Security (TLS) and Secure Sockets Layer (SSL) protocols.
• yaml-cpp: yaml-cpp is a YAML parser and emitter in C++ matching the YAML 1.2 spec.

Dependencies can be installed using vcpkg:

vcpkg install boost
vcpkg install fmt
vcpkg install spdlog
vcpkg install yaml-cpp
vcpkg install nlohmann-json
vcpkg install cpprestsdk
vcpkg install opentracing
vcpkg install thrift
vcpkg install jaegertracing

thrift port in vcpkg requires some manual fixes in the cmake files after installing. jaegertracing port is not available yet (I have a private copy, waiting for some interest by jaeger devs). Jaeger only runs in Unix systems.

Running Jaeger

Start Jaeger, either the docker image:

docker run -d --name jaeger \
  -e COLLECTOR_ZIPKIN_HTTP_PORT=9411 \
  -p 5775:5775/udp \
  -p 6831:6831/udp \
  -p 6832:6832/udp \
  -p 5778:5778 \
  -p 16686:16686 \
  -p 14268:14268 \
  -p 9411:9411 \
  jaegertracing/all-in-one:1.11

or jaeger-all-in-one:

./jaeger-all-in-one --collector.zipkin.http-port=9411

Then start the three services.

Ask for a forecasting:

curl http://127.0.0.1:16000/forecasting/AMZN

See the traces in Jaeger UI.

Running Graylog

Start Graylog:

docker run --name mongo -d mongo:3
docker run --name elasticsearch -e "http.host=0.0.0.0" -e "ES_JAVA_OPTS=-Xms512m -Xmx512m" -d docker.elastic.co/elasticsearch/elasticsearch-oss:6.6.1
docker run --name graylog --link mongo --link elasticsearch -p 9000:9000 -p 12201:12201 -p 1514:1514 -e GRAYLOG_HTTP_EXTERNAL_URI="http://127.0.0.1:9000/" -d graylog/graylog:3.0.0-2

Create a new Global Input (System menu) of type GELF HTTP using port 12201.

Start the services with the flag:

--graylog-host http://localhost:12201