Link prometheus client for grpc builds (#906)

RFC=[0014](https://github.com/googlecartographer/rfcs/blob/master/text/0014-monitoring.md)

CMakeLists.txt

@@ -22,6 +22,7 @@ set(CARTOGRAPHER_PATCH_VERSION 0)
 set(CARTOGRAPHER_VERSION ${CARTOGRAPHER_MAJOR_VERSION}.${CARTOGRAPHER_MINOR_VERSION}.${CARTOGRAPHER_PATCH_VERSION})
 set(CARTOGRAPHER_SOVERSION ${CARTOGRAPHER_MAJOR_VERSION}.${CARTOGRAPHER_MINOR_VERSION})
 option(BUILD_GRPC "build Cartographer gRPC support" false)
+option(BUILD_PROMETHEUS "build Prometheus monitoring support" false)
 
 include("${PROJECT_SOURCE_DIR}/cmake/functions.cmake")
 google_initialize_cartographer_project()
@@ -153,6 +154,10 @@ if(${BUILD_GRPC})
     SRCS
       cartographer_grpc/map_builder_server_main.cc
   )
+  target_link_libraries(cartographer_grpc_server PUBLIC grpc++)
+  if(${BUILD_PROMETHEUS})
+    target_link_libraries(cartographer_grpc_server PUBLIC prometheus-cpp)
+  endif()
 endif()
 
 foreach(ABS_FIL ${ALL_TESTS})
@@ -165,6 +170,9 @@ foreach(ABS_FIL ${ALL_TESTS})
   if(${BUILD_GRPC})
     target_link_libraries("${TEST_TARGET_NAME}" PUBLIC grpc++)
   endif()
+  if(${BUILD_PROMETHEUS})
+    target_link_libraries(${PROJECT_NAME} PUBLIC prometheus-cpp)
+  endif()
 endforeach()
 
 target_include_directories(${PROJECT_NAME} SYSTEM PUBLIC
@@ -199,6 +207,10 @@ target_link_libraries(${PROJECT_NAME} PUBLIC ${PROTOBUF_LIBRARY} pthread)
 if(${BUILD_GRPC})
   target_link_libraries(${PROJECT_NAME} PUBLIC grpc++)
 endif()
+if(${BUILD_PROMETHEUS})
+  target_link_libraries(${PROJECT_NAME} PUBLIC prometheus-cpp)
+  target_compile_definitions(${PROJECT_NAME} PRIVATE USE_PROMETHEUS=1)
+endif()
 
 # Add the binary directory first, so that port.h is included after it has
 # been generated.

Dockerfile.trusty

@@ -21,5 +21,7 @@ COPY scripts/install_proto3.sh cartographer/scripts/
 RUN cartographer/scripts/install_proto3.sh && rm -rf protobuf
 COPY scripts/install_grpc.sh cartographer/scripts/
 RUN cartographer/scripts/install_grpc.sh && rm -rf grpc
+COPY scripts/install_prometheus_cpp.sh cartographer/scripts/
+RUN cartographer/scripts/install_prometheus_cpp.sh && rm -rf prometheus-cpp
 COPY . cartographer
 RUN cartographer/scripts/install_cartographer_cmake_with_grpc.sh && rm -rf cartographer

scripts/install_cartographer_cmake_with_grpc.sh

@@ -21,7 +21,7 @@ set -o verbose
 cd cartographer
 mkdir build
 cd build
-cmake .. -DBUILD_GRPC=ON -G Ninja
+cmake .. -DBUILD_GRPC=ON -DBUILD_PROMETHEUS=ON -G Ninja
 ninja
 CTEST_OUTPUT_ON_FAILURE=1 ninja test
 sudo ninja install

scripts/install_prometheus_cpp.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+# Copyright 2018 The Cartographer Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -o errexit
+set -o verbose
+
+VERSION="v0.2"
+# Digest: a5d981dab82ad6b90f78141eb189694d69c3fe0f
+
+git clone --branch ${VERSION} --depth 1 https://github.com/jupp0r/prometheus-cpp.git
+cd prometheus-cpp
+git submodule update --init
+mkdir build
+cd build
+cmake -DCMAKE_BUILD_TYPE=Release ..
+make
+sudo make install