grpc装起来很麻烦，会有很多坑。按照官方文档或者其他博客的步骤，不注意依赖库的版本页会导致各种问题。
0. 环境
在 https://grpc.io/docs/ grpc的环境依赖如下
| Language | OS | Compilers / SDK |
|---|---|---|
| C/C++ | Linux, Mac | GCC 4.9+, Clang 3.4+ |
0.1 操作系统Ubuntu 18.04.4 LTS （腾讯云的虚拟机）
坑1：为了支持cpp11，gcc版本要4.9+，所以一些比较老的系统比如centos7.6，gcc默认4.8.5，是要升级gcc/g++的。升级gcc有两种方式
- 编译安装，耗时长，软连接和libc的库需要手动更新，不推荐。
- 使用centos-release-scl安装gcc, 升级方便快速
[root@VM-0-16-centos ~]# yum install centos-release-scl
[root@VM-0-16-centos ~]# yum install devtoolset-8-gcc*
[root@VM-0-16-centos ~]# scl enable devtoolset-8 bash
[root@VM-0-16-centos ~]# gcc -v
....
gcc version 4.9.0 (GCC)
如果系统环境对自己不存在束缚，那么推荐直接上Ubuntu18，gcc目前版本是7.5，能够对开发有个良好的支撑，不用考虑兼容问题。
0.2 cmake版本
坑2：Ubuntu18 通过apt方式安装cmake的版本是 3.10.2。对grpc来说，太低了。所以我们直接安装目前的最高版本。
cmake3.20 目前是最新版本，方法如下
坑3: 如果wget慢的像乌龟，那么可以考虑用windows迅雷下载，然后导入linux系统中。如果系统中低版本的cmake，先卸载掉
wget https://cmake.org/files/v3.20/cmake-3.20.0-rc1-linux-x86_64.sh
cmake-3.20.0-rc1-linux-x86_64.sh --prefix=/usr/local --exclude-subdir
0.3 安装zlib
方法如下
wget http://www.zlib.net/zlib-1.2.11.tar.gz
tar -xvf zlib-1.2.11.tar.gz
cd zlib-1.2.11/
./configure
make
sudo make install
这一步如果不安装后面make编译会报zlib.h找不到
1. 复制代码库
坑4：直接从github上拉仓库会奇慢无比，最好用gitee倒一下。自己倒腾也行，用下面我的gitee也行。见本文最后.gitmodules 。
2. 拉取grpc ,指定版本v1.12.0
坑5：新版本我试了好几次，make那一步总出错，而且越补越漏。
git clone https://gitee.com/niubucai/grpc.git
cd grpc/
git tag
git checkout v1.12.0
git submodule sync
git submodule update --init
3. 单独安装protoc
将protoc更新到v3.6.1 make -j4是多和编译，-j后面的参数根据当前系统配置加快编译
cd third_party/protobuf
git tag
git checkout v3.6.1
./autogen.sh
./configure
sudo make -j4
sudo make install
sudo ldconfig
protoc --version
4. 编译安装grpc 加参数 HAS_SYSTEM_PROTOBUF=false
cd ../../ # 这里是grpc的目录
make HAS_SYSTEM_PROTOBUF=false
sudo make install
注意修改下.gitmodules文件，内容如下，如果自己从GitHub上复制了这些库，也可以用自己的拷贝。
5. 测试helloworld
终端1：
ubuntu@VM-0-16-ubuntu:~/grpc$ cd examples/cpp/helloworld/
ubuntu@VM-0-16-ubuntu:~/grpc/examples/cpp/helloworld$ ./greeter_server
Server listening on 0.0.0.0:50051
终端2：
ubuntu@VM-0-16-ubuntu:~/grpc/examples/cpp/helloworld$ ./greeter_client
Greeter received: Hello world
附录
.gitmodules 文件
[submodule "third_party/zlib"]
path = third_party/zlib
url = https://gitee.com/niubucai/zlib.git
# When using CMake to build, the zlib submodule ends up with a
# generated file that makes Git consider the submodule dirty. This
# state can be ignored for day-to-day development on gRPC.
ignore = dirty
[submodule "third_party/protobuf"]
path = third_party/protobuf
url = https://gitee.com/niubucai/protobuf.git
[submodule "third_party/googletest"]
path = third_party/googletest
url = https://gitee.com/niubucai/googletest.git
[submodule "third_party/benchmark"]
path = third_party/benchmark
url = https://gitee.com/niubucai/benchmark
[submodule "third_party/boringssl"]
path = third_party/boringssl
url = https://gitee.com/niubucai/boringssl.git
[submodule "third_party/boringssl-with-bazel"]
path = third_party/boringssl-with-bazel
url = https://gitee.com/niubucai/boringssl.git
[submodule "third_party/re2"]
path = third_party/re2
url = https://gitee.com/niubucai/re2.git
[submodule "third_party/cares/cares"]
path = third_party/cares/cares
url = https://gitee.com/niubucai/c-ares.git
branch = cares-1_12_0
[submodule "third_party/bloaty"]
path = third_party/bloaty
url = https://gitee.com/niubucai/bloaty.git
[submodule "third_party/abseil-cpp"]
path = third_party/abseil-cpp
url = https://gitee.com/niubucai/abseil-cpp.git
branch = lts_2020_02_25
[submodule "third_party/envoy-api"]
path = third_party/envoy-api
url = https://gitee.com/niubucai/data-plane-api.git
[submodule "third_party/googleapis"]
path = third_party/googleapis
url = https://gitee.com/niubucai/googleapis.git
[submodule "third_party/protoc-gen-validate"]
path = third_party/protoc-gen-validate
url = https://gitee.com/niubucai/protoc-gen-validate.git
[submodule "third_party/udpa"]
path = third_party/udpa
url = https://gitee.com/niubucai/udpa.git
[submodule "third_party/libuv"]
path = third_party/libuv
url = https://gitee.com/niubucai/libuv.git
[submodule "third_party/opencensus-proto"]
path = third_party/opencensus-proto
url = https://gitee.com/niubucai/opencensus-proto.git
[submodule "third_party/gflags"]
path = third_party/gflags
url = https://gitee.com/niubucai/gflags.git
文章参考
[1] https://blog.csdn.net/qq_32460819/article/details/114708740
[2] https://grpc.io/docs/guides/