在 openresty 中使用 capnp lua 库
1. 安装必要的工具和库
apt-get install capnproto luarocks
luarocks install lua-capnproto
luarocks install lua-cjson
lua-cjson 库不是必须的，是由于后面的演示程序要使用，就一起装上了。
可以看下库的安装位置：
root@350983744ebf:~# luarocks show lua-capnproto
lua-capnproto 0.1.4-5 - Lua-capnproto is a pure lua implementation of capnproto based on LuaJIT.
Lua-capnproto is a pure lua implementation of capnproto based on LuaJIT.
License: BSD
Homepage: https://github.com/calio/lua-capnproto
Installed in: /usr/local
Modules:
capnp (/usr/local/share/lua/5.1/capnp.lua)
capnp.compile (/usr/local/share/lua/5.1/capnp/compile.lua)
capnp.util (/usr/local/share/lua/5.1/capnp/util.lua)
handwritten_capnp (/usr/local/share/lua/5.1/handwritten_capnp.lua)
handwritten_data_generator (/usr/local/share/lua/5.1/handwritten_data_generator.lua)
random (/usr/local/share/lua/5.1/random.lua)
schema_capnp (/usr/local/share/lua/5.1/schema_capnp.lua)
test (/usr/local/share/lua/5.1/test.lua)
tool (/usr/local/share/lua/5.1/tool.lua)
Depends on:
lua ~> 5.1 (using 5.1-1)
默认库都是安装到了 /usr/local/share/lua/5.1/ 目录下。
2. 编译 capnp 文件
先将 openresty 自带的 luajit 程序目录加入 PATH 路径中：
export PATH=$PATH:/usr/local/openresty/luajit/bin
新建一个AddressBook.capnp 文件，内容如下：
@0xdbb9ad1f14bf0b36; # unique file ID, generated by `capnp id`
struct Person {
id @0 :UInt32;
name @1 :Text;
email @2 :Text;
phones @3 :List(PhoneNumber);
struct PhoneNumber {
number @0 :Text;
type @1 :Type;
enum Type {
mobile @0;
home @1;
work @2;
}
}
employment :union {
unemployed @4 :Void;
employer @5 :Text;
school @6 :Text;
selfEmployed @7 :Void;
# We assume that a person is only one of these.
}
}
struct AddressBook {
people @0 :List(Person);
}
然后编译 capnp 文件：
root@350983744ebf:~# capnp compile -olua AddressBook.capnp
root@350983744ebf:~# ls -lh
total 36K
-rw-r--r-- 1 root root 532 Oct 22 21:18 AddressBook.capnp
-rw-r--r-- 1 root root 21K Oct 22 21:20 AddressBook_capnp.lua
得到 AddressBook_capnp.lua 文件。
3. 写一个测试程序
新建一个目录，将 AddressBook_capnp.lua 文件放到这个目录。
root@350983744ebf:~# mkdir /usr/local/openresty/lua
root@350983744ebf:~# cd /usr/local/openresty/lua
root@350983744ebf:/usr/local/openresty/lua# cp /root/AddressBook_capnp.lua .
在这目录新建一个 lua 程序文件 main.lua，内容如下：
local addressBook = require "AddressBook_capnp"
local capnp = require "capnp"
local cjson = require "cjson"
local util = require "capnp.util"
local data = {
people = {
{
id = 123,
name = "Alice",
email = "[email protected]",
phones = {
{
number = "555-1212",
["type"] = "MOBILE",
},
},
employment = {
school = "MIT",
},
},
{
id = 456,
name = "Bob",
email = "[email protected]",
phones = {
{
number = "555-4567",
["type"] = "HOME",
},
{
number = "555-7654",
["type"] = "WORK",
},
},
employment = {
unemployed = "Void",
},
},
}
}
local bin = addressBook.AddressBook.serialize(data)
local decoded = addressBook.AddressBook.parse(bin)
ngx.say(cjson.encode(decoded))
这个程序将一个 lua 数据【数据格式是按照 AddressBook.capnp 文件定义的】序列化成 capnp 二进制数据，然后将二进制数据反序列化成 lua 数据，最后使用 cjson 库将 lua 数据序列化成 json 格式，使用 nginx 输出。
4. 验证程序
修改 nginx 配置文件【 /usr/local/openresty/nginx/conf/nginx.conf】内容为：
worker_processes 1;
events {
worker_connections 1024;
}
http {
lua_package_path "/usr/local/openresty/lua/?.lua;;";
server {
listen 80;
server_name localhost;
location /capnp {
content_by_lua_file /usr/local/openresty/lua/main.lua;
}
}
}
启动 nginx 并验证结果：
root@350983744ebf:~# /usr/local/openresty/nginx/sbin/nginx
root@350983744ebf:~#
root@350983744ebf:~# curl 127.0.0.1/capnp
{"people":[{"phones":[{"number":"555-1212","type":"MOBILE"}],"id":123,"name":"Alice","employment":{"school":"MIT"},"email":"[email protected]"},{"phones":[{"number":"555-4567","type":"HOME"},{"number":"555-7654","type":"WORK"}],"id":456,"name":"Bob","employment":{"unemployed":"Void"},"email":"[email protected]"}]}
和预期相符。