request help: Profile extensions: Is it possible that allow users to add custom code to the Nginx initialization phase?

[griffenliu]

Issue description

我有一些需求，比如在apisix启动时添加一些自定义的初始化逻辑，在apisix管理API的基础上添加一些自定义的管理API等等。想要在Nginx初始化或者Worker初始化阶段做一些事情。是否可以考虑通过配置允许在这两个阶段添加一些自定义代码？
比如：

init_by_lua_block {
        require "resty.core"
        apisix = require("apisix")

        local dns_resolver = { {% for _, dns_addr in ipairs(dns_resolver or {}) do %} "{*dns_addr*}", {% end %} }
        local args = {
            dns_resolver = dns_resolver,
        }
        apisix.http_init(args)
        <通过配置添加自定义代码>
    }
    init_worker_by_lua_block {
        apisix.http_init_worker()
        <通过配置添加自定义代码>
    }

配置中可以添加：

nginx_config: 
  http_init_by_lua_configuration_snippet: |

  http_init_worker_by_lua_configuration_snippet: |

Environment

• apisix version (cmd: apisix version):
• OS (cmd: uname -a):
• OpenResty / Nginx version (cmd: nginx -V or openresty -V):
• etcd version, if have (cmd: run curl http://127.0.0.1:9090/v1/server_info to get the info from server-info API):
• apisix-dashboard version, if have:
• luarocks version, if the issue is about installation (cmd: luarocks --version):

[tzssangglass]

Worker初始化阶段

we can do this in plugin, see:

apisix/apisix/plugins/example-plugin.lua

Lines 62 to 68 in 22ee20c

	function _M.init()
	-- call this function when plugin is loaded
	local attr = plugin.plugin_attr(plugin_name)
	if attr then
	core.log.info(plugin_name, " get plugin attr val: ", attr.val)
	end
	end

在Nginx初始化

I take a conservative view and I think this is risky. My options are as follows:

• Those who are familiar with the source code will know how to modify it to do this, just as:

  apisix/apisix/init.lua

  Line 82 in 22ee20c

  local ok, err = core.config.init()

• People who are not familiar with the source code may not be able to use it correctly even if it is open.

So I think this feature somewhat useless.

nginx_config:
http_init_by_lua_configuration_snippet: |

http_init_worker_by_lua_configuration_snippet: |

This is not a good way to do this, we can't write code in yaml. Even if we support i, it would be wrote in the plugin.

@spacewander @tokers @membphis what's your options?

[griffenliu]

Does this still require modifying the source code of apisix itself? Is there an entry point for external developers to add patches like this themselves? My intention is not to modify the source code of apisix, we were using version 2.2 and modified a lot of source code. apisix is growing so fast and iterating so fast that version upgrade is a problem.

[tzssangglass]

I got. Perhaps we should discuss how to open the init_by_lua phase. cc @spacewander @membphis

[spacewander]

I think we should provide a way to specify a custom "patch.lua" or a "hook.lua". In this user-provided file, you can inject the code into the phase of APISIX like this:

apisix/apisix/patch.lua

Line 312 in cd97d82

ngx_socket.tcp = function ()

.

BTW, open the init_by_lua doesn't mean your code is always compatible with APISIX. We don't promise any compatibility with the Nginx configuration:

apisix/conf/config-default.yaml

Lines 179 to 182 in cd97d82

	# As user can add arbitrary configurations in the snippet,
	# it is user's responsibility to check the configurations
	# don't conflict with APISIX.
	main_configuration_snippet: |

It is impossible to give this promise with Nginx configuration, and it is more impossible to give it with Lua code.

[griffenliu]

I can understand that, but it's much easier to modify your own code than modifying third-party code.

[griffenliu]

I think the first option is also feasible, I just want a way to inject my own code in these phases, either by adding my own patch.lua or by adding custom code in the init phase.