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feature: added new Lua API for Nginx core's dynamic resolver.
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‎lib/ngx/resolver.lua

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local base = require "resty.core.base"
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local get_request = base.get_request
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local ffi = require "ffi"
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local C = ffi.C
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local ffi_new = ffi.new
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local ffi_str = ffi.string
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local ffi_gc = ffi.gc
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local FFI_OK = base.FFI_OK
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local FFI_ERROR = base.FFI_ERROR
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local FFI_DONE = base.FFI_DONE
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local co_yield = coroutine._yield
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local BUF_SIZE = 256
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local get_string_buf = base.get_string_buf
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local get_size_ptr = base.get_size_ptr
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base.allows_subsystem("http")
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ffi.cdef [[
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typedef intptr_t ngx_int_t;
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typedef unsigned char u_char;
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typedef struct ngx_http_lua_co_ctx_t *curcoctx_ptr;
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typedef struct ngx_http_resolver_ctx_t *rctx_ptr;
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typedef struct {
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ngx_http_request_t *request;
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u_char *buf;
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size_t *buf_size;
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curcoctx_ptr curr_co_ctx;
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rctx_ptr rctx;
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ngx_int_t rc;
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unsigned ipv4:1;
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unsigned ipv6:1;
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} ngx_http_lua_resolver_ctx_t;
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int ngx_http_lua_ffi_resolve(ngx_http_lua_resolver_ctx_t *ctx, const char *hostname);
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void ngx_http_lua_ffi_resolver_destroy(ngx_http_lua_resolver_ctx_t *ctx);
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]]
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local _M = { version = base.version }
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local mt = {
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__gc = C.ngx_http_lua_ffi_resolver_destroy
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}
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local Ctx = ffi.metatype("ngx_http_lua_resolver_ctx_t", mt)
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function _M.resolve(hostname, ipv4, ipv6)
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assert(type(hostname) == "string", "hostname must be string")
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assert(ipv4 == nil or type(ipv4) == "boolean", "ipv4 must be boolean or nil")
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assert(ipv6 == nil or type(ipv6) == "boolean", "ipv6 must be boolean or nil")
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local buf = get_string_buf(BUF_SIZE)
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local buf_size = get_size_ptr()
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buf_size[0] = BUF_SIZE
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local ctx = Ctx({get_request(), buf, buf_size})
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ctx.ipv4 = ipv4 == nil and 1 or ipv4
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ctx.ipv6 = ipv6 == nil and 0 or ipv6
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local rc = C.ngx_http_lua_ffi_resolve(ctx, hostname)
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local res, err
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if (rc == FFI_OK) then
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res, err = ffi_str(buf, buf_size[0]), nil
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elseif (rc == FFI_DONE) then
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res, err = co_yield()
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elseif (rc == FFI_ERROR) then
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res, err = nil, ffi_str(buf, buf_size[0])
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else
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res, err = nil, "unknown error"
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end
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C.ngx_http_lua_ffi_resolver_destroy(ffi_gc(ctx, nil))
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if err ~= nil then
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return res, err
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end
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return res
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end
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return _M

‎lib/ngx/resolver.md

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Name
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====
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`ngx.resolver` - Lua API for Nginx core's dynamic resolver.
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Table of Contents
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=================
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* [Name](#name)
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* [Status](#status)
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* [Synopsis](#synopsis)
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* [Methods](#methods)
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* [resolve](#resolve)
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* [Community](#community)
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* [English Mailing List](#english-mailing-list)
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* [Chinese Mailing List](#chinese-mailing-list)
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* [Bugs and Patches](#bugs-and-patches)
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* [Author](#author)
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* [Copyright and License](#copyright-and-license)
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* [See Also](#see-also)
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Status
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======
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TBD
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Synopsis
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========
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```nginx
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http {
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resolver 8.8.8.8;
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upstream backend {
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server 0.0.0.0;
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balancer_by_lua_block {
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local balancer = require 'ngx.balancer'
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local ctx = ngx.ctx
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local ok, err = balancer.set_current_peer(ctx.peer_addr, ctx.peer_port)
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if not ok then
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ngx.log(ngx.ERR, "failed to set the peer: ", err)
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ngx.exit(500)
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end
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}
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}
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server {
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listen 8080;
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access_by_lua_block {
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local resolver = require 'ngx.resolver'
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local ctx = ngx.ctx
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local addr, err = resolver.resolve('google.com', true, false)
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if addr then
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ctx.peer_addr = addr
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ctx.peer_port = 80
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end
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}
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location / {
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proxy_pass http://backend;
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}
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}
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}
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```
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[Back to TOC](#table-of-contents)
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Methods
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=======
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resolve
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-----------------
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**syntax:** *address,err = resolver.resolve(hostname, ipv4, ipv6)*
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**context:** *rewrite_by_lua*, access_by_lua*, content_by_lua*, ngx.timer.*, ssl_certificate_by_lua*, ssl_session_fetch_by_lua**
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Resolve `hostname` into IP address by using Nginx core's dynamic resolver. Returns IP address string. In case of error, `nil` will be returned as well as a string describing the error.
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The `ipv4` and `ipv6`argument are boolean flags that controls whether A or AAAA DNS records we are interested in.
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Please, note that resolver has its own configuration option `ipv6=on|off`, which has higher precedence over above flags.
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The 'ipv4' flag has default value `true`.
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It is required to configure the [resolver](http://nginx.org/en/docs/http/ngx_http_core_module.html#resolver) directive in the `nginx.conf`.
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[Back to TOC](#table-of-contents)
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Community
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=========
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[Back to TOC](#table-of-contents)
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English Mailing List
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--------------------
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The [openresty-en](https://groups.google.com/group/openresty-en) mailing list is for English speakers.
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[Back to TOC](#table-of-contents)
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Chinese Mailing List
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--------------------
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The [openresty](https://groups.google.com/group/openresty) mailing list is for Chinese speakers.
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[Back to TOC](#table-of-contents)
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Bugs and Patches
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================
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Please report bugs or submit patches by
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1. creating a ticket on the [GitHub Issue Tracker](https://github.com/openresty/lua-resty-core/issues),
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1. or posting to the [OpenResty community](#community).
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[Back to TOC](#table-of-contents)
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Author
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======
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TBD
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Copyright and License
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=====================
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TBD
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[Back to TOC](#table-of-contents)
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See Also
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========
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* library [lua-resty-core](https://github.com/openresty/lua-resty-core)
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* the ngx_lua module: https://github.com/openresty/lua-nginx-module
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* OpenResty: http://openresty.org
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[Back to TOC](#table-of-contents)
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‎t/resolver.t

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# vim:set ft= ts=4 sw=4 et fdm=marker:
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use Test::Nginx::Socket::Lua 'no_plan';
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use lib '.';
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use t::TestCore;
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$ENV{TEST_NGINX_LUA_PACKAGE_PATH} = "$t::TestCore::lua_package_path";
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run_tests();
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__DATA__
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=== TEST 1: use resolver in rewrite_by_lua_block
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--- http_config
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lua_package_path "$TEST_NGINX_LUA_PACKAGE_PATH";
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--- config
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resolver 8.8.8.8;
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rewrite_by_lua "ngx.ctx.addr = require('ngx.resolver').resolve('google.com')";
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location = /resolve {
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content_by_lua "ngx.say(ngx.ctx.addr)";
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}
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--- request
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GET /resolve
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--- response_body_like: ^\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}$
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=== TEST 2: use resolver in access_by_lua_block
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--- http_config
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lua_package_path "$TEST_NGINX_LUA_PACKAGE_PATH";
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--- config
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resolver 8.8.8.8;
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access_by_lua "ngx.ctx.addr = require('ngx.resolver').resolve('google.com')";
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location = /resolve {
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content_by_lua "ngx.say(ngx.ctx.addr)";
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}
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--- request
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GET /resolve
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--- response_body_like: ^\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}$
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=== TEST 3: use resolver in content_by_lua_block
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--- http_config
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lua_package_path "$TEST_NGINX_LUA_PACKAGE_PATH";
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--- config
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resolver 8.8.8.8;
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location = /resolve {
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content_by_lua "ngx.say(require('ngx.resolver').resolve('google.com'))";
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}
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--- request
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GET /resolve
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--- response_body_like: ^\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}$
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=== TEST 4: query IPv6 addresses
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--- http_config
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lua_package_path "$TEST_NGINX_LUA_PACKAGE_PATH";
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--- config
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resolver 8.8.8.8;
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location = /resolve {
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content_by_lua "ngx.say(require('ngx.resolver').resolve('google.com', false, true))";
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}
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--- request
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GET /resolve
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--- response_body_like: ^[a-fA-F0-9:]+$
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=== TEST 5: pass IPv4 address to resolver
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--- http_config
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lua_package_path "$TEST_NGINX_LUA_PACKAGE_PATH";
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--- config
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location = /resolve {
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content_by_lua "ngx.say(require('ngx.resolver').resolve('192.168.0.1'))";
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}
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--- request
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GET /resolve
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--- response_body
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192.168.0.1
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=== TEST 6: pass IPv6 address to resolver
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--- http_config
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lua_package_path "$TEST_NGINX_LUA_PACKAGE_PATH";
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--- config
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location = /resolve {
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content_by_lua "ngx.say(require('ngx.resolver').resolve('2a00:1450:4010:c05::66'))";
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}
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--- request
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GET /resolve
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--- response_body
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2a00:1450:4010:c05::66
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=== TEST 7: pass non-existent domain name to resolver
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--- http_config
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lua_package_path "$TEST_NGINX_LUA_PACKAGE_PATH";
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--- config
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resolver 8.8.8.8;
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resolver_timeout 1s;
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location = /resolve {
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content_by_lua "ngx.say(require('ngx.resolver').resolve('fake-name'))";
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}
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--- request
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GET /resolve
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--- response_body
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nilfake-name could not be resolved (3: Host not found)
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=== TEST 8: check caching in Nginx resolver (2 cache hits)
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--- http_config
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lua_package_path "$TEST_NGINX_LUA_PACKAGE_PATH";
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--- config
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resolver 8.8.8.8 valid=30s;
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location = /resolve {
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content_by_lua_block {
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local resolver = require 'ngx.resolver'
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ngx.say(resolver.resolve('google.com'))
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ngx.say(resolver.resolve('google.com'))
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ngx.say(resolver.resolve('google.com'))
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}
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}
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--- request
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GET /resolve
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--- grep_error_log: resolve cached
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--- grep_error_log_out
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resolve cached
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resolve cached

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