[policy] introduce content phase

need to share context between internal redirect
(openresty/lua-nginx-module#1057)

but then the policies have total control over generating the content
so they can use cosockets / files / upstream / generate content

please note this is higly experimental and should not be merged to
master yet

gateway/conf.d/apicast.conf

@@ -56,6 +56,25 @@ location @out_of_band_authrep_action {
   }
 }
 
+location @upstream {
+  internal;
+
+  rewrite_by_lua_block {
+    require('resty.exec').ctx(ngx.var.ctx_ref)
+}
+
+  proxy_pass $proxy_pass;
+
+  proxy_http_version 1.1;
+  proxy_set_header X-Real-IP  $remote_addr;
+  proxy_set_header Host $http_host;
+  proxy_set_header X-3scale-proxy-secret-token $secret_token;
+  proxy_set_header X-3scale-debug "";
+  proxy_set_header Connection "";
+
+  post_action @out_of_band_authrep_action;
+}
+
 location / {
   set $cached_key null;
   set $credentials null;
@@ -76,6 +95,8 @@ location / {
   set $version '';
   set $real_url null;
 
+  set $ctx_ref -1;
+
   set $post_action_impact null;
   set $original_request_id null;
 
@@ -88,16 +109,6 @@ location / {
 
   content_by_lua_block { require('apicast.executor'):content() }
 
-  proxy_pass $proxy_pass;
-  proxy_http_version 1.1;
-  proxy_set_header X-Real-IP  $remote_addr;
-  proxy_set_header Host $http_host;
-  proxy_set_header X-3scale-proxy-secret-token $secret_token;
-  proxy_set_header X-3scale-debug "";
-  proxy_set_header Connection "";
-
-  post_action @out_of_band_authrep_action;
-
   include ../apicast.d/location.d/*.conf;
 }
 

gateway/src/apicast/policy/apicast/policy.lua

@@ -3,6 +3,7 @@ local math = math
 local setmetatable = setmetatable
 
 local user_agent = require('apicast.user_agent')
+local exec = require('resty.exec')
 
 local noop = function() end
 
@@ -101,6 +102,11 @@ function _M:access(context)
   return ok, err
 end
 
+_M.content = function()
+  ngx.var.ctx_ref = exec.ctx_ref()
+  ngx.exec("@upstream")
+end
+
 _M.body_filter = noop
 _M.header_filter = noop
 

gateway/src/apicast/policy/echo/policy.lua

@@ -19,13 +19,15 @@ function _M.new(configuration)
   return policy
 end
 
+function _M:content()
+  ngx.say(ngx.var.request)
+end
+
 function _M:rewrite()
   if self.status then
     ngx.status = self.status
   end
 
-  ngx.say(ngx.var.request)
-
   if self.exit == 'request' then
     return ngx.exit(ngx.status)
   elseif self.exit == 'phase' then

gateway/src/apicast/policy/policy.lua

@@ -11,6 +11,7 @@ local _M = { }
 local PHASES = {
     'init', 'init_worker',
     'rewrite', 'access', 'balancer',
+    'content',
     'header_filter', 'body_filter',
     'post_action',  'log'
 }

gateway/src/resty/exec.lua

@@ -0,0 +1,68 @@
+local ffi = require 'ffi'
+local debug = require 'debug'
+local base = require "resty.core.base"
+local misc = require "resty.core.misc"
+
+
+local registry = debug.getregistry()
+local new_tab = base.new_tab
+local ref_in_table = base.ref_in_table
+local getfenv = getfenv
+local C = ffi.C
+local FFI_NO_REQ_CTX = base.FFI_NO_REQ_CTX
+local FFI_OK = base.FFI_OK
+local error = error
+
+
+local _M = {
+
+}
+
+local mt = {}
+
+setmetatable(_M, mt)
+
+local exec = ngx.exec
+
+function _M.ctx_ref()
+  local r = getfenv(0).__ngx_req
+
+  if not r then
+    return error("no request found")
+  end
+
+  local ctx = ngx.ctx
+  local ctx_ref = C.ngx_http_lua_ffi_get_ctx_ref(r)
+  if ctx_ref == FFI_NO_REQ_CTX then
+    return error("no request ctx found")
+  end
+
+  local ctxs = registry.ngx_lua_ctx_tables
+  -- TODO: why they are not equal?
+  if ctx_ref == ref_in_table(ctxs, ctx) then
+    return ctx_ref
+  end
+
+  return ctx_ref
+end
+
+function _M.ctx(ref)
+  local r = getfenv(0).__ngx_req
+
+  if not r then
+    return error("no request found")
+  end
+
+  local ctx_ref = tonumber(ref)
+  if not ctx_ref then
+    return
+  end
+
+  if C.ngx_http_lua_ffi_set_ctx_ref(r, ctx_ref) ~= FFI_OK then
+    return nil
+  end
+
+  return true
+end
+
+return _M

spec/policy_spec.lua

@@ -3,7 +3,8 @@ local policy = require 'apicast.policy'
 describe('policy', function()
   local phases = {
     'init', 'init_worker',
-    'rewrite', 'access', 'balancer',
+    'rewrite', 'access',
+    'content', 'balancer',
     'header_filter', 'body_filter',
     'post_action',  'log'
   }