feat: support var in upstream_uri on proxy-rewrite plugin

apisix/plugins/proxy-rewrite.lua

@@ -143,7 +143,7 @@ function _M.rewrite(conf, ctx)
 
     local upstream_uri = ctx.var.uri
     if conf.uri ~= nil then
-        upstream_uri = conf.uri
+        upstream_uri = core.utils.resolve_var(conf.uri, ctx.var)
     elseif conf.regex_uri ~= nil then
         local uri, _, err = re_sub(ctx.var.uri, conf.regex_uri[1],
                                    conf.regex_uri[2], "jo")

t/plugin/proxy-rewrite.t

@@ -1249,3 +1249,41 @@ version: nginx_var_does_not_exist
 x-real-ip: 127.0.0.1
 --- no_error_log
 [error]
+
+
+
+=== TEST 42: set route(rewrite uri based on ctx.var)
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/routes/1',
+                 ngx.HTTP_PUT,
+                 [[{
+                        "plugins": {
+                            "proxy-rewrite": {
+                                "uri": "/$consumer_name"
+                            }
+                        },
+                        "upstream": {
+                            "nodes": {
+                                "127.0.0.1:1980": 1
+                            },
+                            "type": "roundrobin"
+                        },
+                        "uri": "/hello"
+                }]]
+                )
+
+            if code >= 300 then
+                ngx.status = code
+            end
+            ngx.say(body)
+        }
+    }
+--- request
+GET /t
+--- response_body
+passed
+--- no_error_log
+[error]