From 9285a13ffe7e46c2869ca6e8c63848be928a40cb Mon Sep 17 00:00:00 2001
From: Yuansheng <membphis@gmail.com>
Date: Wed, 23 Sep 2020 21:49:17 +0800
Subject: [PATCH 01/11] test: add test.

---
 t/plugin/http-logger-new-line.t | 223 ++++++++++++++++++++++++++++++++
 1 file changed, 223 insertions(+)
 create mode 100644 t/plugin/http-logger-new-line.t

diff --git a/t/plugin/http-logger-new-line.t b/t/plugin/http-logger-new-line.t
new file mode 100644
index 000000000000..85d48ed9b212
--- /dev/null
+++ b/t/plugin/http-logger-new-line.t
@@ -0,0 +1,223 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+use t::APISIX 'no_plan';
+
+log_level('info');
+repeat_each(1);
+no_long_string();
+no_root_location();
+run_tests;
+
+__DATA__
+
+=== TEST 1: sanity, batch_max_size=1
+--- 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": {
+                            "http-logger": {
+                                "uri": "http://127.0.0.1:1980/log",
+                                "batch_max_size": 1,
+                                "max_retry_count": 1,
+                                "retry_delay": 2,
+                                "buffer_duration": 2,
+                                "inactive_timeout": 2,
+                                "concat_method": "new_line"
+                            }
+                        },
+                        "upstream": {
+                            "nodes": {
+                                "127.0.0.1:1982": 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]
+
+
+
+=== TEST 2: hit route and report http logger
+--- request
+GET /hello
+--- response_body
+hello world
+--- wait: 0.5
+--- no_error_log
+[error]
+--- error_log
+request log: {"upstream":"127.0.0.1:1982"
+
+
+
+=== TEST 3: sanity, batch_max_size=1
+--- 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": {
+                            "http-logger": {
+                                "uri": "http://127.0.0.1:1980/log",
+                                "batch_max_size": 3,
+                                "max_retry_count": 3,
+                                "retry_delay": 2,
+                                "buffer_duration": 2,
+                                "inactive_timeout": 1,
+                                "concat_method": "new_line"
+                            }
+                        },
+                        "upstream": {
+                            "nodes": {
+                                "127.0.0.1:1982": 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]
+
+
+
+=== TEST 4: hit route, and no report log
+--- request
+GET /hello
+--- response_body
+hello world
+--- no_error_log
+[error]
+request log:
+
+
+
+=== TEST 5: hit route, and report log
+--- config
+location /t {
+    content_by_lua_block {
+        local t = require("lib.test_admin").test
+
+        for i = 1, 6 do
+            t('/hello', ngx.HTTP_GET)
+        end
+
+        ngx.sleep(3)
+        ngx.say("done")
+    }
+}
+--- request
+GET /t
+--- timeout: 4
+--- no_error_log
+[error]
+--- grep_error_log eval
+qr/request log:/
+--- grep_error_log_out
+request log:
+request log:
+
+
+
+=== TEST 6: hit route, and report log
+--- config
+location /t {
+    content_by_lua_block {
+        local t = require("lib.test_admin").test
+
+        for i = 1, 6 do
+            t('/hello', ngx.HTTP_GET)
+        end
+
+        ngx.sleep(3)
+        ngx.say("done")
+    }
+}
+--- request
+GET /t
+--- timeout: 4
+--- no_error_log
+[error]
+--- grep_error_log eval
+qr/"upstream":"127.0.0.1:1982"/
+--- grep_error_log_out
+"upstream":"127.0.0.1:1982"
+"upstream":"127.0.0.1:1982"
+"upstream":"127.0.0.1:1982"
+"upstream":"127.0.0.1:1982"
+"upstream":"127.0.0.1:1982"
+"upstream":"127.0.0.1:1982"
+
+
+
+=== TEST 7: hit route, and report log
+--- config
+location /t {
+    content_by_lua_block {
+        local t = require("lib.test_admin").test
+
+        for i = 1, 5 do
+            t('/hello', ngx.HTTP_GET)
+        end
+
+        ngx.sleep(3)
+        ngx.say("done")
+    }
+}
+--- request
+GET /t
+--- timeout: 4
+--- no_error_log
+[error]
+--- grep_error_log eval
+qr/"upstream":"127.0.0.1:1982"/
+--- grep_error_log_out
+"upstream":"127.0.0.1:1982"
+"upstream":"127.0.0.1:1982"
+"upstream":"127.0.0.1:1982"
+"upstream":"127.0.0.1:1982"
+"upstream":"127.0.0.1:1982"

From 44b6843112ce231086a3e491b47618172fedb72a Mon Sep 17 00:00:00 2001
From: Yuansheng <membphis@gmail.com>
Date: Wed, 23 Sep 2020 23:01:10 +0800
Subject: [PATCH 02/11] feat: support user-defined `log_format`, default is
 json encoding format.

---
 apisix/plugin.lua                 |  16 +++
 apisix/plugins/http-logger.lua    |  70 ++++++++--
 bin/apisix                        |   2 +-
 t/plugin/http-logger-log-format.t | 122 ++++++++++++++++
 t/plugin/http-logger-new-line.t   | 223 ------------------------------
 t/plugin/tcp-logger.t             |   2 +-
 6 files changed, 202 insertions(+), 233 deletions(-)
 create mode 100644 t/plugin/http-logger-log-format.t
 delete mode 100644 t/plugin/http-logger-new-line.t

diff --git a/apisix/plugin.lua b/apisix/plugin.lua
index 8c498831ef05..c2d40ce5ab0f 100644
--- a/apisix/plugin.lua
+++ b/apisix/plugin.lua
@@ -25,6 +25,7 @@ local type          = type
 local local_plugins = core.table.new(32, 0)
 local ngx           = ngx
 local tostring      = tostring
+local error         = error
 local local_plugins_hash    = core.table.new(0, 32)
 local stream_local_plugins  = core.table.new(32, 0)
 local stream_local_plugins_hash = core.table.new(0, 32)
@@ -391,6 +392,21 @@ end
 
 function _M.init_worker()
     _M.load()
+
+    local plugin_metadatas, err = core.config.new("/plugin_metadata",
+        {automatic = true}
+    )
+    if not plugin_metadatas then
+        error("failed to create etcd instance for fetching /plugin_metadatas : "
+              .. err)
+    end
+
+    _M.plugin_metadatas = plugin_metadatas
+end
+
+
+function _M.plugin_metadata(name)
+    return _M.plugin_metadatas:get(name)
 end
 
 
diff --git a/apisix/plugins/http-logger.lua b/apisix/plugins/http-logger.lua
index 44df6aeff99c..5b8c1ca29619 100644
--- a/apisix/plugins/http-logger.lua
+++ b/apisix/plugins/http-logger.lua
@@ -14,15 +14,24 @@
 -- See the License for the specific language governing permissions and
 -- limitations under the License.
 --
-local core = require("apisix.core")
-local log_util = require("apisix.utils.log-util")
+
 local batch_processor = require("apisix.utils.batch-processor")
-local plugin_name = "http-logger"
-local ngx = ngx
+local log_util        = require("apisix.utils.log-util")
+local core            = require("apisix.core")
+local http            = require("resty.http")
+local url             = require("net.url")
+local plugin          = require("apisix.plugin")
+local ngx      = ngx
 local tostring = tostring
-local http = require "resty.http"
-local url = require "net.url"
+local pairs    = pairs
+
+
+local plugin_name = "http-logger"
 local buffers = {}
+local lru_log_format = core.lrucache.new({
+    ttl = 300, count = 512
+})
+
 
 local schema = {
     type = "object",
@@ -42,11 +51,24 @@ local schema = {
 }
 
 
+local metadata_schema = {
+    type = "object",
+    properties = {
+        log_format = {
+            type = "object",
+            default = {},
+        },
+    },
+    additionalProperties = false,
+}
+
+
 local _M = {
     version = 0.1,
     priority = 410,
     name = plugin_name,
     schema = schema,
+    metadata_schema = metadata_schema,
 }
 
 
@@ -121,8 +143,40 @@ local function send_http_data(conf, log_message)
 end
 
 
-function _M.log(conf)
-    local entry = log_util.get_full_log(ngx, conf)
+function _M.log(conf, ctx)
+    local metadata = plugin.plugin_metadata(plugin_name)
+    core.log.info("metadata: ", core.json.delay_encode(metadata))
+
+    local log_format = lru_log_format(metadata, nil, function()
+        local log_format = {}
+        for k, var_name in pairs(metadata.value.log_format) do
+            if var_name:sub(1, 1) == "$" then
+                log_format[k] = {true, var_name:sub(2)}
+            else
+                log_format[k] = {false, var_name}
+            end
+        end
+        core.log.info("log_format: ", core.json.delay_encode(log_format))
+        return log_format
+    end)
+
+    local entry
+    if log_format then
+        entry = core.table.new(0, core.table.nkeys(log_format))
+        for k, var_attr in pairs(log_format) do
+            if var_attr[1] then
+                entry[k] = ctx.var[var_attr[2]]
+            else
+                entry[k] = var_attr[2]
+            end
+        end
+        local matched_route = ctx.matched_route and ctx.matched_route.value
+
+        entry.service_id = matched_route.service_id
+        entry.route_id = matched_route.id
+    else
+        entry = log_util.get_full_log(ngx, conf)
+    end
 
     if not entry.route_id then
         core.log.error("failed to obtain the route id for http logger")
diff --git a/bin/apisix b/bin/apisix
index 342c0fc58fca..bab34c6890cd 100755
--- a/bin/apisix
+++ b/bin/apisix
@@ -1025,7 +1025,7 @@ local function init_etcd(show_output)
         for _, dir_name in ipairs({"/routes", "/upstreams", "/services",
                                    "/plugins", "/consumers", "/node_status",
                                    "/ssl", "/global_rules", "/stream_routes",
-                                   "/proto"}) do
+                                   "/proto", "/plugin_metadata"}) do
             local key =  (etcd_conf.prefix or "") .. dir_name .. "/"
 
             local base64_encode = require("base64").encode
diff --git a/t/plugin/http-logger-log-format.t b/t/plugin/http-logger-log-format.t
new file mode 100644
index 000000000000..babed4b31128
--- /dev/null
+++ b/t/plugin/http-logger-log-format.t
@@ -0,0 +1,122 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+use t::APISIX 'no_plan';
+
+log_level('info');
+repeat_each(1);
+no_long_string();
+no_root_location();
+
+run_tests;
+
+__DATA__
+
+=== TEST 1: add plugin metadata
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/plugin_metadata/http-logger',
+                ngx.HTTP_PUT,
+                [[{
+                    "log_format": {
+                        "host": "$host",
+                        "@timestamp": "$time_iso8601",
+                        "client_ip": "$remote_addr"
+                    }
+                }]],
+                [[{
+                    "node": {
+                        "value": {
+                            "log_format": {
+                                "host": "$host",
+                                "@timestamp": "$time_iso8601",
+                                "client_ip": "$remote_addr"
+                            }
+                        }
+                    },
+                    "action": "set"
+                }]]
+                )
+
+            ngx.status = code
+            ngx.say(body)
+        }
+    }
+--- request
+GET /t
+--- response_body
+passed
+--- no_error_log
+[error]
+
+
+
+=== TEST 2: sanity, batch_max_size=1
+--- 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": {
+                            "http-logger": {
+                                "uri": "http://127.0.0.1:1980/log",
+                                "batch_max_size": 1,
+                                "max_retry_count": 1,
+                                "retry_delay": 2,
+                                "buffer_duration": 2,
+                                "inactive_timeout": 2,
+                                "concat_method": "new_line"
+                            }
+                        },
+                        "upstream": {
+                            "nodes": {
+                                "127.0.0.1:1982": 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]
+
+
+
+=== TEST 3: hit route and report http logger
+--- request
+GET /hello
+--- response_body
+hello world
+--- wait: 0.5
+--- no_error_log
+[error]
+--- error_log
+request log: {"host":"localhost"
diff --git a/t/plugin/http-logger-new-line.t b/t/plugin/http-logger-new-line.t
deleted file mode 100644
index 85d48ed9b212..000000000000
--- a/t/plugin/http-logger-new-line.t
+++ /dev/null
@@ -1,223 +0,0 @@
-#
-# Licensed to the Apache Software Foundation (ASF) under one or more
-# contributor license agreements.  See the NOTICE file distributed with
-# this work for additional information regarding copyright ownership.
-# The ASF licenses this file to You under the Apache License, Version 2.0
-# (the "License"); you may not use this file except in compliance with
-# the License.  You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-use t::APISIX 'no_plan';
-
-log_level('info');
-repeat_each(1);
-no_long_string();
-no_root_location();
-run_tests;
-
-__DATA__
-
-=== TEST 1: sanity, batch_max_size=1
---- 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": {
-                            "http-logger": {
-                                "uri": "http://127.0.0.1:1980/log",
-                                "batch_max_size": 1,
-                                "max_retry_count": 1,
-                                "retry_delay": 2,
-                                "buffer_duration": 2,
-                                "inactive_timeout": 2,
-                                "concat_method": "new_line"
-                            }
-                        },
-                        "upstream": {
-                            "nodes": {
-                                "127.0.0.1:1982": 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]
-
-
-
-=== TEST 2: hit route and report http logger
---- request
-GET /hello
---- response_body
-hello world
---- wait: 0.5
---- no_error_log
-[error]
---- error_log
-request log: {"upstream":"127.0.0.1:1982"
-
-
-
-=== TEST 3: sanity, batch_max_size=1
---- 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": {
-                            "http-logger": {
-                                "uri": "http://127.0.0.1:1980/log",
-                                "batch_max_size": 3,
-                                "max_retry_count": 3,
-                                "retry_delay": 2,
-                                "buffer_duration": 2,
-                                "inactive_timeout": 1,
-                                "concat_method": "new_line"
-                            }
-                        },
-                        "upstream": {
-                            "nodes": {
-                                "127.0.0.1:1982": 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]
-
-
-
-=== TEST 4: hit route, and no report log
---- request
-GET /hello
---- response_body
-hello world
---- no_error_log
-[error]
-request log:
-
-
-
-=== TEST 5: hit route, and report log
---- config
-location /t {
-    content_by_lua_block {
-        local t = require("lib.test_admin").test
-
-        for i = 1, 6 do
-            t('/hello', ngx.HTTP_GET)
-        end
-
-        ngx.sleep(3)
-        ngx.say("done")
-    }
-}
---- request
-GET /t
---- timeout: 4
---- no_error_log
-[error]
---- grep_error_log eval
-qr/request log:/
---- grep_error_log_out
-request log:
-request log:
-
-
-
-=== TEST 6: hit route, and report log
---- config
-location /t {
-    content_by_lua_block {
-        local t = require("lib.test_admin").test
-
-        for i = 1, 6 do
-            t('/hello', ngx.HTTP_GET)
-        end
-
-        ngx.sleep(3)
-        ngx.say("done")
-    }
-}
---- request
-GET /t
---- timeout: 4
---- no_error_log
-[error]
---- grep_error_log eval
-qr/"upstream":"127.0.0.1:1982"/
---- grep_error_log_out
-"upstream":"127.0.0.1:1982"
-"upstream":"127.0.0.1:1982"
-"upstream":"127.0.0.1:1982"
-"upstream":"127.0.0.1:1982"
-"upstream":"127.0.0.1:1982"
-"upstream":"127.0.0.1:1982"
-
-
-
-=== TEST 7: hit route, and report log
---- config
-location /t {
-    content_by_lua_block {
-        local t = require("lib.test_admin").test
-
-        for i = 1, 5 do
-            t('/hello', ngx.HTTP_GET)
-        end
-
-        ngx.sleep(3)
-        ngx.say("done")
-    }
-}
---- request
-GET /t
---- timeout: 4
---- no_error_log
-[error]
---- grep_error_log eval
-qr/"upstream":"127.0.0.1:1982"/
---- grep_error_log_out
-"upstream":"127.0.0.1:1982"
-"upstream":"127.0.0.1:1982"
-"upstream":"127.0.0.1:1982"
-"upstream":"127.0.0.1:1982"
-"upstream":"127.0.0.1:1982"
diff --git a/t/plugin/tcp-logger.t b/t/plugin/tcp-logger.t
index 7343f0ddf5f9..05bd3c470685 100644
--- a/t/plugin/tcp-logger.t
+++ b/t/plugin/tcp-logger.t
@@ -233,4 +233,4 @@ GET /t
 --- error_log
 failed to connect to TCP server: host[312.0.0.1] port[2000]
 [error]
---- wait: 1.5
+--- wait: 3

From a5766a4100249f102262f9b3fea995c4299862f3 Mon Sep 17 00:00:00 2001
From: Yuansheng <membphis@gmail.com>
Date: Thu, 24 Sep 2020 06:47:08 +0800
Subject: [PATCH 03/11] revert code.

---
 t/plugin/tcp-logger.t | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/t/plugin/tcp-logger.t b/t/plugin/tcp-logger.t
index 05bd3c470685..7343f0ddf5f9 100644
--- a/t/plugin/tcp-logger.t
+++ b/t/plugin/tcp-logger.t
@@ -233,4 +233,4 @@ GET /t
 --- error_log
 failed to connect to TCP server: host[312.0.0.1] port[2000]
 [error]
---- wait: 3
+--- wait: 1.5

From 4e202b1e9a0e58928d9c5035cb0fe705d3d3a647 Mon Sep 17 00:00:00 2001
From: Yuansheng <membphis@gmail.com>
Date: Thu, 24 Sep 2020 07:05:37 +0800
Subject: [PATCH 04/11] test: added test api.

---
 apisix/plugins/http-logger.lua | 28 +++++++++++++++-------------
 t/lib/server.lua               |  6 ++++++
 2 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/apisix/plugins/http-logger.lua b/apisix/plugins/http-logger.lua
index 5b8c1ca29619..6d4b0f00fbe7 100644
--- a/apisix/plugins/http-logger.lua
+++ b/apisix/plugins/http-logger.lua
@@ -143,24 +143,26 @@ local function send_http_data(conf, log_message)
 end
 
 
+local function gen_log_format(metadata)
+    local log_format = {}
+    for k, var_name in pairs(metadata.value.log_format) do
+        if var_name:sub(1, 1) == "$" then
+            log_format[k] = {true, var_name:sub(2)}
+        else
+            log_format[k] = {false, var_name}
+        end
+    end
+    core.log.info("log_format: ", core.json.delay_encode(log_format))
+    return log_format
+end
+
+
 function _M.log(conf, ctx)
     local metadata = plugin.plugin_metadata(plugin_name)
     core.log.info("metadata: ", core.json.delay_encode(metadata))
 
-    local log_format = lru_log_format(metadata, nil, function()
-        local log_format = {}
-        for k, var_name in pairs(metadata.value.log_format) do
-            if var_name:sub(1, 1) == "$" then
-                log_format[k] = {true, var_name:sub(2)}
-            else
-                log_format[k] = {false, var_name}
-            end
-        end
-        core.log.info("log_format: ", core.json.delay_encode(log_format))
-        return log_format
-    end)
-
     local entry
+    local log_format = lru_log_format(metadata, nil, gen_log_format, metadata)
     if log_format then
         entry = core.table.new(0, core.table.nkeys(log_format))
         for k, var_attr in pairs(log_format) do
diff --git a/t/lib/server.lua b/t/lib/server.lua
index c9e89e9af2f9..3a0edae251ad 100644
--- a/t/lib/server.lua
+++ b/t/lib/server.lua
@@ -282,4 +282,10 @@ function _M.headers()
     ngx.say("/headers")
 end
 
+function _M.log()
+    ngx.req.read_body()
+    local body = ngx.req.get_body_data()
+    ngx.log(ngx.WARN, "request log: ", body or "nil")
+end
+
 return _M

From 09d5b0c9510a19e7c2e74d2cfd52197394f7b75b Mon Sep 17 00:00:00 2001
From: Yuansheng <membphis@gmail.com>
Date: Thu, 24 Sep 2020 07:26:16 +0800
Subject: [PATCH 05/11] Chinese doc

---
 doc/zh-cn/plugins/http-logger.md | 52 ++++++++++++++++++++++++--------
 1 file changed, 39 insertions(+), 13 deletions(-)

diff --git a/doc/zh-cn/plugins/http-logger.md b/doc/zh-cn/plugins/http-logger.md
index 7ea7dc11c8c0..cc37823abf76 100644
--- a/doc/zh-cn/plugins/http-logger.md
+++ b/doc/zh-cn/plugins/http-logger.md
@@ -50,23 +50,23 @@
 
 ## 如何开启
 
-1. 这是有关如何为特定路由启用 http-logger 插件的示例。
+这是有关如何为特定路由启用 http-logger 插件的示例。
 
 ```shell
 curl http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
 {
-      "plugins": {
-            "http-logger": {
-                 "uri": "127.0.0.1:80/postendpoint?param=1"
-            }
-       },
-      "upstream": {
-           "type": "roundrobin",
-           "nodes": {
-               "127.0.0.1:1980": 1
-           }
-      },
-      "uri": "/hello"
+    "plugins": {
+        "http-logger": {
+                "uri": "127.0.0.1:80/postendpoint?param=1"
+        }
+    },
+    "upstream": {
+        "type": "roundrobin",
+        "nodes": {
+            "127.0.0.1:1980": 1
+        }
+    },
+    "uri": "/hello"
 }'
 ```
 
@@ -81,6 +81,32 @@ HTTP/1.1 200 OK
 hello, world
 ```
 
+## 插件元数据设置
+
+| 名称             | 类型    | 必选项 | 默认值        | 有效值  | 描述                                             |
+| ---------------- | ------- | ------ | ------------- | ------- | ------------------------------------------------ |
+| log_format       | object  | 可选   |               |         | 以 Hash 对象方式声明日志格式。对 value 部分，仅支持字符串。如果是以`$`开头，则表明是要获取 [Nginx 内置变量](http://nginx.org/en/docs/varindex.html)。特别的，该设置是全局生效的，意味着指定 log_format 后，将对所有绑定 http-logger 的 Route 或 Service 生效。 |
+
+### 设置日志格式示例
+
+```shell
+curl http://127.0.0.1:9080/apisix/admin/plugin_metadata/http-logger -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
+{
+    "log_format": {
+        "host": "$host",
+        "@timestamp": "$time_iso8601",
+        "client_ip": "$remote_addr"
+    }
+}'
+```
+
+在日志收集处，将得到类似下面的日志：
+
+```shell
+{"host":"localhost","@timestamp":"2020-09-23T19:05:05-04:00","client_ip":"127.0.0.1","route_id":"1"}
+{"host":"localhost","@timestamp":"2020-09-23T19:05:05-04:00","client_ip":"127.0.0.1","route_id":"1"}
+```
+
 ## 禁用插件
 
 在插件配置中删除相应的 json 配置以禁用 http-logger。APISIX 插件是热重载的，因此无需重新启动 APISIX：

From b939f6aa3b9198886a0e7b5236b149d612b196e6 Mon Sep 17 00:00:00 2001
From: Yuansheng <membphis@gmail.com>
Date: Thu, 24 Sep 2020 09:55:22 +0800
Subject: [PATCH 06/11] test: delete the plugin metadata at the end of test
 file.

---
 t/plugin/http-logger-log-format.t | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/t/plugin/http-logger-log-format.t b/t/plugin/http-logger-log-format.t
index babed4b31128..84849075925d 100644
--- a/t/plugin/http-logger-log-format.t
+++ b/t/plugin/http-logger-log-format.t
@@ -120,3 +120,28 @@ hello world
 [error]
 --- error_log
 request log: {"host":"localhost"
+
+
+
+=== TEST 4: remove plugin metadata
+--- config
+    location /t {
+        content_by_lua_block {
+            local t = require("lib.test_admin").test
+            local code, body = t('/apisix/admin/plugin_metadata/http-logger',
+                ngx.HTTP_DELETE
+            )
+
+            if code >= 300 then
+                ngx.status = code
+            end
+
+            ngx.say(body)
+        }
+    }
+--- request
+GET /t
+--- response_body
+passed
+--- no_error_log
+[error]

From 00ba1dc5df3fe91e0bbcb6d466c77a2614f68743 Mon Sep 17 00:00:00 2001
From: Yuansheng <membphis@gmail.com>
Date: Thu, 24 Sep 2020 14:02:07 +0800
Subject: [PATCH 07/11] bug: use empty table if there was no plugin metadata.

---
 apisix/core/table.lua          |  2 +-
 apisix/plugins/http-logger.lua | 14 +++++++++++---
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/apisix/core/table.lua b/apisix/core/table.lua
index 4ad92caa104d..23248408af8d 100644
--- a/apisix/core/table.lua
+++ b/apisix/core/table.lua
@@ -26,7 +26,6 @@ local ngx_re       = require("ngx.re")
 
 
 local _M = {
-    version = 0.2,
     new     = new_tab,
     clear   = require("table.clear"),
     nkeys   = nkeys,
@@ -35,6 +34,7 @@ local _M = {
     sort    = table.sort,
     clone   = require("table.clone"),
     isarray = require("table.isarray"),
+    empty_tab = {},
 }
 
 
diff --git a/apisix/plugins/http-logger.lua b/apisix/plugins/http-logger.lua
index 31dcfa089439..89ebdf8351d0 100644
--- a/apisix/plugins/http-logger.lua
+++ b/apisix/plugins/http-logger.lua
@@ -140,7 +140,15 @@ end
 
 
 local function gen_log_format(metadata)
-    local log_format = {}
+    local log_format = core.table.empty_tab
+    if not metadata or
+       not metadata.value or
+       not metadata.value.log_format or
+       core.talbe.nkeys(metadata.value.log_format) == 0
+    then
+        return log_format
+    end
+
     for k, var_name in pairs(metadata.value.log_format) do
         if var_name:sub(1, 1) == "$" then
             log_format[k] = {true, var_name:sub(2)}
@@ -158,8 +166,8 @@ function _M.log(conf, ctx)
     core.log.info("metadata: ", core.json.delay_encode(metadata))
 
     local entry
-    local log_format = lru_log_format(metadata, nil, gen_log_format, metadata)
-    if log_format then
+    local log_format = lru_log_format(metadata or "", nil, gen_log_format, metadata)
+    if log_format ~= core.table.empty_tab then
         entry = core.table.new(0, core.table.nkeys(log_format))
         for k, var_attr in pairs(log_format) do
             if var_attr[1] then

From 8750b97470f8516bb6c4f6d26e4bbb3653dd9d77 Mon Sep 17 00:00:00 2001
From: Yuansheng <membphis@gmail.com>
Date: Thu, 24 Sep 2020 14:02:26 +0800
Subject: [PATCH 08/11] chore: code style.

---
 apisix/plugins/http-logger.lua | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/apisix/plugins/http-logger.lua b/apisix/plugins/http-logger.lua
index 89ebdf8351d0..761f7543cf44 100644
--- a/apisix/plugins/http-logger.lua
+++ b/apisix/plugins/http-logger.lua
@@ -166,7 +166,8 @@ function _M.log(conf, ctx)
     core.log.info("metadata: ", core.json.delay_encode(metadata))
 
     local entry
-    local log_format = lru_log_format(metadata or "", nil, gen_log_format, metadata)
+    local log_format = lru_log_format(metadata or "", nil, gen_log_format,
+                                      metadata)
     if log_format ~= core.table.empty_tab then
         entry = core.table.new(0, core.table.nkeys(log_format))
         for k, var_attr in pairs(log_format) do

From 6f1ddf8125a6d8586f85502bdc3bf8f815b045f1 Mon Sep 17 00:00:00 2001
From: Yuansheng <membphis@gmail.com>
Date: Thu, 24 Sep 2020 14:43:54 +0800
Subject: [PATCH 09/11] typo

---
 apisix/plugins/http-logger.lua | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/apisix/plugins/http-logger.lua b/apisix/plugins/http-logger.lua
index 761f7543cf44..a483ab1c4dcb 100644
--- a/apisix/plugins/http-logger.lua
+++ b/apisix/plugins/http-logger.lua
@@ -144,7 +144,7 @@ local function gen_log_format(metadata)
     if not metadata or
        not metadata.value or
        not metadata.value.log_format or
-       core.talbe.nkeys(metadata.value.log_format) == 0
+       core.table.nkeys(metadata.value.log_format) == 0
     then
         return log_format
     end

From 90e307393d08f53a30a096363c009059459d1b54 Mon Sep 17 00:00:00 2001
From: Yuansheng <membphis@gmail.com>
Date: Thu, 24 Sep 2020 15:25:01 +0800
Subject: [PATCH 10/11] test: update match context

---
 t/plugin/http-logger-log-format.t | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/t/plugin/http-logger-log-format.t b/t/plugin/http-logger-log-format.t
index 84849075925d..d092eebba66f 100644
--- a/t/plugin/http-logger-log-format.t
+++ b/t/plugin/http-logger-log-format.t
@@ -119,7 +119,7 @@ hello world
 --- no_error_log
 [error]
 --- error_log
-request log: {"host":"localhost"
+request log: {
 
 
 

From c8fe4c79e2041d90806fb954e2aeb721a439ed54 Mon Sep 17 00:00:00 2001
From: Yuansheng <membphis@gmail.com>
Date: Thu, 24 Sep 2020 16:19:15 +0800
Subject: [PATCH 11/11] test: use `apple.com` to replace `baidu.com`, it is
 more stable in CI env.

---
 t/node/route-domain-with-local-dns.t | 4 ++--
 t/node/route-domain.t                | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/t/node/route-domain-with-local-dns.t b/t/node/route-domain-with-local-dns.t
index d913c1d63d70..650247e44538 100644
--- a/t/node/route-domain-with-local-dns.t
+++ b/t/node/route-domain-with-local-dns.t
@@ -43,7 +43,7 @@ __DATA__
                         "upstream": {
                             "nodes": {
                                 "127.0.0.1:1980": 1,
-                                "baidu.com:80": 0
+                                "apple.com:80": 0
                             },
                             "type": "roundrobin"
                         },
@@ -89,4 +89,4 @@ hello world
 --- no_error_log
 [error]
 --- error_log eval
-qr/dns resolver domain: baidu.com to \d+.\d+.\d+.\d+/
+qr/dns resolver domain: apple.com to \d+.\d+.\d+.\d+/
diff --git a/t/node/route-domain.t b/t/node/route-domain.t
index 6fbd31da4b13..6ca1c017af31 100644
--- a/t/node/route-domain.t
+++ b/t/node/route-domain.t
@@ -37,7 +37,7 @@ __DATA__
                         "upstream": {
                             "nodes": {
                                 "127.0.0.1:1980": 1,
-                                "baidu.com:80": 0
+                                "apple.com:80": 0
                             },
                             "type": "roundrobin"
                         },
@@ -79,7 +79,7 @@ hello world
 --- no_error_log
 [error]
 --- error_log eval
-qr/dns resolver domain: baidu.com to \d+.\d+.\d+.\d+/
+qr/dns resolver domain: apple.com to \d+.\d+.\d+.\d+/
 
 
 
@@ -97,7 +97,7 @@ qr/dns resolver domain: baidu.com to \d+.\d+.\d+.\d+/
                             },
                             "type": "roundrobin",
                             "pass_host": "rewrite",
-                            "upstream_host": "httpbin.org"                        
+                            "upstream_host": "httpbin.org"
                         },
                         "uri": "/uri"
                 }]]