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feat(log): add nested log format support for logger plugins #12697

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4061b9d
feat: add nested log format support for logger plugins
TaeyeongKwak Oct 21, 2025
f557997
fix: update for lint
TaeyeongKwak Oct 28, 2025
26d38c4
feat: enforce max depth for nested log_format
TaeyeongKwak Oct 28, 2025
478ef32
docs: update the logger plugin docs
TaeyeongKwak Oct 28, 2025
d925f7c
Merge origin/master into feat-support-nested-log-format
Oct 31, 2025
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32 changes: 28 additions & 4 deletions apisix/utils/log-util.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ local expr = require("resty.expr.v1")
local content_decode = require("apisix.utils.content-decode")
local ngx = ngx
local pairs = pairs
local type = type
local ngx_now = ngx.now
local ngx_header = ngx.header
local os_date = os.date
Expand All @@ -32,6 +33,7 @@ local is_http = ngx.config.subsystem == "http"
local req_get_body_file = ngx.req.get_body_file
local MAX_REQ_BODY = 524288 -- 512 KiB
local MAX_RESP_BODY = 524288 -- 512 KiB
local MAX_LOG_FORMAT_DEPTH = 5
local io = io

local lru_log_format = core.lrucache.new({
Expand Down Expand Up @@ -69,22 +71,35 @@ local function get_request_body(max_bytes)
end


local function gen_log_format(format)
local function do_gen_log_format(format, depth)
local log_format = {}
for k, var_name in pairs(format) do
if var_name:byte(1, 1) == str_byte("$") then
if type(var_name) == "table" then
if depth >= MAX_LOG_FORMAT_DEPTH then
core.log.warn("log_format nesting exceeds max depth ",
MAX_LOG_FORMAT_DEPTH, ", truncating")
log_format[k] = {false, {}}
else
local nested_format = do_gen_log_format(var_name, depth + 1)
log_format[k] = {false, nested_format}
end
elseif type(var_name) == "string" and var_name:byte(1, 1) == str_byte("$") then
log_format[k] = {true, var_name:sub(2)}
else
log_format[k] = {false, var_name}
end
end
return log_format
end

local function gen_log_format(format)
local log_format = do_gen_log_format(format, 1)
core.log.info("log_format: ", core.json.delay_encode(log_format))
return log_format
end


local function get_custom_format_log(ctx, format, max_req_body_bytes)
local log_format = lru_log_format(format or "", nil, gen_log_format, format)
local function build_log_entry(ctx, log_format, max_req_body_bytes)
local entry = core.table.new(0, core.table.nkeys(log_format))
for k, var_attr in pairs(log_format) do
if var_attr[1] then
Expand All @@ -100,10 +115,19 @@ local function get_custom_format_log(ctx, format, max_req_body_bytes)
else
entry[k] = ctx.var[var_attr[2]]
end
elseif type(var_attr[2]) == "table" then
entry[k] = build_log_entry(ctx, var_attr[2], max_req_body_bytes)
else
entry[k] = var_attr[2]
end
end
return entry
end


local function get_custom_format_log(ctx, format, max_req_body_bytes)
local log_format = lru_log_format(format or "", nil, gen_log_format, format)
local entry = build_log_entry(ctx, log_format, max_req_body_bytes)

local matched_route = ctx.matched_route and ctx.matched_route.value
if matched_route then
Expand Down
4 changes: 2 additions & 2 deletions docs/en/latest/plugins/clickhouse-logger.md
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Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,7 @@ The `clickhouse-logger` Plugin is used to push logs to [ClickHouse](https://clic
| timeout | integer | False | 3 | [1,...] | Time to keep the connection alive for after sending a request. |
| name | string | False | "clickhouse logger" | | Unique identifier for the logger. If you use Prometheus to monitor APISIX metrics, the name is exported in `apisix_batch_process_entries`. |
| ssl_verify | boolean | False | true | [true,false] | When set to `true`, verifies SSL. |
| log_format | object | False | | | Log format declared as key value pairs in JSON format. Values only support strings. [APISIX](../apisix-variable.md) or [Nginx](http://nginx.org/en/docs/varindex.html) variables can be used by prefixing the string with `$`. |
| log_format | object | False | | | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |
| include_req_body | boolean | False | false | [false, true] | When set to `true` includes the request body in the log. If the request body is too big to be kept in the memory, it can't be logged due to Nginx's limitations. |
| include_req_body_expr | array | False | | | Filter for when the `include_req_body` attribute is set to `true`. Request body is only logged when the expression set here evaluates to `true`. See [lua-resty-expr](https://github.com/api7/lua-resty-expr) for more. |
| include_resp_body | boolean | False | false | [false, true] | When set to `true` includes the response body in the log. |
Expand Down Expand Up @@ -103,7 +103,7 @@ You can also set the format of the logs by configuring the Plugin metadata. The

| Name | Type | Required | Default | Description |
| ---------- | ------ | -------- | ----------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| log_format | object | False | | Log format declared as key value pairs in JSON format. Values only support strings. [APISIX](../apisix-variable.md) or [Nginx](http://nginx.org/en/docs/varindex.html) variables can be used by prefixing the string with `$`. |
| log_format | object | False | | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |
| max_pending_entries | integer | False | | Maximum number of pending entries that can be buffered in batch processor before it starts dropping them. |

:::info IMPORTANT
Expand Down
6 changes: 5 additions & 1 deletion docs/en/latest/plugins/elasticsearch-logger.md
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ The `elasticsearch-logger` Plugin pushes request and response logs in batches to
| endpoint_addrs | array[string] | True | | Elasticsearch API endpoint addresses. If multiple endpoints are configured, they will be written randomly. |
| field | object | True | | Elasticsearch `field` configuration. |
| field.index | string | True | | Elasticsearch [_index field](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-index-field.html#mapping-index-field). |
| log_format | object | False | | Custom log format in key-value pairs in JSON format. Support [APISIX](../apisix-variable.md) or [NGINX variables](http://nginx.org/en/docs/varindex.html) in values. |
| log_format | object | False | | Custom log format as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX variables](http://nginx.org/en/docs/varindex.html) can be referenced by prefixing with `$`. |
| auth | array | False | | Elasticsearch [authentication](https://www.elastic.co/guide/en/elasticsearch/reference/current/setting-up-authentication.html) configuration. |
| auth.username | string | True | | Elasticsearch [authentication](https://www.elastic.co/guide/en/elasticsearch/reference/current/setting-up-authentication.html) username. |
| auth.password | string | True | | Elasticsearch [authentication](https://www.elastic.co/guide/en/elasticsearch/reference/current/setting-up-authentication.html) password. |
Expand All @@ -61,8 +61,12 @@ This Plugin supports using batch processors to aggregate and process entries (lo

| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
<<<<<<< HEAD
| log_format | object | False | | Custom log format as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX variables](../apisix-variable.md) and [NGINX variables](http://nginx.org/en/docs/varindex.html) can be referenced by prefixing with `$`. |
=======
| log_format | object | False | | Custom log format in key-value pairs in JSON format. Support [APISIX variables](../apisix-variable.md) and [NGINX variables](http://nginx.org/en/docs/varindex.html) in values. |
| max_pending_entries | integer | False | | Maximum number of pending entries that can be buffered in batch processor before it starts dropping them. |
>>>>>>> origin/master

## Examples

Expand Down
17 changes: 12 additions & 5 deletions docs/en/latest/plugins/file-logger.md
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Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,7 @@ The `file-logger` Plugin is used to push log streams to a specific location.
| Name | Type | Required | Description |
| ---- | ------ | -------- | ------------- |
| path | string | True | Log file path. |
| log_format | object | False | Log format declared as key value pairs in JSON format. Values only support strings. [APISIX](../apisix-variable.md) or [Nginx](http://nginx.org/en/docs/varindex.html) variables can be used by prefixing the string with `$`. |
| log_format | object | False | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |
| include_req_body | boolean | False | When set to `true` includes the request body in the log. If the request body is too big to be kept in the memory, it can't be logged due to Nginx's limitations. |
| include_req_body_expr | array | False | Filter for when the `include_req_body` attribute is set to `true`. Request body is only logged when the expression set here evaluates to `true`. See [lua-resty-expr](https://github.com/api7/lua-resty-expr) for more. |
| include_resp_body | boolean | False | When set to `true` includes the response body in the log file. |
Expand Down Expand Up @@ -103,7 +103,7 @@ You can also set the format of the logs by configuring the Plugin metadata. The

| Name | Type | Required | Default | Description |
| ---------- | ------ | -------- | ----------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| log_format | object | False | | Log format declared as key value pairs in JSON format. Values only support strings. [APISIX](../apisix-variable.md) or [Nginx](http://nginx.org/en/docs/varindex.html) variables can be used by prefixing the string with `$`. |
| log_format | object | False | | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |

The example below shows how you can configure through the Admin API:

Expand All @@ -122,16 +122,23 @@ curl http://127.0.0.1:9180/apisix/admin/plugin_metadata/file-logger -H "X-API-KE
"log_format": {
"host": "$host",
"@timestamp": "$time_iso8601",
"client_ip": "$remote_addr"
"client_ip": "$remote_addr",
"request": {
"method": "$request_method",
"uri": "$request_uri"
},
"response": {
"status": "$status"
}
}
}'
```

With this configuration, your logs would be formatted as shown below:

```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"}
{"host":"localhost","@timestamp":"2020-09-23T19:05:05-04:00","client_ip":"127.0.0.1","request":{"method":"GET","uri":"/hello"},"response":{"status":200},"route_id":"1"}
{"host":"localhost","@timestamp":"2020-09-23T19:05:05-04:00","client_ip":"127.0.0.1","request":{"method":"GET","uri":"/hello"},"response":{"status":200},"route_id":"1"}
```

## Enable Plugin
Expand Down
10 changes: 6 additions & 4 deletions docs/en/latest/plugins/google-cloud-logging.md
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Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,7 @@ This plugin also allows to push logs as a batch to your Google Cloud Logging Ser
| ssl_verify | False | true | When set to `true`, enables SSL verification as mentioned in [OpenResty docs](https://github.com/openresty/lua-nginx-module#tcpsocksslhandshake). |
| resource | False | {"type": "global"} | Google monitor resource. See [MonitoredResource](https://cloud.google.com/logging/docs/reference/v2/rest/v2/MonitoredResource) for more details. |
| log_id | False | apisix.apache.org%2Flogs | Google Cloud logging ID. See [LogEntry](https://cloud.google.com/logging/docs/reference/v2/rest/v2/LogEntry) for details. |
| log_format | False | | Log format declared as key value pairs in JSON format. Values only support strings. [APISIX](../apisix-variable.md) or [Nginx](http://nginx.org/en/docs/varindex.html) variables can be used by prefixing the string with `$`. |
| log_format | False | | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |

NOTE: `encrypt_fields = {"auth_config.private_key"}` is also defined in the schema, which means that the field will be stored encrypted in etcd. See [encrypted storage fields](../plugin-develop.md#encrypted-storage-fields).

Expand Down Expand Up @@ -90,7 +90,7 @@ You can also set the format of the logs by configuring the Plugin metadata. The

| Name | Type | Required | Default | Description |
| ---------- | ------ | -------- | ----------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| log_format | object | False | | Log format declared as key value pairs in JSON format. Values only support strings. [APISIX](../apisix-variable.md) or [Nginx](http://nginx.org/en/docs/varindex.html) variables can be used by prefixing the string with `$`. |
| log_format | object | False | | Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, [APISIX](../apisix-variable.md) or [NGINX](http://nginx.org/en/docs/varindex.html) variables can be referenced by prefixing with `$`. |
| max_pending_entries | integer | False | | Maximum number of pending entries that can be buffered in batch processor before it starts dropping them. |

:::info IMPORTANT
Expand All @@ -116,15 +116,17 @@ curl http://127.0.0.1:9180/apisix/admin/plugin_metadata/google-cloud-logging -H
"log_format": {
"host": "$host",
"@timestamp": "$time_iso8601",
"client_ip": "$remote_addr"
"client_ip": "$remote_addr",
"request": { "method": "$request_method", "uri": "$request_uri" },
"response": { "status": "$status" }
}
}'
```

With this configuration, your logs would be formatted as shown below:

```json
{"partialSuccess":false,"entries":[{"jsonPayload":{"client_ip":"127.0.0.1","host":"localhost","@timestamp":"2023-01-09T14:47:25+08:00","route_id":"1"},"resource":{"type":"global"},"insertId":"942e81f60b9157f0d46bc9f5a8f0cc40","logName":"projects/apisix/logs/apisix.apache.org%2Flogs","timestamp":"2023-01-09T14:47:25+08:00","labels":{"source":"apache-apisix-google-cloud-logging"}}]}
{"partialSuccess":false,"entries":[{"jsonPayload":{"host":"localhost","client_ip":"127.0.0.1","@timestamp":"2023-01-09T14:47:25+08:00","request":{"method":"GET","uri":"/hello"},"response":{"status":200},"route_id":"1"},"resource":{"type":"global"},"insertId":"942e81f60b9157f0d46bc9f5a8f0cc40","logName":"projects/apisix/logs/apisix.apache.org%2Flogs","timestamp":"2023-01-09T14:47:25+08:00","labels":{"source":"apache-apisix-google-cloud-logging"}}]}
```

## Enable Plugin
Expand Down
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