SkyeYoung commented on code in PR #12383:
URL: https://github.com/apache/apisix/pull/12383#discussion_r2220706155
##########
apisix/plugins/prometheus/exporter.lua:
##########
@@ -498,10 +506,70 @@ local function collect(ctx, stream_only)
end
end
+ return core.table.concat(prometheus:metric_data())
+end
+
+
+local function exporter_timer(premature)
+ if premature then
+ return
+ end
+
+ if not prometheus then
+ return
+ end
+
+ local refresh_interval = DEFAULT_REFRESH_INTERVAL
+ local attr = plugin.plugin_attr("prometheus")
+ if attr and attr.refresh_interval then
+ refresh_interval = attr.refresh_interval
+ end
+
+ ngx.timer.at(refresh_interval, exporter_timer)
+
+ if exporter_timer_running then
+ core.log.warn("Previous calculation still running, skipping")
+ return
+ end
+
+ exporter_timer_running = true
+
+ local ok, res = pcall(collect)
+ if not ok then
+ core.log.error("Failed to collect metrics: ", res)
+ return
+ end
+ ngx.shared["prometheus-cache"]:set(CACHED_METRICS_KEY, res)
+
+ exporter_timer_running = false
+end
+
+local function init_exporter_timer()
+ if process.type() ~= "privileged agent" then
+ return
+ end
+
+ ngx.timer.at(0, exporter_timer)
Review Comment:
After the modification, this place can still only be asynchronous at the
moment.
If synchronization is needed, we need to modify the following parts:
https://github.com/apache/apisix/blob/6fb9bf94281525c1fca397f681b4890b69440369/apisix/plugins/prometheus/exporter.lua#L467-L494
The reason is that this part requests the API, which will lead to the
following error when directly using `exporter_timer()`:
```txt
2025/07/21 14:41:12 [error] 464992#464992: init_worker_by_lua error:
/home/xxx/apisix//deps/share/lua/5.1/resty/http.lua:74: API disabled in the
context of init_worker_by_lua*
stack traceback:
[C]: in function 'co_create'
/home/xxx/apisix//deps/share/lua/5.1/resty/http.lua:74: in function
'_body_reader'
/home/xxx/apisix//deps/share/lua/5.1/resty/http.lua:821: in function
'request'
/home/xxx/apisix//deps/share/lua/5.1/resty/etcd/v3.lua:120: in function
'request_uri_via_unix_socket'
/home/xxx/apisix//deps/share/lua/5.1/resty/etcd/v3.lua:160: in function
'http_request_uri'
/home/xxx/apisix//deps/share/lua/5.1/resty/etcd/v3.lua:251: in function
'server_version'
/home/xxx/apisix/apisix/core/config_etcd.lua:1066: in function
'server_version'
/home/xxx/apisix/apisix/plugins/prometheus/exporter.lua:474: in function
'collect'
/home/xxx/apisix/apisix/plugins/prometheus/exporter.lua:537: in function
'exporter_timer'
/home/xxx/apisix/apisix/plugins/prometheus/exporter.lua:553: in function
'init_exporter_timer'
/home/xxx/apisix/apisix/plugin.lua:808: in function 'init_prometheus'
/home/xxx/apisix/apisix/init.lua:161: in function 'http_init_worker'
init_worker_by_lua:2: in main chunk
```
So, if we need to ensure synchronized initialization, we need to continue
the discussion: whether to remove or move the collection of this part of the
indicators.
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