bhuvan-somisetty opened a new issue, #14000:
URL: https://github.com/apache/apisix/issues/14000
### Current Behavior
In `apisix/plugins/datadog.lua`, when `prefer_name` is enabled (default is
`true`), the plugin attempts to resolve the service name:
```lua
-- if prefer_name is set, fetch the service/route name. If the name is nil,
fall back to id.
if conf.prefer_name then
if entry.service_id and entry.service_id ~= "" then
local svc = service_fetch(entry.service_id)
if svc and svc.value.name ~= "" then
entry.service_id = svc.value.name
end
end
...
```
In Lua, `nil ~= ""` evaluates to `true`. When a service exists in APISIX but
has no `name` property set (the `name` field in Service schema is optional),
`svc.value.name` is `nil`.
Because `nil ~= ""` is `true`, the condition `if svc and svc.value.name ~=
""` evaluates to `true`, and `entry.service_id` is assigned `svc.value.name`
(`nil`), overwriting the valid service ID.
Consequently, when `generate_tag()` builds the metric tags:
```lua
local variable_tags = {
...
{"service_name", entry.service_id},
...
}
```
`entry.service_id` is `nil`, so the `service_name` tag is completely omitted
from the emitted DogStatsD metric datagrams instead of falling back to the
service ID as intended.
### Expected Behavior
When a Service does not have a `name` configured (`svc.value.name == nil`),
`entry.service_id` should remain set to the service's ID, and
`service_name:<id>` should be emitted in Datadog metrics tags.
### Error Logs
No error logs are printed because Lua executes the assignment silently.
However, inspecting the emitted UDP DogStatsD datagrams reveals that
`service_name` is missing from the tags list whenever the associated service
lacks an explicit `name`.
### Steps to Reproduce
1. Create an upstream and a service without specifying a `name`:
```bash
curl -i http://127.0.0.1:9180/apisix/admin/services/s1 -H 'X-API-KEY:
edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
"upstream": {
"type": "roundrobin",
"nodes": {"127.0.0.1:1980": 1}
}
}'
```
2. Create a route referencing service `s1` with `datadog` plugin enabled
(`prefer_name: true` by default):
```bash
curl -i http://127.0.0.1:9180/apisix/admin/routes/1 -H 'X-API-KEY:
edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
"uri": "/hello",
"service_id": "s1",
"plugins": {
"datadog": {}
}
}'
```
3. Send a request to `/hello`.
4. Observe the DogStatsD UDP packets received at port 8125: the tags contain
`route_name:1`, `path:...`, but `service_name:s1` is completely absent because
`entry.service_id` was overwritten with `nil`.
### Environment
- APISIX version (run `apisix version`): 3.19.0 (master @ c6b2adc3)
- Operating system (run `uname -a`): Linux / POSIX
- OpenResty / Nginx version (run `openresty -V` or `nginx -V`): OpenResty
1.25+
- etcd version, if relevant: N/A
- APISIX Dashboard version, if relevant: N/A
- Plugin runner version, for issues related to plugin runners: N/A
- LuaRocks version, for installation issues: N/A
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