Summary

When parsing comma-separated annotation values in the APISIX Ingress Controller, the implementation performs a simple strings.Split(value, ",") without trimming whitespace from the resulting elements. This causes leading or trailing spaces to be preserved in values following a comma.

As a result, annotations that define multiple IP addresses fail if a space is included after the comma.

Example

If an annotation is defined as:
127.0.0.1, 0.0.0.0
After splitting on , the resulting values are:
["127.0.0.1", " 0.0.0.0"]
The second value contains a leading space, which causes IP validation to fail.

Why This Is Problematic

1. A space character is never valid in an IP address.
2. Including a space after a comma is extremely common and idiomatic in programming and configuration formats.
3. Users do not typically expect comma-separated configuration values to require manual whitespace management.
4. This creates unnecessary fragility in configuration and leads to avoidable validation errors.

Related snippet

Proposed Resolution

Either:

1. Trim whitespace on each split element (preferred)
   or
2. Explicitly document that whitespace is not allowed in comma-separated annotation values.

Potential problems

This splitting helper appears to be shared across annotations, so trimming would change parsing behavior globally.