CDN-Loop header
RFC 8586 is particular in how the CDN-Loop header should be modified. As such:
other filters in the filter chain should not modify the CDN-Loop header and
The filter will coalesce multiple CDN-Loop headers into a single, comma-separated header.
The filter is configured with the name envoy.filters.http.cdn_loop.
The cdn_id field sets the identifier that the filter will look for within and append to the CDN-Loop header. RFC 8586 calls this field the “cdn-id”; “cdn-id” can either be a pseudonym or a hostname the CDN provider has control of. The cdn_id field must not be empty.