chore(plugin): convert traceid in http response headers to hex format

CHANGELOG.md

@@ -99,6 +99,8 @@
   [#9746](https://github.com/Kong/kong/pull/9746)
 - **Proxy-Cache**: add `ignore_uri_case` to configuring cache-key uri to be handled as lowercase
   [#10453](https://github.com/Kong/kong/pull/10453)
+- **Zipkin&Opentelemetry**: convert traceid in http response headers to hex format
+  [#10534](https://github.com/Kong/kong/pull/10534)
 
 #### PDK
 

kong/plugins/opentelemetry/handler.lua

@@ -21,6 +21,7 @@ local null = ngx.null
 local encode_traces = otlp.encode_traces
 local translate_span_trace_id = otlp.translate_span
 local encode_span = otlp.transform_span
+local to_hex = require "resty.string".to_hex
 
 local _log_prefix = "[otel] "
 
@@ -158,6 +159,7 @@ function OpenTelemetryHandler:header_filter(conf)
       local root_span = ngx.ctx.KONG_SPANS and ngx.ctx.KONG_SPANS[1]
       trace_id = root_span and root_span.trace_id
     end
+    local trace_id = to_hex(trace_id)
     kong.response.add_header(conf.http_response_header_for_traceid, trace_id)
   end
 end

kong/plugins/zipkin/handler.lua

@@ -13,6 +13,7 @@ local split = ngx_re.split
 local subsystem = ngx.config.subsystem
 local fmt = string.format
 local rand_bytes = utils.get_rand_bytes
+local to_hex = require "resty.string".to_hex
 
 local ZipkinLogHandler = {
   VERSION = kong_meta.version,
@@ -221,7 +222,8 @@ if subsystem == "http" then
     end
 
     if conf.http_response_header_for_traceid then
-      kong.response.add_header(conf.http_response_header_for_traceid, proxy_span.trace_id)
+      local trace_id = to_hex(proxy_span.trace_id)
+      kong.response.add_header(conf.http_response_header_for_traceid, trace_id)
     end
   end
 

spec/03-plugins/34-zipkin/zipkin_spec.lua

@@ -488,6 +488,10 @@ for _, strategy in helpers.each_strategy() do
 
       assert.response(r).has.status(200)
       assert.response(r).has.header("X-B3-TraceId")
+      local trace_id = r.headers["X-B3-TraceId"]
+      local trace_id_regex = [[^[a-f0-9]{32}$]]
+      local m = ngx.re.match(trace_id, trace_id_regex, "jo")
+      assert.True(m ~= nil, "trace_id does not match regex: " .. trace_id_regex)
     end)
   end)
 end

spec/03-plugins/37-opentelemetry/05-otelcol_spec.lua

@@ -99,6 +99,10 @@ for _, strategy in helpers.each_strategy() do
           assert.is_nil(err)
           assert.same(200, res.status)
           assert.not_nil(res.headers["x-trace-id"])
+          local trace_id = res.headers["x-trace-id"]
+          local trace_id_regex = [[^[a-f0-9]{32}$]]
+          local m = ngx.re.match(trace_id, trace_id_regex, "jo")
+          assert.True(m ~= nil, "trace_id does not match regex: " .. trace_id_regex)
         end
         httpc:close()
       end)