feat(*) adds config.default_header_type property

kong/plugins/zipkin/handler.lua

@@ -168,7 +168,7 @@ if subsystem == "http" then
       or ngx_now_mu()
     get_or_add_proxy_span(zipkin, access_start)
 
-    tracing_headers.set(conf.header_type, zipkin.header_type, zipkin.proxy_span)
+    tracing_headers.set(conf.header_type, zipkin.header_type, zipkin.proxy_span, conf.default_header_type)
   end
 
 

kong/plugins/zipkin/schema.lua

@@ -55,6 +55,8 @@ return {
           { traceid_byte_count = { type = "integer", required = true, default = 16, one_of = { 8, 16 } } },
           { header_type = { type = "string", required = true, default = "preserve",
                             one_of = { "preserve", "b3", "b3-single", "w3c" } } },
+          { default_header_type = { type = "string", required = true, default = "b3",
+                                    one_of = { "b3", "b3-single", "w3c" } } },
           { static_tags = { type = "array", elements = static_tag,
                             custom_validator = validate_static_tags } }
         },

kong/plugins/zipkin/tracing_headers.lua

@@ -273,7 +273,7 @@ local function parse(headers)
 end
 
 
-local function set(conf_header_type, found_header_type, proxy_span)
+local function set(conf_header_type, found_header_type, proxy_span, conf_default_header_type)
   local set_header = kong.service.request.set_header
 
   if conf_header_type ~= "preserve" and
@@ -283,8 +283,9 @@ local function set(conf_header_type, found_header_type, proxy_span)
     kong.log.warn("Mismatched header types. conf: " .. conf_header_type .. ". found: " .. found_header_type)
   end
 
+  found_header_type = found_header_type or conf_default_header_type or "b3"
+
   if conf_header_type == "b3"
-  or found_header_type == nil
   or found_header_type == "b3"
   then
     set_header("x-b3-traceid", to_hex(proxy_span.trace_id))

spec/tracing_headers_spec.lua

@@ -364,20 +364,35 @@ describe("tracing_headers.set", function()
 
       headers = {}
 
+      set("preserve", "b3-single", proxy_span)
+      assert.same(b3_single_headers, headers)
+
+      headers = {}
+
+      set("preserve", "w3c", proxy_span)
+      assert.same(w3c_headers, headers)
+
+      assert.same({}, warnings)
+    end)
+
+    it("sets headers according to default_header_type when no headers are provided", function()
       set("preserve", nil, proxy_span)
       assert.same(b3_headers, headers)
 
       headers = {}
 
-      set("preserve", "b3-single", proxy_span)
+      set("preserve", nil, proxy_span, "b3")
+      assert.same(b3_headers, headers)
+
+      headers = {}
+
+      set("preserve", nil, proxy_span, "b3-single")
       assert.same(b3_single_headers, headers)
 
       headers = {}
 
-      set("preserve", "w3c", proxy_span)
+      set("preserve", "w3c", proxy_span, "w3c")
       assert.same(w3c_headers, headers)
-
-      assert.same({}, warnings)
     end)
   end)
 

spec/zipkin_spec.lua

@@ -162,7 +162,8 @@ describe("http integration tests with zipkin server [#"
         traceid_byte_count = traceid_byte_count,
         static_tags = {
           { name = "static", value = "ok" },
-        }
+        },
+        default_header_type = "b3-single",
       }
     })
 
@@ -532,7 +533,6 @@ describe("http integration tests with zipkin server [#"
       local span_id = gen_span_id()
       local parent_id = gen_span_id()
 
-
       local r = proxy_client:get("/", {
         headers = {
           b3 = fmt("%s-%s-%s-%s", trace_id, span_id, "1", parent_id),
@@ -687,6 +687,20 @@ describe("http integration tests with zipkin server [#"
       assert.equals(trace_id, proxy_span.traceId)
     end)
   end)
+
+  describe("header type with 'preserve' config and no inbound headers", function()
+    it("uses whatever is set in the plugin's config.default_header_type property", function()
+      local r = proxy_client:get("/", {
+        headers = {
+          -- no tracing header
+          host = "http-route"
+        },
+      })
+      local body = assert.response(r).has.status(200)
+      local json = cjson.decode(body)
+      assert.not_nil(json.headers.b3)
+    end)
+  end)
 end)
 end
 end