Fixed failing tests

Removed use of `NewTestAgent`, per review comment
Removed CLI flag, per review comment
Updated website documentation
Added changelog entry

.changelog/9067.txt

@@ -0,0 +1,3 @@
+```release-note:feature
+agent: add config flag `MaxHeaderBytes` to control the maximum size of the http header per client request.
+```

agent/agent_test.go

@@ -250,57 +250,85 @@ func TestAgent_HTTPMaxHeaderBytes(t *testing.T) {
 	tests := []struct {
 		name                 string
 		maxHeaderBytes       int
-		expectError          bool
 		expectedHTTPResponse int
 	}{
 		{
 			"max header bytes 1 returns 431 http response when too large headers are sent",
 			1,
-			false,
 			431,
 		},
 		{
 			"max header bytes 0 returns 200 http response, as the http.DefaultMaxHeaderBytes size of 1MB is used",
 			0,
-			false,
 			200,
 		},
 		{
 			"negative maxHeaderBytes returns 200 http response, as the http.DefaultMaxHeaderBytes size of 1MB is used",
 			-10,
-			false,
 			200,
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			a := NewTestAgent(t, fmt.Sprintf(`
-				http_config {
-					max_header_bytes = %d
-				}
-			`, tt.maxHeaderBytes))
-			defer a.Shutdown()
+			ports, err := freeport.Take(1)
+			require.NoError(t, err)
+			t.Cleanup(func() { freeport.Return(ports) })
 
-			require.Equal(t, tt.maxHeaderBytes, a.Agent.config.HTTPMaxHeaderBytes)
+			caConfig := tlsutil.Config{}
+			tlsConf, err := tlsutil.NewConfigurator(caConfig, hclog.New(nil))
+			require.NoError(t, err)
 
-			req, err := http.NewRequest(http.MethodGet, "http://"+a.HTTPAddr()+"/v1/health/state/passing", nil)
-			require.NoError(t, err, "unexpected error creating new http request")
+			bd := BaseDeps{
+				Deps: consul.Deps{
+					Logger:          hclog.NewInterceptLogger(nil),
+					Tokens:          new(token.Store),
+					TLSConfigurator: tlsConf,
+				},
+				RuntimeConfig: &config.RuntimeConfig{
+					HTTPAddrs: []net.Addr{
+						&net.TCPAddr{IP: net.ParseIP("127.0.0.1"), Port: ports[0]},
+					},
+					HTTPMaxHeaderBytes: tt.maxHeaderBytes,
+				},
+				Cache: cache.New(cache.Options{}),
+			}
+			a, err := New(bd)
+			require.NoError(t, err)
 
-			// This is directly pulled from the testing of request limits in the net/http source
-			// https://github.com/golang/go/blob/go1.15.3/src/net/http/serve_test.go#L2897-L2900
-			var bytesPerHeader = len("header12345: val12345\r\n")
-			t.Logf("bytesPerHeader: %d", bytesPerHeader)
-			for i := 0; i < ((tt.maxHeaderBytes+4096)/bytesPerHeader)+1; i++ {
-				req.Header.Set(fmt.Sprintf("header%05d", i), fmt.Sprintf("val%05d", i))
+			srvs, err := a.listenHTTP()
+			require.NoError(t, err)
+
+			require.Equal(t, tt.maxHeaderBytes, a.config.HTTPMaxHeaderBytes)
+
+			ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+			t.Cleanup(cancel)
+
+			g := new(errgroup.Group)
+			for _, s := range srvs {
+				g.Go(s.Run)
 			}
 
-			var res *http.Response
-			res, err = http.DefaultClient.Do(req)
-			require.True(t, (tt.expectError && (err != nil)) || !tt.expectError && (err == nil))
-			require.Equal(t, tt.expectedHTTPResponse, res.StatusCode, "expected a '%d' http response, got '%d'", tt.expectedHTTPResponse, res.StatusCode)
+			require.Len(t, srvs, 1)
+
+			client := &http.Client{}
+			for _, s := range srvs {
+				u := url.URL{Scheme: s.Protocol, Host: s.Addr.String()}
+				req, err := http.NewRequest(http.MethodGet, u.String(), nil)
+				require.NoError(t, err)
+
+				// This is directly pulled from the testing of request limits in the net/http source
+				// https://github.com/golang/go/blob/go1.15.3/src/net/http/serve_test.go#L2897-L2900
+				var bytesPerHeader = len("header12345: val12345\r\n")
+				for i := 0; i < ((tt.maxHeaderBytes+4096)/bytesPerHeader)+1; i++ {
+					req.Header.Set(fmt.Sprintf("header%05d", i), fmt.Sprintf("val%05d", i))
+				}
+
+				resp, err := client.Do(req.WithContext(ctx))
+				require.NoError(t, err)
+				require.Equal(t, tt.expectedHTTPResponse, resp.StatusCode, "expected a '%d' http response, got '%d'", tt.expectedHTTPResponse, resp.StatusCode)
+			}
 		})
 	}
-
 }
 
 func TestAgent_ReconnectConfigWanDisabled(t *testing.T) {

agent/config/flags.go

@@ -75,7 +75,6 @@ func AddFlags(fs *flag.FlagSet, f *BuilderOpts) {
 	add(&f.Config.HTTPConfig.AllowWriteHTTPFrom, "allow-write-http-from", "Only allow write endpoint calls from given network. CIDR format, can be specified multiple times.")
 	add(&f.Config.EncryptKey, "encrypt", "Provides the gossip encryption key.")
 	add(&f.Config.Ports.GRPC, "grpc-port", "Sets the gRPC API port to listen on (currently needed for Envoy xDS only).")
-	add(&f.Config.HTTPConfig.MaxHeaderBytes, "http-max-header-bytes", "Sets the HTTP Server's Max Header Bytes.")
 	add(&f.Config.Ports.HTTP, "http-port", "Sets the HTTP API port to listen on.")
 	add(&f.Config.Ports.HTTPS, "https-port", "Sets the HTTPS API port to listen on.")
 	add(&f.Config.StartJoinAddrsLAN, "join", "Address of an agent to join at start time. Can be specified multiple times.")

agent/config/runtime_test.go

@@ -7675,6 +7675,7 @@ func TestSanitize(t *testing.T) {
 		],
 		"HTTPBlockEndpoints": [],
 		"HTTPMaxConnsPerClient": 0,
+		"HTTPMaxHeaderBytes": 0,
 		"HTTPPort": 0,
 		"HTTPResponseHeaders": {},
 		"HTTPUseCache": false,

website/pages/docs/agent/options.mdx

@@ -1631,6 +1631,8 @@ Valid time units are 'ns', 'us' (or 'µs'), 'ms', 's', 'm', 'h'."
 
   - `use_cache` ((#http_config_use_cache)) Defaults to true. If disabled, the agent won't be using [agent caching](/api/features/caching) to answer the request. Even when the url parameter is provided.
 
+  - `max_header_bytes` This setting controls the maximum number of bytes the consul http server will read parsing the request header's keys and values, including the request line. It does not limit the size of the request body.  If zero, or negative, http.DefaultMaxHeaderBytes is used, which equates to 1 Megabyte.
+
 - `leave_on_terminate` If enabled, when the agent receives a TERM signal, it will send a `Leave` message to the rest of the cluster and gracefully leave. The default behavior for this feature varies based on whether or not the agent is running as a client or a server (prior to Consul 0.7 the default value was unconditionally set to `false`). On agents in client-mode, this defaults to `true` and for agents in server-mode, this defaults to `false`.
 
 - `limits` Available in Consul 0.9.3 and later, this is a nested