in_tcp: Add send_keepalive_packet option

This adds a new option "send_keepalive_packet" which enables SO_KEEPALIVE on underlying sockets. This is especially useful for connecting to Fluentd over network boundary (i.e. to prevent firewalls from closing connections). Signed-off-by: I326463 <[email protected]> Signed-off-by: Fujimoto Seiji <[email protected]>
fluent · Nov 22, 2022 · 66c4a8b · 66c4a8b
1 parent e89092c
commit 66c4a8b
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Showing 2 changed files with 17 additions and 2 deletions.
diff --git a/lib/fluent/plugin/in_tcp.rb b/lib/fluent/plugin/in_tcp.rb
@@ -40,6 +40,8 @@ class TcpInput < Input
 
     desc 'The payload is read up to this character.'
     config_param :delimiter, :string, default: "\n" # syslog family add "\n" to each message and this seems only way to split messages in tcp stream
+    desc 'Check the remote connection is still available by sending a keepalive packet if this value is true.'
+    config_param :send_keepalive_packet, :bool, default: false
 
     # in_forward like host/network restriction
     config_section :security, required: false, multi: false do
@@ -101,7 +103,7 @@ def start
       log.info "listening tcp socket", bind: @bind, port: @port
       del_size = @delimiter.length
       if @_extract_enabled && @_extract_tag_key
-        server_create(:in_tcp_server_single_emit, @port, bind: @bind, resolve_name: !!@source_hostname_key) do |data, conn|
+        server_create(:in_tcp_server_single_emit, @port, bind: @bind, resolve_name: !!@source_hostname_key, send_keepalive_packet: @send_keepalive_packet) do |data, conn|
           unless check_client(conn)
             conn.close
             next
@@ -131,7 +133,7 @@ def start
           buf.slice!(0, pos) if pos > 0
         end
       else
-        server_create(:in_tcp_server_batch_emit, @port, bind: @bind, resolve_name: !!@source_hostname_key) do |data, conn|
+        server_create(:in_tcp_server_batch_emit, @port, bind: @bind, resolve_name: !!@source_hostname_key, send_keepalive_packet: @send_keepalive_packet) do |data, conn|
           unless check_client(conn)
             conn.close
             next

diff --git a/test/plugin/test_in_tcp.rb b/test/plugin/test_in_tcp.rb
@@ -156,6 +156,19 @@ def create_tcp_socket(host, port, &block)
     assert_equal hostname, event[2]['host']
   end
 
+  test "send_keepalive_packet_can_be_enabled" do
+    d = create_driver(base_config + %!
+      format none
+      send_keepalive_packet true
+    !)
+    assert_true d.instance.send_keepalive_packet
+
+    d = create_driver(base_config + %!
+      format none
+    !)
+    assert_false d.instance.send_keepalive_packet
+  end
+
   test 'source_address_key' do
     d = create_driver(base_config + %!
       format none