Extending MySQL 5.7  /  ...  /  Using the Test Protocol Trace Plugin

4.4.11.1 Using the Test Protocol Trace Plugin

MySQL includes a test protocol trace plugin that serves to illustrate the information available from such plugins, and as a guide to writing other protocol trace plugins. To see how the test plugin works, use a MySQL source distribution; binary distributions are built with the test plugin disabled.

Enable the test protocol trace plugin by configuring MySQL with the WITH_TEST_TRACE_PLUGIN CMake option enabled. This causes the test trace plugin to be built and MySQL client programs to load it, but the plugin has no effect by default. Control the plugin using these environment variables:

  • MYSQL_TEST_TRACE_DEBUG: Set this variable to a value other than 0 to cause the test plugin to produce diagnostic output on stderr.

  • MYSQL_TEST_TRACE_CRASH: Set this variable to a value other than 0 to cause the test plugin to abort the client program if it detects an invalid trace event.

Caution

Diagnostic output from the test protocol trace plugin can disclose passwords and other sensitive information.

Given a MySQL installation built from source with the test plugin enabled, you can see a trace of the communication between the mysql client and the MySQL server as follows:

shell> export MYSQL_TEST_TRACE_DEBUG=1
shqll> mysql
test_trace: Test trace plugin initialized
test_trace: Starting tracing in stage CONNECTING
test_trace: stage: CONNECTING, event: CONNECTING
test_trace: stage: CONNECTING, event: CONNECTED
test_trace: stage: WAIT_FOR_INIT_PACKET, event: READ_PACKET
test_trace: stage: WAIT_FOR_INIT_PACKET, event: PACKET_RECEIVED
test_trace: packet received: 87 bytes
  0A 35 2E 37 2E 33 2D 6D  31 33 2D 64 65 62 75 67   .5.7.3-m13-debug
  2D 6C 6F 67 00 04 00 00  00 2B 7C 4F 55 3F 79 67   -log.....+|OU?yg
test_trace: 004: stage: WAIT_FOR_INIT_PACKET, event: INIT_PACKET_RECEIVED
test_trace: 004: stage: AUTHENTICATE, event: AUTH_PLUGIN
test_trace: 004: Using authentication plugin: mysql_native_password
test_trace: 004: stage: AUTHENTICATE, event: SEND_AUTH_RESPONSE
test_trace: 004: sending packet: 188 bytes
  85 A6 7F 00 00 00 00 01  21 00 00 00 00 00 00 00   .?......!.......
  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00   ................
...
mysql> quit
test_trace: 008: stage: READY_FOR_COMMAND, event: SEND_COMMAND
test_trace: 008: QUIT
test_trace: 008: stage: READY_FOR_COMMAND, event: PACKET_SENT
test_trace: 008: packet sent: 0 bytes
test_trace: 008: stage: READY_FOR_COMMAND, event: DISCONNECTED
test_trace: 008: Connection  closed
test_trace: 008: Tracing connection has ended
Bye
test_trace: Test trace plugin de-initialized

To disable trace output, do this:

shell> MYSQL_TEST_TRACE_DEBUG=