Problems debugging mserver5 - monetdb

Question

I have recently started debugging the mserver5 application using vscode and a very comfy plugin for cmake called CMake Tools. Moreover, I am using gcc 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04) as a compiler together with the following launch.json debug configuration for mserver5 in vscode:
{
"version": "0.2.0",
"configurations": [
{
"name": "(gdb) mserver5 triangleDB",
"type": "cppdbg",
"request": "launch",
// Resolved by CMake Tools:
"program": "${command:cmake.launchTargetPath}",
"args": ["--dbpath=/home/mledl/dbfarm/triangleDB", "--set", "mapi_port=0"],
"stopAtEntry": false,
"cwd": "${workspaceFolder}/build",
"environment": [
{
// add the directory where our target was built to the PATHs
// it gets resolved by CMake Tools:
"name": "PATH",
"value": "$PATH:${command:cmake.launchTargetDirectory}"
},
],
"externalConsole": true,
"MIMode": "gdb",
"setupCommands": [
{
"description": "Enable pretty-printing for gdb",
"text": "-enable-pretty-printing",
"ignoreFailures": true
},
{ "description":"In this mode GDB will be attached to both processes after a call to fork() or vfork().",
"text": "-gdb-set detach-on-fork off",
"ignoreFailures": true
},
{ "description": "The new process is debugged after a fork. The parent process runs unimpeded.",
"text": "-gdb-set follow-fork-mode child",
"ignoreFailures": true
}
]
}
]
}
The database I am connecting to (here triangleDB) has been created within a dbfarm using the monetdb application and I am going to connect to it using the mclient application with the default username and password combination monetdb. I can successfully connect to and query my triangleDB when starting it using the monetdb application withing a running dbfarm.
When starting up the mserver5 for debugging from vscode using the above launch.json file and connecting to it using mclient and the monetdb user I cannot authenticate somehow and get the following error printed to the mserver5 logs:
client1: createExceptionInternal: !ERROR: InvalidCredentialsException:checkCredentials:invalid credentials for user 'monetdb'
Does anybody know why mserver5 cannot retrieve the default user? Does it rely on the deamon monetdbd to retrieve the user data from? Can someone tell me what I am missing or how I can efficiently debug the mserver5?
Another point is that I need to set mapi_port=0 in order to make mserver5 bind to available ports since it is opening two mapi connections somehow when debugging with vscode and CLion. The application crashes when using a specific port since the second binding attempt will be on an already use address. The following section shows that two connections are opened when debugging:
# MonetDB 5 server v11.40.0
# This is an unreleased version
# Serving database 'triangleDB', using 24 threads
# Compiled for x86_64-pc-linux-gnu/64bit with 128bit integers
# Found 31.349 GiB available main-memory of which we use 25.549 GiB
# Copyright (c) 1993 - July 2008 CWI.
# Copyright (c) August 2008 - 2021 MonetDB B.V., all rights reserved
# Visit https://www.monetdb.org/ for further information
# Listening for connection requests on mapi:monetdb://localhost:46093/
# Listening for connection requests on mapi:monetdb://localhost:40387/
Thanks in advance for everybody that can help me out on this one. Looking forward to hearing from you and sty safe everyone.

Answer 1

If your database was created using monetdb and you want to start it directly using mserver5, you need to tell mserver5 where the .vaultkey is.
In you dbfarm, do a grep monet_vault_key merovingian.log, copy the whole --set monet_vault_key=/<path-to>/dbfarm/demo/.vaultkey and add this option to the start-up command of your mserver5.

Answer 2

I am giving an additional answer here, because I want to make clear what I had to do in order to debug the mserver5 using vscode and interact with it using the mclient application.
While trying to figure out why certain modules/libraries could not be loaded, I noticed that the GDK kernel is missing an environment variable called monet_mod_path which can be set using the --set monet_mod_path=/usr/local/lib/monetdb5 option for mserver5. The missing monet_mod_path has also been the reason why mserver5 listened on two addresses for a mapi connection.
I am now using the following command to start mserver5 for debugging:
mserver5 --dbpath=/home/mledl/dbfarm/triangleDB --set monet_vault_key=/home/mledl/dbfarm/triangleDB/.vaultkey --set monet_mod_path=/usr/local/lib/monetdb5 --set gdk_nr_threads=24 --set max_clients=64 --set sql_optimizer=default_pipe
A minimal working configuration would be the following one:
mserver5 --dbpath=/path/to/your/db --set monet_vault_key=/path/to/your/db/.vaultkey --set monet_mod_path=/usr/local/lib/monetdb5
Note: I installed the application into default installation directory. If you choose a custom one the monet module path has the following pattern:
monet_mod_path=/path/to/install/lib/monetdb5
I hope this answer will help someone in the future and saves all the investigation time I had to put in.