Version detection is using global mongod not the configured one

[p-mongo]

When I use --binarypath option, the binary I am specifying is not used by mlaunch for server version detection and it tries to obtain the version (only) from global mongod.

I don't know how to get this sort of output out of unmodified mlaunch, I added this patch:

serene2% git diff
diff --git a/mtools/mlaunch/mlaunch.py b/mtools/mlaunch/mlaunch.py
index f16b9d2..683c300 100755
--- a/mtools/mlaunch/mlaunch.py
+++ b/mtools/mlaunch/mlaunch.py
@@ -907,6 +907,7 @@ class MLaunchTool(BaseCmdLineTool):
             binary = os.path.join(self.args['binarypath'], binary)

         try:
+            import pdb;pdb.set_trace()
             out = check_mongo_server_output(binary, '--version')
         except Exception:
             return "0.0"
@@ -2116,6 +2117,7 @@ class MLaunchTool(BaseCmdLineTool):

     def _construct_mongod(self, dbpath, logpath, port, replset=None, extra=''):
         """Construct command line strings for mongod process."""
+        print(self.current_version)
         rs_param = ''
         if replset:
             rs_param = '--replSet %s' % replset

This prints the detected version when launching mongod.

On my system there isn't a mongod in PATH.

Expected behavior

The binary I referenced used for version detection.

Actual/current behavior

The global mongod is used, which doesn't exist on my system, version ends up being set to 0.0 which I think is a separate problem - this would cause mlaunch to assume behavior (e.g. with respect to tls/ssl options) that may be incorrect.

Running mlaunch --replicaset --name ruby-driver-rs --auth --username dev --password dev --dir /mnt/zram/mongodb/4.0-rs-auth --setParameter diagnosticDataCollectionEnabled=false --wiredTigerCacheSizeGB 0.25 --setParameter honorSystemUmask=true --networkMessageCompressors snappy,zlib --setParameter enableTestCommands=1 --filePermissions 0666 --binarypath /usr/local/m/versions/4.0 --port 27150 --verbose
> /home/m/.local/lib/python3.10/site-packages/mtools/mlaunch/mlaunch.py(911)getMongoDVersion()
-> out = check_mongo_server_output(binary, '--version')
(Pdb) c
Failed to launch mongod: [Errno 2] No such file or directory: 'mongod'
creating directory: /mnt/zram/mongodb/4.0-rs-auth/ruby-driver-rs/rs1/db
0.0
creating directory: /mnt/zram/mongodb/4.0-rs-auth/ruby-driver-rs/rs2/db
0.0
creating directory: /mnt/zram/mongodb/4.0-rs-auth/ruby-driver-rs/rs3/db
0.0
writing .mlaunch_startup file.
Generating keyfile: /mnt/zram/mongodb/4.0-rs-auth/keyfile
waiting for nodes to shutdown...
launching: "/usr/local/m/versions/4.0/mongod" --replSet ruby-driver-rs --dbpath "/mnt/zram/mongodb/4.0-rs-auth/ruby-driver-rs/rs1/db" --logpath "/mnt/zram/mongodb/4.0-rs-auth/ruby-driver-rs/rs1/mongod.log" --port 27150 --fork --auth --keyFile "/mnt/zram/mongodb/4.0-rs-auth/keyfile" --setParameter "diagnosticDataCollectionEnabled=false" --wiredTigerCacheSizeGB "0.25" --setParameter "honorSystemUmask=true" --networkMessageCompressors "snappy,zlib" --setParameter "enableTestCommands=1" --filePermissions "0666" 
launching: "/usr/local/m/versions/4.0/mongod" --replSet ruby-driver-rs --dbpath "/mnt/zram/mongodb/4.0-rs-auth/ruby-driver-rs/rs2/db" --logpath "/mnt/zram/mongodb/4.0-rs-auth/ruby-driver-rs/rs2/mongod.log" --port 27151 --fork --auth --keyFile "/mnt/zram/mongodb/4.0-rs-auth/keyfile" --setParameter "diagnosticDataCollectionEnabled=false" --wiredTigerCacheSizeGB "0.25" --setParameter "honorSystemUmask=true" --networkMessageCompressors "snappy,zlib" --setParameter "enableTestCommands=1" --filePermissions "0666" 
launching: "/usr/local/m/versions/4.0/mongod" --replSet ruby-driver-rs --dbpath "/mnt/zram/mongodb/4.0-rs-auth/ruby-driver-rs/rs3/db" --logpath "/mnt/zram/mongodb/4.0-rs-auth/ruby-driver-rs/rs3/mongod.log" --port 27152 --fork --auth --keyFile "/mnt/zram/mongodb/4.0-rs-auth/keyfile" --setParameter "diagnosticDataCollectionEnabled=false" --wiredTigerCacheSizeGB "0.25" --setParameter "honorSystemUmask=true" --networkMessageCompressors "snappy,zlib" --setParameter "enableTestCommands=1" --filePermissions "0666" 
waiting for nodes to start...
initializing replica set 'ruby-driver-rs' with configuration: {'_id': 'ruby-driver-rs', 'members': [{'_id': 0, 'host': 'localhost:27150'}, {'_id': 1, 'host': 'localhost:27151'}, {'_id': 2, 'host': 'localhost:27152'}]}
replica set 'ruby-driver-rs' initialized.
waiting for nodes to start...
waiting for primary to add a user.
added user dev on admin database
Username "dev", password "dev"
done.

Steps to reproduce the actual/current behavior

Run patched mlaunch printing detected version.

Environment

Software	Version
mtools	develop
Python	3.10
MongoDB server	4.0
Operating system	Debian

[p-mongo]

Use of incorrect mongod causes mlaunch to fail when starting sharded clusters. This condition is responsible for setting csrs for 3.6+ servers:

        # add the 'csrs' parameter as default for MongoDB >= 3.3.0
        if (LooseVersion(self.current_version) >= LooseVersion("3.3.0") or
                LooseVersion(self.current_version) == LooseVersion("0.0.0")):
            self.args['csrs'] = True

Since self.current_version is erroneously set to 0.0, the csrs flag isn't set, and subsequently the following condition:

        # CSRS config servers (MongoDB >=3.1.0)
        if self.args['csrs']:
            config_string.append(self._construct_config(self.dir, nextport,
                                                        "configRepl", True))
        else:
            for name in config_names:
                self._construct_config(self.dir, nextport, name)
                config_string.append('%s:%i' % (self.args['hostname'],
                                                nextport))
                nextport += 1

... goes into else branch instead of if and produces a broken configdb parameter (host names only without the replica set name).

The else branch doesn't look right also because the value of _construct_config isn't used anywhere.

[p-mongo]

Workaround for sharded clusters on 3.6+: https://github.com/p-mongodb/mtools-legacy/commit/90b1bc19aed3729d13409193f829a0516e62a7c9