I installed MongoDb yesterday on a Mac Snow Leopard and got the following error message
Mongo::ConnectionFailure: Failed to connect to a master node at localhost
The easiest way to run mongodb on Mac OS is:
Download binary package from http://www.mongodb.org/downloads, for me, I am using lastest 64 bit version (http://fastdl.mongodb.org/osx/mongodb-osx-x86_64-2.0.2.tgz)
mkdir -p $HOME/opt
cd $HOME/opt
wget http://fastdl.mongodb.org/osx/mongodb-osx-x86_64-2.0.2.tgz
to download the latest (2.0.2 for now) 64 bit binary package for Mac OStar xf mongodb-osx-x86_64-2.0.2.tgz -C $HOME/opt
to unpack the package, and it will be unpacked to $HOME/opt/mongodb-osx-x86_64-2.0.2
mkdir -p $HOME/opt/mongodata
to create the data directory for mongodb$HOME/opt/mongodb-osx-x86_64-2.0.2/bin/mongod --dbpath=$HOME/opt/mongodata --logpath=$HOME/opt/mongod.log
to start the mongodb daemon$HOME/opt/mongodb-osx-x86_64-2.0.2/bin/mongo
to connect to your local mongodb serviceYou can also have http://www.mongodb.org/display/DOCS/Quickstart+OS+X as additional reference