Iris is written in Go and requires a setup Go (>= 1.7) environment https://golang.org/doc/install to build to code. Iris is written in pure Go and supports all the platforms that Go does.
Once you have downloaded Iris the quickest way to run it without additional configuration is with the command iris -insecure -nostela. This will run Iris on the default port 32000 with an ssl cert or with the location of the Stela instance.
If you remove the -nostela flag Iris will look for Stela on its default address 127.0.0.1:31000. If this is not the correct Stela address you can use the -stela flag to specify it. By using Stela you can launch multiple instances of Iris and they will use raft consensus to add fault tolerance to your key value store.
The -raftdir flag specifies the location of the key value store db. By default its a folder called raftDir but you can specify it to be whatever you like. This will persist between runs.
The -join flag will specify the address of the raft leader and not rely on Stela to find it.