A customized Kali docker build to avoid the overhead of running a full Kali VM. The docker-compose file also includes a postgres container to be used for persistent storage of the metasploit module cache data and workspace data.
Install docker-compose using your distro's package manager and create a directory for postgres to use as the data directory (e.g. mkdir postgres). Then, start the containers with docker-compose up -d. You can connect to a bash shell within kali with ./connect. When you're done, stop the containers with docker-compose down.
You can add further customizations, such as installing new packages, in the Dockerfile.