Fabric is a Python library for executing shell commands remotely over SSH in serial or parallel mode. I used Fabric 1 for years and it was - and still is - an excellent tool. While Fabric’s use-cases overlap somewhat with those of Ansible, the difference is that Fabric is not state-based. In other words, in Fabric you don’t tell that “file a should have contents n and mode m”. Instead, you just run commands on the target host which hopefully result in the end state you’re looking for. Or maybe you’re not even interested in end-state per se, but just need to run some commands. Both approaches have their use-cases. Fabric and Ansible are quite powerful as orchestration tools: they allow running task a on server x, then task b on server y. For enforcing infrastructure to be in a certain state we prefer Puppet and Terraform over Ansible.