Automating things in software development is more than useful and using Ansible is one way to automate software provisioning, configuration management, and application deployment. Normally you would install Ansible to your control node just like any other application but an alternate strategy is to deploy Ansible inside a standalone Docker image. But why would you do that? This approach has benefits to i.a. operational processes.
Although Ansible does not require installation of any agents within managed nodes, the environment where Ansible is installed is not so simple to setup. In control node it requires specific Python libraries and their system dependencies. So instead of using package manager to install Ansible and it’s dependencies we just pull a Docker image.
By creating an Ansible Docker image you get the Ansible version you want and isolate all of the required dependencies from the host machine which potentially might break things in other area