How do I automate dependency installation after pulling code from repository?

Question

My collegue and I develop a small Python application. We use Vagrant to set up development environments.

Suppose my collegue introduces a new feature into the application. Feature's implementation requires a new python dependency (3rd party package) and the dependency itself needs some system libraries. If I do not read through all pulled commits carefully I can miss, that some systems libraries have to be installed prior running the project.

Of course we update Vagrantfile to install such non-python dependencies during provisioning, so if someone clones project's repository and issues vagrant up he will get a fully working development environment, but what shoud I do to automate updates in my existing environment?

How should we indicate, that a new dependency (python or non-python) was added and we need to install it by firing a specific command?

UPD I can try and run the application and if I encounter any errors it is a sign to reprovision my vagrant box, but it seems tedious to me to test a feature by hands and run provisioning scripts later

Answer 1

I ran into this with Ruby as well. We used Bundler, which is a dependency management system for Ruby. If I pulled in new code, ran it and got funky exceptions saying that a certain dependency was missing, I just knew it was time for a bundle install from the command line. The solution to your problem is the same. If you run the code and get errors saying a dependency is missing, your default response to that exception should be to vagrant up on the command line, and try again.

Barring that, sending an email to your teammates with instructions about the new or updated dependency is a good way to go, especially if a vagrant up is insufficient to resolve the missing or incorrect dependency.