Expert Python Programming - Third Edition

Isolation

Reasons for isolation as well as recommended tools were already discussed in Chapter 2, Modern Python Development Environments. These are: better environment reproducibility and solving the inevitable problems of dependency conflicts. For the purpose of deployments, there is only one important thing to add. You should always isolate project dependencies for each release of your application. In practice, it means that, whenever you deploy a new version of the application, you should create a new isolated environment for this release (using virtualenv or venv). Old environments should be left for some time on your hosts, so that, in case of issues, you can easily perform a rollback to one of the older versions of your application. ...