Immutable Infrastructure: No SSH - Blog - Boxfuse • Immutable Infrastructure Made Easy.
Why is drift a problem?
The first question to ask is really: why is drift itself a problem? Or to put it differently: why is having identical machines important?
One of the primary ways to reduce risk in a software system is testing. Both manual and automated testing rely on the same three step workflow:
- Put the system in a known state
- Perform an action
- Compare the results against your expectations
Putting the system in a known state does not only apply to data, it also applies to the versions of all the software components installed. Once your system is correctly set up, your tests will then validate version X of your code running on version Y of your platform while having version Z of a library on board. All other combinations are unknown and must be validated separately. In other words, there is no guarantee that the exact version of your code will work identically when combined with older or newer versions of the platform and libraries as older versions may still contain bugs and newer versions could have regressions or subtle changes.
For the investment you have made with your tests to have any value, you must therefore ensure the known state of the system and the versions of all components can be easily and safely replicated across machines and environments.
Or to put it more simply: to have any guarantee that things will work, you need to run in production what you tested in test.
The same thing of course also applies within a single environment. If you have multiple machines serving clients behind a load balancer and want to keep your sanity, you also want these to be absolutely identical.
Read full article from Immutable Infrastructure: No SSH - Blog - Boxfuse • Immutable Infrastructure Made Easy.
No comments:
Post a Comment