4 ms·

If you think of the system(s) that you're targeting, and the mutation operations that you're defining in the CM language; the configuration files and their cont

by nurple 3y ago

If you think of the system(s) that you're targeting, and the mutation operations that you're defining in the CM language; the configuration files and their contents, binaries and their instances, etc are all contained as a giant bag of state we call the OS and its filesystem and memory contents. None of the popular configuration management systems can guarantee determinism in mutations over this state, no matter how much the interface and documentation tries to sell it as a feature, it's just not possible. If it's not apparent why this is the case, then I'd highly recommend not embarking on the process of attempting to create such a system as absolutely enormous amounts of code behind the scenes of the existing systems are aimed at attempting to make it _seem_ like they can be deterministic.

linsomniac 3y ago
When you say that none of the popular CMs can guarantee determinism, are you meaning things like package drift as the OS upstream updates packages and that sort of thing? It's a little early to be recommending I don't embark on creating this; you have an idea in your head which the phrase "bag of state" isn't adequate to convey into my head. The CMs are largely about conveying a state into a system, though there are obviously some places where the state is "leaky" such as if I say "the system will have neovim" and it's leaky because today I may get neovim v0.9.X but tomorrow I may get v0.10.Y? Or are you meaning something like "my laptop install that I've been using for 3 years has a state that is very different from a clean install, so running this playbook on two systems and requesting "nvim" may produce v0.9.x on one, but alpha v0.11.Z on another because I've added a PPA to it"? I'm honestly just trying to understand what issue you are bringing up, and I appreciate the discussion. For some context: I've been using Ansible for ~7 years now, my combined "main.yml" files total just over 19K lines, nearly my entire Linux infrastructure comes up from a base OS install and an Ansible run, ~200 machines, and I respin half my dev+stg infrastructure every night to make sure I'm running against my latest playbooks.

by nurple 3y ago

linsomniac 3y ago

When you say that none of the popular CMs can guarantee determinism, are you meaning things like package drift as the OS upstream updates packages and that sort of thing? It's a little early to be recommending I don't embark on creating this; you have an idea in your head which the phrase "bag of state" isn't adequate to convey into my head. The CMs are largely about conveying a state into a system, though there are obviously some places where the state is "leaky" such as if I say "the system will have neovim" and it's leaky because today I may get neovim v0.9.X but tomorrow I may get v0.10.Y? Or are you meaning something like "my laptop install that I've been using for 3 years has a state that is very different from a clean install, so running this playbook on two systems and requesting "nvim" may produce v0.9.x on one, but alpha v0.11.Z on another because I've added a PPA to it"? I'm honestly just trying to understand what issue you are bringing up, and I appreciate the discussion. For some context: I've been using Ansible for ~7 years now, my combined "main.yml" files total just over 19K lines, nearly my entire Linux infrastructure comes up from a base OS install and an Ansible run, ~200 machines, and I respin half my dev+stg infrastructure every night to make sure I'm running against my latest playbooks.