subtree(users/wpcarro): docking briefcase at '24f5a642'

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users/wpcarro/website/blog/content/english/lets-learn-nix-caching.md

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+---
+title: "Lets Learn Nix Caching"
+date: 2020-03-17T18:05:38Z
+draft: true
+---
+
+## TL;DR
+
+1. I use `NixOS/nixpkgs-channels` instead of `NixOS/nixpkgs` and avoid
+   `nix-channel`.
+
+## More information
+
+- By default the Nix package manager uses cache.nixos.org as a binary cache.
+- Visit status.nixos.org
+- `git clone git@github.com:NixOS/nixpkgs-channels` instead of
+  `NixOS/nixpkgs`. The former mirrors the latter and uses Git branches to track
+  the published channels.
+
+## What is a Nix channel
+
+If you run...
+
+```shell
+$ git clone git@github.com:NixOS/nixpkgs ~/nixpkgs
+$ export NIX_PATH="nixpkgs=$(realpath ~/nixpkgs)"
+```
+
+One benefit to cloning nixpkgs is that you can browse the source code on your
+machine using tools like `git` and `emacs`. You can also experimentally patch
+and test Nix code this way.
+
+If any of the above appeals to you, clone `nixpkgs-channels` instead.
+
+The Nix maintainers build and test the commits from `nixpkgs` using Hydra. Tests
+include reproducibility tests, etc.
+
+Various channels have different verification phases.
+
+The cache at cache.nixos.org is populate the cache at cache.nixos.org.
+
+You want to increase the likelihood that you are hitting this cache. For
+example, `google-chrome` takes hours to build.
+
+## What is a binary cache?
+
+## What is Hydra (Nix CI)?
+
+## What is Cachix?