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3e5d089707
Mainly on the SUSE cloud native fundamentals scholarship program from Udacity along with various CLI programs I learnt to use over the days trying to complete it piecewise... Offhand comment, it is pretty nice so far.
77 lines
3.0 KiB
Org Mode
77 lines
3.0 KiB
Org Mode
:PROPERTIES:
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:ID: 892676b3-76cb-4cd4-9689-910c1fe6587a
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:END:
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#+title: The basics of Nix package manager
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#+date: "2021-06-05 12:34:49 +08:00"
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#+date_modified: "2021-06-09 17:39:23 +08:00"
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#+language: en
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[[id:3b3fdcbf-eb40-4c89-81f3-9d937a0be53c][Nix package manager]] is a great tool for reproducibility as you can easily set up your environment.
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Taking it up to the next level with NixOS, your whole installation.
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* Ecosystem
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- Nix has tools to make setting up environments easier with direnv, lorri, and [[id:c05e1aa9-0619-4617-abb6-870fceca3430][Niv]]
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You can create a [[https://nix.dev/tutorials/ad-hoc-developer-environments#reproducible-executables][reproducible executable]] that only requires Nix.
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#+begin_src bash
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#!/usr/bin/env nix-shell
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#! nix-shell --pure -i bash -p curl jq fzf findutils
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# A quick command line interface for creating a gitignore with the API from https://gitignore.io.
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# This script comes with a simple caching to avoid creating too much requests.
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set -eo pipefail
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CACHE_FILE="${XDG_CACHE_DIR:-$HOME/.cache}/gitignore-io.langs.json"
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# Check if the language list is downloaded for the last hour (3600 seconds).
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if [ ! -e $CACHE_FILE ] || test $(expr $(date "+%s") - $(date -r $CACHE_FILE "+%s")) -gt 3600
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then
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ping "gitignore.io" --count 4 && curl --silent --location --output $CACHE_FILE "https://gitignore.io/api/list?format=json"
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fi
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KEYS=$(jq 'keys | .[] | @text' --raw-output $CACHE_FILE | fzf --multi | while read lang; do echo " .[\"$lang\"].contents"; done | paste -s -d ',')
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jq "$KEYS" --raw-output $CACHE_FILE
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#+end_src
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* Components of the package manager
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Holistically, Nix is made up of at least four components: the store, the language, the derivations, and the sandbox.
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- The store is a immutable centralized location where all of the outputs are placed.
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- The derivations are essentially build instructions.
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- The language (also called as Nix but we'll refer to it as Nixlang) is a domain-specific language for creating derivations.
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- The build process can be locked in a sandbox, improving the reproducibility of a setup and lowering the attack surface for a malicious package.
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* Overlays
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You can override values in Nix as a way to customize nixpkgs.
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For example, if you want to use a different version from the nixpkgs channel, you can change the appropriate value.
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#+begin_src nix
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let overlay = self: super:
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{
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ncmpcpp = super.ncmpcpp.override { visualizerSupport = true; };
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}
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#+end_src
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# TODO: Bring more examples
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For another example, you can see some examples from [[https://github.com/neovim/neovim/blob/f695457f815544d0dc16469569c70556e3165bb6/contrib/flake.nix][Neovim]] (which also uses Nix flakes).
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You can set overlays automatically either by setting =nixpkgs.overlays= from your system configuration or =~/.config/nixpkgs/overlays/= folder for user-specific settings.
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You could also set overlays for standalone Nix code similarly through the =overlays= key — e.g., ~import <nixpkgs> ? { overlays = (self: super: { } ); };~.
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