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Most of them are random updates. Also moving up to Lesson 5 from the SUSE Cloud native fundamentals program.
77 lines
3.1 KiB
Org Mode
77 lines
3.1 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: "2021-06-15 10:37:05 +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]] and [[https://gitlab.com/veloren/veloren/-/tree/685f4971ac0deb31b301e9d2bc0201d2531fd895/nix][Veloren]] (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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