presentations_compsoc/src/slides/skynet/3_nix.md

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title   = "Skynet: Nix"
date    = 2023-10-08
slides  = true
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# *nix, Nix and Nixos

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## *nix

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Skynet runs on a flavor of Linux called NixOS

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Normal linux commands apply (basic primer)

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``cd`` - change directory

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``mkdir`` - make directory

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``ls`` - list directory

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``touch {filename}`` - create file named {filename}

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``nano {filename}`` - edit {filename}

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``history`` - view history of previous commands

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``grep "{query}" {filename/path}`` - find {query} in a file

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There is also piping where:  
The output of one command is piped into another command

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Often called [Unix philosophy][1]

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Can make really powerful programs from smaller simple programs.

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``history | grep "nano"`` - search the history for any mention of ``nano``

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## Nix

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Nix is a (lazy) functional language

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```nix
a = 1              # int
b = 1.001          # float
c = /path/to/thing # path
d = "42"           # string
e = true           # boolean
```

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```nix
double = x: x*2
mul = a: b: a*b

double 2
mul 2 3
```

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```nix
s = { foo = "bar"; biz = "baz"; }
s.foo # bar
s.biz # baz
```

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Info:
1. [Offical guide][2]
2. [Nix Pills][3]

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## NixOS

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Some crazy person saw Nix and thought "I want to make an OS with that"

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In essence a giant function is created with an OS as the output

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This does have quite a few advantages

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* Config as Code
* Deterministic
* Reproducible

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Skynet 2.0 had its config spread across different servers.  
Making it hard to get a good overview

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Skynet 3.0 is fully source controlled on [gitlab.skynet.ie][4]

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Deterministic and Reproducible go hand in hand.

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Deterministic means that for the same inputs you get the same output.

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Reproducible is that you are able to create the same output from  
the source code.

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We use Flakes, which adds a lockfile, reduces hassle for the dev.

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Questions?

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[1]: https://en.wikipedia.org/wiki/Unix_philosophy
[2]: https://nix.dev/tutorials/first-steps/
[3]: https://nixos.org/guides/nix-pills/#
[4]: https://gitlab.skynet.ie/compsoc1/skynet/nixos