Nix shell basically just downloads the software (if it's not already downloaded) and then modifies your PATH to include the new software.
Persistent data stay persistent.
Nix shell has one use case common with docker (local development), but other than that the solutions are not similar at all.
Services like databases that manage runtime information usually store that information in /var or your home directory as usual.
In general Nix doesn't manage persistent data. It will be stored in whatever location the tool writes it to.
nix-shell is a very simple program. Basically it downloads/builds the package you have configured, then sets up environment variables like PATH to include that package. It would be similar to downloading a pre-built tarball run running ./foo inside of that.
For most built-in modules this will be /var/lib/foo for a service foo. If you run nix-shell the service will write data wherever it would normally write data on any other distribution.
Okay, that's good to know. I just wanted to make sure that if I had something like MariaDB or Postgres get installed with nix-shell that I wouldn't lose everything thus having to set everything back up next time I start the shell again.
No, you won't lose anything. However do be aware that unless you specifically configure different data directories using the same DBMS in multiple projects will use the same underlying data files.
Typically this won't be a problem, and you can just create different logical databases if necessary.
Okay, hopefully someone here can point out where I am going wrong with setting up my dev shell the way I want. I am currently using direnv and nix-direnv to manage the dev shell, and I found this blog post which shows a way to start and stop MySQL/Mariadb but I am having some weird issues with it.
Currently my flake looks like this:
{
description = "A basic flake with a shell";
inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
inputs.flake-utils.url = "github:numtide/flake-utils";
outputs = { nixpkgs, flake-utils, ... }@inputs:
flake-utils.lib.eachDefaultSystem (system:
let
pkgs = nixpkgs.legacyPackages.${system};
in
{
devShells.default = pkgs.mkShell {
packages = with pkgs; [
bashInteractive
php
];
buildInputs = [ pkgs.mariadb ];
shellHook = ''
export MYSQL_BASEDIR=${pkgs.mariadb}
export MYSQL_HOME=$PWD/.direnv/mysql
export MYSQL_DATADIR=$MYSQL_HOME/data
export MYSQL_UNIX_PORT=$MYSQL_HOME/mysql.sock
export MYSQL_PID_FILE=$MYSQL_HOME/mysql.pid
alias mysql='mysql -u root'
if [[ ! -d $MYSQL_HOME ]]; then
mariadb-install-db --auth-root-authentication-method=normal \
--datadir="$MYSQL_DATADIR" --basedir="$MYSQL_BASEDIR" \
--pid-file="$MYSQL_PID_FILE"
fi
mariadbd --datadir=$MYSQL_DATADIR --pid-file=$MYSQL_PID_FILE \
--socket=$MYSQL_UNIX_PORT --tmpdir='/tmp' 2>/dev/null &
MYSQL_PID=$!
'';
};
});
}
When I run it like this mariadbd starts just fine, but doesn't get backgrounded dispite the & making that shell session useless which is not what I want as I have to spawn a second shell just to do anything.
Even weirder is when I add the finish() function and the call to trap like in the blog post then mariadbd doesn't start (or starts and immedently gets killed).
mariadb doesn't get backgrounded? Are you sure? Are you able to type commands and see their output? Also, what happens when putting set -x at the start of your shell hook? You should see the last line printed e.g MYSQL_PID=12345
I just heard about NixOS today and decided to blow away my ubuntu that was laggy and try it. So far i like what i see, but i can tell i have some learning to do. I really need to learn to compile from source and how to fix build errors. Theres a package ubuntu has that only comes in a .deb or source.
https://github.com/haveno-dex/haveno
https://github.com/haveno-dex/haveno/blob/master/docs/installing.md
How do you use your computer? Did you really just blow away your OS and jump to one you just heard about? I ask because I spend many months preparing to make the move, and I'm still working at a deficit, since my 4 year old OS had so many hours of tinkering that went undocumented and forgotten. Im still slowly configuring my nixos box. How did you use your computer?
I backed up my 2 year old Debian 2 weeks ago and burned it down for NixOs. With the exception of getting Nvidia prime straight and having to learn configs multiple times as I did the start with flakes or home manager, It's been incredibly smooth sailing.
It took me two or three days on Debian to get OBS and plugins straightened out. Nix worked with just a couple lines of config. I had Nix back to where I left off with Debian after approximately 2 days.
Being able to see other people's configs and dork around with what other people are playing with without screwing up my system we're going through dependency hell is nothing short of amazing.
Well, part of the point of NixOS is to eliminate that whole issue of forgotten tinkering -- the whole system is defined right there in a few modules, or even one file, and there's no way for un-tracked tinkering to exist outside those files.
But can I ask how you use your computer? What goes into these months of prep? I really can't imagine it.
My old OS is kind of a blackbox, in the that I played with countless tools, and I'm not really sure what I will want to reference later. For instance
...and on. I played with a lot of things without regard for longevity or preservation. I didn't even takes notes on what I did most of the time. So I got very worried about just switching OSs without a plan in place. Ultimately, I ended up doing the following to transition.
But of course...I'm on NixOS now! So much of these configurations and lists of software packages, will be documented forever.
Honestly, I barely use it at all these days. I do most of my computing from my phone, so would be very hesitant to just blow that away on a whim like that. But on the desktop where I don't do much, it's fine.