3.3 KiB
| title | description | date | weight |
|---|---|---|---|
| Chapter 1: Packages | Here we show where packages come from | 2023-06-13T19:36:57+02:00 | 1 |
In this chapter we describe where the packages available in the cluster come from and how to load them.
Where packages come from
The packages in the jungle cluster are constructed by layers. Each layer applies some changes over the previous one:
- The first layer is nixpkgs, a large repository of packages maintained by the NixOS community. It provides packages like gcc, bash, gcc or the linux kernel.
- The second layer is bscpkgs, it takes the nixpkgs set of packages and expands it by adding custom packages from the BSC such as Nanos6, nOS-V, NODES, ovni or wxparaver.
- The third layer is jungle, it takes the extended packages from bscpkgs and configures them for the jungle cluster. For example, we configure MPICH to use the OmniPath network and set it as the default implementation.
These layers are called overlays in Nix and they are the default mechanism used to modify the packages. Generally you will use the packages defined in the last layer (jungle) but you can define your own additional layer to specify custom changes. For example, instead of choosing MPICH, you may want to use Intel MPI instead by default.
Loading packages in an ephemeral shell
You can manually load packages in a new shell with nix shell jungle#<pkg>,
for example:
hut% which ovniemu
ovniemu not found
hut% nix shell jungle#bsc.ovni
hut% which ovniemu
/nix/store/0yzas8007x9djlpbb0pckcr1vhd0mcfy-ovni-1.3.0/bin/ovniemu
hut% exit
hut%
You can also specify multiple packages by listing them as parameters of nix shell:
hut% nix shell jungle#bsc.ovni jungle#bsc.osumb
hut% which osu_bw
/nix/store/lnjirzllhjn2fadlqzrz7a547iawl8jc-osu-micro-benchmarks-7.1-1/bin/osu_bw
hut% exit
Or make the bash (zsh in this case) shell expand them:
hut% echo nix shell jungle#bsc.{ovni,osumb}
nix shell jungle#bsc.ovni jungle#bsc.osumb
hut% nix shell jungle#bsc.{ovni,osumb}
hut% which osu_bw
/nix/store/lnjirzllhjn2fadlqzrz7a547iawl8jc-osu-micro-benchmarks-7.1-1/bin/osu_bw
hut% exit
You can use TAB to see which packages are available:
hut% nix shell jungle#bsc.n<TAB>
jungle\#bsc.nanos6 jungle\#bsc.nixtools
jungle\#bsc.nanos6Debug jungle\#bsc.nix-wrap
jungle\#bsc.nanos6Git jungle\#bsc.nodes
jungle\#bsc.nanos6GlibcxxDebug jungle\#bsc.nodesGit
jungle\#bsc.nanos6-icc jungle\#bsc.nodesRelease
jungle\#bsc.nanos6-icx jungle\#bsc.nodesWithOvni
jungle\#bsc.nanos6Release jungle\#bsc.nosv
jungle\#bsc.nix-mn4
Notice that these packages are evaluated at the moment the command is invoked. So if you come back a month later and run the same command, you may find that the packages have been updated and that could be problematic.
In the next section we will create a new flake that defines the packages of the shell and also records the exact version of the packages that we used at the evaluation time for future use.
In the next chapter we will see how to create a permanent shell that will retain the same packages even if they are upgraded in the cluster, until we decide to upgrade them.