First, you want a "dependency manager". That's not what Nix is, clearly. Nix is a package manager.
Second, to use this package manager, you first need to install direnv. How do you install it? with brew, a different package manager.
Third, you have to learn a new functional programming language. Right. Because normally to put together a toolbox, I often learn to speak a few phrases in Swahili first.
Fourth, finally, we get to install a simple Unix program, that any package manager could have provided.
For the fifth trick, freezing dependencies, you first have to have all the correct versions of all the dependencies to do what you want. How do you establish the right ones? Manually. Just like with any other package manager that builds apps against a specific tree of build deps. "Reproducibility!" Because no other package manager could possibly download the same tarballs and run the same commands. Must be all that functional programming magic.
And sixth, the idea that this will work forever. Right. Because any other distro and package manager could not possibly work again in the future, with a mirror of all the packages in a release. That's only for super cool futuristic package managers. No way to reproduce the same packages in the future with old package managers.
Look, Nixians, this is all old hat. Every decent package manager can do all these things, just in a less complicated way. Modern systems use containers, and they don't need Nix for that. Nix is basically just the new Gentoo: a distro for hobbyists who tell themselves they're advanced while all the professionals use something else.
It's not about what is possible, it is about ergonomics. We could have used email for conversations online, yet we use Slack. Other tool require lots of thought and carefull execution for what Nix gives you for free.
> Other tool require lots of thought and carefull execution for what Nix gives you for free.
How do I pin ruby version to 2.6.3 in Nix? This is given to me for free in other tools. As are reproducible builds because all modern package/dependency managers lock versions.
Last week I had a problem with our CI/CD pipeline because an old package that's a sub dependency wouldn't install anymore. [1]
See that `rev` line in the sources.json? The whole build system is pinned by on git commit. If it builds today, it will build tomorrow. No matter what. That alone resolves a huge category of potential problems.
There's much, much more to it. Nix stores each package in its own path. [2] This makes it possible to install multiple versions of one application or library next to each other. With the power of direnv only the versions one needs are included.
[1] https://github.com/tikitu/jsmin/issues/33
[2] > ls /nix/store/ |head 000dm655691b5zis34klvhlil3hrv7j5-fftw-3.3.9.tar.gz.drv 005m4pqd29k976if66fpbggjsdxhchdg-python3.8-astroid-2.5.1.drv 007hqps3i495yjk223vhckin27vggk81-recode-3.7.8.tar.gz.drv 009815w1n26nl10rgffgahk7aka80p1m-nodejs-14.17.0 00a9nyyhwxisv4vc4rvwzp71nfip53x9-user-environment.drv 00m5h0pfzw2182qmyganlkaa9j4l2hps-vector-th-unbox-0.2.1.9.drv 010v6j5jjk2wpniznas31hbwvz1p1f5d-zapfding.r31835.tar.xz.drv 013sdi43bca33mnc3gn0v5r8lifrgcdj-hwdata-0.347.drv 01c3690lhmk0za0hnnh23n6mfgmiijpf-libdv-1.0.0.drv 01kc15hni6gff4z1p3y14v9f1395x2pf-python3.8-tap.py-3.0.drv
> a problem with our CI/CD pipeline because an old package that's a sub dependency wouldn't install anymore
> The whole build system is pinned by on git commit. If it builds today, it will build tomorrow. No matter what.
If that commit is still available. This still doesn't answer the question of how I easily pin a version. The package versions in the post point to what amounts to a random package version.
And that's on top the fact that "if you tried to follow this article step by step, you’ll have noticed that the versions of ruby and node you installed are probably slightly different from the ones above"
> Nix stores each package in its own path.
This is a part that I like.
Why wouldn't it be available? Nix packages are on github. [1]
> And that's on top the fact that "if you tried to follow this article step by step, you’ll have noticed that the versions of ruby and node you installed are probably slightly different from the ones above"
That's the same as on any other host. If I write about installing ruby on ubuntu today and you read the blog post a whole later you'll probably get a newer version.