NixOS Nix announcements, 29 Jan 2022

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From YouTube: What's new in Nix 2.6.0?

Description

An overview of changes in Nix 2.6.0.

https://nixos.org/blog/announcements.html#nix-2.6.0

Chapters:
00:00 Intro
00:10 Welcome
01:24 builtins.zipAttrsWith
03:12 builtins.fromTOML
04:10 :show-trace in REPL
05:44 nix store copy-logs
08:07 Resolve flake root from anywhere int he project
10:20 commit-lockfile-summary
12:12 docker run -ti nixos/nix:master
13:45 Final comments
14:52 Outro

Links:
Nix 2.6 eval improvements - https://zimbatm.com/notes/nix-26-eval-improvement
Use builtins.zipAttrsWith in nixpkgs - https://github.com/NixOS/nixpkgs/commit/2dcae7d82f5ef0b373413d2fbfc1001141561c74
Improvemed builtins.fromTOML PR - https://github.com/NixOS/nix/pull/5795
New TOML library used - https://github.com/ToruNiina/toml11
Resolve project root PR from subfolders - https://github.com/NixOS/nix/pull/5720
Custom update lockfile message - https://github.com/NixOS/nix/commit/3e5a9ad7ff15e5263d8b31288095ebd2e489b8e1

Happy hacking!

A

Hi, I'm rogarbas.

B

And I'm tom breckney we're from the knicks marketing team and we'd like to welcome you to the knicks 2.6 release overview. This is the first video in a series of nick's release, notes, videos.

A

I hope you will find this visual walkthrough, informative and worth your time. As always, feedback is more than appreciated, either via the comments below or by contacting the next marketing team on matrix.

B

Overall next 2.6 is incremental release of the nyx package manager. This includes some bug, fixes and small additions to the core feature set, as well as improvements and continued development of exciting upcoming experimental features. Nyx has moved to a six-week release cycle and we feel would help to announce relevant changes.

B

The release notes are available at nixos.org. Some of the changes are technical, while some are user-facing we'd like to present those to you. Let's start with the first feature, rock.

A

Let's start a highlight of this release is a new built-in function called built-ins, zip, adders width with this, which is which has the same functionality as uh the corresponding function in mixed packages under the same name, but this one is much more efficient.

A

Let me show you about which function I'm talking about, so we can see on our.

A

A

Address- and you can see it's a function that accepts as a function is a first parameter with two uh arguments and returns uh a list of attribute sets.

A

So this is now done much more efficiently and this function is used for some critical portions of nick's packages, evaluation and is and was identified as a bottleneck for performance by hope. I don't butcher his name but pennai in short, nixel eventual evaluation uh of nick's packages is now 11 to 17 percent faster in mix 2.6 compared to 2.5.

A

You don't have to take my word for it. The comparison was actually done by zimbabwean and you can read his blog. You will find the links to all the links we're showing in the description of the video.

A

It's also worth to mention that mix packages unstable channel uh already received an um an update uh earlier this year to take the advantage of this optimization, but only if nix 2.6 is used, so it kind of works with all the next releases.

B

Okay, thank you. Another update is to the nyx tommel parser. This built-in has been around for some time, but it's now been replaced by a more compliant one, uh thanks to uh nicholas matia for ensuring we can correctly parse heterogeneous arrays and produce better error messages.

B

uh Also note: uh we can have better uh error messages that are a bit more colorful and kind of point out a little bit about like where the error occurred, uh making it easier to debug problems. um The similar error on the other side you could see is not as expressive about where the error occurred, making it a little bit more difficult in larger, complex projects to figure out exactly where your mistake or typo was in so again. uh Thank you very much to uh nicola.

A

Yeah and airmen nice error messages are nice.

A

um The next uh change that landed was um a usual a usual case when working with mixed language, language is often that we use nick's reply to debug or explore the nyx code and with 2.6 we now have a chance to um uh to able uh to uh how do you say it yeah to abel's uh trace report uh in our nick's repo. This is done by abe lining. This will now show the traces and you can toggle it back or kind of use.

A

The full um name show trace, and now it will not show you so, let's show an example of this, so I'm going to import the next packages.

A

And an example of an error that is being thrown and we are looking where this error is coming it, for example, let's say lip survey, so it throws out throws an error and we are not exactly sure why and how uh this error got uh here. In this case, we can able uh straight uh traces error, traces, I'm gonna. Just for the and running it again. You will see it shows us all. The uh trace, error, traces uh of the error being raised.

B

Okay, thank you. uh So next up we have um the uh nyx copy logs. So uh nyx has powerful features to copy closures between machines and binary caches. We can also take build plans. We call them derivations. We could push these around to do interesting deployment options such as pushing a build plan, building somewhere else, copying things back and forth, but missing from this was the similar ability for logs. So now we have the added capability to copy logs between stores.

B

We expect this to be used primarily in ci systems to obtain and collect logs from build servers and also as a general utility during debugging or trying to solve a problem so to make this uh feature work, um I'm going to enable some options uh in to in our nics.conf and if we can make this full screen. um That would be helpful.

B

And they get into a bash, so we're going to enable um nyx command and flakes uh just to get this example working. uh This should work without flakes as well. um Just makes this a very simple example to describe so the we. What we want to do is we want to copy uh the log, the build log for the hello package um and get this from the cache uh for nixos.org, because let's say it's something interesting.

B

What I'm going to look into or when I have this locally, and so this uh new knicks store copy log command um should make this uh relatively easy to do.

B

uh While we're waiting on that to occur uh there, we go, we'll go, take a look at where it shows up and we should see there. It is our hello logs uh have then showed up the help, for this is going to be in next door copy log and we'll just take a look at some of the documentation about how to use this thing. Using this with an eval store is uh generally helpful if you're going to get something from a binary cache, but you can also push back and forth between ssh enabled remote machines.

B

So good luck with this feature.

A

Yeah and let's keep the pace so the next feature. What landed in 2.6 was that nick's comment line can now be used anywhere in your uh folder structure of your project of your project. uh You can build or test or run any nix commands in your project from anywhere.

A

This is similar uh to the behavior that you are used to from git, and let me show you an example, so we we already abled the nix command and flakes experimental features, as shown here. uh I'm not gonna do this again, but uh for this purpose we're gonna create a new um project.

A

Let's say bash hello uh and let's call it a project. Okay, so this created a project uh we can see it's. It's only has a flake mix inside with a corresponding lock.

A

Now, if we build it, you will see it works as before, but uh what also enables us is okay, let's wait for this to be built.

A

And in a few minutes yeah, but it will uh after we will build it uh our build command, so you can see it built, uh but now, let's create a subdirectory move to it and now run the same thing.

A

There we go it ran, so if I remove from the the result from before it just notified us that uh this is not does not contain the flake mix and it's searching up the the folder chain uh and this this is this feature tom.

B

So the next feature is uh it's only applicable in certain scenarios, but it can come in handy, um so the commit lock option uh lock file option for nyx update uh right now makes a git commit for you after updating a lock file uh when you're. This is an automation or you know, scripted workflow. uh This can be handy.

B

um The error, the message that gets put into your git log uh is: has it there's a default one, and if you want to customize what that default is the new addition is what can help you here? It is called commit, lock, file summary it can be set to a non-empty string.

B

So let's kind of give this uh an experiment. So let's make a project.

B

Okay, so we have some sort of a project. Let's say we have a flight doc flake.nixon here.

B

And let's give us a simple commit.

B

So at this point, uh if someone wants to do some work with updating the flake, the question is, you know I'll do this automatically and they want to give it some sort of a custom message: they're going to run a flake update, call they're going to say they want to commit that lock file, and they want to give this thing some sort of a better summary than what you have by default.

B

Okay and let's go take a look at the git log and it looks like we now have a custom message in our in our commit. uh This could be useful. Sometimes there are uh workflows that are triggered by uh what the message might be, and so we see that as one possible usage of this feature.

B

Thank you uh to drock.

A

Yeah, as the last feature, um you probably already know uh that nick's docker image was re-implemented with nyx version 2.4. It is now based on alpine. It used to be based on alpine image, but it's not anymore it. We now use nyx to build the nyx docker image from scratch with 2.6 release.

A

We are also now pushing all the latest versions of from the master branch and, let's see what's happening in the master branch, so we will exit, uh we will actually exit and I'm actually going to show you that we were all the time running inside the docker image already uh and to kind of make it even more interesting. You can also see the rebel from previous image uh here. We uh we can also exit it and you will see we were running the docker image for 251..

A

This is an easy way how you can actually experiment and test different nyx versions, especially if you encounter some problems. So in this case, let's run the latest from the master. It is as easy as running.

A

The master command- it's gonna take some time uh because we've, I just cleaned up my cache, uh but I think this will be very useful feature.

B

Okay, uh thank you um and uh with that uh those are kind of a a quick whirlwind tour of some of the features that are specific to the uh nyx 2.6 release, and we expect to have similar sorts of run-throughs of features as they come off. um You know the pipeline right now we're looking at a six-week release cycle.

B

So every six weeks we should see new releases new features, um you know more work and uh this puts the community to a good sort of cadence uh with which to kind of adopt, explore and start to utilize. um Some of these things.

A

Now it's never been better time to actually start contributing to nyx uh it's because of the cadence. I think you will see your work being released uh in a timely manner and now that the image is done, we can already check.

A

This is the latest development version which is 2.7 and happy hacking.

A

A