From 366df8852f503523cc4f9046d82ba9a99dd51d7f Mon Sep 17 00:00:00 2001 From: Akshay Date: Sun, 12 Feb 2023 12:13:49 +0530 Subject: new art: lapse --- docs/posts/novice_nix:_flake_templates/index.html | 171 ++++++++++++++-------- 1 file changed, 108 insertions(+), 63 deletions(-) (limited to 'docs/posts/novice_nix:_flake_templates/index.html') diff --git a/docs/posts/novice_nix:_flake_templates/index.html b/docs/posts/novice_nix:_flake_templates/index.html index 480f85d..302bafe 100644 --- a/docs/posts/novice_nix:_flake_templates/index.html +++ b/docs/posts/novice_nix:_flake_templates/index.html @@ -42,13 +42,25 @@ Novice Nix: Flake Templates
-

Flakes are very handy to setup entirely pure, project-specific dependencies (not just dependencies, but build steps, shell environments and more) in a declarative way. Writing Flake expressions can get repetitive though, oftentimes, you’d much rather start off with a skeleton. Luckily, nix already supports templates!

-

You might already be familiar with nix flake init, that drops a “default” flake expression into your current working directory. If you head over to the manpage:

-
nix flake init --help
-

You will read that nix flake init creates a flake using the “default template”. Additionally, you can create a flake from a specific template by passing the -t flag. Where does this default originate from?

+

Flakes are very handy to setup entirely pure, project-specific +dependencies (not just dependencies, but build steps, shell environments +and more) in a declarative way. Writing Flake expressions can get +repetitive though, oftentimes, you’d much rather start off with a +skeleton. Luckily, nix already supports templates!

+

You might already be familiar with nix flake init, that +drops a “default” flake expression into your current working directory. +If you head over to the manpage:

+
nix flake init --help
+

You will read that nix flake init creates a flake using +the “default template”. Additionally, you can create a flake from a +specific template by passing the -t flag. Where does this +default originate from?

Flake Registries

-

Quick detour into registries! Registries are a way to alias popular flakes using identifiers:

-
# list a few predefined registries
+
Quick detour into registries! Registries are a way to alias popular
+flakes using identifiers:

+
# list a few predefined registries
 $ nix registry list
 . . . 
 global flake:nixpkgs github:NixOS/nixpkgs
@@ -66,8 +78,11 @@
 
 # which is short for
 $ nix flake show git+https://github.com/tweag/nickel

-
You might notice a registry called templates aliased to github:NixOS/templates. Take a peek with nix flake show:

-
$ nix flake show templates
+
You might notice a registry called templates aliased to
+github:NixOS/templates. Take a peek with
+nix flake show:

+
$ nix flake show templates
 github:NixOS/templates/79f48a7b822f35c068c5e235da2e9fbd154cecee
 ├───defaultTemplate: template: A very basic flake
 └───templates
@@ -76,8 +91,12 @@
     ├───rust-web-server: template: A Rust web server including a NixOS module
     ├───simpleContainer: template: A NixOS container running apache-httpd
     └───trivial: template: A very basic flake

-
Aha! There is a flake output called defaultTemplate. This is the template being sourced when you run nix flake init. Astute readers may conclude the following:

-
$ nix flake init
+
Aha! There is a flake output called defaultTemplate.
+This is the template being sourced when you run
+nix flake init. Astute readers may conclude the
+following:

+
$ nix flake init
 
 # is equivalent to
 $ nix flake init -t templates#defaultTemplate
@@ -88,7 +107,8 @@
 # which is short for
 $ nix flake init -t git+https://github.com/NixOS/templates#defaultTemplate

 
Similarly, the other templates can be accessed via:

-
$ nix flake init -t templates#c-hello
+
$ nix flake init -t templates#c-hello
 $ nix flake init -t templates#simpleContainer
 # I think you get the drift ...

 
Rolling your own templates

@@ -96,38 +116,52 @@
 
    
 
  • create a flake with a templates output
    • 
 
  • populate our template directories with content
    • 
-
  • (optionally) alias our custom templates flake to an identifier using registries, for easier access
    • 
+
  • (optionally) alias our custom templates flake to an
+identifier using registries, for easier access
    • 
 

-
Start off by creating a directory to store your templates in (we will be converting this to a registry later):

-
$ mkdir ~/mytemplates

-
A flake that exposes a “template” as its output looks something like this:

-
# inside ~/mytemplates/flake.nix
+
Start off by creating a directory to store your templates in (we will
+be converting this to a registry later):

+
$ mkdir ~/mytemplates

+
A flake that exposes a “template” as its output looks something like
+this:

+
# inside ~/mytemplates/flake.nix
 
-{
-  description = "Pepper's flake templates";
+{
+  description = "Pepper's flake templates";
 
-  outputs = { self, ... }: {
-    templates = {
-      latex-report = {
-        path = ./latex-report-template;
-        description = "A latex whitepaper project";
-      };
-      rust-hello = {
-        path = ./rust-hello-template;
-        description = "Simple Hello World in Rust";
-      };
-    };
-  };
-}

-
The path attribute to each template is what gets copied over when you initialize a flake. Running nix flake init -t .#latex-report will initialize the current directory with the contents of ./latex-report-template (we are yet to populate these directories).

-
The output of nix flake show should be something like:

-
$ nix flake show
+  outputs = { self, ... }: {
+    templates = {
+      latex-report = {
+        path = ./latex-report-template;
+        description = "A latex whitepaper project";
+      };
+      rust-hello = {
+        path = ./rust-hello-template;
+        description = "Simple Hello World in Rust";
+      };
+    };
+  };
+}

+
The path attribute to each template is what gets copied
+over when you initialize a flake. Running
+nix flake init -t .#latex-report will initialize the
+current directory with the contents of
+./latex-report-template (we are yet to populate these
+directories).

+
The output of nix flake show should be something
+like:

+
$ nix flake show
 path:/home/np/code/nix-stuff/template-tests?narHash=sha256-{...}
 └───templates
     ├───latex-report: template: A latex whitepaper project
     └───rust-hello: template: Simple Hello World in Rust

-
Populate your template directories with content, here are my template directories for example:

-
$ tree mytemplates
+
Populate your template directories with content, here are my template
+directories for example:

+
$ tree mytemplates
 mytemplates/
 ├── flake.nix
 ├── latex-report-template
@@ -142,15 +176,18 @@
     └── src
         └── main.rs

 
And that’s it! Start using your templates with:

-
$ nix flake init -t ~/mytemplates#rust-hello
+
$ nix flake init -t ~/mytemplates#rust-hello
 $ tree .
 .
 ├── Cargo.toml
 ├── flake.nix
 └── src
     └── main.rs

-
To avoid writing ~/mytemplates each time, simply alias it to a registry:

-
# alias it to `biscuits`
+
To avoid writing ~/mytemplates each time, simply alias
+it to a registry:

+
# alias it to `biscuits`
 $ nix registry add biscuits ~/mytemplates
 
 # you will see it listed under `user` registries
@@ -160,34 +197,42 @@
 . . .
 
 $ nix flake init -t biscuits#latex-report

-
Extending the official templates

-
I personally, would like the biscuits registry to include not just my homemade templates, but also the templates from NixOS/templates (and maybe a couple of other repositories in the wild):

-
 {
-   description = "Pepper's flake templates";
+
Extending the official
+templates

+
I personally, would like the biscuits registry to
+include not just my homemade templates, but also the templates from
+NixOS/templates (and maybe a couple of other repositories
+in the wild):

+
 {
+   description = "Pepper's flake templates";
  
-+  inputs = {
-+    official-templates.url = github:NixOS/templates;
-+    other-templates.url = github:some-other/templates;
-+  };
++  inputs = {
++    official-templates.url = github:NixOS/templates;
++    other-templates.url = github:some-other/templates;
++  };
  
-   outputs = { self, official-templates, other-templates ... }: {
+   outputs = { self, official-templates, other-templates ... }: {
  
-     templates = {
-       latex-report = {
-         path = ./latex-report-template;
-         description = "A latex whitepaper project";
-       };
-       rust-hello = {
-         path = ./rust-hello-template;
-         description = "Simple Hello World in Rust, with overloaded Rust toolchain";
-       };
-     }
-+    // official-templates.templates
-+    // other-templates.templates;
+     templates = {
+       latex-report = {
+         path = ./latex-report-template;
+         description = "A latex whitepaper project";
+       };
+       rust-hello = {
+         path = ./rust-hello-template;
+         description = "Simple Hello World in Rust, with overloaded Rust toolchain";
+       };
+     }
++    // official-templates.templates
++    // other-templates.templates;
  
-   };
- }

-
Running nix flake show biscuits will now list templates from the biscuits registry as well as the ones from NixOS/templates. Ensure that the names don’t collide though.

+   };
+ }

+
Running nix flake show biscuits will now list templates
+from the biscuits registry as well as the ones from
+NixOS/templates. Ensure that the names don’t collide
+though.

 
           

           
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