Rename file to proper date and write content on Guix and NixOS

2 files changed, 149 insertions, 52 deletions

diff --git a/site/posts/2018-07-15-running-guix-on-nixos.org b/site/posts/2018-07-15-running-guix-on-nixos.org
deleted file mode 100644
index ebf5400..0000000
--- a/site/posts/2018-07-15-running-guix-on-nixos.org
+++ /dev/null
@@ -1,52 +0,0 @@
----
-title: Running Guix on NixOS
-date: 2018-07-15
----
-https://riot.im/app/#/room/#freenode_#guix:matrix.org/$1531510045400627zjGbq:matrix.org
-* h1
-** h2
-#+BEGIN_SRC nix -n
-  # FIXME: add line number
-  { config, pkgs, ...}:
-
-  {
-
-    # NixOS usual config
-
-    users = {
-      mutableUsers = false;
-
-      extraUsers =
-        let
-          andrehUser =  {
-            andreh = {
-              # my custom user config
-            };
-          };
-          # From the Guix manual:
-          # https://www.gnu.org/software/guix/manual/en/html_node/Build-Environment-Setup.html#Build-Environment-Setup
-          buildUser = (i:
-            {
-              "guixbuilder${i}" = {                   # guixbuilder$i
-                group = "guixbuild";                  # -g guixbuild
-                extraGroups = ["guixbuild"];          # -G guixbuild
-                home = "/var/empty";                  # -d /var/empty
-                shell = pkgs.nologin;                 # -s `which nologin`
-                description = "Guix build user ${i}"; # -c "Guix buid user $i"
-                isSystemUser = true;                  # --system
-              };
-            }
-          );
-        in
-          # merge all users
-          pkgs.lib.fold (str: acc: acc // buildUser str)
-                        andrehUser
-                        # for i in `seq -w 1 10`
-                        (map (pkgs.lib.fixedWidthNumber 2) (builtins.genList (n: n+1) 10));
-
-      extraGroups.guixbuild = {
-        name = "guixbuild";
-      };
-    };
-  }
-#+END_SRC
diff --git a/site/posts/2018-07-17-running-guix-on-nixos.org b/site/posts/2018-07-17-running-guix-on-nixos.org
new file mode 100644
index 0000000..535b271
--- /dev/null
+++ b/site/posts/2018-07-17-running-guix-on-nixos.org
@@ -0,0 +1,149 @@
+---
+title: Running Guix on NixOS
+date: 2018-07-17
+---
+I wanted to run Guix on a NixOS machine. Even though the Guix manual explains how to do it [[https://www.gnu.org/software/guix/manual/en/html_node/Binary-Installation.html#Binary-Installation][step by step]], I needed a few extra steps to make it work properly.
+
+I couldn't just install GuixSD because the wireless network card doesn't have any free/libre drivers (yet).
+** Creating =guixbuilder= users
+Guix requires you to create non-root users that will be used to perform the builds in the isolated environments.
+
+The [[https://www.gnu.org/software/guix/manual/en/html_node/Build-Environment-Setup.html#Build-Environment-Setup][manual]] already provides you with a ready to run (as root) command for creating the build users:
+#+BEGIN_SRC bash -n
+groupadd --system guixbuild
+for i in `seq -w 1 10`;
+do
+  useradd -g guixbuild -G guixbuild           \
+          -d /var/empty -s `which nologin`    \
+          -c "Guix build user $i" --system    \
+          guixbuilder$i;
+done
+#+END_SRC
+However, In my personal NixOS I have disabled =users.mutableUsers=, which means that even if I run the above command it means that they'll be removed once I rebuild my OS:
+#+BEGIN_SRC
+removing user ‘guixbuilder7’
+removing user ‘guixbuilder3’
+removing user ‘guixbuilder10’
+removing user ‘guixbuilder1’
+removing user ‘guixbuilder6’
+removing user ‘guixbuilder9’
+removing user ‘guixbuilder4’
+removing user ‘guixbuilder2’
+removing user ‘guixbuilder8’
+removing user ‘guixbuilder5’
+#+END_SRC
+Instead of enabling =users.mutableUsers= I could add the Guix users by adding them to my system configuration:
+#+BEGIN_SRC nix -n
+{ config, pkgs, ...}:
+
+{
+
+  # ... NixOS usual config ellided ...
+
+  users = {
+    mutableUsers = false;
+
+    extraUsers =
+      let
+        andrehUser =  {
+          andreh = {
+            # my custom user config
+          };
+        };
+        buildUser = (i:
+          {
+            "guixbuilder${i}" = {                   # guixbuilder$i
+              group = "guixbuild";                  # -g guixbuild
+              extraGroups = ["guixbuild"];          # -G guixbuild
+              home = "/var/empty";                  # -d /var/empty
+              shell = pkgs.nologin;                 # -s `which nologin`
+              description = "Guix build user ${i}"; # -c "Guix buid user $i"
+              isSystemUser = true;                  # --system
+            };
+          }
+        );
+      in
+        # merge all users
+        pkgs.lib.fold (str: acc: acc // buildUser str)
+                      andrehUser
+                      # for i in `seq -w 1 10`
+                      (map (pkgs.lib.fixedWidthNumber 2) (builtins.genList (n: n+1) 10));
+
+    extraGroups.guixbuild = {
+      name = "guixbuild";
+    };
+  };
+}
+#+END_SRC
+Here I used =fold= and the =//= operator to merge all of the configuration sets into a single =extraUsers= value.
+** Creating the =systemd= service
+One other thing missing was the =systemd= service.
+
+First I couldn't just copy the =.service= file to =/etc= since in NixOS that folder isn't writable. But also I wanted the service to be better integrated with the OS.
+
+That was a little easier than creating the users, all I had to do was translate the provided =guix-daemon.service= configuration to an equivalent Nix expression
+#+BEGIN_SRC ini -n
+# This is a "service unit file" for the systemd init system to launch
+# 'guix-daemon'.  Drop it in /etc/systemd/system or similar to have
+# 'guix-daemon' automatically started.
+
+[Unit]
+Description=Build daemon for GNU Guix
+
+[Service]
+ExecStart=/var/guix/profiles/per-user/root/guix-profile/bin/guix-daemon --build-users-group=guixbuild
+Environment=GUIX_LOCPATH=/root/.guix-profile/lib/locale
+RemainAfterExit=yes
+StandardOutput=syslog
+StandardError=syslog
+
+# See <https://lists.gnu.org/archive/html/guix-devel/2016-04/msg00608.html>.
+# Some package builds (for example, go@1.8.1) may require even more than
+# 1024 tasks.
+TasksMax=8192
+
+[Install]
+WantedBy=multi-user.target
+#+END_SRC
+This sample =systemd= configuration file became:
+#+BEGIN_SRC nix -n
+# Derived from Guix guix-daemon.service.in
+# https://git.savannah.gnu.org/cgit/guix.git/tree/etc/guix-daemon.service.in?id=00c86a888488b16ce30634d3a3a9d871ed6734a2
+guix-daemon = {
+  enable = true;
+  description = "Build daemon for GNU Guix";
+  serviceConfig = {
+    ExecStart = "/var/guix/profiles/per-user/root/guix-profile/bin/guix-daemon --build-users-group=guixbuild";
+    Environment="GUIX_LOCPATH=/root/.guix-profile/lib/locale";
+    RemainAfterExit="yes";
+    StandardOutput="syslog";
+    StandardError="syslog";
+    TaskMax= "8192";
+  };
+  wantedBy = [ "multi-user.target" ];
+};
+#+END_SRC
+There you go! After running =sudo nixos-rebuild switch= I could get Guix up and running:
+#+BEGIN_SRC bash -n
+$ guix package -i hello
+The following package will be installed:
+   hello        2.10    /gnu/store/bihfrh609gkxb9dp7n96wlpigiv3krfy-hello-2.10
+
+substitute: updating substitutes from 'https://mirror.hydra.gnu.org'... 100.0%
+The following derivations will be built:
+   /gnu/store/nznmdn6inpwxnlkrasydmda4s2vsp9hg-profile.drv
+   /gnu/store/vibqrvw4c8lacxjrkqyzqsdrmckv77kq-fonts-dir.drv
+   /gnu/store/hi8alg7wi0wgfdi3rn8cpp37zhx8ykf3-info-dir.drv
+   /gnu/store/cvkbp378cvfjikz7mjymhrimv7j12p0i-ca-certificate-bundle.drv
+   /gnu/store/d62fvxymnp95rzahhmhf456bsf0xg1c6-manual-database.drv
+Creating manual page database...
+1 entries processed in 0.0 s
+2 packages in profile
+$ hello
+Hello, world!
+#+END_SRC
+Some improvements to this approach are:
+1. looking into [[https://nixos.org/nixos/manual/index.html#sec-writing-modules][NixOS modules]] and trying to bundle everything together into a single logical unit;
+2. [[https://www.gnu.org/software/guix/manual/en/html_node/Requirements.html#Requirements][build Guix from source]] and share the Nix store and daemon with Guix.
+
+Happy Guix/Nix hacking!