Creating a NixOS live CD: Difference between revisions

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Revision as of 18:28, 21 August 2017

motivation

creating a modified NIXOS live CD out of a working nixos installation gives you the benefits:

verify what is included
no need to download it
it is easy to add your own programs to the image

how to build such an image

we will use the NIXREPOS variable, which points to the nixpkgs/nixos checkouts, see Create and debug nix packages

just run this command (for 64 bit):

export NIX_PATH=$NIXREPOS
nix-build -A iso_graphical.x86_64-linux $NIXREPOS/nixos/release.nix

for 32 bit:

export NIX_PATH=$NIXREPOS
nix-build -A iso_graphical.i686-linux $NIXREPOS/nixos/release.nix

once the building process is over, you should see multiple nix distributions built (for multiple archs). See contents to find iso image path:

$ cat /nix/store/2y4bivmrzg4d2dgby2b7prvfj7445088-nixos-iso-0.1pre1234/nix-support/hydra-build-products 
file iso /nix/store/94rrfklbk2hcqhkr4627vsrlprlyva50-iso9660-image/iso/nixos-minimal-0.1pre1234-i686-linux-test.iso

and copy the new image from there to your USB drive (or use unetbootin).

adding additional software to the image

the basic script /etc/nixos/nixos/release.nix contains several entry points for custom images. as we are using -A iso_minimal have a look at: iso_minimal which will redirect us to:

./modules/installer/cd-dvd/installation-cd-minimal.nix -> /etc/nixos/nixos/modules/installer/cd-dvd/installation-cd-minimal.nix

# This module defines a small NixOS installation CD.  It does not
# contain any graphical stuff.
{config, pkgs, ...}:
{
  require = [
    ./installation-cd-base.nix
    ../../profiles/minimal.nix
  ];
}

=== Start SSH with your SSH key

In your configuration.nix:

 services.openssh = {
   enable = true;
   hostKeys = [
     { bits = 8192; type = "ed25519"; path = "/etc/ssh/ssh_host_ed25519_key"; }
   ];
 };
 # enable ssh in the iso boot process
 systemd.services.sshd.wantedBy = lib.mkForce [ "multi-user.target" ];
 users.users.root.openssh.authorizedKeys.keys [
   "ssh-rsa AAAAB3NzaC1y...== me@my-laptop"
 ];

software installation inside the 'once' deployed and booted image

in case you have booted from your image you can add software as described here:

install/remove software

references

See also section "Building your own NixOS CD" of the NixOS manual.

@@ Line 1: / Line 1: @@
 == motivation ==
 creating a modified NIXOS live CD out of a working nixos installation gives you the benefits:
@@ Line 37: / Line 38: @@
   }
-=== step 1/3: starting ssh automatically in the image and adding a ssh key to it ===
+=== Start SSH with your SSH key
-setting a default password on the boot cdrom (so that nobody can login using the default 'unset' password:
-TODO
-=== step 2/3: starting ssh automatically in the image and adding a ssh key to it ===
+In your configuration.nix:
-this is a hack, however it surely gives you an idea how to modify the stuff there:
-in '''/etc/nixos/nixos/modules/installer/cd-dvd/installation-cd-base.nix''' add:
+<code>
-        mkdir -p /root/.ssh/
+  services.openssh = {
-        echo 'ssh-rsa ssh-rsa  AAAAB3Nz...(cut here)...AzV foo@bar' > /root/.ssh/authorized_keys
+    enable = true;
-at the end of
+    hostKeys = [
-* boot.postBootCommands =
+      { bits = 8192; type = "ed25519"; path = "/etc/ssh/ssh_host_ed25519_key"; }
+    ];
+  };
+  # enable ssh in the iso boot process
+  systemd.services.sshd.wantedBy = lib.mkForce [ "multi-user.target" ];
+  users.users.root.openssh.authorizedKeys.keys [
+    "ssh-rsa AAAAB3NzaC1y...== me@my-laptop"
+  ];
-=== step 3/3: starting ssh automatically in the image and adding a ssh key to it ===
+</code>
-'''THIS IS NOT WORKING YET: IGNORE LINES BELOW'''
- vi /etc/nixos/nixos/modules/installer/cd-dvd/system-tarball-pc.nix
-comment this line with a leading '#':
- jobs.openssh.startOn = "network interfaces started";
 == software installation inside the 'once' deployed and booted image ==
 in case you have booted from your image you can add software as described here:
 * [[install/remove software]]
-<del>Without NixOS you need to supply the [https://svn.nixos.org/repos/nix/nixos/trunk/ source] instead of /etc/nixos/nixos.</del>(SVN is dead, https://github.com/NixOS/nixpkgs ? )
 == references ==
@@ Line 68: / Line 67: @@
 [[Category:Installation]]
 [[Category:Deployment]]
+[[Category:HOW-TO]]