[RFC] bringup: add semantics to start NixOS support

[Luis Chamberlain <mcgrof@kernel.org>]

Tons still left to do... but hey, at least we get to trim clutter out
and can aim for a simple setup. TODO:

- playbooks/bringup_nixos.yml
- playbooks/update_ssh_config_nixos.yml

We can probably just trim nixos.nix.j2 so to at least bring up
a libvirt guest first, and then the second step is to use process
a set of target nodes under a simple workflow.

So the only thing here this does is show how we need to first
add tons of "support" bools and make terraform and guestfs to select
them. That should probably just be its own patch before all this.

Then the makefile shows the bare bones bringup we need. But we can
probably simplify that more.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
 Kconfig                                       |  8 ++
 kconfigs/Kconfig.bringup                      | 47 +++++++++++
 kconfigs/Kconfig.kdevops                      |  2 +
 playbooks/roles/gen_nodes/defaults/main.yml   |  6 ++
 playbooks/roles/gen_nodes/tasks/main.yml      | 21 ++++-
 .../roles/gen_nodes/templates/nixos.nix.j2    | 34 ++++++++
 scripts/nixos.Makefile                        | 77 +++++++++++++++++++
 7 files changed, 194 insertions(+), 1 deletion(-)
 create mode 100644 playbooks/roles/gen_nodes/templates/nixos.nix.j2
 create mode 100644 scripts/nixos.Makefile

diff --git a/Kconfig b/Kconfig
index 988782a9dc83..2b8363aeaccd 100644
--- a/Kconfig
+++ b/Kconfig
@@ -67,18 +67,26 @@ menu "Bring up methods"
 source "kconfigs/Kconfig.bringup"
 endmenu
 
+if KDEVOPS_SUPPORTS_BRINGUP
 menu "Bring up goals"
 source "kconfigs/Kconfig.bringup.goals"
 endmenu
+endif
 
+if KDEVOPS_SUPPORTS_SYSCTL
 menu "Node sysctl configuration"
 source "kconfigs/Kconfig.sysctl"
 endmenu
+endif
 
+if KDEVOPS_SUPPORTS_WORKFLOWS
 menu "Target workflows"
 source "kconfigs/workflows/Kconfig"
 endmenu
+endif
 
+if KDEVOPS_SUPPORTS_CONFIG
 menu "Kdevops configuration"
 source "kconfigs/Kconfig.kdevops"
 endmenu
+endif
diff --git a/kconfigs/Kconfig.bringup b/kconfigs/Kconfig.bringup
index a9aefc56e3fa..77493a5cec8d 100644
--- a/kconfigs/Kconfig.bringup
+++ b/kconfigs/Kconfig.bringup
@@ -1,6 +1,31 @@
 config BRINGUP_SUPPORTS_CXL
 	bool
 
+config KDEVOPS_SUPPORTS_BRINGUP
+	bool
+
+config KDEVOPS_SUPPORTS_SYSCTL
+	bool
+
+config KDEVOPS_SUPPORTS_WORKFLOWS
+	bool
+
+config KDEVOPS_SUPPORTS_CONFIG
+	bool
+
+config KDEVOPS_SUPPORTS_LEGACY_KERNELCI
+	bool
+
+config KDEVOPS_NODE_PATH
+	string
+	output yaml
+	default "{{ guestfs_path }}" if KDEVOPS_ENABLE_GUESTFS
+	default "{{ nixos_path }}" if KDEVOPS_ENABLE_NIXOS
+
+config KDEVOPS_GENERATE_NODES
+	bool
+	output yaml
+
 config KDEVOPS_ENABLE_GUESTFS
 	bool
 	output yaml
@@ -13,6 +38,12 @@ config GUESTFS
 	bool "Use guestfs-tools for local virtualization via KVM and libvirt"
 	select KDEVOPS_ENABLE_GUESTFS
 	select EXTRA_STORAGE_SUPPORTS_LARGEIO
+	select KDEVOPS_GENERATE_NODES
+	select KDEVOPS_SUPPORTS_BRINGUP
+	select KDEVOPS_SUPPORTS_SYSCTL
+	select KDEVOPS_SUPPORTS_WORKFLOWS
+	select KDEVOPS_SUPPORTS_CONFIG
+	select KDEVOPS_SUPPORTS_LEGACY_KERNELCI
 	help
 	  This option will use libguestfs utilities instead of Vagrant to build
 	  guest images and spin them up using libvirt with KVM.
@@ -23,6 +54,10 @@ config TERRAFORM
 	select EXTRA_STORAGE_SUPPORTS_1K
 	select EXTRA_STORAGE_SUPPORTS_2K
 	select EXTRA_STORAGE_SUPPORTS_4K
+	select KDEVOPS_SUPPORTS_BRINGUP
+	select KDEVOPS_SUPPORTS_SYSCTL
+	select KDEVOPS_SUPPORTS_WORKFLOWS
+	select KDEVOPS_SUPPORTS_CONFIG
 	help
 	  This option will enable use of Vagrant. Enable this if you want to
 	  use terraform to create nodes on a cloud environment such as:
@@ -39,6 +74,18 @@ config TERRAFORM
 
 	  If you are not using a cloud environment just disable this.
 
+config KDEVOPS_ENABLE_NIXOS
+	bool "Nix OS setup"
+	output yaml
+	select EXTRA_STORAGE_SUPPORTS_512
+	select EXTRA_STORAGE_SUPPORTS_1K
+	select EXTRA_STORAGE_SUPPORTS_2K
+	select EXTRA_STORAGE_SUPPORTS_4K
+	select KDEVOPS_GENERATE_NODES
+	select KDEVOPS_SUPPORTS_CONFIG
+	help
+	  Select this if you want to experiment with Nix OS.
+
 config SKIP_BRINGUP
 	bool "Skip bring up - bare metal or existing nodes"
 	select EXTRA_STORAGE_SUPPORTS_512
diff --git a/kconfigs/Kconfig.kdevops b/kconfigs/Kconfig.kdevops
index c613ff20c193..685abd4e3ce3 100644
--- a/kconfigs/Kconfig.kdevops
+++ b/kconfigs/Kconfig.kdevops
@@ -192,6 +192,8 @@ menu "Ansible post-bring up provisioning configuration"
 source "kconfigs/Kconfig.ansible_provisioning"
 endmenu
 
+if KDEVOPS_SUPPORTS_LEGACY_KERNELCI
 menu "Kernel continous integration configuration"
 source "kconfigs/Kconfig.kernel-ci"
 endmenu
+endif
diff --git a/playbooks/roles/gen_nodes/defaults/main.yml b/playbooks/roles/gen_nodes/defaults/main.yml
index 8ff9b87993a7..5d420dc5e6b3 100644
--- a/playbooks/roles/gen_nodes/defaults/main.yml
+++ b/playbooks/roles/gen_nodes/defaults/main.yml
@@ -1,5 +1,7 @@
 # SPDX-License-Identifier GPL-2.0+
 ---
+kdevops_generate_nodes: False
+kdevops_enable_nixos: False
 kdevops_enable_guestfs: False
 kdevops_enable_terraform: False
 kdevops_enable_vagrant: False
@@ -19,6 +21,10 @@ kdevops_smbd_enable: False
 kdevops_krb5_enable: False
 kdevops_enable_iscsi: false
 
+
+kdevops_node_path: ""
+nixos_path: "{{ topdir_path }}/nixos"
+
 virtualbox_provider: False
 libvirt_provider: False
 
diff --git a/playbooks/roles/gen_nodes/tasks/main.yml b/playbooks/roles/gen_nodes/tasks/main.yml
index 8c6a1f705ee2..7f5b64bcd68f 100644
--- a/playbooks/roles/gen_nodes/tasks/main.yml
+++ b/playbooks/roles/gen_nodes/tasks/main.yml
@@ -18,6 +18,18 @@
   command: "id -g -n"
   register: my_group
 
+- name: Create NixOS directory
+  ansible.builtin.file:
+    path: "{{ kdevops_nix_path }}"
+    state: directory
+  when: kdevops_enable_nixos|bool
+
+- name: Generate NixOS devshell.nix
+  template:
+    src: devshell.nix.j2
+    dest: "{{ kdevops_nix_path }}"
+  when: kdevops_enable_nixos|bool
+
 - name: Fail if kdevops_host_prefix contains a dash
   fail:
     msg: "Invalid kdevops_host_prefix '{{ kdevops_host_prefix }}'. The prefix cannot contain a dash ('-')."
@@ -544,7 +556,14 @@
   include_vars: "{{ topdir_path }}/{{ kdevops_nodes }}"
   ignore_errors: yes
   when:
-    - kdevops_enable_guestfs|bool
+    - kdevops_generate_nodes|bool
+
+- name: Create local directories for each of the guests
+  ansible.builtin.file:
+    path: "{{ kdevops_node_path }}/{{ item.name }}"
+    state: directory
+  with_items: "{{ guestfs_nodes }}"
+  when: kdevops_enable_guestfs|bool
 
 - name: Create local directories for each of the guests
   ansible.builtin.file:
diff --git a/playbooks/roles/gen_nodes/templates/nixos.nix.j2 b/playbooks/roles/gen_nodes/templates/nixos.nix.j2
new file mode 100644
index 000000000000..40eb59853e90
--- /dev/null
+++ b/playbooks/roles/gen_nodes/templates/nixos.nix.j2
@@ -0,0 +1,34 @@
+{ config, pkgs, ... }:
+
+{
+  imports = [ ./hardware-configuration.nix ];
+
+  networking.hostName = "{{ guest_hostname }}";
+  networking.useDHCP = false;
+
+  networking.interfaces.enp1s0.ipv4.addresses = [{
+    address = "{{ guest_ip }}";
+    prefixLength = 24;
+  }];
+  networking.defaultGateway = "{{ guest_gateway }}";
+  networking.nameservers = [ "{{ guest_dns }}" ];
+
+  time.timeZone = "UTC";
+
+  environment.systemPackages = with pkgs; [
+    git
+    htop
+    sysbench
+    docker
+  ];
+
+  services.openssh.enable = true;
+
+  users.users.kdevops = {
+    isNormalUser = true;
+    extraGroups = [ "wheel" ];
+    password = "kdevops"; # for testing only; better to use hashedPassword
+  };
+
+  system.stateVersion = "24.05";
+}
diff --git a/scripts/nixos.Makefile b/scripts/nixos.Makefile
new file mode 100644
index 000000000000..65eec5efa8d0
--- /dev/null
+++ b/scripts/nixos.Makefile
@@ -0,0 +1,77 @@
+# SPDX-License-Identifier: copyleft-next-0.3.1
+
+NIXOIS_ARGS :=
+
+KDEVOPS_NODES_TEMPLATE :=	$(KDEVOPS_NODES_ROLE_TEMPLATE_DIR)/nixos_nodes.j2
+KDEVOPS_NODES :=		$(KDEVOPS_NODE_PATH)/kdevops_nodes.yaml
+
+export KDEVOPS_PROVISIONED_SSH := $(KDEVOPS_PROVISIONED_SSH_DEFAULT_GUARD)
+
+NIXOS_ARGS += data_home_dir=/home/kdevops
+NIXOS_ARGS += kdevops_storage_pool_user='$(USER)'
+
+NIXOS_ARGS += libvirt_provider=True
+
+QEMU_GROUP:=$(subst ",,$(CONFIG_LIBVIRT_QEMU_GROUP))
+NIXOS_ARGS += kdevops_storage_pool_group='$(QEMU_GROUP)'
+NIXOS_ARGS += storage_pool_group='$(QEMU_GROUP)'
+
+ANSIBLE_EXTRA_ARGS += $(NIXOS_ARGS)
+
+NIXOS_BRINGUP_DEPS :=
+NIXOS_BRINGUP_DEPS +=  install_nixos
+
+KDEVOPS_PROVISION_METHOD		:= bringup_nixos
+KDEVOPS_PROVISION_STATUS_METHOD		:= status_nixos
+KDEVOPS_PROVISION_DESTROY_METHOD	:= destroy_nixos
+
+$(KDEVOPS_PROVISIONED_SSH):
+	$(Q)if [[ "$(CONFIG_KDEVOPS_SSH_CONFIG_UPDATE)" == "y" ]]; then \
+		ansible-playbook $(ANSIBLE_VERBOSE) --connection=local \
+			--inventory localhost, \
+			playbooks/update_ssh_config_nixos.yml \
+			--extra-vars=@./extra_vars.yaml \
+			-e 'ansible_python_interpreter=/usr/bin/python3' ;\
+		LIBVIRT_DEFAULT_URI=$(CONFIG_LIBVIRT_URI) $(TOPDIR)/scripts/update_ssh_config_nixos.py; \
+	fi
+	$(Q)ansible $(ANSIBLE_VERBOSE) -i hosts all -e 'ansible_python_interpreter=/usr/bin/python3' -m wait_for_connection
+	$(Q)touch $(KDEVOPS_PROVISIONED_SSH)
+
+install_nixos:
+	$(Q)ansible-playbook $(ANSIBLE_VERBOSE) --connection=local \
+		--inventory localhost, \
+		playbooks/bringup_nixos.yml \
+		-e 'ansible_python_interpreter=/usr/bin/python3' \
+		--extra-vars=@./extra_vars.yaml \
+		--tags install-deps
+
+bringup_nixos: $(NIXOS_BRINGUP_DEPS)
+	$(Q)ansible-playbook $(ANSIBLE_VERBOSE) --connection=local \
+		--inventory localhost, \
+		playbooks/bringup_nixos.yml \
+		-e 'ansible_python_interpreter=/usr/bin/python3' \
+		--extra-vars=@./extra_vars.yaml \
+		--tags bringup
+PHONY += bringup_nixos
+
+status_nixos:
+	$(Q)ansible-playbook $(ANSIBLE_VERBOSE) --connection=local \
+		--inventory localhost, \
+		playbooks/bringup_nixos.yml \
+		-e 'ansible_python_interpreter=/usr/bin/python3' \
+		--extra-vars=@./extra_vars.yaml \
+		--tags status
+PHONY += status_nixos
+
+destroy_nixos:
+	$(Q)ansible-playbook $(ANSIBLE_VERBOSE) --connection=local \
+		--inventory localhost, \
+		playbooks/bringup_nixos.yml \
+		-e 'ansible_python_interpreter=/usr/bin/python3' \
+		--extra-vars=@./extra_vars.yaml \
+		--tags destroy
+	$(Q)rm -f $(KDEVOPS_PROVISIONED_SSH) $(KDEVOPS_PROVISIONED_DEVCONFIG)
+PHONY += destroy_nixos
+
+cleancache:
+	$(Q)echo fixme
-- 
2.47.2