[PATCH 2/2] declared_hosts: add support for pre-existing infrastructure

[Luis Chamberlain <mcgrof@kernel.org>]

This adds support for using pre-existing infrastructure (bare metal
servers, pre-provisioned VMs) that already have SSH access configured.
This is useful for environments where kdevops bringup/teardown is not
desired or possible.

Key features:
- New DECLARE_HOSTS CLI parameter to specify existing hosts
- Automatic detection of CLI override to enable declared hosts mode
- SKIP_BRINGUP is automatically selected when using declared hosts
- Hosts can be specified as space or comma-separated list
- For A/B testing workflows, odd-numbered hosts become baseline nodes
  and even-numbered hosts become dev nodes
- New Kconfig.declared_hosts for configuration options
- New declared-hosts.j2 template for generating inventory

Usage:
  make defconfig-xfs_reflink_4k DECLARE_HOSTS='server1 server2 server3'
  make  # Will skip bringup and use the declared hosts

The implementation assumes SSH access is already configured in the user's
~/.ssh/config or via SSH keys. No SSH configuration is generated by kdevops
when using declared hosts.

This feature integrates cleanly with the refactored template system,
using the same hosts.j2 entry point with a dedicated declared-hosts.j2
template for this mode.

Generated-by: Claude AI
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
 Makefile                                      |   7 +
 kconfigs/Kconfig.bringup                      |   7 +
 kconfigs/Kconfig.declared_hosts               |  65 ++++++
 playbooks/roles/devconfig/tasks/main.yml      |  60 +++++
 .../templates/workflows/declared-hosts.j2     | 219 ++++++++++++++++++
 playbooks/roles/gen_nodes/tasks/main.yml      |   5 +
 6 files changed, 363 insertions(+)
 create mode 100644 kconfigs/Kconfig.declared_hosts
 create mode 100644 playbooks/roles/gen_hosts/templates/workflows/declared-hosts.j2

diff --git a/Makefile b/Makefile
index 83c67340..fcb626ae 100644
--- a/Makefile
+++ b/Makefile
@@ -19,6 +19,13 @@ export KDEVOPS_NODES :=
 export PYTHONUNBUFFERED=1
 export TOPDIR=./
 export TOPDIR_PATH = $(shell readlink -f $(TOPDIR))
+
+# Export CLI override variables for Kconfig to detect them
+# Note: We accept DECLARE_HOSTS but export as DECLARED_HOSTS for consistency
+ifdef DECLARE_HOSTS
+export DECLARED_HOSTS := $(DECLARE_HOSTS)
+endif
+
 include scripts/refs.Makefile
 
 KDEVOPS_NODES_ROLE_TEMPLATE_DIR :=		$(KDEVOPS_PLAYBOOKS_DIR)/roles/gen_nodes/templates
diff --git a/kconfigs/Kconfig.bringup b/kconfigs/Kconfig.bringup
index 8caf07be..f7f9735a 100644
--- a/kconfigs/Kconfig.bringup
+++ b/kconfigs/Kconfig.bringup
@@ -9,8 +9,14 @@ config KDEVOPS_ENABLE_NIXOS
 	bool
 	output yaml
 
+# CLI override detection for DECLARED_HOSTS which should enable SKIP_BRINGUP
+config SKIP_BRINGUP_SET_BY_CLI
+	bool
+	default $(shell, scripts/check-cli-set-var.sh DECLARED_HOSTS)
+
 choice
 	prompt "Node bring up method"
+	default SKIP_BRINGUP if SKIP_BRINGUP_SET_BY_CLI
 	default GUESTFS
 
 config GUESTFS
@@ -80,6 +86,7 @@ config LIBVIRT
 source "kconfigs/Kconfig.guestfs"
 source "kconfigs/Kconfig.nixos"
 source "terraform/Kconfig"
+source "kconfigs/Kconfig.declared_hosts"
 if LIBVIRT
 source "kconfigs/Kconfig.libvirt"
 endif
diff --git a/kconfigs/Kconfig.declared_hosts b/kconfigs/Kconfig.declared_hosts
new file mode 100644
index 00000000..56b56845
--- /dev/null
+++ b/kconfigs/Kconfig.declared_hosts
@@ -0,0 +1,65 @@
+# Configuration for declared hosts that skip bringup process
+
+# CLI override support for DECLARED_HOSTS
+config KDEVOPS_DECLARED_HOSTS_SET_BY_CLI
+	bool
+	output yaml
+	default $(shell, scripts/check-cli-set-var.sh DECLARED_HOSTS)
+
+config KDEVOPS_USE_DECLARED_HOSTS
+	bool "Use declared hosts (skip bringup process)"
+	depends on SKIP_BRINGUP || KDEVOPS_DECLARED_HOSTS_SET_BY_CLI
+	select WORKFLOW_INFER_USER_AND_GROUP
+	output yaml
+	default y if SKIP_BRINGUP
+	default y if KDEVOPS_DECLARED_HOSTS_SET_BY_CLI
+	help
+	  Enable this option to use pre-existing hosts that you have already
+	  configured with SSH access. This is useful for:
+
+	  * Bare metal systems
+	  * Pre-provisioned VMs or cloud instances
+	  * Systems managed by other infrastructure tools
+
+	  When this option is enabled:
+	  - SSH keys will not be generated (assumes you already have access)
+	  - Bringup and teardown operations will be skipped
+	  - User and group settings will be inferred from the target hosts
+	  - You must provide the list of hosts in KDEVOPS_DECLARED_HOSTS
+
+	  This option automatically:
+	  - Selects WORKFLOW_INFER_USER_AND_GROUP to detect the correct
+	    user and group on the target systems
+	  - Assumes SSH access is already configured
+
+if KDEVOPS_USE_DECLARED_HOSTS
+
+config KDEVOPS_DECLARED_HOSTS
+	string "List of declared hosts (space or comma separated)"
+	output yaml
+	default $(shell, ./scripts/append-makefile-vars.sh $(DECLARED_HOSTS)) if KDEVOPS_DECLARED_HOSTS_SET_BY_CLI
+	default ""
+	help
+	  Provide a space or comma-separated list of hostnames or IP addresses
+	  that are already accessible via SSH.
+
+	  Examples:
+	  - Single host: "server1.example.com"
+	  - Multiple hosts: "server1.example.com server2.example.com"
+	  - IP addresses: "192.168.1.10 192.168.1.11"
+	  - Mixed: "server1.example.com 10.0.0.5 server2.local"
+
+	  For A/B testing workflows with baseline/dev configurations, you can
+	  provide an even number of hosts. The odd-numbered hosts will be used
+	  as baseline nodes and even-numbered hosts as dev nodes.
+
+	  Requirements:
+	  - SSH access must already be configured for these hosts
+	  - The user running kdevops must have passwordless SSH access
+	  - The hosts should have the required dependencies installed
+
+	  Note: kdevops assumes you have already configured SSH access to these
+	  hosts in your ~/.ssh/config or have appropriate SSH keys set up.
+	  Ansible will use your existing SSH configuration to connect.
+
+endif # KDEVOPS_USE_DECLARED_HOSTS
diff --git a/playbooks/roles/devconfig/tasks/main.yml b/playbooks/roles/devconfig/tasks/main.yml
index fccd1fcf..0d69f5fd 100644
--- a/playbooks/roles/devconfig/tasks/main.yml
+++ b/playbooks/roles/devconfig/tasks/main.yml
@@ -17,6 +17,66 @@
   ansible.builtin.setup:
   tags: always
 
+- name: Determine the actual user's home directory when using inferred user
+  block:
+    - name: Get the current username
+      ansible.builtin.command: whoami
+      register: current_user
+      changed_when: false
+
+    - name: Get home directory for the current user
+      ansible.builtin.shell: |
+        # When workflow_infer_user_and_group is enabled, we need to use the actual SSH user
+        # not the hardcoded 'kdevops' user from group_vars/all
+        actual_user="{{ current_user.stdout }}"
+        if [ -n "$actual_user" ]; then
+          getent passwd "$actual_user" | cut -d: -f6
+        else
+          echo "/root"
+        fi
+      register: inferred_home_dir
+      changed_when: false
+
+    - name: Set data_user and data_home_dir based on inferred user
+      set_fact:
+        data_user: "{{ current_user.stdout }}"
+        data_home_dir: "{{ inferred_home_dir.stdout }}"
+        dev_gitconfig_dest: "{{ inferred_home_dir.stdout }}/.gitconfig"
+        dev_bash_config: "{{ inferred_home_dir.stdout }}/.bashrc"
+        dev_bash_config_hacks_dest: "{{ inferred_home_dir.stdout }}/.{{ dev_bash_config_hacks_name }}"
+  when: workflow_infer_user_and_group | default(false) | bool
+
+# Also handle the case when workflow_infer_user_and_group is false but we're using declared hosts
+# In this case, we should still use the SSH user's actual home directory
+- name: Check if using declared hosts without infer setting
+  block:
+    - name: Get the current username for declared hosts
+      ansible.builtin.command: whoami
+      register: current_user_declared
+      changed_when: false
+
+    - name: Get home directory for declared hosts user
+      ansible.builtin.shell: |
+        actual_user="{{ current_user_declared.stdout }}"
+        if [ -n "$actual_user" ]; then
+          getent passwd "$actual_user" | cut -d: -f6
+        else
+          echo "/root"
+        fi
+      register: declared_home_dir
+      changed_when: false
+
+    - name: Override data paths for declared hosts
+      set_fact:
+        data_user: "{{ current_user_declared.stdout }}"
+        data_home_dir: "{{ declared_home_dir.stdout }}"
+        dev_gitconfig_dest: "{{ declared_home_dir.stdout }}/.gitconfig"
+        dev_bash_config: "{{ declared_home_dir.stdout }}/.bashrc"
+        dev_bash_config_hacks_dest: "{{ declared_home_dir.stdout }}/.{{ dev_bash_config_hacks_name }}"
+  when:
+    - kdevops_use_declared_hosts | default(false) | bool
+    - not (workflow_infer_user_and_group | default(false) | bool)
+
 # Update /etc/hostname first so the change gets picked up by the reboot
 # that occurs during the distro-specific tasks
 
diff --git a/playbooks/roles/gen_hosts/templates/workflows/declared-hosts.j2 b/playbooks/roles/gen_hosts/templates/workflows/declared-hosts.j2
new file mode 100644
index 00000000..61b51885
--- /dev/null
+++ b/playbooks/roles/gen_hosts/templates/workflows/declared-hosts.j2
@@ -0,0 +1,219 @@
+{# Template for declared hosts that skip bringup process #}
+{# This template is used when users have pre-existing infrastructure like:
+   - Bare metal servers
+   - Pre-provisioned VMs
+   - Cloud instances managed outside of kdevops
+   - Any hosts with existing SSH access
+
+   The hosts are provided via kdevops_declared_hosts variable which contains
+   a list of hostnames/IPs that are already accessible via SSH.
+#}
+{# Parse declared hosts - handle both string and list formats #}
+{% if kdevops_declared_hosts is string %}
+{% set parsed_hosts = kdevops_declared_hosts | regex_replace(',', ' ') | split() %}
+{% elif kdevops_declared_hosts is iterable and kdevops_declared_hosts is not string %}
+{% set parsed_hosts = kdevops_declared_hosts %}
+{% else %}
+{% set parsed_hosts = [kdevops_declared_hosts] %}
+{% endif %}
+[all]
+localhost ansible_connection=local
+{# Loop through parsed hosts #}
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[all:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% if kdevops_workflows_dedicated_workflow %}
+{# For workflows, organize hosts into baseline/dev groups for A/B testing #}
+{% if kdevops_baseline_and_dev %}
+[baseline]
+{# Odd-numbered hosts become baseline nodes #}
+{% for host in parsed_hosts %}
+{% if loop.index is odd %}
+{{ host }}
+{% endif %}
+{% endfor %}
+
+[baseline:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+[dev]
+{# Even-numbered hosts become dev nodes #}
+{% for host in parsed_hosts %}
+{% if loop.index is even %}
+{{ host }}
+{% endif %}
+{% endfor %}
+
+[dev:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% else %}
+{# Without A/B testing, all hosts are baseline #}
+[baseline]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[baseline:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+{% endif %}
+
+{# Add workflow-specific groups based on enabled workflow #}
+{% if workflows_reboot_limit %}
+[reboot-limit]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[reboot-limit:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% elif kdevops_workflow_enable_fio_tests %}
+[fio_tests]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[fio_tests:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% elif kdevops_workflow_enable_fstests %}
+[fstests]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[fstests:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{# Add per-section groups if needed #}
+{% for section in sections|default([]) %}
+[fstests_{{ section | replace('-', '_') }}]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[fstests_{{ section | replace('-', '_') }}:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+{% endfor %}
+
+{% elif kdevops_workflow_enable_blktests %}
+[blktests]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[blktests:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% elif kdevops_workflow_enable_selftests %}
+[selftests]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[selftests:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% elif kdevops_workflow_enable_mmtests %}
+[mmtests]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[mmtests:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% elif kdevops_workflow_enable_sysbench %}
+[sysbench]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[sysbench:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% elif kdevops_workflow_enable_ai|default(false)|bool %}
+[ai]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[ai:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% elif kdevops_workflow_enable_minio|default(false)|bool %}
+[minio]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[minio:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% elif kdevops_workflow_enable_cxl %}
+[cxl]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[cxl:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% elif kdevops_workflow_enable_pynfs %}
+[pynfs]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[pynfs:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% elif kdevops_workflow_enable_gitr %}
+[gitr]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[gitr:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% elif kdevops_workflow_enable_ltp %}
+[ltp]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[ltp:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+
+{% elif kdevops_workflow_enable_nfstest %}
+[nfstest]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[nfstest:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+{% endif %}
+
+{% else %}
+{# Non-workflow setup - just use baseline group #}
+[baseline]
+{% for host in parsed_hosts %}
+{{ host }}
+{% endfor %}
+
+[baseline:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
+{% endif %}
+
+[service]
+{# Service nodes are typically not needed for declared hosts #}
+
+[service:vars]
+ansible_python_interpreter = "{{ kdevops_python_interpreter }}"
diff --git a/playbooks/roles/gen_nodes/tasks/main.yml b/playbooks/roles/gen_nodes/tasks/main.yml
index b1a1946f..0fa778bf 100644
--- a/playbooks/roles/gen_nodes/tasks/main.yml
+++ b/playbooks/roles/gen_nodes/tasks/main.yml
@@ -20,6 +20,11 @@
   register: my_group
   changed_when: false
 
+- name: Skip node generation if using declared hosts
+  meta: end_play
+  when:
+    - kdevops_use_declared_hosts|default(false)|bool
+
 - name: Create guestfs directory
   ansible.builtin.file:
     path: "{{ guestfs_path }}"
-- 
2.50.1