llm-inference-multimodel: role + day1 playbook (phase 0 discover approved)

ansible/roles/llm-inference-multimodel/tasks/discover.yml

@@ -0,0 +1,87 @@
+---
+# ------------------------------------------------------------------------------
+# FILE: roles/llm-inference-multimodel/tasks/discover.yml
+# DESCRIPTION: Phase 0 — READ-ONLY fact gathering on how the existing Gemma
+#              llama-server is actually managed on astro-orbiter TODAY.
+#
+#              Per plan §0/§4: "Service management: unverified — plan requires
+#              confirming systemd unit exists before touching anything.
+#              Do not assume." This file performs that confirmation. It makes
+#              NO changes to the host — no `state: present/started/stopped`,
+#              no file writes, no service actions. Every task here is either
+#              a `_facts` module, a `command`/`shell` in check-safe read mode,
+#              or a `stat`.
+#
+#              Outcomes recorded as facts for later phases/for a human to read
+#              in the play recap — this file does not branch role behavior
+#              on the result (that would be over-engineering a role meant to
+#              run once); it surfaces what's true so a human confirms before
+#              Phase 2 proceeds.
+# ------------------------------------------------------------------------------
+
+- name: Gather service facts (systemd unit inventory)
+  ansible.builtin.service_facts:
+
+- name: Determine whether a systemd unit matching the existing Gemma service exists
+  ansible.builtin.set_fact:
+    llm_existing_gemma_unit_found: "{{ (llm_existing_gemma_service_name_guess + '.service') in ansible_facts.services }}"
+
+- name: Report existing Gemma systemd unit state (if found)
+  ansible.builtin.debug:
+    msg: >-
+      Existing unit '{{ llm_existing_gemma_service_name_guess }}.service' found:
+      state={{ ansible_facts.services[llm_existing_gemma_service_name_guess + '.service'].state | default('unknown') }},
+      status={{ ansible_facts.services[llm_existing_gemma_service_name_guess + '.service'].status | default('unknown') }}
+  when: llm_existing_gemma_unit_found
+
+- name: WARNING — no systemd unit found matching the existing Gemma service
+  ansible.builtin.debug:
+    msg: >-
+      No systemd unit named '{{ llm_existing_gemma_service_name_guess }}.service'
+      was found via service_facts. This means the current single-model
+      llama-server is likely run some other way (manual nohup, screen/tmux,
+      or a differently-named unit). DO NOT PROCEED to Phase 2 assuming a
+      clean rollback target exists. Before continuing: (1) check for any
+      running llama-server process via `ansible -m command -a "pgrep -fa
+      llama-server"`, (2) if found running ad hoc, codify it as a proper
+      systemd unit FIRST (reusing roles/llm-inference's existing
+      llama-server.service.j2 pattern) so plan §6's rollback story
+      ("systemctl start llama-server-gemma to fully revert") is real and
+      not aspirational. This is a human decision point, not something this
+      role auto-remediates.
+  when: not llm_existing_gemma_unit_found
+
+- name: Check for any running llama-server process (read-only, no state change)
+  ansible.builtin.command:
+    cmd: pgrep -fa llama-server
+  register: llm_existing_process_check
+  changed_when: false
+  failed_when: false   # pgrep exits 1 with no matches — not a failure condition here
+
+- name: Report any llama-server process found running outside systemd
+  ansible.builtin.debug:
+    msg: "Running llama-server process(es): {{ llm_existing_process_check.stdout_lines }}"
+  when: llm_existing_process_check.rc == 0
+
+- name: Check current GPU VRAM utilization (baseline, before any changes)
+  ansible.builtin.command:
+    cmd: nvidia-smi --query-gpu=memory.used,memory.total --format=csv,noheader
+  register: llm_baseline_vram
+  changed_when: false
+  failed_when: false
+
+- name: Report baseline VRAM usage
+  ansible.builtin.debug:
+    msg: "Baseline GPU VRAM (before this role's changes): {{ llm_baseline_vram.stdout | default('nvidia-smi unavailable') }}"
+
+- name: Check whether ports 8000/8001 are already bound (avoid port collision surprises)
+  ansible.builtin.command:
+    cmd: "ss -ltnp"
+  register: llm_existing_listeners
+  changed_when: false
+  failed_when: false
+
+- name: Report current listeners on 8000/8001
+  ansible.builtin.debug:
+    msg: "{{ llm_existing_listeners.stdout_lines | select('search', ':(8000|8001)\\s') | list }}"
+  when: llm_existing_listeners.rc == 0