fix: re-enable Loki with v6.10.0 and minimal working config

ansible/roles/observability/tasks/main.yml

@@ -52,7 +52,26 @@
     --timeout 10m
   changed_when: true
 
-- name: Remove legacy Loki resources (if present)
+- name: Write Loki values
+  template:
+    src: loki-values.yaml.j2
+    dest: /tmp/loki-values.yaml
+    mode: "0644"
+  when: loki_enabled
+
+- name: Validate Loki chart produces resources
+  command: >-
+    helm template loki grafana/loki
+    --namespace {{ observability_namespace }}
+    --version {{ loki_chart_version }}
+    --values /tmp/loki-values.yaml
+  register: loki_template
+  changed_when: false
+  failed_when: 
+    - loki_template.rc != 0 or 'kind: StatefulSet' not in loki_template.stdout
+  when: loki_enabled
+
+- name: Remove legacy Loki resources
   command: >-
     kubectl -n {{ observability_namespace }} delete
     deployment/loki-gateway
@@ -67,7 +86,48 @@
     --ignore-not-found=true
   changed_when: false
   failed_when: false
-  when: not loki_enabled
+  when: loki_enabled
+
+- name: Install Loki
+  command: >-
+    helm upgrade --install loki grafana/loki
+    --namespace {{ observability_namespace }}
+    --version {{ loki_chart_version }}
+    --values /tmp/loki-values.yaml
+    --wait
+    --timeout 10m
+  changed_when: true
+  when: loki_enabled
+
+- name: Write Promtail values
+  template:
+    src: promtail-values.yaml.j2
+    dest: /tmp/promtail-values.yaml
+    mode: "0644"
+  when: loki_enabled
+
+- name: Install Promtail
+  command: >-
+    helm upgrade --install promtail grafana/promtail
+    --namespace {{ observability_namespace }}
+    --version {{ promtail_chart_version }}
+    --values /tmp/promtail-values.yaml
+    --wait
+    --timeout 10m
+  changed_when: true
+  when: loki_enabled
+
+- name: Write Grafana Loki datasource manifest
+  template:
+    src: grafana-datasource-loki.yaml.j2
+    dest: /tmp/grafana-datasource-loki.yaml
+    mode: "0644"
+  when: loki_enabled
+
+- name: Create Grafana Loki datasource
+  command: kubectl apply -f /tmp/grafana-datasource-loki.yaml
+  changed_when: true
+  when: loki_enabled
 
 - name: Show observability access details
   debug:
@@ -77,4 +137,8 @@
       Grafana (tailnet): kubectl -n {{ observability_namespace }} port-forward svc/kube-prometheus-stack-grafana 3000:80
       Prometheus (tailnet): kubectl -n {{ observability_namespace }} port-forward svc/kube-prometheus-stack-prometheus 9090:9090
       Grafana admin password: {{ grafana_password_effective }}
-      Note: Loki logging disabled (set loki_enabled=true to enable)
+      {% if loki_enabled %}
+      Loki: Enabled - logs available in Grafana
+      {% else %}
+      Loki: Disabled
+      {% endif %}