Add Langfuse as a self-hosted eval and trace viewer

infra/argocd/applications/langfuse.yaml

@@ -0,0 +1,48 @@
+# Langfuse (LLM observability / eval viewer) — reads OTel-style traces and
+# Ragas eval scores, not part of the RAG chat path itself.
+#
+# Multi-source Application: source[0] is the upstream `langfuse/langfuse-k8s`
+# chart (not vendored into this repo); source[1] is this repo, providing only
+# the override values file via the `$values` ref. Same disaster-recovery
+# property as the other two Applications here: applying this file recreates
+# the Application's structure, no follow-up step needed since this release
+# carries no inline secrets (see infra/helm/langfuse/values-production.yaml
+# for why: the app's own SALT/ENCRYPTION_KEY/NEXTAUTH_SECRET are chart-
+# auto-generated on first install, and the Postgres password is read from
+# the medical-chatbot-data release's existing Secret by name, never
+# duplicated here).
+#
+# Deliberately targets the `medical-chatbot-data` namespace, not its own —
+# see the values file's header comment for why (Secrets don't cross
+# namespaces, and this needs the Postgres one that already lives there).
+# This Application does NOT own the PersistentVolumeClaims that release
+# depends on (postgres/qdrant) — it only adds new resources (its own
+# ClickHouse/Redis/web/worker) into the same namespace. `prune: true` below
+# only prunes resources Langfuse's own chart previously created, standard
+# ArgoCD behavior scoped to this Application's own tracked resources.
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: langfuse
+  namespace: argocd
+spec:
+  project: default
+  sources:
+    - repoURL: https://langfuse.github.io/langfuse-k8s
+      chart: langfuse
+      targetRevision: 2.0.0
+      helm:
+        valueFiles:
+          - $values/infra/helm/langfuse/values-production.yaml
+    - repoURL: https://github.com/BaoVu2k4/vsf-duocthu.git
+      targetRevision: master
+      ref: values
+  destination:
+    server: https://kubernetes.default.svc
+    namespace: medical-chatbot-data
+  syncPolicy:
+    automated:
+      prune: true
+      selfHeal: true
+    syncOptions:
+      - CreateNamespace=true