feat(helm): compose DATABASE_URL_READ_REPLICA from a reader host secret key (#37109)

* feat(helm): compose DATABASE_URL_READ_REPLICA from a reader host secret key

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* test(helm): cover reader host composition and readReplicaUrlKey precedence

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* fix(helm): suppress unused reader host env when readReplicaUrlKey is set

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

* fix(helm): emit reader host only when readReplicaUrl composition is active

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

---------

Co-authored-by: milan <milan@berri.ai>
Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: Yassin Kortam <yassin@berri.ai>

helm/litellm-helm/templates/deployment.yaml

@@ -100,6 +100,13 @@ spec:
             - name: DATABASE_URL
               value: {{ .Values.db.url | quote }}
             {{- end }}
+            {{- if and .Values.db.useExisting .Values.db.readReplicaUrl .Values.db.secret.readReplicaEndpointKey (not .Values.db.secret.readReplicaUrlKey) }}
+            - name: DATABASE_READER_HOST
+              valueFrom:
+                secretKeyRef:
+                  name: {{ .Values.db.secret.name }}
+                  key: {{ .Values.db.secret.readReplicaEndpointKey }}
+            {{- end }}
             {{- if and .Values.db.useExisting .Values.db.secret.readReplicaUrlKey }}
             - name: DATABASE_URL_READ_REPLICA
               valueFrom:

helm/litellm-helm/tests/deployment_tests.yaml

@@ -80,6 +80,96 @@ tests:
               secretKeyRef:
                 name: my-secret
                 key: my-key
+  - it: should inject DATABASE_READER_HOST from readReplicaEndpointKey before DATABASE_URL_READ_REPLICA
+    template: deployment.yaml
+    set:
+      db:
+        deployStandalone: false
+        useExisting: true
+        secret:
+          name: postgres
+          usernameKey: username
+          passwordKey: password
+          readReplicaEndpointKey: reader-host
+        readReplicaUrl: postgresql://$(DATABASE_USERNAME):$(DATABASE_PASSWORD)@$(DATABASE_READER_HOST):5432/$(DATABASE_NAME)?sslmode=require
+    asserts:
+      - contains:
+          path: spec.template.spec.containers[0].env
+          content:
+            name: DATABASE_READER_HOST
+            valueFrom:
+              secretKeyRef:
+                name: postgres
+                key: reader-host
+      - contains:
+          path: spec.template.spec.containers[0].env
+          content:
+            name: DATABASE_URL_READ_REPLICA
+            value: postgresql://$(DATABASE_USERNAME):$(DATABASE_PASSWORD)@$(DATABASE_READER_HOST):5432/$(DATABASE_NAME)?sslmode=require
+      # $(VAR) interpolation only resolves vars defined EARLIER in the env
+      # array, so the reader host must precede the composed URL
+      - equal:
+          path: spec.template.spec.containers[0].env[7].name
+          value: DATABASE_READER_HOST
+      - equal:
+          path: spec.template.spec.containers[0].env[8].name
+          value: DATABASE_URL_READ_REPLICA
+  - it: should omit reader host when readReplicaUrl is unset
+    template: deployment.yaml
+    set:
+      db:
+        deployStandalone: false
+        useExisting: true
+        secret:
+          name: postgres
+          usernameKey: username
+          passwordKey: password
+          readReplicaEndpointKey: reader-host
+    asserts:
+      - notContains:
+          path: spec.template.spec.containers[0].env
+          content:
+            name: DATABASE_READER_HOST
+            valueFrom:
+              secretKeyRef:
+                name: postgres
+                key: reader-host
+  - it: should prefer readReplicaUrlKey over readReplicaEndpointKey composition
+    template: deployment.yaml
+    set:
+      db:
+        useExisting: true
+        secret:
+          name: postgres
+          usernameKey: username
+          passwordKey: password
+          readReplicaUrlKey: reader-url
+          readReplicaEndpointKey: reader-host
+        readReplicaUrl: postgresql://ignored
+    asserts:
+      - contains:
+          path: spec.template.spec.containers[0].env
+          content:
+            name: DATABASE_URL_READ_REPLICA
+            valueFrom:
+              secretKeyRef:
+                name: postgres
+                key: reader-url
+      - notContains:
+          path: spec.template.spec.containers[0].env
+          content:
+            name: DATABASE_URL_READ_REPLICA
+            value: postgresql://ignored
+      # the unused reader-host secret ref must be suppressed so a missing
+      # key can't fail pod creation
+      - notContains:
+          path: spec.template.spec.containers[0].env
+          content:
+            name: DATABASE_READER_HOST
+            valueFrom:
+              secretKeyRef:
+                name: postgres
+                key: reader-host
   - it: should work with extraEnvVars
     template: deployment.yaml
     set:

helm/litellm-helm/values.yaml

@@ -277,6 +277,14 @@ db:
     # written to db.readReplicaUrl ends up visible in the rendered pod spec
     # and the Helm release secret.
     readReplicaUrlKey: ""
+    # Optional: when set, a DATABASE_READER_HOST env var is sourced from this
+    # secret key, so db.readReplicaUrl can compose the reader URL from
+    # individual secret components, e.g.
+    # postgresql://$(DATABASE_USERNAME):$(DATABASE_PASSWORD)@$(DATABASE_READER_HOST):5432/$(DATABASE_NAME)
+    # Use this when your secret store holds the bare reader hostname rather
+    # than a full connection URL. Only takes effect when readReplicaUrl is
+    # set; ignored when readReplicaUrlKey is set.
+    readReplicaEndpointKey: ""
 
   # Optional read-replica routing. When set, the proxy sends read-only
   # queries (find_*, count, group_by, query_raw/_first) to this URL while