braintrustdata · Erik Weathers (erikdw) · Aug 17, 2026
diff --git a/braintrust/README.md b/braintrust/README.md
@@ -243,9 +243,9 @@ api:
 
 When enabled for a pool, that pool's `replicas` setting is ignored and the HPA controls the replica count. With `api.workloadIsolation.enabled`, ingest and background pools inherit these settings and can override `minReplicas` / `maxReplicas` under `api.workloadIsolation.<pool>.autoscaling`.
 
-## EKS API Autoscaling
+## EKS / AKS API Autoscaling
 
-On AWS (`cloud: aws`), the same `api.autoscaling` values deploy an in-chart Prometheus scrape of each API pool's health `/metrics` endpoint and a prometheus-adapter that exposes event-loop gauges to HPA via `custom.metrics.k8s.io`. Targets match GKE / ECS defaults (CPU 50% on the `api` container, event-loop utilization `0.4`, delay mean `0.05s`).
+On AWS (`cloud: aws`) or Azure (`cloud: azure`), the same `api.autoscaling` values deploy an in-chart Prometheus scrape of each API pool's health `/metrics` endpoint and a prometheus-adapter that exposes event-loop gauges to HPA via `custom.metrics.k8s.io`. Targets match GKE / ECS defaults (CPU 50% on the `api` container, event-loop utilization `0.4`, delay mean `0.05s`).
 
 Requires API image **v2.9.0+**. With workload isolation enabled, Prometheus scrapes every pool (`api.name`, ingest, and background).
 

diff --git a/braintrust/templates/_helpers.tpl b/braintrust/templates/_helpers.tpl
@@ -125,8 +125,8 @@ EKS uses in-chart Prometheus + prometheus-adapter (no GKE CRD).
 {{- if not (.Capabilities.APIVersions.Has "autoscaling.gke.io/v1beta1") }}
 {{- fail "api.autoscaling requires the AutoscalingMetric API (autoscaling.gke.io/v1beta1). Use GKE 1.35.1 or later, or verify with: kubectl api-resources | grep autoscalingmetric. For helm template without a cluster, pass --api-versions=autoscaling.gke.io/v1beta1." }}
 {{- end }}
-{{- else if ne .Values.cloud "aws" }}
-{{- fail "api.autoscaling is currently only supported when cloud is google (GKE) or aws (EKS)" }}
+{{- else if and (ne .Values.cloud "aws") (ne .Values.cloud "azure") }}
+{{- fail "api.autoscaling is currently only supported when cloud is google (GKE), aws (EKS), or azure (AKS)" }}
 {{- end }}
 {{- end -}}
 

diff --git a/braintrust/templates/api-autoscaling-prometheus-adapter.yaml b/braintrust/templates/api-autoscaling-prometheus-adapter.yaml
@@ -1,4 +1,4 @@
-{{- if and .Values.api.autoscaling.enabled (eq .Values.cloud "aws") }}
+{{- if and .Values.api.autoscaling.enabled (or (eq .Values.cloud "aws") (eq .Values.cloud "azure")) }}
 apiVersion: v1
 kind: ServiceAccount
 metadata:

diff --git a/braintrust/templates/api-autoscaling-prometheus.yaml b/braintrust/templates/api-autoscaling-prometheus.yaml
@@ -1,4 +1,4 @@
-{{- if and .Values.api.autoscaling.enabled (eq .Values.cloud "aws") }}
+{{- if and .Values.api.autoscaling.enabled (or (eq .Values.cloud "aws") (eq .Values.cloud "azure")) }}
 {{- $scrapeApps := list .Values.api.name -}}
 {{- if .Values.api.workloadIsolation.enabled -}}
 {{- $scrapeApps = append $scrapeApps .Values.api.workloadIsolation.ingest.name -}}

diff --git a/braintrust/templates/api-hpa.yaml b/braintrust/templates/api-hpa.yaml
@@ -62,7 +62,7 @@ spec:
         target:
           type: AverageValue
           averageValue: {{ $api.autoscaling.eventLoopDelayMean.targetAverageValue | quote }}
-    {{- else if eq $root.Values.cloud "aws" }}
+    {{- else if or (eq $root.Values.cloud "aws") (eq $root.Values.cloud "azure") }}
     - type: Pods
       pods:
         metric:

diff --git a/braintrust/tests/api-autoscaling_test.yaml b/braintrust/tests/api-autoscaling_test.yaml
@@ -40,14 +40,14 @@ tests:
     template: api-hpa.yaml
     values:
       - __fixtures__/base-values.yaml
-      - __fixtures__/azure-values.yaml
     set:
+      cloud: unsupported
       api.autoscaling.enabled: true
     release:
       namespace: "braintrust"
     asserts:
       - failedTemplate:
-          errorMessage: "api.autoscaling is currently only supported when cloud is google (GKE) or aws (EKS)"
+          errorMessage: "api.autoscaling is currently only supported when cloud is google (GKE), aws (EKS), or azure (AKS)"
 
   - it: should render AutoscalingMetric for GKE with event-loop gauges
     template: api-autoscaling-metric.yaml
@@ -572,3 +572,87 @@ tests:
       - matchRegex:
           path: data["config.yaml"]
           pattern: "braintrust_api_event_loop_utilization_ratio"
+
+  - it: should not render GKE AutoscalingMetric on Azure
+    template: api-autoscaling-metric.yaml
+    values:
+      - __fixtures__/base-values.yaml
+      - __fixtures__/azure-values.yaml
+    set:
+      api.autoscaling.enabled: true
+    release:
+      namespace: "braintrust"
+    asserts:
+      - hasDocuments:
+          count: 0
+
+  - it: should render HPA on Azure with prometheus-adapter metric names
+    template: api-hpa.yaml
+    values:
+      - __fixtures__/base-values.yaml
+      - __fixtures__/azure-values.yaml
+    set:
+      api.autoscaling.enabled: true
+    release:
+      namespace: "braintrust"
+    asserts:
+      - isKind:
+          of: HorizontalPodAutoscaler
+      - equal:
+          path: spec.metrics[0].type
+          value: ContainerResource
+      - equal:
+          path: spec.metrics[0].containerResource.container
+          value: api
+      - equal:
+          path: spec.metrics[1].pods.metric.name
+          value: event_loop_utilization_ratio
+      - equal:
+          path: spec.metrics[1].pods.target.averageValue
+          value: "0.4"
+      - equal:
+          path: spec.metrics[2].pods.metric.name
+          value: event_loop_delay_mean_seconds
+      - equal:
+          path: spec.metrics[2].pods.target.averageValue
+          value: "0.05"
+
+  - it: should scrape health server metrics on Azure Prometheus
+    template: api-autoscaling-prometheus.yaml
+    documentSelector:
+      path: kind
+      value: ConfigMap
+    values:
+      - __fixtures__/base-values.yaml
+      - __fixtures__/azure-values.yaml
+    set:
+      api.autoscaling.enabled: true
+    release:
+      namespace: "braintrust"
+    asserts:
+      - matchRegex:
+          path: data["prometheus.yml"]
+          pattern: ":8001"
+      - matchRegex:
+          path: data["prometheus.yml"]
+          pattern: "metrics_path: /metrics"
+
+  - it: should render prometheus-adapter rules for event-loop gauges on Azure
+    template: api-autoscaling-prometheus-adapter.yaml
+    documentSelector:
+      path: kind
+      value: ConfigMap
+    values:
+      - __fixtures__/base-values.yaml
+      - __fixtures__/azure-values.yaml
+    set:
+      api.autoscaling.enabled: true
+    release:
+      namespace: "braintrust"
+    asserts:
+      - matchRegex:
+          path: data["config.yaml"]
+          pattern: "braintrust_api_event_loop_delay_mean_seconds"
+      - matchRegex:
+          path: data["config.yaml"]
+          pattern: "braintrust_api_event_loop_utilization_ratio"
diff --git a/braintrust/values.yaml b/braintrust/values.yaml
@@ -125,8 +125,8 @@ api:
   # - the Autoscaling API in the service perimeter when using VPC Service Controls
   # Helm install/upgrade fails if autoscaling.gke.io/v1beta1 is not on the cluster.
   # See: https://docs.cloud.google.com/kubernetes-engine/docs/how-to/expose-custom-metrics-autoscaling
-  # cloud=aws (EKS): in-chart Prometheus + prometheus-adapter + HPA (custom.metrics).
-  # When enabled for a pool, that pool's replicas setting is ignored.
+  # cloud=aws|azure (EKS/AKS): in-chart Prometheus + prometheus-adapter + HPA
+  # (custom.metrics). When enabled for a pool, that pool's replicas setting is ignored.
   autoscaling:
     enabled: false
     minReplicas: 4
@@ -147,7 +147,7 @@ api:
         stabilizationWindowSeconds: 300
       scaleUp:
         stabilizationWindowSeconds: 60
-    # Used when cloud=aws (Prometheus + prometheus-adapter).
+    # Used when cloud=aws or cloud=azure (Prometheus + prometheus-adapter).
     prometheus:
       image:
         repository: prom/prometheus