具有不同命名空间的HPA

Question

我有一个kubernetes设置，下面是

sn.  type          service  namespace
1.   statefulset   rabbitmq rabbitmq
2.   deployment    pods     default
3.   hpa           hpa      default

度量被导出到'/api/custom.metrics.k8s。Io/v1beta1如下

{
"kind": "APIResourceList",
"apiVersion": "v1",
"groupVersion": "custom.metrics.k8s.io/v1beta1",
"resources": [
{
"name": "services/rabbitmq_queue_messages_ready",
"singularName": "",
"namespaced": true,
"kind": "MetricValueList",
"verbs": [
"get"
]
},
{
"name": "namespaces/rabbitmq_queue_messages_ready",
"singularName": "",
"namespaced": false,
"kind": "MetricValueList",
"verbs": [
"get"
]
},
{
"name": "pods/rabbitmq_queue_messages_ready",
"singularName": "",
"namespaced": true,
"kind": "MetricValueList",
"verbs": [
"get"
]
}
]
}

hpa配置

apiVersion: autoscaling/v2beta2
kind: HorizontalPodAutoscaler
metadata:
name: demo-hpa
namespace: default
spec:
scaleTargetRef:
apiVersion: apps/v1
kind: Deployment
name: test-pod2
minReplicas: 1
maxReplicas: 2
metrics:
- type: Object
object:
metric:
name: "rabbitmq_queue_messages_ready"
describedObject:
apiVersion: custom.metrics.k8s.io/v1/beta1
kind: Service
name: rabbitmq
target:
type: Value
value: 50

每当我尝试在default命名空间中部署hpa时，我都会得到以下错误:

ScalingActive  False   FailedGetObjectMetric  the HPA was unable to compute the replica count: unable to get metric rabbitmq_queue_messages_ready: Service on default rabbitmq/unable to fetch metrics from custom metrics API: the server could not find the metric rabbitmq_queue_messages_ready for services rabbitmq

但是当相同的hpa被设置为名称空间rabbitmq时，使用hpa

apiVersion: autoscaling/v2beta2
kind: HorizontalPodAutoscaler
metadata:
name: demo-hpa
namespace: rabbitmq
spec:
scaleTargetRef:
apiVersion: apps/v1
kind: Deployment
name: test-pod2
minReplicas: 1
maxReplicas: 2
metrics:
- type: Object
object:
metric:
name: "rabbitmq_queue_messages_ready"
describedObject:
apiVersion: custom.metrics.k8s.io/v1/beta1
kind: Service
name: rabbitmq
target:
type: Value
value: 50

和部署。yaml是

apiVersion: apps/v1
kind: Deployment
metadata:
name: test-pod2
labels:
app: test-pod2
namespace: rabbimtq
spec:
replicas: 1
selector:
matchLabels:
app: test-pod2
template:
metadata:
labels:
app: test-pod2
spec:
containers:
- name: test-pod2
image: golang:1.16
command: ["sh", "-c", "tail -f /etc/hosts"]

部署工作完美。

是否有一种方法，我可以从rabbitmq命名空间导出服务rabbitmq的指标到任何其他命名空间然后我可以用它来缩放??

Answer 1

HPA是一个命名空间资源。这意味着它只能扩展与HPA本身在同一名称空间中的部署。这就是为什么只有当HPA和部署都在namespace: rabbitmq中时才有效。您可以在您的集群中检查它，通过运行:

kubectl api-resources --namespaced=true | grep hpa
NAME                        SHORTNAMES   APIGROUP                    NAMESPACED   KIND
horizontalpodautoscalers    hpa          autoscaling                 true         HorizontalPodAutoscaler

使其工作的最简单方法是简单地将HPA的Namespace值设置为您想要扩展的部署名称空间。例如，如果您的部署设置如下:

apiVersion: apps/v1
kind: Deployment
metadata:
namespace: rabbimtq

HPA也必须在同一个命名空间中:

apiVersion: autoscaling/v2beta2
kind: HorizontalPodAutoscaler
metadata:
namespace: rabbitmq

换句话说:将HPA的metadata.namespace值设置为部署的metadata.namespace值，因为HPA无法在其命名空间之外扩展部署。

命名空间就像单独的"在您的集群中。命名空间资源不能在它们所在的命名空间之外工作。他们无法看到不在他们的"框"中的资源。

这样做就不需要重新配置自定义度量。