LimitRange介绍
- LimitRange也是一种资源，在名称空间内有效；限制同一个名称空间下pod容器的申请资源的最大值，最小值
- pod的resources中requests和limits必须在这个范围内，否则pod无法创建。当然pod也可以不使用resources进行创建
- type: 限制对象可以是 ontainer、Pod、PersistentVolumeClaim
应用场景：
-
开发或测试环境中的所有容器设置统一的资源限制时
-
当需要防止某个 Pod 占用过多资源影响其他 Pod 运行时
-
当想要简化资源配置过程，避免每次创建 Pod 时都详细指定资源请求和限制
01 编写limitrange
提示：操作之前确认kube-public名称空间下没有其他相关的资源限制，以避免干扰
1.编写LimitRange资源清单
cat > 01-cpu-memory-min-max.yaml <<EOF
apiVersion: v1
kind: LimitRange
metadata:
name: cpu-memory-min-max
namespace: kube-public
spec:
limits:
# 容器能设置limit的最大值
- max:
cpu: 2
memory: 4Gi
# 容器能设置limit的最小值
min:
cpu: 200m
memory: 100Mi
# 限制的类型是容器
type: Container
EOF
查看资源限制，虽然没有设置默认值。但是自动设置了默认值。
[root@master231~]# kubectl -n kube-public describe limitranges
Name: cpu-memory-min-max
Namespace: kube-public
Type Resource Min Max Default Request Default Limit Max Limit/Request Ratio
---- -------- --- --- --------------- ------------- -----------------------
Container cpu 200m 2 2 2 -
Container memory 100Mi 4Gi 4Gi 4Gi -
2.创建第1个pod。limitrange中限制了CPU的最小值200Mi，pod的CPU资源请求为100Mi，明显低于这个数，因此是不会创建的。
cat > 02-pods.yaml <<EOF
apiVersion: v1
kind: Pod
metadata:
name: pods-nginx
namespace: kube-public
spec:
containers:
- name: web
image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1
resources:
requests:
cpu: 0.1
memory: 1Gi
limits:
cpu: 1
memory: 2Gi
EOF
kubectl apply -f 02-pods.yaml
Error from server (Forbidden): error when creating “02-pods.yaml”: pods “pods-nginx” is forbidden: minimum cpu usage per Container is 200m, but request is 100m
3.继续创建pod，这次在request中限制内存最大使用为5Gi，超过了limitrange中设置的最大值4Gi。因此也不能创建成功
cat > 03-pods.yaml <<EOF
apiVersion: v1
kind: Pod
metadata:
name: pods-nginx-02
namespace: kube-public
spec:
containers:
- name: web
image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1
resources:
requests:
cpu: 0.5
memory: 1Gi
limits:
cpu: 1
memory: 5Gi
EOF
kubectl apply -f 03-pods.yaml
Error from server (Forbidden): error when creating “03-pods.yaml”: pods “pods-nginx-02” is forbidden: maximum memory usage per Container is 4Gi, but limit is 5Gi
4.不设置限制的方式创建pod可以成功
cat > 04-pods.yaml <<EOF
apiVersion: v1
kind: Pod
metadata:
name: pods-nginx-04
namespace: kube-public
spec:
containers:
- name: web
image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1
EOF
[root@master231~]# kubectl -n kube-public get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE
pods-nginx-04 1/1 Running 0 18s 10.100.203.155 worker232
在worker232节点使用docker status命令查看其状态
CONTAINER ID NAME CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS
26de8eac876c k8s_web... 0.00% 8.992MiB / 4GiB 0.22% 0B / 0B 0B / 12.3kB 13
5.这个pod也在范围内，也可以创建成功。
cat > 05-pods.yaml <<EOF
apiVersion: v1
kind: Pod
metadata:
name: pods-nginx-05
namespace: kube-public
spec:
containers:
- name: web
image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1
resources:
requests:
cpu: 0.5
memory: 1Gi
limits:
cpu: 2
memory: 3Gi
EOF
[root@master231~]# kubectl -n kube-public get pods -o wide | grep pods-nginx-05
pods-nginx-05 1/1 Running 0 104s 10.100.140.93 worker233
02 为pod设置request默认值
1.没有设置默认值，自动使用最大值作为默认值。
[root@master231~]# kubectl describe limits -n kube-public
Name: cpu-memory-min-max
Namespace: kube-public
Type Resource Min Max Default Request Default Limit Max Limit/Request Ratio
---- -------- --- --- --------------- ------------- -----------------------
Container cpu 200m 2 2 2 -
Container memory 100Mi 4Gi 4Gi 4Gi -
运行1个资源清单设置默认值
cat > 01-cpu-memory-default.yaml <<EOF
apiVersion: v1
kind: LimitRange
metadata:
name: cpu-memory-min-max-default
namespace: kube-public
spec:
limits:
- max:
cpu: 2
memory: 4Gi
min:
cpu: 200m
memory: 100Mi
type: Container
# 设置默认值的Request
defaultRequest:
cpu: 200m
memory: 500Mi
# 设置默认值的Limit
default:
cpu: 1
memory: 2Gi
EOF
2.查看符合default结果
[root@master231~]# kubectl -n kube-public describe limitranges
Name: cpu-memory-min-max
Namespace: kube-public
Type Resource Min Max Default Request Default Limit Max Limit/Request Ratio
---- -------- --- --- --------------- ------------- -----------------------
Container cpu 200m 2 2 2 -
Container memory 100Mi 4Gi 4Gi 4Gi -
Name: cpu-memory-min-max-default
Namespace: kube-public
Type Resource Min Max Default Request Default Limit Max Limit/Request Ratio
---- -------- --- --- --------------- ------------- -----------------------
Container memory 100Mi 4Gi 500Mi 2Gi -
Container cpu 200m 2 200m 1 -
