# 分析
pod
首先，我们先从最小的调度单位pod开始。
我的k8s集群中目前有一个pod，它的name为admin-mysql-1d29997-5db458497c-h6rrs
[[email protected] ~]# kubectl get pod admin-mysql-1d29997-5db458497c-h6rrs
NAME READY STATUS RESTARTS AGE
admin-mysql-1d29997-5db458497c-h6rrs 1/1 Running 0 5d23h查看一下pod的详细内容：
[[email protected] ~]# kubectl describe pod admin-mysql-1d29997-5db458497c-h6rrs
Name: admin-mysql-1d29997-5db458497c-h6rrs
Namespace: default
Priority: 0
PriorityClassName: <none>
Node: k8s-node1/192.168.0.247
Start Time: Fri, 01 Nov 2019 10:57:47 +0800
Labels: name=mysql
pod-template-hash=5db458497c
Annotations: <none>
Status: Running
IP: 10.244.1.72
Controlled By: ReplicaSet/admin-mysql-1d29997-5db458497c
Containers:
mysql57-container:
Container ID: docker://7e68cae8d4e9840ed908965252ae7aff8281ca81954ab0b5d58e053f5371bb5d
Image: mysql57:5.7
Image ID: docker://sha256:f6509bac49801f48628167728aba66d64533aaa7d384e03b75a8fe4e6c0f6599
Port: 3306/TCP
Host Port: 0/TCP
State: Running
Started: Fri, 01 Nov 2019 10:57:48 +0800
Ready: True
Restart Count: 0
Environment:
MYSQL_ROOT_PASSWORD: welcome1
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-9rfpv (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
default-token-9rfpv:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-9rfpv
Optional: false
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events: <none>
[[email protected] ~]# 在这里能看到吗，pod是被一个名字为admin-mysql-1d29997-5db458497c的ReplicaSet管理的，所以我们认为，RS是比Pod高一级别的专门用来管理pod的组件。一个RS会管理一批pod。
Controlled By: ReplicaSet/admin-mysql-1d29997-5db458497c
ReplicateSet(rs)
接下来，我们就看看这个RS的详细情况
[[email protected] ~]# kubectl describe rs admin-mysql-1d29997-5db458497c
Name: admin-mysql-1d29997-5db458497c
Namespace: default
Selector: name=mysql,pod-template-hash=5db458497c
Labels: name=mysql
pod-template-hash=5db458497c
Annotations: deployment.kubernetes.io/desired-replicas: 1
deployment.kubernetes.io/max-replicas: 2
deployment.kubernetes.io/revision: 1
Controlled By: Deployment/admin-mysql-1d29997
Replicas: 1 current / 1 desired
Pods Status: 1 Running / 0 Waiting / 0 Succeeded / 0 Failed
Pod Template:
Labels: name=mysql
pod-template-hash=5db458497c
Containers:
mysql57-container:
Image: mysql57:5.7
Port: 3306/TCP
Host Port: 0/TCP
Environment:
MYSQL_ROOT_PASSWORD: welcome1
Mounts: <none>
Volumes: <none>
Events: <none>
[[email protected] ~]# 抓住关键信息Controlled By: Deployment/admin-mysql-1d29997
这个RS被名字为admin-mysql-1d29997的Deployment控制，这样看，Deployment是比RS高一级别用于管理RS的组件。
在RS级别上发生的事件，均是对pod的操作，创建pod，删除pod
Deployment
接下来，我们来看看Delpoyment
[[email protected] ~]# kubectl describe deploy admin-mysql-1d29997
Name: admin-mysql-1d29997
Namespace: default
CreationTimestamp: Fri, 01 Nov 2019 10:57:46 +0800
Labels: name=mysql
Annotations: deployment.kubernetes.io/revision: 1
Selector: name=mysql
Replicas: 1 desired | 1 updated | 1 total | 1 available | 0 unavailable
StrategyType: RollingUpdate
MinReadySeconds: 0
RollingUpdateStrategy: 25% max unavailable, 25% max surge
Pod Template:
Labels: name=mysql
Containers:
mysql57-container:
Image: mysql57:5.7
Port: 3306/TCP
Host Port: 0/TCP
Environment:
MYSQL_ROOT_PASSWORD: welcome1
Mounts: <none>
Volumes: <none>
Conditions:
Type Status Reason
---- ------ ------
Available True MinimumReplicasAvailable
Progressing True NewReplicaSetAvailable
OldReplicaSets: <none>
NewReplicaSet: admin-mysql-1d29997-5db458497c (1/1 replicas created)
Events: <none>
[[email protected] ~]# 可以看出，在deployment级别上，不再受其他组件的控制，而他的状态的转变是作为API被调用而产生的。我们看到，在deployment级别上发生的事件一般是创建服务、滚动升级一个服务，或者是操作RS伸缩Pod集群。
service
最后，到这里也很明白量，service其实是在这一整套基础之上提供给外部的稳定的服务。
原文地址：https://blog.51cto.com/1345992/2448398
时间： 2024-07-31 10:57:02