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单列唯一约束

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ALTER TABLE `t_user` ADD unique(`username`);

create unique index UserNameIndex on 't_user' ('username');

多列联合唯一约束

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ALTER TABLE table_name ADD UNIQUE KEY(key1, key2);

索引

约束

单列

多列

外键

数字

精度

有无符号

io.netty错误

RocktMQ Version 4.2.0

如果在配合gRPC使用的时候，会出现io.netty库多版本问题，造成部署失败

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<!-- RocketMQ -->
<dependency>
    <groupId>org.apache.rocketmq</groupId>
    <artifactId>rocketmq-common</artifactId>
    <version>4.2.0</version>
    <exclusions>
        <exclusion>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
        </exclusion>
        <exclusion>
            <groupId>io.netty</groupId>
            <artifactId>netty-tcnative</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>org.apache.rocketmq</groupId>
    <artifactId>rocketmq-client</artifactId>
    <version>4.2.0</version>
    <exclusions>
        <exclusion>
            <groupId>io.netty</groupId>
            <artifactId>netty-all</artifactId>
        </exclusion>
        <exclusion>
            <groupId>io.netty</groupId>
            <artifactId>netty-tcnative</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>io.netty</groupId>
    <artifactId>netty-tcnative</artifactId>
    <version>1.1.33.Fork22</version>
</dependency>

found a illegal magic code 0x6d626f6c / found a illegal magic code 0x30317d0b

RemotingTooMuchRequestException: sendDefaultImpl call timeout

原因：服务器存在多网卡

解决：在broker的配置文件中指定brokerIP参数的ip地址即可

org.apache.rocketmq.remoting.exception.RemotingTimeoutException: wait response on the channel <:10909> timeout

https://github.com/apache/rocketmq/issues/428

获取Nginx转发请求的Client IP

1. Nginx配置转发

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proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

2. Zuul获取Real IP

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val split = request.getHeader("X-Forwarded-For").split(",")
val realIP = split[0]
val dockerIP = split[1]

获取非转发情况下的Client IP

1. REMOTE_ADDR - This contains the real IP address of the client. That is the most reliable value you can find from the user.

2. REMOTE_HOST - This will fetch the Host name from which the user is viewing the current page. But for this script to work, Hostname Lookups On inside httpd.conf must be configured.

注意

spring-cloud-starter-zuul本身已经集成了hystrix和ribbon，所以Zuul天生就拥有线程隔离和断路器的自我保护能力，以及对服务调用的客户端负载均衡功能。

但是，我们需要注意，当使用path与url的映射关系来配置路由规则时，对于路由转发的请求则不会采用HystrixCommand来包装，所以这类路由请求就没有线程隔离和断路器保护功能，并且也不会有负载均衡的能力。因此，我们在使用Zuul的时候尽量使用path和serviceId的组合进行配置，这样不仅可以保证API网关的健壮和稳定，也能用到Ribbon的客户端负载均衡功能。

查看服务器信息

info

查看键值

查看所有健值

查询所有的键，会遍历所有的键值，复杂度O(n)

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keys *

键总数

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dbsize

检查键

exists key 存在返回1，不存在返回0

key操作

获取键

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get key

查看过期

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pttl key

参考链接

https://segmentfault.com/a/1190000010999677

Depoloy

Zone

1. 1 node(s) had volume node affinity conflict

The error “volume node affinity conflict” happens when the persistent volume claims that the pod is using are scheduled on different zones, rather than on one zone, and so the actual pod was not able to be scheduled because it cannot connect to the volume from another zone.

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kind: StorageClass
apiVersion: storage.k8s.io/v1beta1
metadata:
  name: pd-standard
provisioner: kubernetes.io/gce-pd
reclaimPolicy: Retain
parameters:
  type: pd-standard
volumeBindingMode: WaitForFirstConsumer
allowedTopologies:
  - matchLabelExpressions:
      - key: failure-domain.beta.kubernetes.io/zone
        values:
          - asia-east2-b

Mongo

1. 部署集群时候出错:’pods is forbidden: User “system:serviceaccount:default:default” cannot list pods at the cluster scope: Unknown user “system:serviceaccount:default:default”‘

由于Container Engine在创建角色或ClusterRole时检查权限的方式，因此必须先创建一个RoleBinding，以授予您要创建的角色中包含的所有权限。

• 查看当前所使用的账户

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gcloud info | grep Account

• 赋予上面账户管理员权限

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kubectl create clusterrolebinding myname-cluster-admin-binding \
  --clusterrole=cluster-admin \
  --user=myname@example.org

• 创建应用部署权限账号

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apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:
  name: mongo-role
rules:
- apiGroups: [""]
  resources: ["pods"]
  verbs: ["list"]
- nonResourceURLs: ["/metrics"]
  verbs: ["get"]
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: mongo-account
  namespace: default

---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: mongo-role-binding
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: mongo-role
subjects:
- kind: ServiceAccount
  name: mongo-account
  namespace: default

• 部署应用增加权限

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apiVersion: apps/v1beta1
kind: StatefulSet
metadata:
  name: mongo-deployment
spec:
  serviceName: "mongo-headless-service"
  replicas: 3
  template:
    metadata:
      labels:
        app: mongo
    spec:
      serviceAccountName: mongo-account

PV,PVC

AttachVolume.Attach failed for volume

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AttachVolume.Attach failed for volume "pvc-9f48652a-e478-4f91-8fc8-42b27587338d" : failed to attach e7246a1a-3def-4e33-97d1-b26ff3b66ade volume to 9e202548-f70f-4422-b870-2c9629f718b0 compute: Expected HTTP response code [200] when accessing [POST https://compute.bhs5.cloud.ovh.net/v2.1/9132a2edd6544bd794768a0286a9a24a/servers/9e202548-f70f-4422-b870-2c9629f718b0/os-volume_attachments], but got 409 instead {"conflictingRequest": {"message": "Cannot 'attach_volume' instance 9e202548-f70f-4422-b870-2c9629f718b0 while it is in task_state migrating", "code": 409}}

PV PVC

PV访问模式

• ReadWriteOnce：是最基本的方式，可读可写，但只支持被单个Pod挂载。

• ReadOnlyMany：可以以只读的方式被多个Pod挂载。

• ReadWriteMany：这种存储可以以读写的方式被多个Pod共享。

Memory

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spec:
  volumes:
  - name: dshm
    emptyDir:
      medium: Memory
  containers:
  - image: gcr.io/project/image
    volumeMounts:
      - mountPath: /dev/shm
        name: dshm

StorageClass

优势

1. 减轻用户对于存储资源细节的关注

2. 减轻管理员手工管理PV的工作，由系统完成PV的创建和绑定，实现动态的资源供应

注意

1. StorageClass 一旦被创建出来，将无法修改。只能删除后，重新创建。

使用举例

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kind: StorageClass
apiVersion: storage.k8s.io/v1beta1
metadata:
  name: pd-standard
provisioner: kubernetes.io/gce-pd
reclaimPolicy: Retain
parameters:
  type: pd-standard

策略类型：

• Retain 手动重新使用

• Recycle 基本的数据擦除 (“rm -rf /thevolume/*”)

GKE

https://cloud.google.com/compute/docs/load-balancing/http/#fundamentals

https://cloud.google.com/vpc/docs/firewalls#ingress_cases

https://cloud.google.com/vpc/docs/vpc-peering

Proxy

https://cloud.google.com/vpc/docs/special-configurations

查看本机IP

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ip addr show