diff --git a/install/maintain/certs.md b/install/maintain/certs.md
index 964cf9d..f18b7f7 100644
--- a/install/maintain/certs.md
+++ b/install/maintain/certs.md
@@ -9,4 +9,16 @@ meta:
 
 <AdSenseTitle/>
 
-正在撰写...
+> 参考文档： [Certificate Management with kubeadm](https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-certs/)
+
+**FEATURE STATE:** Kubernetes v1.15 \[stable\]
+
+通过 kubeadm 安装集群时，所生成的客户端证书的有效期为一年。本文讲述了如何使用 kubeadm 更新证书（只适用于通过 kubeadm 安装的集群，如果使用其他方式或工具安装的集群，请参考对应工具的文档）。
+
+
+... 正在更新
+
+
+::: tip
+apiserver 访问 kubelet 时，并不校验 kubelet 的服务端证书，kubeadm 也并不提供更新 kubelet 服务端证书的办法。
+:::
diff --git a/install/maintain/pki.md b/install/maintain/pki.md
new file mode 100644
index 0000000..889f810
--- /dev/null
+++ b/install/maintain/pki.md
@@ -0,0 +1,276 @@
+---
+layout: LearningLayout
+description: Kubernete教程_Kubernetes组件_PKI 证书和要求
+meta:
+  - name: keywords
+    content: Kubernetes 教程,Kubernetes 组件,PKI 证书和要求
+---
+
+# Kubernetes PKI 证书和要求
+
+> 以下内容翻译自自 [PKI certificates and requirements](https://kubernetes.io/docs/setup/best-practices/certificates/)。
+
+Kubernetes 需要 PKI 证书才能进行基于 TLS 的身份验证。当您使用
+[kubeadm](/install/install-k8s.html) 安装的 Kubernetes 集群时，kubeadm 将自动生成集群所需的证书。
+此外，您也可以使用自己手动生成的证书，这种情况下，您可以将私钥不存储在 API 服务器上，以便让私钥更加安全。此页面说明了 Kubernetes 集群所必需的证书。
+
+
+
+<!-- body -->
+
+<!--
+## How certificates are used by your cluster
+
+Kubernetes requires PKI for the following operations:
+-->
+## 集群是如何使用证书的
+
+Kubernetes 需要以下 PKI 才能执行对应的操作：
+
+<!--
+* Client certificates for the kubelet to authenticate to the API server
+* Server certificate for the API server endpoint
+* Client certificates for administrators of the cluster to authenticate to the API server
+* Client certificates for the API server to talk to the kubelets
+* Client certificate for the API server to talk to etcd
+* Client certificate/kubeconfig for the controller manager to talk to the API server
+* Client certificate/kubeconfig for the scheduler to talk to the API server.
+* Client and server certificates for the [front-proxy](/docs/tasks/extend-kubernetes/configure-aggregation-layer/)
+-->
+* Kubelet 访问 Apiserver 的客户端证书，用来执行身份认证
+* Apiserver 的服务端证书
+* 集群管理员访问 apiserver 的客户端证书，当集群管理员使用 kubectl 访问 apiserver 时，用来执行身份认证
+* Apiserver 访问 kubelet 的客户端证书，用于 Apiserver 向 kubelet 发起的会话
+* Apiserver 访问 etcd 的客户度证书，用于 apiserver 访问 etcd 时的会话
+* Kube-controller 访问 apiserver 的客户端证书（存储在对应的 kubeconfig 文件中），当 kube-controller 访问 apiserver 时，用作身份认证
+* Kube-scheduler 访问 apiserver 的客户端证书（存储在对应的 kubeconfig 文件中），当 kube-scheduler 访问 apiserver 时，用作身份认证
+* [前端代理](/docs/tasks/extend-kubernetes/configure-aggregation-layer/) 的客户端及服务端证书
+
+<!--
+`front-proxy` certificates are required only if you run kube-proxy to support [an extension API server](/docs/tasks/access-kubernetes-api/setup-extension-api-server/).
+-->
+::: tip
+通常，只有第三方发行版才需要 [扩展 API 服务器](/learning/k8s-advanced/extend/aggregation.html) 时，才需要用到 `front-proxy` 证书，原生 kubernetes 集群并不需要 `front-proxy` 证书。
+:::
+
+<!--
+etcd also implements mutual TLS to authenticate clients and peers.
+-->
+etcd 还需要通过双向 TLS 来对客户端和对其他对等节点进行身份验证。
+
+<!--
+## Where certificates are stored
+
+If you install Kubernetes with kubeadm, certificates are stored in `/etc/kubernetes/pki`. All paths in this documentation are relative to that directory.
+-->
+## 证书的存放位置
+
+如果你的 Kubernetes 集群是通过 kubeadm 安装的，则所有证书都存放在 `/etc/kubernetes/pki` 目录下。本文所有相关的路径都是基于该路径的相对路径。
+
+<!--
+## Configure certificates manually
+
+If you don't want kubeadm to generate the required certificates, you can create them in either of the following ways.
+-->
+## 手动配置证书
+
+如果你不想通过 kubeadm 生成所需要的证书，你可以通过下面两种方式的任何一种来手动创建所需要的证书。
+
+<!--
+### Single root CA
+
+You can create a single root CA, controlled by an administrator. This root CA can then create multiple intermediate CAs, and delegate all further creation to Kubernetes itself.
+-->
+### 单根 CA
+
+集群管理员创建一个单根 CA，并由该 root CA 可以创建多个中间 CA，并由 Kubernetes 进一步创建其他所需的证书。
+
+<!--
+Required CAs:
+
+| 路径                    | 默认 CN                    | 描述                             |
+|------------------------|---------------------------|----------------------------------|
+| ca.crt,key             | kubernetes-ca             | Kubernetes general CA            |
+| etcd/ca.crt,key        | etcd-ca                   | For all etcd-related functions   |
+| front-proxy-ca.crt,key | kubernetes-front-proxy-ca | For the [front-end proxy](/docs/tasks/extend-kubernetes/configure-aggregation-layer/) |
+
+On top of the above CAs, it is also necessary to get a public/private key pair for service account management, `sa.key` and `sa.pub`.
+-->
+需要的 CA 如下列表所示：
+
+> 以下路径均相对于目录 `/etc/kubernetes/pki`
+
+| 路径                    | 默认 CN                    | 描述                             |
+|------------------------|---------------------------|----------------------------------|
+| ca.crt,ca.key                  | kubernetes-ca             | Kubernetes root CA                |
+| etcd/ca.crt,etcd/ca.key        | etcd-ca                   | 与 etcd 相关的所有功能              |
+| front-proxy-ca.crt,front-proxy-ca.key | kubernetes-front-proxy-ca | 用于 [扩展 API 服务器](/learning/k8s-advanced/extend/aggregation.html) |
+
+除了以上的 CA 之外，还需要提供用于服务账户管理的密钥对， `sa.key` 和 `sa.pub`。
+
+<!--
+### All certificates
+
+If you don't wish to copy the CA private keys to your cluster, you can generate all certificates yourself.
+
+Required certificates:
+-->
+### 所有的证书
+
+如果你不想将 CA 的私钥拷贝至你的集群中，你也可以自己生成全部的证书。
+
+所需的证书如下列表所示：
+
+> 以下路径均相对于目录 `/etc/kubernetes/pki`
+
+| 默认 CN                    | 父级 CA                 | O (位于 Subject 中) | 类型                                   | 主机 (SAN)                                 |
+|-------------------------------|---------------------------|----------------|----------------------------------------|---------------------------------------------|
+| kube-etcd                     | etcd-ca                   |                | server, client                         | `localhost`, `127.0.0.1`                        |
+| kube-etcd-peer                | etcd-ca                   |                | server, client                         | `<hostname>`, `<Host_IP>`, `localhost`, `127.0.0.1` |
+| kube-etcd-healthcheck-client  | etcd-ca                   |                | client                                 |                                             |
+| kube-apiserver-etcd-client    | etcd-ca                   | system:masters | client                                 |                                             |
+| kube-apiserver                | kubernetes-ca             |                | server                                 | `<hostname>`, `<Host_IP>`, `<advertise_IP>`, `其他 IP 或 DNS 名称 [1]` |
+| kube-apiserver-kubelet-client | kubernetes-ca             | system:masters | client                                 |                                             |
+| front-proxy-client            | kubernetes-front-proxy-ca |                | client                                 |                                             |
+
+<!--
+[1]: any other IP or DNS name you contact your cluster on (as used by [kubeadm](/docs/reference/setup-tools/kubeadm/kubeadm/) the load balancer stable IP and/or DNS name, `kubernetes`, `kubernetes.default`, `kubernetes.default.svc`,
+`kubernetes.default.svc.cluster`, `kubernetes.default.svc.cluster.local`)
+
+where `kind` maps to one or more of the [x509 key usage](https://godoc.org/k8s.io/api/certificates/v1beta1#KeyUsage) types:
+-->
+[1]: 访问集群时，可能用到的其他 IP 或 DNS 名称
+（例如，为 kube-apiserver 配置的负载均衡所使用的固定 IP 或 DNS 名，`kubernetes`、`kubernetes.default`、`kubernetes.default.svc`、`kubernetes.default.svc.cluster`、`kubernetes.default.svc.cluster.local`）。
+
+其中，`kind` 对应一种或多种类型的 [x509 密钥用途](https://godoc.org/k8s.io/api/certificates/v1beta1#KeyUsage)：
+
+<!--
+| kind   | Key usage                                                                       |
+|--------|---------------------------------------------------------------------------------|
+| server | digital signature, key encipherment, server auth                                |
+| client | digital signature, key encipherment, client auth                                |
+-->
+| kind   | 密钥用途                                                                         |
+|--------|---------------------------------------------------------------------------------|
+| server | 数字签名、密钥加密、服务端认证                                                       |
+| client | 数字签名、密钥加密、客户端认证                                                       |
+
+
+
+<!--
+Hosts/SAN listed above are the recommended ones for getting a working cluster; if required by a specific setup, it is possible to add additional SANs on all the server certificates.
+-->
+::: tip
+上面列出的 Hosts/SAN 是推荐的配置方式；如果需要特殊安装，则可以在所有服务器证书上添加其他 SAN。
+:::
+
+<!--
+For kubeadm users only:
+
+* The scenario where you are copying to your cluster CA certificates without private keys is referred as external CA in the kubeadm documentation.
+* If you are comparing the above list with a kubeadm generated PKI, please be aware that `kube-etcd`, `kube-etcd-peer` and `kube-etcd-healthcheck-client` certificates
+  are not generated in case of external etcd.
+-->
+::: tip
+
+如果使用 kubeadm 安装集群：
+
+* 安装集群时可以仅将证书的公钥复制到集群，而将集群的私钥由管理员另外保管，这种仅提供公钥的方案被称为外部 CA。
+* 如果对比以上列表与 kubeadm 生成的 PKI，将会发现，如果使用外部 etcd，则不会生成 `kube-etcd`、`kube-etcd-peer` 和 `kube-etcd-healthcheck-client` 证书。
+
+:::
+
+<!--
+### Certificate paths
+
+Certificates should be placed in a recommended path (as used by [kubeadm](/docs/reference/setup-tools/kubeadm/kubeadm/)). Paths should be specified using the given argument regardless of location.
+-->
+### 证书路径
+
+下表罗列了证书存放的推荐路径（以便 [kubeadm](/docs/reference/setup-tools/kubeadm/kubeadm/) 使用），同时也罗列了通过什么参数可以自定义证书的存放路径。
+
+| 默认 CN                   | 建议的密钥路径         | 建议的证书路径       | 命令        | 密钥参数               | 证书参数                             |
+|------------------------------|------------------------------|-----------------------------|----------------|------------------------------|-------------------------------------------|
+| etcd-ca                      |     etcd/ca.key                         | etcd/ca.crt                 | kube-apiserver |                              | --etcd-cafile                             |
+| kube-apiserver-etcd-client   | apiserver-etcd-client.key    | apiserver-etcd-client.crt   | kube-apiserver | --etcd-keyfile               | --etcd-certfile                           |
+| kubernetes-ca                |    ca.key                          | ca.crt                      | kube-apiserver |                              | --client-ca-file                          |
+| kubernetes-ca                |    ca.key                          | ca.crt                      | kube-controller-manager | --cluster-signing-key-file      | --client-ca-file, --root-ca-file, --cluster-signing-cert-file  |
+| kube-apiserver               | apiserver.key                | apiserver.crt               | kube-apiserver | --tls-private-key-file       | --tls-cert-file                           |
+| kube-apiserver-kubelet-client|     apiserver-kubelet-client.key                         | apiserver-kubelet-client.crt| kube-apiserver | --kubelet-client-key | --kubelet-client-certificate              |
+| front-proxy-ca               |     front-proxy-ca.key                         | front-proxy-ca.crt          | kube-apiserver |                              | --requestheader-client-ca-file            |
+| front-proxy-ca               |     front-proxy-ca.key                         | front-proxy-ca.crt          | kube-controller-manager |                              | --requestheader-client-ca-file |
+| front-proxy-client           | front-proxy-client.key       | front-proxy-client.crt      | kube-apiserver | --proxy-client-key-file      | --proxy-client-cert-file                  |
+| etcd-ca                      |         etcd/ca.key                     | etcd/ca.crt                 | etcd           |                              | --trusted-ca-file, --peer-trusted-ca-file |
+| kube-etcd                    | etcd/server.key              | etcd/server.crt             | etcd           | --key-file                   | --cert-file                               |
+| kube-etcd-peer               | etcd/peer.key                | etcd/peer.crt               | etcd           | --peer-key-file              | --peer-cert-file                          |
+| etcd-ca                      |                              | etcd/ca.crt                 | etcdctl    |                              | --cacert                                  |
+| kube-etcd-healthcheck-client | etcd/healthcheck-client.key  | etcd/healthcheck-client.crt | etcdctl     | --key                        | --cert                                    |
+
+<!--
+Same considerations apply for the service account key pair:
+-->
+下表罗列了 service account 的密钥对存放路径和自定义路径参数：
+
+| 私钥路径            | 公钥路径            | 命令                 | 参数                             |
+|------------------------------|-----------------------------|-------------------------|--------------------------------------|
+|  sa.key                      |                             | kube-controller-manager | --service-account-private-key-file              |
+|                              | sa.pub                      | kube-apiserver          | --service-account-key-file                  |
+
+<!--
+## Configure certificates for user accounts
+
+You must manually configure these administrator account and service accounts:
+-->
+## 为用户帐户配置证书
+
+如下 ServiceAccount 必须手工配置：
+
+| 文件名                  | 凭据名称                   | 默认 CN                        | O (位于 Subject 中) |
+|-------------------------|----------------------------|--------------------------------|---------------------|
+| admin.conf              | default-admin              | kubernetes-admin               | system:masters      |
+| kubelet.conf            | default-auth               | system:node:`<nodeName>` （参阅注释） | system:nodes |
+| controller-manager.conf | default-controller-manager | system:kube-controller-manager |                     |
+| scheduler.conf          | default-scheduler          | system:kube-scheduler          |                     |
+
+<!--
+The value of `<nodeName>` for `kubelet.conf` **must** match precisely the value of the node name provided by the kubelet as it registers with the apiserver. For further details, read the [Node Authorization](/docs/reference/access-authn-authz/node/).
+-->
+::: tip 注释
+`kubelet.conf` 中 `<nodeName>` 的值 **必须** 与 kubelet 向 apiserver 注册时提供的节点名称的值完全匹配。
+有关更多详细信息，请阅读[节点授权](/docs/reference/access-authn-authz/node/)。
+:::
+
+<!--
+1. For each config, generate an x509 cert/key pair with the given CN and O.
+
+2. Run `kubectl` as follows for each config:
+-->
+1. 对于每个配置，请使用指定的 CN 和 O 生成 x509 证书/密钥对。
+
+2. 为每个配置运行下面的 `kubectl` 命令：
+
+```shell
+KUBECONFIG=<filename> kubectl config set-cluster default-cluster --server=https://<host ip>:6443 --certificate-authority <path-to-kubernetes-ca> --embed-certs
+KUBECONFIG=<filename> kubectl config set-credentials <credential-name> --client-key <path-to-key>.pem --client-certificate <path-to-cert>.pem --embed-certs
+KUBECONFIG=<filename> kubectl config set-context default-system --cluster default-cluster --user <credential-name>
+KUBECONFIG=<filename> kubectl config use-context default-system
+```
+
+<!--
+These files are used as follows:
+
+| filename                | command                 | comment                                                               |
+|-------------------------|-------------------------|-----------------------------------------------------------------------|
+| admin.conf              | kubectl                 | Configures administrator user for the cluster                                      |
+| kubelet.conf            | kubelet                 | One required for each node in the cluster.                            |
+| controller-manager.conf | kube-controller-manager | Must be added to manifest in `manifests/kube-controller-manager.yaml` |
+| scheduler.conf          | kube-scheduler          | Must be added to manifest in `manifests/kube-scheduler.yaml`          |
+-->
+生成的文件用途如下：
+
+| 文件名                   | 命令                     | 说明                                                                  |
+|-------------------------|-------------------------|-----------------------------------------------------------------------|
+| admin.conf              | kubectl                 | 配置集群的管理员                                                         |
+| kubelet.conf            | kubelet                 | 集群中的每个节点都需要一份                                                 |
+| controller-manager.conf | kube-controller-manager | 必需添加到 `manifests/kube-controller-manager.yaml` 清单中               |
+| scheduler.conf          | kube-scheduler          | 必需添加到 `manifests/kube-scheduler.yaml` 清单中                        |
diff --git a/install/v3-upgrade.md b/install/v3-upgrade.md
index 9d4fcc8..019fc7f 100644
--- a/install/v3-upgrade.md
+++ b/install/v3-upgrade.md
@@ -10,6 +10,10 @@ meta:
 
 <AdSenseTitle/>
 
+点击此处，查看 [版本更新说明](/support/change-log/v3.0.x.html)
+
+按照如下步骤，可以将 kuboard v3 更新到最新版本。
+
 1. 停止已有 kuboard 容器
 
   ``` sh
@@ -30,7 +34,7 @@ meta:
     -e KUBOARD_AGENT_SERVER_UDP_PORT="10081" \
     -e KUBOARD_AGENT_SERVER_TCP_PORT="10081" \
     -v /root/kuboard-data:/data \
-    eipwork/kuboard:v3.0.0.3
+    eipwork/kuboard:v3.1.0.3
   ```
 
   ::: danger 请注意
diff --git a/learning/carreer/career.md b/learning/carreer/career.md
deleted file mode 100644
index eef5c47..0000000
--- a/learning/carreer/career.md
+++ /dev/null
@@ -1,11 +0,0 @@
----
-description: 不少初学者加我微信后_都表示感到迷茫_问我学会K8S未来能挣多少钱_问将来自己的职业发展该怎么走_在这里作为一个十多年的老兵_算是分享一下自己的一些观点吧_也许对年轻的你会有用
----
-
-# 技术人的职业发展之我见
-
-国内技术从业者的
-
-# 职场价值衡量体系
-
-# 跳槽
diff --git a/support/change-log/v3.0.x.md b/support/change-log/v3.0.x.md
index a08d5f0..dd009ff 100644
--- a/support/change-log/v3.0.x.md
+++ b/support/change-log/v3.0.x.md
@@ -11,6 +11,21 @@ description: 本文描述了Kuboard_v3.0.x的版本变更说明
 
 <!-- <CurrentVersion/> -->
 
+## v3.1.0.3
+
+**发布日期**
+
+2021年2月25日
+
+**优化**
+
+* 检查证书有效期：
+  * 不检查 kubelet 的证书有效期，因为 apiserver 访问 kubelet 时不校验证书，kubeadm 也并未提供更新 kubelet server 证书的方法；
+
+**BUG修正**
+
+* 导入集群时，如果选择自定义镜像，不能保存的问题；
+
 ## v3.1.0.2
 
 **发布日期**