YAML最佳实践 | KubeLinter

介绍

在Kubernetes的世界中，我们使用YAML文件，对其进行部署以创建各种Kubernetes对象，但挑战在于编写它们时是否遵循最佳实践？我们使用的是正确的标准配置集吗？在部署应用程序甚至Helm图表之前，可以检查YAML吗？所有这些问题的答案都是肯定的，我们可以。2020年10月28日，StackRox引入了一个名为KubeLinter的新开源工具，旨在识别YAML文件中的任何错误配置。

根据定义，KubeLinter是一个静态分析工具，用于检查Kubernetes YAML文件和Helm图表，以确保其中所代表的应用程序遵循最佳实践。将YAML文件提供给该工具后，它将通过内置检查运行，然后详细报告任何错误以及解决这些错误的补救措施。关于此工具的最好之处在于它是可配置和可扩展的：可以启用或禁用内置检查，并且您可以定义和使用自己的自定义检查。

用法

我将在Mac上安装KubeLinter，但只需下载适用于您操作系统的发行版，即可将相同的说明用于Linux。

你可以从https://github.com/stackrox/kube-linter/releases/下载KubeLinter CLI，如下所示：

代码语言：javascript复制

$ curl -LO https://github.com/stackrox/kube-linter/releases/download/0.1.1/kube-linter-darwin.zip
$ unzip kube-linter-darwin.zip
$ mv kube-linter /usr/local/bin

#check if it's working
$ kube-linter version
0.1.1

现在，为了简单地检查单个YAML文件，只需提供YAML文件名。假设deploy.yaml您要检查以下文件，以检查其当前目录中保存的最佳安全性和配置做法：

代码语言：javascript复制

apiVersion: apps/v1
kind: Deployment
metadata:
  name: portainer
  namespace: portainer
  labels:
    io.portainer.kubernetes.application.stack: portainer
    app.kubernetes.io/name: portainer
    app.kubernetes.io/instance: portainer
    app.kubernetes.io/version: "2.0.0"
spec:
  replicas: 1
  strategy:
    type: "Recreate"
  selector:
    matchLabels:
      app.kubernetes.io/name: portainer
      app.kubernetes.io/instance: portainer
  template:
    metadata:
      labels:
        app.kubernetes.io/name: portainer
        app.kubernetes.io/instance: portainer
    spec:
      serviceAccountName: portainer-sa-clusteradmin
      volumes:
         - name: "data"
           persistentVolumeClaim:
             claimName: portainer
      containers:
        - name: portainer
          image: "portainer/portainer-ce:latest"
          imagePullPolicy: IfNotPresent
          args:  [ '--tunnel-port','30776' ]
          volumeMounts:
            - name: data
              mountPath: /data
          ports:
            - name: http
              containerPort: 9000
              protocol: TCP
            - name: tcp-edge
              containerPort: 8000
              protocol: TCP
          livenessProbe:
            httpGet:
              path: /
              port: 9000
          readinessProbe:
            httpGet:
              path: /
              port: 9000
          resources:
            {}

让我们进行测试kube-linter lint deploy.yaml。我们应该得到如下输出：

代码语言：javascript复制

deploy.yaml: (object: portainer/portainer apps/v1, Kind=Deployment) container "portainer" does not have a read-only root file system (check: no-read-only-root-fs, remediation: Set readOnlyRootFilesystem to true in your container's securityContext.)

deploy.yaml: (object: portainer/portainer apps/v1, Kind=Deployment) serviceAccount "portainer-sa-clusteradmin" not found (check: non-existent-service-account, remediation: Make sure to create the service account, or to refer to an existing service account.)

deploy.yaml: (object: portainer/portainer apps/v1, Kind=Deployment) container "portainer" is not set to runAsNonRoot (check: run-as-non-root, remediation: Set runAsUser to a non-zero number, and runAsNonRoot to true, in your pod or container securityContext. See https://kubernetes.io/docs/tasks/configure-pod-container/security-context/ for more details.)

deploy.yaml: (object: portainer/portainer apps/v1, Kind=Deployment) container "portainer" has cpu request 0 (check: unset-cpu-requirements, remediation: Set your container's CPU requests and limits depending on its requirements. See https://kubernetes.io/docs/concepts/configuration/manage-resources-containers/#requests-and-limits for more details.)

deploy.yaml: (object: portainer/portainer apps/v1, Kind=Deployment) container "portainer" has cpu limit 0 (check: unset-cpu-requirements, remediation: Set your container's CPU requests and limits depending on its requirements. See https://kubernetes.io/docs/concepts/configuration/manage-resources-containers/#requests-and-limits for more details.)

deploy.yaml: (object: portainer/portainer apps/v1, Kind=Deployment) container "portainer" has memory request 0 (check: unset-memory-requirements, remediation: Set your container's memory requests and limits depending on its requirements. See https://kubernetes.io/docs/concepts/configuration/manage-resources-containers/#requests-and-limits for more details.)

deploy.yaml: (object: portainer/portainer apps/v1, Kind=Deployment) container "portainer" has memory limit 0 (check: unset-memory-requirements, remediation: Set your container's memory requests and limits depending on its requirements. See https://kubernetes.io/docs/concepts/configuration/manage-resources-containers/#requests-and-limits for more details.)

Error: found 7 lint errors

检测类型

如您所见，YAML文件中发现了错误，每个错误都有明确的补救步骤。

如果您想看一下内置检查，可以在https://github.com/stackrox/kube-linter/blob/main/docs/genic/checks.md中列出所有这些检查，或者也可以使用KubeLinter查看清单：

代码语言：javascript复制

$ kube-linter checks list
Name: dangling-service
Description: Alert on services that don't have any matching deployments
Remediation: Make sure your service's selector correctly matches the labels on one of your deployments.
Template: dangling-service
Parameters: map[]
Enabled by default: true

------------------------------

Name: default-service-account
Description: Alert on pods that use the default service account
Remediation: Create a dedicated service account for your pod. See https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/ for more details.
Template: service-account
Parameters: map[serviceAccount:^(|default)$]
Enabled by default: false
|
|
|
and many more

忽略检测

您可以使用以下注释忽略针对YAML文件的特定检查，也可以根据需要忽略检查组：

代码语言：javascript复制

ignore-check.kube-linter.io/<check-name>

例如：

代码语言：javascript复制

ignore-check.kube-linter.io/unset-cpu-requirements

您可以像上面这样在上面的部署文件示例中添加忽略检查规则：

代码语言：javascript复制

metadata:
  name: portainer
  namespace: portainer
  labels:
    io.portainer.kubernetes.application.stack: portainer
    app.kubernetes.io/name: portainer
    app.kubernetes.io/instance: portainer
    app.kubernetes.io/version: "2.0.0"
  annotations:
    ignore-check.kube-linter.io/unset-cpu-requirements : "cpu requirements not required"

现在，当您kube-linter lint deploy.yaml再次运行时，您应该不会看到与CPU要求相关的错误提示。

使用配置运行

KubeLinter也可以使用配置运行，您可以在其中提供要包含/排除的所有检测信息。以下是存储库中的示例配置：

代码语言：javascript复制

# customChecks defines custom checks.
customChecks:
- name: "required-label-app"
  template: "required-label"
  params:
    key: "app"
checks:
  # if doNotAutoAddDefaults is true, default checks are not automatically added.
  doNotAutoAddDefaults: false

  # addAllBuiltIn, if set, adds all built-in checks. This allows users to
  # explicitly opt-out of checks that are not relevant using Exclude.
  # Takes precedence over doNotAutoAddDefaults, if both are set.
  addAllBuiltIn: false

  # include explicitly adds checks, by name. You can reference any of the built-in checks.
  # Note that customChecks defined above are included automatically.
  include:
  - "required-label-owner"
  # exclude explicitly excludes checks, by name. exclude has the highest priority: if a check is
  # in exclude, then it is not considered, even if it is in include as well.
  exclude:
    - "privileged"

如果你运行kubelinter --config config lint deploy.yaml，其中config与上述配置的文件，你应该可以看到添加了需要标签的检查：

deploy.yaml: (object: portainer/portainer apps/v1, Kind=Deployment) no label matching "owner=<any>" found (check: required-label-owner, remediation: Add an email annotation to your object with information about the object's owner.)

当内置到CI管道中时，KubeLinter可以证明是非常有用的工具。可以检查和验证推送到存储库中的编排文件，以获取最佳实践和安全考虑，并在检测到问题时生成警报。

这样，可以将部署到集群的应用程序进行健康的就绪检查。该项目处于Alpha阶段，但有望作为CI集成工具在实际部署到生产之前验证所有部署。

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