初识OpenShift部署

Service Catalog

OpenShift初始安装中含有一些样例APP供大家学习使用。其中有Apache HTTP Server和Apache HTTP Server(httpd)，这两者有什么区别？分别点击进入可以发现：

Apache HTTP Server使用template(template名字为httpd-example)部署方式。

Apache HTTP Server(httpd)使用builder image(image stream名字为httpd)部署方式。
Service Catalog样例使用了template和builder image(image+source)两种部署方式。

查看template和image stream

使用Application Console，进入openshift项目

查看template，点击Resources -> Other Resources -> Template：

查看Image Stream，点击Builds -> Images：

使用oc命令

查看所有template和image stream：

$ oc new-app --list

单独查看template或image stream：

$ oc get templates -n openshift
$ oc get imagestreams -n openshift

查看httpd-example template详细信息：

$ oc describe template httpd-example -n openshift

查看httpd image stream详细信息：

$ oc describe imagestream httpd -n openshift

查看httpd-example template的YAML定义：

$ oc new-app --search --template=httpd-example --output=yaml

从所有template、image stream、docker image中查找"httpd"：

$  oc new-app --search httpd

其他部署方式
在Service Catalog中，除从Catalog直接选择Item外，还提供了其他三种方式：

Deploy Image可以直接从image或image stream部署应用：

Import YAML / JSON 用来从YAML或JSON创建资源，比如image stream、template：

Select from Project 从指定的Project中选择template来部署应用：

部署Apache HTTP Server

Apache HTTP Server的两种部署方式本质上是相同的，都是使用S2I(Source-to-Image)构建的Docker镜像来部署应用。Source均使用Apache HTTP Server (httpd) S2I Sample Application，Docker基础镜像(builder image)均使用Apache HTTP Server Container Image。
以下是httpd-example template中BuildConfig部分的定义：

- apiVersion: v1
  kind: BuildConfig
  metadata:
    annotations:
      description: Defines how to build the application
      template.alpha.openshift.io/wait-for-ready: 'true'
    name: '${NAME}'
  spec:
    output:
      to:
        kind: ImageStreamTag
        name: '${NAME}:latest'
    source:
      contextDir: '${CONTEXT_DIR}'
      git:
        ref: '${SOURCE_REPOSITORY_REF}'
        uri: '${SOURCE_REPOSITORY_URL}'
      type: Git
    strategy:
      sourceStrategy:
        from:
          kind: ImageStreamTag
          name: 'httpd:2.4'
          namespace: '${NAMESPACE}'
      type: Source
    triggers:
      - type: ImageChange
      - type: ConfigChange
      - github:
          secret: '${GITHUB_WEBHOOK_SECRET}'
        type: GitHub
      - generic:
          secret: '${GENERIC_WEBHOOK_SECRET}'
        type: Generic

参数定义及默认值：

parameters:
  - description: The name assigned to all of the frontend objects defined in this template.
    displayName: Name
    name: NAME
    required: true
    value: httpd-example
  - description: The OpenShift Namespace where the ImageStream resides.
    displayName: Namespace
    name: NAMESPACE
    required: true
    value: openshift
  - description: Maximum amount of memory the container can use.
    displayName: Memory Limit
    name: MEMORY_LIMIT
    required: true
    value: 512Mi
  - description: The URL of the repository with your application source code.
    displayName: Git Repository URL
    name: SOURCE_REPOSITORY_URL
    required: true
    value: 'https://github.com/openshift/httpd-ex.git'
  - description: >-
      Set this to a branch name, tag or other ref of your repository if you are
      not using the default branch.
    displayName: Git Reference
    name: SOURCE_REPOSITORY_REF
  - description: >-
      Set this to the relative path to your project if it is not in the root of
      your repository.
    displayName: Context Directory
    name: CONTEXT_DIR
  - description: >-
      The exposed hostname that will route to the httpd service, if left blank a
      value will be defaulted.
    displayName: Application Hostname
    name: APPLICATION_DOMAIN
...

Builder Image
我们先使用builder image方式部署Apache，来了解一下部署的整体流程：

在Application Console查看项目的Applications和Builds，可以发现部署过程中会自动创建Service、Route、Build、Deployment，创建ImageStream、Pod，其中会创建3个pod：httpd-1-build、http-1-deploy、httpd-1-xxxxx，在部署完毕后http-1-deploy会自动删除。

下面先解释一下基本概念。

Service (Kubernetes Service)内部load balancer

apiVersion: v1
kind: Service
metadata:
  annotations:
    openshift.io/generated-by: OpenShiftWebConsole
  creationTimestamp: '2019-03-26T02:12:50Z'
  labels:
    app: httpd
  name: httpd
  namespace: my-project
  resourceVersion: '3004428'
  selfLink: /api/v1/namespaces/my-project/services/httpd
  uid: a81c759f-4f6c-11e9-9a7d-02fa2ffc40e6
spec:
  clusterIP: 172.30.225.159
  ports:
    - name: 8080-tcp
      port: 8080
      protocol: TCP
      targetPort: 8080
  selector:
    deploymentconfig: httpd
  sessionAffinity: None
  type: ClusterIP
status:
  loadBalancer: {}

其中，clusterIP用于OKD内部网络访问Service，selector定义了查找container(pod)进行负载均衡的标签。

Route 定义一个host name来公开Service，以便外部客户可以访问Service，默认host name为：[app-name]-[project-name].[openshift_master_default_subdomain]。
Build 执行S2I(本例)，即从builder image和Source Code来构建App Image

查看Builds -> httpd -> #1 的YAML文本，可以了解Build流程为FetchInputs -> Assemble -> CommitContainer -> PushImage：

...
status:
  completionTimestamp: '2019-03-26T02:13:30Z'
  config:
    kind: BuildConfig
    name: httpd
    namespace: my-project
  duration: 40000000000
  output:
    to:
      imageDigest: 'sha256:5c1f20f20baaa796f4518d11ded13c6fac33e7a377774cfec77aa1e6e6a7cbb2'
  outputDockerImageReference: 'docker-registry.default.svc:5000/my-project/httpd:latest'
  phase: Complete
  stages:
    - durationMilliseconds: 3434
      name: FetchInputs
      startTime: '2019-03-26T02:12:56Z'
      steps:
        - durationMilliseconds: 3434
          name: FetchGitSource
          startTime: '2019-03-26T02:12:56Z'
    - durationMilliseconds: 2127
      name: CommitContainer
      startTime: '2019-03-26T02:13:11Z'
      steps:
        - durationMilliseconds: 2127
          name: CommitContainer
          startTime: '2019-03-26T02:13:11Z'
    - durationMilliseconds: 3426
      name: Assemble
      startTime: '2019-03-26T02:13:10Z'
      steps:
        - durationMilliseconds: 3426
          name: AssembleBuildScripts
          startTime: '2019-03-26T02:13:10Z'
    - durationMilliseconds: 16143
      name: PushImage
      startTime: '2019-03-26T02:13:14Z'
      steps:
        - durationMilliseconds: 16143
          name: PushImage
          startTime: '2019-03-26T02:13:14Z'
  startTimestamp: '2019-03-26T02:12:50Z'

Image变化时会自动重新Build，当然也可以手动Build。

...
  triggeredBy:
    - imageChangeBuild:
        fromRef:
          kind: ImageStreamTag
          name: 'httpd:2.4'
          namespace: openshift
        imageID: >-
          docker-registry.default.svc:5000/openshift/httpd@sha256:4b6ea8da8647328a17e0ce5b763fafd195bb0c72df88d7aeb3708f36491c10e4
      message: Image change
...

Deployment 部署App Image，包含三种对象：DeploymentConfig、ReplicationController、Pod。

DeploymentConfig描述部署策略、template、trigger等，ReplicationController描述复制相关信息。
进入Deployments -> httpd -> #1，编辑Replicas或调节pods数可以增删pod：

App Image变化时会自动重新Deploy，也可以手动Deploy。

ImageStream 引用Docker Image的OpenShift抽象，image stream和tag定义了和docker image的映射关系。Build成功后会自动创建ImageStream。

apiVersion: image.openshift.io/v1
kind: ImageStream
metadata:
  annotations:
    openshift.io/generated-by: OpenShiftWebConsole
  creationTimestamp: '2019-03-26T02:12:50Z'
  generation: 1
  labels:
    app: httpd
  name: httpd
  namespace: my-project
  resourceVersion: '3004571'
  selfLink: /apis/image.openshift.io/v1/namespaces/my-project/imagestreams/httpd
  uid: a81b14bf-4f6c-11e9-9a7d-02fa2ffc40e6
spec:
  lookupPolicy:
    local: false
status:
  dockerImageRepository: 'docker-registry.default.svc:5000/my-project/httpd'
  tags:
    - items:
        - created: '2019-03-26T02:13:30Z'
          dockerImageReference: >-
            docker-registry.default.svc:5000/my-project/httpd@sha256:5c1f20f20baaa796f4518d11ded13c6fac33e7a377774cfec77aa1e6e6a7cbb2
          generation: 1
          image: >-
            sha256:5c1f20f20baaa796f4518d11ded13c6fac33e7a377774cfec77aa1e6e6a7cbb2
      tag: latest

部署成功后，测试访问Apache Server(Route定义的Hostname)，页面如下：

Template
了解了以上过程和术语就很容易理解httpd-example template了，其定义了整体的部署流程并实现了参数化，包含以下部分：Service、Route、ImageStream、BuildConfig、DeploymentConfig、parameters。您可以自己部署测试，此处不再赘述。

oc new-app

继续之前，先将以前创建的测试project删除或新建一个project。

$ oc delete project my-project
$ oc new-project my-project

在Service Catalog一节我们提到了创建应用的三种方式：template、builder image(image+source)、image，对应的命令如下：

$ oc new-app httpd-example -p APPLICATION_DOMAIN=httpd-example.apps.itrunner.org
$ oc new-app openshift/httpd:2.4~https://github.com/openshift/httpd-ex.git --name=httpd-ex
$ oc new-app my-project/httpd-ex --name=httpd

说明：

image+source的语法为[image]~[source]
第三种方式使用的image为第二种方式中生成的
后面两种方式不会自动创建Route，需要手工创建：

$ oc expose service httpd-ex --name httpd-ex --hostname=httpd-ex.apps.itrunner.org
$ oc expose service httpd --name httpd --hostname=httpd.apps.itrunner.org

使用oc命令还可以直接从source code创建应用，可以使用本地或远程source code：

$ oc new-app /path/to/source/code
$ oc new-app https://github.com/sclorg/cakephp-ex

可以指定子目录：

$ oc new-app https://github.com/sclorg/s2i-ruby-container.git --context-dir=2.0/test/puma-test-app

可以指定branch：

$ oc new-app https://github.com/openshift/ruby-hello-world.git#beta4

OpenShift自动检测代码中是否含有Docker、Pipeline

再谈Route

$ oc create route edge http-ex -n my-project --hostname http-ex.apps.iata-asd.org --service httpd-ex

待续

S2I

待续

快速部署OpenShift应用

初识OpenShift部署

Service Catalog

部署Apache HTTP Server

oc new-app

再谈Route

S2I

Python实现大麦网抢票的四大关键技术点解析

salesforce零基础学习（一百三十八）零碎知识点小总结（十）

一款开源的.NET程序集反编译、编辑和调试神器

关于接口协议，你必须要知道这些！

【2024-05-21】以茶会友

AWS RHEL/CentOS 7快速安裝配置OpenShift 3.11

AWS學習筆記(九)--ECS

利用JSPWiki搭建簡易企業wiki平臺

Spring Boot集成Spring Scheduler和Quartz Scheduler

Spring Boot/Angular整合Keycloak實現單點登錄

https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

linux以太網驅動總結