初識OpenShift部署

Service Catalog

OpenShift初始安裝中含有一些樣例APP供大家學習使用。其中有Apache HTTP Server和Apache HTTP Server(httpd)，這兩者有什麼區別？分別點擊進入可以發現：

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

Apache HTTP Server(httpd)使用builder image(image stream名字爲httpd)部署方式。
Service Catalog樣例使用了template和builder image(image+source)兩種部署方式。

查看template和image stream

使用Application Console，進入openshift項目

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

查看Image Stream，點擊Builds -> Images：

使用oc命令

查看所有template和image stream：

$ oc new-app --list

單獨查看template或image stream：

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

查看httpd-example template詳細信息：

$ oc describe template httpd-example -n openshift

查看httpd image stream詳細信息：

$ oc describe imagestream httpd -n openshift

查看httpd-example template的YAML定義：

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

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

$  oc new-app --search httpd

其他部署方式
在Service Catalog中，除從Catalog直接選擇Item外，還提供了其他三種方式：

Deploy Image可以直接從image或image stream部署應用：

Import YAML / JSON 用來從YAML或JSON創建資源，比如image stream、template：

Select from Project 從指定的Project中選擇template來部署應用：

部署Apache HTTP Server

Apache HTTP Server的兩種部署方式本質上是相同的，都是使用S2I(Source-to-Image)構建的Docker鏡像來部署應用。Source均使用Apache HTTP Server (httpd) S2I Sample Application，Docker基礎鏡像(builder image)均使用Apache HTTP Server Container Image。
以下是httpd-example template中BuildConfig部分的定義：

- 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

參數定義及默認值：

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
我們先使用builder image方式部署Apache，來了解一下部署的整體流程：

在Application Console查看項目的Applications和Builds，可以發現部署過程中會自動創建Service、Route、Build、Deployment，創建ImageStream、Pod，其中會創建3個pod：httpd-1-build、http-1-deploy、httpd-1-xxxxx，在部署完畢後http-1-deploy會自動刪除。

下面先解釋一下基本概念。

Service (Kubernetes Service)內部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用於OKD內部網絡訪問Service，selector定義了查找container(pod)進行負載均衡的標籤。

Route 定義一個host name來公開Service，以便外部客戶可以訪問Service，默認host name爲：[app-name]-[project-name].[openshift_master_default_subdomain]。
Build 執行S2I(本例)，即從builder image和Source Code來構建App Image

查看Builds -> httpd -> #1 的YAML文本，可以瞭解Build流程爲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變化時會自動重新Build，當然也可以手動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，包含三種對象：DeploymentConfig、ReplicationController、Pod。

DeploymentConfig描述部署策略、template、trigger等，ReplicationController描述複製相關信息。
進入Deployments -> httpd -> #1，編輯Replicas或調節pods數可以增刪pod：

App Image變化時會自動重新Deploy，也可以手動Deploy。

ImageStream 引用Docker Image的OpenShift抽象，image stream和tag定義了和docker image的映射關係。Build成功後會自動創建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

部署成功後，測試訪問Apache Server(Route定義的Hostname)，頁面如下：

Template
瞭解了以上過程和術語就很容易理解httpd-example template了，其定義了整體的部署流程並實現了參數化，包含以下部分：Service、Route、ImageStream、BuildConfig、DeploymentConfig、parameters。您可以自己部署測試，此處不再贅述。

oc new-app

繼續之前，先將以前創建的測試project刪除或新建一個project。

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

在Service Catalog一節我們提到了創建應用的三種方式：template、builder image(image+source)、image，對應的命令如下：

$ 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

說明：

image+source的語法爲[image]~[source]
第三種方式使用的image爲第二種方式中生成的
後面兩種方式不會自動創建Route，需要手工創建：

$ 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命令還可以直接從source code創建應用，可以使用本地或遠程source code：

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

可以指定子目錄：

$ 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自動檢測代碼中是否含有Docker、Pipeline

再談Route

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

待續

S2I

待續

快速部署OpenShift應用

初識OpenShift部署

Service Catalog

部署Apache HTTP Server

oc new-app

再談Route

S2I

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