openshift 创建一个Serverless应用程序

文章目录

• • 1. Serverless Lab
  • 2. 将Barista应用程序转换为无服务器服务
  • • 2.1 Delete Barista Deployment and Service
    • 2.2 Deploy Barista Component as Knative Service
  • 3 更新咖啡店ConfigMap访问Knative咖啡师服务
  • • 3.1 Fix ConfigMap that Associates `coffee-shop` and `barista`
    • 3.2 Restart coffee-shop Application
    • 3.3 Access coffee-shop Web Application
  • 4 Examine Logs

1. Serverless Lab

使用Knative Serverless，您可以轻松地在Kubernetes上运行无服务器容器。Knative负责网络、自动伸缩(甚至为零)和修订跟踪的细节。这让你能够专注于你的核心逻辑。
在本实验室中，您将学习如何将无服务器应用程序部署为“服务”应用程序。

Serverless服务
减少资源消耗的一种好方法是确定哪些服务需要24/7运行。示例咖啡店应用程序有三个组件: a database, a front-end coffee shop, and a service barista that makes drinks。似乎只有在咖啡订单实际提交时才需要咖啡师服务，而咖啡店前端应该始终运行。因此，有必要将咖啡师服务转换为无服务器服务，在不使用时可以扩展到零副本。

目标：

• 将咖啡师应用程序转换为无服务器服务
• 观察日志的变化

2. 将Barista应用程序转换为无服务器服务

咖啡师应用程序不需要一直运行。它只需要在创建新订单时运行。因此，当咖啡店没有流量时，应用程序不需要消耗资源。

2.1 Delete Barista Deployment and Service

1. Go to your Red Hat® OpenShift® Container Platform web console and log in as admin.
2. Use the perspective switcher to switch to the Developer perspective.
3. If a pop-up window appears, click Cancel.
4. In the navigation menu, click Topology.

A graphical representation of your application appears, displaying the app components, plus a cron job that orders drinks every minute:

1. Click D barista to display the details panel.
2. You need to delete this barista OpenShift service and the baristadeployment before you can deploy a Knative service by the same name.
3. Click S barista to open the Service details page.
4. Select Actions → Delete Service and confirm.
5. Go back to Topology and click D barista again to verify that the service was deleted.
6. Select Actions → Delete deployment to delete the barista deployment.

Confirm the deletion.

2.2 Deploy Barista Component as Knative Service

在本节中，您将把咖啡师容器映像部署为Knative无服务器服务。Knative服务的API包不同于Kubernetes服务，扮演着不同的角色。

1. On the navigation menu, click Add.
2. Click Container Images.
3. Fill in the Image stream from internal registry fields as follows:
   Project: dev-coffeeshop
   Image Stream: barista
   Tag: latest
4. Complete the remaining fields as follows:
   Runtime icon: select the Knative icon
   Application: coffee-shop
   Name: barista
   Resources: select the Knative Service radio button
   Create a route to the Application: check this box
5. Click Create
   Expect the Topology view to appear with the new KSVC barista service along with its revision number.

3 更新咖啡店ConfigMap访问Knative咖啡师服务

The route to the barista part of the application has changed, so the coffee shop component cannot find it.

The old service URL was http://barista:8080/processes. The new service URL (Knative route) is http://barista.dev-coffeeshop.svc.cluster.local/processes. Knative使用项目名而不是服务名，并且端口现在由Knative处理。这将断开咖啡店应用程序和咖啡师应用程序之间的连接。

In this exercise, you reconnect them.

3.1 Fix ConfigMap that Associates coffee-shop and barista

The coffee-shop application gets its BARISTA_URL from a ConfigMap.

1. In the navigation menu, click ConfigMaps and then click CM coffee-shop.
2. Scroll down to the Data section and the BARISTA_URL of http://barista:8080/processes.
3. Select Actions → Edit ConfigMap.
4. In the YAML listing that opens, copy and paste the following URL into the BARISTA_URL value:
   http://barista.dev-coffeeshop.svc.cluster.local/processes.

3.2 Restart coffee-shop Application

在本节中，您将向下扩展咖啡店部署并备份以获取ConfigMap更改。

1. Return to Topology and click D coffee-shop.
2. In the panel that appears, click the Details tab.
   Expect to see three running pods.
   3.使用箭头按钮来缩小到0，然后返回到3

3.3 Access coffee-shop Web Application

要确保coffee-shop应用程序工作，请在coffee-shop应用程序上单击Open URL，而不是barista应用程序:

预计会出现一两行JSON输出。

2. Add /index.html to the end of the URL to access the application.

3. 点一杯饮料，并验证咖啡师应用程序可以扩展到处理请求

Expect to see some beverages already ordered by the order-drinks cron job. Your order is at the bottom of the list.

The order-drinks cron job orders two new drinks every minute from the coffee-shop application in the dev-coffeeshop namespace.

4 Examine Logs

如果您返回Kibana接口，您会看到结构化类型中现在有更多的字段。它们大多是当您从Kubernetes部署更改为Knative应用程序时，应用程序捕获的应用程序异常。

1. 返回Kibana web界面，从左侧导航面板单击Discovery。
2. 从“可用字段”一节中，将*t* structured.error.message添加到日志发现中。
3. 使用顶部的时间滑块来关注带有错误消息的事件。
   希望很容易找到错误消息，例如“RESTEASY004655: Unable to invoke r .”
   java.net.NoRouteToHostException: No route to host (Host unreachable)".

您使用Knative将一个无服务器应用程序部署为一个服务应用程序。
现在，在下一个模块中，我们将继续学习GitOps。使用GitOps，您可以将咖啡馆应用程序的部署自动化到生产环境，所有这些都来自一个Git存储库。