如何在将REST查询传递给容器时触发容器以启动另一个容器并终止该容器? [英] How to trigger a container to start another container and terminate it when a REST query is passed to it?

问题描述

我有两个带有docker映像的单独容器，其中一个正在运行REST应用程序，另一个正在运行用于下载卫星映像的进程. 我的目标是，当我在主应用程序中传递带有已定义参数的查询后，单击下载按钮时，它应启动容器进行下载，一旦下载，则应停止容器.能够通过在部署文件中为其docker映像提供所有必需的环境变量来独立运行容器以进行下载，但是从长远来看，这些变量应该作为查询中的参数出现.我该如何做到这一点? 这是当前的部署文件和运行映像所需的参数:

---
kind: Deployment
apiVersion: apps/v1
metadata:
  name: back
spec:
  replicas: 1
  selector:
    matchLabels:
      app: back
  template:
    metadata:
      creationTimestamp: 
      labels:
        app: back
    spec:
      containers:
      - name: back
        image: back:latest
        imagePullPolicy: Never
        env:
        - name: scihub_username
          value: test
        - name: scihub_password
          value: test
        - name: CDINRW_BASE_URL
          value: 10.1.40.11:8081/swagger-ui.html
        - name: CDINRW_JOB_ID
          value: 3fa85f64-5717-4562-b3fc-2c963f66afa6
        ports:
        - containerPort: 8081
          protocol: TCP
        volumeMounts:
        - mountPath: /data
          name: test-volume
      volumes:
      - name: test-volume
        hostPath:
          # directory location on host
          path: /back
          # this field is optional
          type: Directory

docker run --rm -v $(pwd):/out_data \
-e scihub_username=test \
-e scihub_password=test \
-e producttype=S2MSI2A \
-e platformname=Sentinel-2 \
-e start_date=2019-06-09T00:00:00.000Z \
-e end_date=2019-06-12T00:00:00.000Z \
-e days_back=7 \
-e footprint="POLYGON((5.8664000 50.3276000,9.4623000 50.3276000,9.4623000 52.5325000,5.8664000 52.5325000,5.8664000 50.3276000))" \
-e max_cloud_cover_percentage=10 \
-e CDINRW_BASE_URL=10.1.40.11:8081/swagger-ui.html \
-e CDINRW_JOB_ID=3fa85f64-5717-4562-b3fc-2c963f66afa6 \
ingestion

解决方案

对于这样的工作负载，更好的设计是部署像

解决方案

For a workload like this, a better design is to deploy a job queue system like RabbitMQ and have two long-running containers (Deployments, since you're using Kubernetes). One of them runs the REST server, and when it receives a request, writes the details of the request into a queue. The second listens to the queue, pulls off messages one at a time, and does the network fetch.

Especially in Kubernetes, this approach has a couple of advantages. You can easily build and test it without requiring Docker or Kubernetes. If you get swamped with requests, they back up in the job queue instead of launching dozens or hundreds of containers. If you see you have a long queue and want to do fetches faster, you can kubectl scale deployment very easily and run more workers.

If you don't want to go that approach, you should use the Kubernetes API to create a Job, which can restart if it fails, isn't tightly bound to the same node, and doesn't require root-level permission on the host to launch. You should not run docker commands from inside a Kubernetes pod basically ever. (And since running docker commands raises the potential of rooting the whole host, you want to be very very careful about doing it from a Web server in any case.)

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