Kubernetes 中的作业出错（如何使用 Kubernetes 部署 Rails 应用程序？）

Question

我用 rails + mysql + vue.js + webpacker 制作了我的项目。

然后我创建了Dockerfile 和docker-compose.yml，所以我可以在localhost 中运行它。

现在我想用 K8s 部署它们，但是我在 K8s 中的 Job 有问题。 实际上这是我第一次使用 K8s，所以如果有什么遗漏或错误，请让我知道我需要做什么。这是我的 Dockerfile 和 ymls。

ps。 khjoo19/line-manager:v1 是我上传到 docker hub 的 docker 镜像。

Dockerfile

FROM ruby:2.5.5
ENV LANG C.UTF-8
RUN apt-get update -qq && apt-get install -y build-essential libpq-dev nodejs && \
    curl -sL https://deb.nodesource.com/setup_7.x | bash - && \
    apt-get install nodejs

RUN apt-get update && apt-get install -y curl apt-transport-https wget && \
    curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - && \
    echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list && \
    apt-get update && apt-get install -y yarn && \
    gem install bundler

WORKDIR /tmp
COPY Gemfile Gemfile
COPY Gemfile.lock Gemfile.lock
RUN bundle install

COPY entrypoint.sh /usr/bin/
RUN chmod +x /usr/bin/entrypoint.sh
ENTRYPOINT [ "entrypoint.sh" ]

ENV APP_HOME /line_manager
RUN mkdir -p $APP_HOME
WORKDIR $APP_HOME
COPY . /line_manager
RUN yarn upgrade

docker-compose.yml

version: '3'
services:
  db:
    image: mysql:5.7
    environment:
      DB_USER: root
      DB_ROOT_PASSWORD: password
      DB_PASSWORD: password
      DB_HOST: db

  webpacker:
    build: .
    command: bundle exec bin/webpack-dev-server
    volumes:
      - .:/line_manager
    ports:
      - "8080:8080"

  web:
    build: .
    command: /bin/sh -c "rm -f tmp/pids/server.pid && bundle exec rails s -p 3000 -b '0.0.0.0'"
    volumes:
      - .:/line_manager
    environment:
      DB_USER: root
      DB_ROOT_PASSWORD: password
      DB_PASSWORD: password
      DB_HOST: db
      RAILS_ENV: development
    ports:
      - "3000:3000"
    depends_on:
      - db
      - webpacker
    tty: true
    stdin_open: true

mysql.yml (K8s)

apiVersion: v1
kind: Service
metadata:
  namespace: line-manager
  name: db
  labels:
    app: web
spec:
  selector:
    app: web
  clusterIP: None
  ports:
    - port: 3306
---
kind: PersistentVolume
apiVersion: v1
metadata:
  namespace: line-manager
  name: db-pv
  labels:
    app: web
spec:
  capacity:
    storage: 20Gi
  accessModes:
  - ReadWriteOnce
  storageClassName: standard
  hostPath:
    path: "/tmp/mysql"
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  namespace: line-manager
  name: db-pvc
  labels:
    app: web
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 20Gi
  storageClassName: standard
---
apiVersion: apps/v1
kind: Deployment
metadata:
  namespace: line-manager
  name: db
  labels:
    app: web
spec:
  selector:
    matchLabels:
      app: web
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: web
    spec:
      containers:
      - name: mysql
        image: mysql:5.7.17
        envFrom:
        - configMapRef:
            name: rails-config
        ports:
        - containerPort: 3306
          name: db
        volumeMounts:
        - name: db-pv
          mountPath: /var/lib/mysql
      volumes:
      - name: db-pv
        persistentVolumeClaim:
          claimName: db-pvc

rails-config.yaml(K8s)

apiVersion: v1
kind: ConfigMap
metadata:
  namespace: line-manager
  name: rails-config
data:
  RAILS_ENV: 'development'
  DB_HOST: 'db'
  DB_USER: 'root'
  DB_ROOT_PASSWORD: 'password'
  DB_PASSWORD: 'password'

rails-job.yaml(K8s)

apiVersion: batch/v1
kind: Job
metadata:
  namespace: line-manager
  name: web-job
  labels:
    app: web
spec:
  template:
    metadata:
      namespace: line-manager
      name: web-job
      labels:
        app: web
    spec:
      containers:
      - name: web-job
        image: khjoo19/line-manager:v1
        imagePullPolicy: Always
        command: ["/bin/sh"]
        args: ["-c", "bundle exec rake db:create && bundle exec rake db:migrate"]
        envFrom:
        - configMapRef:
            name: rails-config
      restartPolicy: Never

Answer 1

我应用了您的部署，首先我看到的是 mysql 数据库崩溃。在使用kubectl logs -n line-manager <db-pod-name> 检查日志后，我看到了这个：

error: database is uninitialized and password option is not specified 
  You need to specify one of MYSQL_ROOT_PASSWORD, MYSQL_ALLOW_EMPTY_PASSWORD and MYSQL_RANDOM_ROOT_PASSWORD

所以我将MYSQL_ROOT_PASSWORD: 'password' 添加到rails-config configmap 并开始工作。

然后我部署了 web-job 作业，发现它也崩溃了，所以我检查了日志：

...
Mysql2::Error: No database selected
...

在./config/database.yml 文件中的容器khjoo19/line-manager:v1 中，我找到了这一行：database: <%= ENV['DB_DATABASE'] %>，这表明代码正在尝试从DB_DATABASE 环境变量加载数据库名称，该环境变量没有在任何地方设置，所以我添加了这个rails-config 的 env 变量：

apiVersion: v1
kind: ConfigMap
metadata:
  namespace: line-manager
  name: rails-config
data:
  ...
  DB_DATABASE: 'database'

然后它工作并成功完成。

如果有帮助，请告诉我。