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来奉献几分钟提交：2020 年 CNCF 中国云原生问卷
问卷链接（https://www.wjx.cn/jq/9714648…）
作者：Alkin Tezuysal
Django 是 Python 应用程序开发人员罕用的框架。它蕴含的包能够简化受权和内容治理等工作。Django 反对包含 MySQL 在内的许多数据库，这使得不须要批改利用程序代码就能够在 Vitess 上运行 Django 应用程序。让咱们看看如何联合这两个开放源码框架的长处。
咱们应用 Vitess 操作器构建这个示例。你能够在这篇博客文章中看到 Vitess 操作器实现的细节。
先决条件
- 本地 Python 环境（3.X）
- Kubernetes 环境（minikube、GKE）
- 通过 Vitess 反对 Django ORM
在本例中，咱们将在 GKE 应用一个现有的 Kubernetes 集群。你也能够通过本地的 minikube 来实现此操作。
咱们应用的 Django 示例是“天气应用程序”。咱们首先应用提供的配置启动 vitess 操作器。
以下局部包含这些步骤：
- 创立 Vitess 操作器 pod
- 构建 Vitess 集群组件（1x 主 tablet、1x 复制 tablet、3x etcd pod、1x vtgate、1x vtctld、1x vitessbackup）
- 创立“weatherapp”数据库模式和用户。
$ kubectl apply -f operator.yaml
customresourcedefinition.apiextensions.k8s.io/etcdlockservers.planetscale.com created
customresourcedefinition.apiextensions.k8s.io/vitessbackups.planetscale.com created
customresourcedefinition.apiextensions.k8s.io/vitessbackupstorages.planetscale.com created
customresourcedefinition.apiextensions.k8s.io/vitesscells.planetscale.com created
customresourcedefinition.apiextensions.k8s.io/vitessclusters.planetscale.com created
customresourcedefinition.apiextensions.k8s.io/vitesskeyspaces.planetscale.com created
customresourcedefinition.apiextensions.k8s.io/vitessshards.planetscale.com created
serviceaccount/vitess-operator created
role.rbac.authorization.k8s.io/vitess-operator created
rolebinding.rbac.authorization.k8s.io/vitess-operator created
priorityclass.scheduling.k8s.io/vitess created
priorityclass.scheduling.k8s.io/vitess-operator-control-plane created
deployment.apps/vitess-operator created
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
vitess-operator-7f9c9d58f6-q5zlf 1/1 Running 0 20s用一个名为“weatherapp”的示例数据库初始化这个集群，拜访它的用户 / 明码将嵌入到配置文件中。咱们基本上是在创立一个数据库，相似于 Vitess 中的密钥空间。
$ kubectl apply -f 101_initial_cluster.yaml.django
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
example-90089e05-vitessbackupstorage-subcontroller 1/1 Running 0 94s
example-etcd-faf13de3-1 1/1 Running 0 94s
example-etcd-faf13de3-2 1/1 Running 0 94s
example-etcd-faf13de3-3 1/1 Running 0 94s
example-vttablet-zone1-1542279354-edf1c7bf 2/3 Running 1 94s
example-vttablet-zone1-3763665199-476cbd65 2/3 Running 2 94s
example-weatherapp-x-x-vtbackup-init-75efaeeb 0/1 Completed 0 74s
example-zone1-vtctld-1d4dcad0-67bfd56b8b-4dr9s 1/1 Running 2 94s
example-zone1-vtgate-bc6cde92-59b88bc8d8-6wz86 1/1 Running 2 94s
vitess-operator-7f9c9d58f6-q5zlf 1/1 Running 0 4m30s如你所见，这将带来一个功能齐全的托管 Vitess 集群，其中蕴含一个未分片的密钥空间，其中包含一个“主”和一个“正本”。
步骤 1 – 设置 portforward
$ cat pf.sh ; ./pf.sh &
#!/bin/sh
kubectl port-forward --address localhost "$(kubectl get service --selector="planetscale.com/component=vtctld"-o name | head -n1)" 15000 15999 &
process_id1=$!
kubectl port-forward --address localhost "$(kubectl get service --selector="planetscale.com/component=vtgate,!planetscale.com/cell"-o name | head -n1)" 15306:3306 &
process_id2=$!
sleep 2
echo "You may point your browser to http://localhost:15000, use the following aliases as shortcuts:"
echo 'alias vtctlclient="vtctlclient -server=localhost:15999 -logtostderr"'echo'alias mysql="mysql -h 127.0.0.1 -P 15306 -u user"'
echo "Hit Ctrl-C to stop the port forwards"
wait $process_id1
wait $process_id2查看 Tablets：
$ vtctlclient ListAllTablets
Handling connection for 15999
zone1-1542279354 weatherapp - replica 10.100.1.75:15000 10.100.1.75:3306 [] <null>
zone1-3763665199 weatherapp - master 10.100.3.57:15000 10.100.3.57:3306 [] 2020-10-16T09:06:59Z步骤 2 – 验证数据库
$ alias mysql="mysql -h 127.0.0.1 -P 15306 -u djangouser -p"
$ mysql
mysql: [Warning] Using a password on the command line interface can be insecure.
Handling connection for 15306
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 1
Server version: 5.7.9-Vitess MySQL Community Server (GPL)
Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.
mysql> show databases;
+------------+
| Databases |
+------------+
| weatherapp |
+------------+
1 row in set (0.16 sec)
步骤 3 – 设置应用程序环境
当初咱们曾经设置了具备 MySQL 后端的 Vitess 集群，接下来能够构建 Django 应用程序了。咱们将应用 Django-admin 命令构建一个 Django 我的项目。
$ mkdir my_weather_app
$ cd my_weather_app
$ python3 -m venv env
$ . env/bin/activate
(env) askdba:my_weather_app askdba$
$ pip install django
$ django-admin startproject weatherapp
$ cd weatherapp/
$ ls -la
total 8
drwxr-xr-x 4 askdba staff 128 Oct 16 12:19 .
drwxr-xr-x 4 askdba staff 128 Oct 16 12:18 ..
-rwxr-xr-x 1 askdba staff 666 Oct 16 12:18 manage.py
drwxr-xr-x 7 askdba staff 224 Oct 16 12:18 weatherapp
Edit configuration file and update following section.
$ vi weatherapp/settings.py [link to sample file]
import os
# Database
# https://docs.djangoproject.com/en/3.0/ref/settings/#databases
DATABASES = {
'default': {
'ENGINE': 'custom_db_backends.vitess',
'OPTIONS': {'read_default_file': '/usr/local/mysql/my.cnf',},
}
}
STATIC_ROOT = os.path.join(BASE_DIR, 'static')
...
# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True
ALLOWED_HOSTS = ['127.0.0.1']
# Application definition
...将 customs_db_backends 目录复制到我的项目目录。你能够将 Vitess 我的项目克隆到本地目录。
$ cp -r ~/vitess/support/django/custom_db_backends .
$ vi /usr/local/mysql/my.cnf [link to sample my.cnf]
[client]
database = weatherapp
user = djangouser
password = ********
port = 15306
host = 127.0.0.1
default-character-set = utf8mb4步骤 4 – 装置 MySQL 客户端连接器
$ pip install mysqlclient
Collecting mysqlclient
Using cached mysqlclient-2.0.1.tar.gz (87 kB)
Using legacy 'setup.py install' for mysqlclient, since package 'wheel' is not installed.
Installing collected packages: mysqlclient
Running setup.py install for mysqlclient ... done
Successfully installed mysqlclient-2.0.1步骤 5 – 在 Vitess 集群上构建 Django 框架
在这个阶段，咱们曾经筹备好运行迁徙来创立初始的 Django 元数据。
$ python manage.py migrate
Operations to perform:
Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
Applying contenttypes.0001_initial... OK
Applying auth.0001_initial... OK
Applying admin.0001_initial... OK
Applying admin.0002_logentry_remove_auto_add... OK
Applying admin.0003_logentry_add_action_flag_choices... OK
Applying contenttypes.0002_remove_content_type_name... OK
Applying auth.0002_alter_permission_name_max_length... OK
Applying auth.0003_alter_user_email_max_length... OK
Applying auth.0004_alter_user_username_opts... OK
Applying auth.0005_alter_user_last_login_null... OK
Applying auth.0006_require_contenttypes_0002... OK
Applying auth.0007_alter_validators_add_error_messages... OK
Applying auth.0008_alter_user_username_max_length... OK
Applying auth.0009_alter_user_last_name_max_length... OK
Applying auth.0010_alter_group_name_max_length... OK
Applying auth.0011_update_proxy_permissions... OK
Applying auth.0012_alter_user_first_name_max_length... OK
Applying sessions.0001_initial... OK步骤 6 – 创立一个管理员用户
创立一个治理用户来拜访 Django 治理界面。
$ python manage.py createsuperuser
Username (leave blank to use 'askdba'): askdba
Email address: alkin@planetscale.com
Password:
Password (again):
The password is too similar to the email address.
This password is too short. It must contain at least 8 characters.
Bypass password validation and create user anyway? [y/N]: y
Superuser created successfully.
(env) askdba:weatherapp askdba$步骤 7 – 启动 Django 守护过程
$ python manage.py runserver 127.0.0.1:8000
Watching for file changes with StatReloader
Performing system checks...
System check identified no issues (0 silenced).
October 16, 2020 - 09:37:02
Django version 3.1.2, using settings 'weatherapp.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.步骤 8 – 转到 Django 治理页面
将浏览器指向 http://127.0.0.1:8000/admin
管理员登录界面
用户 / 角色治理屏幕
你能够通过这里持续构建应用程序。
总结
Vitess 是一个十分弱小的切分框架，它带有一个内置的管制立体，容许后端开发人员轻松地调整他们的应用程序。联合弱小的应用程序框架（如 Django），开发人员能够利用开源工具的弱小性能，开箱即用地创立可伸缩的应用程序。
参考文献
How To Make a Django Blog App and Connect it to MySQL
Getting Started With Django: Build A Weather App
Django MySQL Notes
点击浏览网站原文。
CNCF (Cloud Native Computing Foundation) 成立于 2015 年 12 月，隶属于 Linux Foundation，是非营利性组织。
CNCF（云原生计算基金会）致力于培养和保护一个厂商中立的开源生态系统，来推广云原生技术。咱们通过将最前沿的模式民主化，让这些翻新为公众所用。扫描二维码关注 CNCF 微信公众号。
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