Python项目容器化实践(八) - 将lyanna应用部署在本地Kubernetes上运行
/ / / 阅读数:5405上篇已经演示了 lyanna 用到的 Memcached、Redis、Mariadb、arq 等内容,这篇介绍 lyanna 应用以及怎么在本地跑起来它。
lyanna 应用
应用配置都在 k8s/app.yaml 里面,直接在代码中注释:
apiVersion: apps/v1 kind: Deployment # lyanna应用是无状态的应用,所以选择用Deployment这种资源对象 metadata: name: lyanna-deployment labels: app.kubernetes.io/name: lyanna spec: replicas: 4 # 启动4个副本(进程)接受请求 selector: matchLabels: app.kubernetes.io/name: lyanna # 这个和Service部分一致,服务请求会打到符合这个标记的Pod上 strategy: rollingUpdate: # 使用滚动更新 maxSurge: 25% # 指定可以超过期望的Pod数量的最大百分比,当然写个数也可以,这里表示最多可以部署5个 maxUnavailable: 25% # 指定在升级过程中不可用Pod的最大数量,这里表示允许最多一个Pod不可用 type: RollingUpdate template: metadata: labels: app.kubernetes.io/name: lyanna spec: containers: # Pod里只有一个容器 - image: dongweiming/lyanna:latest # 每次push代码到master后,Docker服务会自动构建latest标签的镜像 name: lyanna-web command: ['sh', '-c', './gunicorn app:app --bind 0.0.0.0:8000 --worker-class sanic.worker.GunicornWorker --threads=2'] # 运行的命令和之前类似,没有直接用python app.py,而是用Python应用服务器gunicorn env: # 指定环境变量,之前配置的各种服务都是通过环境变量让应用获得的(当然变量的值可能是一个内部域名) - name: MEMCACHED_HOST valueFrom: configMapKeyRef: name: lyanna-cfg key: memcached_host - name: DB_URL valueFrom: configMapKeyRef: name: lyanna-cfg key: db_url - name: REDIS_SENTINEL_SVC_HOST valueFrom: configMapKeyRef: name: lyanna-cfg key: redis_sentinel_host - name: REDIS_SENTINEL_SVC_POST valueFrom: configMapKeyRef: name: lyanna-cfg key: redis_sentinel_port - name: PYTHONPATH # 依然需要PYTHONPATH value: $PYTHONPATH:/usr/local/src/aiomcache:/usr/local/src/tortoise:/usr/local/src/arq:/usr/local/src #imagePullPolicy: Always imagePullPolicy: IfNotPresent ports: - containerPort: 8000 name: http protocol: TCP initContainers: # 使用了init容器配置,也就是先要做下面三种检查,都可用了才启动容器lyanna-web - name: init-memcached # 确认memcached服务正常 image: busybox command: ['sh', '-c', 'until nslookup lyanna-memcached; do echo waiting for Memcached; sleep 0.5; done;'] - name: init-redis # 确认redis服务正常 image: busybox command: ['sh', '-c', 'until nslookup redis-sentinel; do echo waiting for Redis; sleep 0.5; done;'] - name: init-mariadb # 确认mariadb服务正常 image: busybox command: ['sh', '-c', 'until nslookup lyanna-mariadb; do echo waiting for MariaDB; sleep 0.5; done;'] restartPolicy: Always --- apiVersion: v1 kind: Service # 对外提供Service的配置 metadata: name: lyanna-svc labels: app.kubernetes.io/name: lyanna spec: ports: - name: http port: 80 # 暴露80端口 protocol: TCP targetPort: 8000 # 流量转发到Pod的8000端口 selector: app.kubernetes.io/name: lyanna # 这个要和前面Deployment的选择器条件一致 sessionAffinity: ClientIP # 用户的所有后续请求都会被分发到同一台应用服务器上 type: NodePort --- apiVersion: extensions/v1beta1 kind: Ingress # Ingress服务 metadata: name: lyanna-ing labels: app.kubernetes.io/name: lyanna spec: rules: - host: lyanna.local http: paths: - backend: serviceName: lyanna-svc # 后端都由lyanna-svc服务来处理 servicePort: 80 path: / |
这里面有 2 个重点:
command。容器里面运行的命令没有指定 workers 参数 (-w),也就是没有显式的控制 Gunicorn 进程数,事实上在容器里面只运行了一个 Master + 一个 Worker。一开始我理解它是单个进程,所以按照之前官方优化建议 (延伸阅读链接 1) 加了这么一段
--workers=`python -c "import multiprocessing;print(multiprocessing.cpu_count() * 2 + 1)"` |
虚拟机一会就卡顿到崩溃甚至需要我重建虚拟机... 一个不成熟的建议是希望大家不要试图在容器中使用多进程。
Ingress。之前的文章中我使用 Traefik 作为 Ingress 控制器,后来问了下我厂用的是官方的 NGINX Ingress (延伸阅读链接 2),所以这次我也换用了它。另外用那种 Ingress 控制器,配置文件都是一样的不用动。
安装 NGINX Ingress
在 Minikube 虚拟机搭建 NGINX Ingress 非常方便:
❯ minikube addons enable ingress ✅ ingress was successfully enabled ❯ echo "$(minikube ip) lyanna.local" | sudo tee -a /etc/hosts # 指一下本机的host文件,一会访问这个域名就能看到本地运行效果了 |
这样就可以了,稍等一会可以在系统 Pod 列表中找到控制器是运行状态:
❯ kubectl get pods -n kube-system ❯ kubectl get pods -n kube-system | grep nginx-ingress-controller nginx-ingress-controller-57bf9855c8-lb8nl 1/1 Running 71 24h |
如果发现镜像没有拉下来是网络问题,可以使用代理后手动 pull 或者使用国内源再打回标签:
# 方法1: 使用代理后 ❯ docker pull quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.25.1 # 未来可能镜像版本会改变 # 方法2: 使用国内源 ❯ docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/nginx-ingress-controller:0.25.1 ❯ docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/nginx-ingress-controller:0.25.1 quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.25.1 ❯ docker rmi registry.cn-hangzhou.aliyuncs.com/google_containers/nginx-ingress-controller:0.25.1 |
本地部署 lyanna
我重新把整个部署过程演示一遍:
❯ minikube start --vm-driver hyperkit --cache-images --image-repository=registry.cn-hangzhou.aliyuncs.com/google_containers # 启动使用hyperkit驱动的虚拟机,使用国内源 ❯ minikube ssh # 进入虚拟机 $ sudo mkdir -p /etc/docker $ sudo tee /etc/docker/daemon.json <<-'EOF' # 添加国内源,要不然拉镜像很慢 { "registry-mirrors" : [ "http://hub-mirror.c.163.com", "http://docker.mirrors.ustc.edu.cn", "http://dockerhub.azk8s.cn" ], "experimental" : false, "debug" : true } EOF $ sudo systemctl daemon-reload $ sudo systemctl restart docker # 重启Docker进程 $ exit # 退出虚拟机 ❯ kubectl apply -f k8s/ -R # 创建lyanna需要的全部资源对象 deployment.apps/lyanna-deployment created service/lyanna-svc created ingress.extensions/lyanna-ing created daemonset.apps/lyanna-arq created configmap/lyanna-cfg created statefulset.apps/lyanna-memcached created service/lyanna-memcached created persistentvolume/mariadb-master created persistentvolume/mariadb-slave created configmap/lyanna-mariadb-master created configmap/lyanna-mariadb-slave created statefulset.apps/lyanna-mariadb-master created statefulset.apps/lyanna-mariadb-slave created service/lyanna-mariadb created service/lyanna-mariadb-slave created pod/redis-master created service/redis-sentinel created replicaset.apps/redis created replicaset.apps/redis-sentinel created # 第一次需要拉镜像需要等几分钟,之后再看都应该是Running状态 ❯ kubectl get pods NAME READY STATUS RESTARTS AGE lyanna-arq-g22j8 1/1 Running 1 8m45s lyanna-deployment-5c59c6b5d5-6lvwn 1/1 Running 0 8m45s lyanna-deployment-5c59c6b5d5-7hz5c 1/1 Running 0 8m44s lyanna-deployment-5c59c6b5d5-8vmcv 1/1 Running 0 8m44s lyanna-deployment-5c59c6b5d5-rqf78 1/1 Running 0 8m44s lyanna-mariadb-master-0 1/1 Running 0 8m44s lyanna-mariadb-slave-0 1/1 Running 0 8m45s lyanna-memcached-0 1/1 Running 0 8m45s lyanna-memcached-1 1/1 Running 0 4m32s lyanna-memcached-2 1/1 Running 0 4m24s redis-jnrwn 1/1 Running 1 8m44s redis-kzkv5 1/1 Running 1 8m44s redis-master 2/2 Running 0 8m46s redis-sentinel-6v5kq 1/1 Running 0 8m44s # 基本看Pod的名字就知道它属于那一部分了 # 接着需要支持初始化脚本setup.sh,在有lyanna源代码的任意Pod上执行即可,例如下面这样: ❯ kubectl exec -it lyanna-deployment-5c59c6b5d5-6lvwn -- sh -c ./setup.sh Init Finished! User admin created!!! ID: 1 # 在看看Service/DaemonSet/StatefulSet/ReplicaSet/Ingress ❯ kubectl get svc # Service NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 16m # 系统自己的 lyanna-mariadb ClusterIP None <none> 3306/TCP 12m lyanna-mariadb-slave ClusterIP None <none> 3306/TCP 12m lyanna-memcached ClusterIP None <none> 11211/TCP 12m lyanna-svc NodePort 10.104.253.19 <none> 80:30362/TCP 12m redis-sentinel ClusterIP 10.102.28.182 <none> 26379/TCP 12m ❯ kubectl get ds # DaemonSet NAME DESIRED CURRENT READY UP-TO-DATE AVAILABLE NODE SELECTOR AGE lyanna-arq 1 1 1 1 1 <none> 12m ❯ kubectl get statefulset NAME READY AGE lyanna-mariadb-master 1/1 13m lyanna-mariadb-slave 1/1 13m lyanna-memcached 3/3 13m ❯ kubectl get rs # ReplicaSet NAME DESIRED CURRENT READY AGE lyanna-deployment-5c59c6b5d5 4 4 4 13m redis 2 2 2 13m redis-sentinel 2 2 2 13m ❯ kubectl get ing # Ingress NAME HOSTS ADDRESS PORTS AGE lyanna-ing lyanna.local 80 14m |
到这里,一切正常,浏览器访问
有同学问「为什么 MariaDB 的配置要放在独立的子目录下 (k8s/optional)?」,前面介绍了我的博客运行在云服务器上,用的是云数据库所以使用 k8s 部署时不需要跑 MariaDB,我不需要使用-R
参数:
❯ kubectl apply -f k8s/ # 这样就不创建子目录下的那部分资源对象了
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当然 Redis、Memcached 等都可以作为可选的服务安装,只要修改 k8s/config.yaml 文件对应的设置项能正确连接即可。
后记
全部源码能在 lyanna 项目的 k8s 目录 下找到
nice