Docker & Kubernetes 3 : minikube Django with Redis and Celery

Continued from the previous Kubernetes minikube (Docker & Kubernetes 2 : minikube Django with Postgres - persistent volume), we'll use Django with additional apps such as Redis and Celery.

Kubernetes version info:

$ kubectl version
Client Version: version.Info{Major:"1", Minor:"11", GitVersion:"v1.11.3", GitCommit:"a4529464e4629c21224b3d52edfe0ea91b072862", GitTreeState:"clean", BuildDate:"2018-09-10T11:44:36Z", GoVersion:"go1.11", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"10", GitVersion:"v1.10.0", GitCommit:"fc32d2f3698e36b93322a3465f63a14e9f0eaead", GitTreeState:"clean", BuildDate:"2018-03-26T16:44:10Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"linux/amd64"}

We need to switch Python 3.6 because the Celery's "async" does not supported on 3.7.

We'll use Redis as a broker over other message brokers such as RabbitMQ, ActiveMQ or Kafka.

We'll also use Celery, an asynchronous task queue based on distributed message passing while the Redis as the message broker. Celery is task queue for a real time processing based on the producer consumer design pattern.

Picture from Python - Django

To integrate Celery with Django, create a __init__.py in the project root directory. Then another Python file celery.py in our kube_django app directory:

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'kube_django.settings')

app = Celery('kube_django')
...
app.autodiscover_tasks()

We define the environment variable DJANGO_SETTINGS_MODULE and the line, autodiscover_tasks() will run through all our modules and look for asynchronous task registered Django app configs.

from __future__ import absolute_import, unicode_literals

from .celery import app as celery_app

__all__ = ['celery_app']

After adding these codes, add the following variable into our main kube_django/settings.py:

# REDIS
REDIS_URL = "redis://{host}:{port}/1".format(
    host=os.getenv('REDIS_HOST', 'localhost'),
    port=os.getenv('REDIS_PORT', '6379')
)

CACHES = {
    "default": {
        "BACKEND": "django_redis.cache.RedisCache",
        "LOCATION": REDIS_URL,
        "OPTIONS": {
            "CLIENT_CLASS": "django_redis.client.DefaultClient"
        },
        "KEY_PREFIX": "example"
    }
}

# CELERY
BROKER_URL = REDIS_URL
CELERY_BROKER_URL = REDIS_URL

This would define the host of our Redis instance. Celery will look for variables with ‘CELERY_’ prefix in the settings.py defined in system environment.

Now, all our integration is done but definition of async tasks. To define an async task, simply import and add the decorator @shared_task to each method or function.

# Python
from datetime import datetime

# Celery
from celery import shared_task

@shared_task
def display_time():
    print("The time is %s :" % str(datetime.now()))
    return True

To spawn workers, we use the following command in deploy/celery/worker.yaml:

    spec:
      containers:
        - name: celery-worker
          image: dockerbogo/django_minikube:3.0.6
          command: ['celery', '-A', 'kube_django', 'worker', '-l', 'info']

To have a celery cron job running, we need to start celery with the celery beat command:

    spec:
      containers:
        - name: celery-worker
          image: dockerbogo/django_minikube:3.0.6
          command: ['celery', '-A', 'kube_django', 'worker', '-l', 'info']

To test if our Django app works with local virtual environment. Start the Postgres:

$ pg_ctl -D /usr/local/var/postgres start
...
...listening on IPv4 address "127.0.0.1", port 5432
...listening on Unix socket "/tmp/.s.PGSQL.5432"

 done
server started

$ postgres -V
postgres (PostgreSQL) 10.5

May need to install redis as well and run it:

$ brew install redis

$ redis-server

$ redis-client ping
Pong

Virtualenv:

$ virtualenv venv

$ source venv/bin/activate

(venv) $ pip install -r requirements.txt

(venv) $ python manage.py makemigrations

(venv) $ python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, db, sessions
Running migrations:
  No migrations to apply.

Now we can test if our app is working with database by starting up the Django development server:

(venv) $ python manage.py runserver 0.0.0.0:8000
Django version 2.1, using settings 'kube_django.settings'
Starting development server at http://0.0.0.0:8000/
Quit the server with CONTROL-C.

In the web browser, visit the server's domain name or IP address followed by :8000 to reach default Django root page:

http://server_domain_or_IP:8000

We should see the following pages:

We can see our Django app is workings. So, exit from virtualenv and move on to minikube:

(venv) $ deactivate

$ minikube start

$ kubectl config current-context
minikube

$ eval $(minikube docker-env)

Before building an image, remove "venv" if created.

Let's create the image and push it to DockerHub:

$ docker build -t dockerbogo/django-minikube-c:2.0.0 .

$ docker push dockerbogo/django-minikube-c:2.0.0

Two ways of updating resources:

1. We may want to delete any objects we created earlier and create new ones:

$ kubectl delete -f deploy/postgres/  
$ kubectl delete -f deploy/redis/
$ kubectl delete -f deploy/django/
$ kubectl delete -f deploy/celery/

$ kubectl create -f deploy/postgres/  
$ kubectl create -f deploy/redis/
$ kubectl create -f deploy/django/
$ kubectl create -f deploy/celery/

2. Or we can just use kubectl apply our configurations to create resources:

$ kubectl apply -f deploy/postgres/  
$ kubectl apply -f deploy/redis/
$ kubectl apply -f deploy/django/
$ kubectl apply -f deploy/celery/

To view the resources on our local cluster, we need to open up the minikube dashboard:

$ minikube dashboard

We can get the same info using kubectl:

$ kubectl get pods
NAME                             READY     STATUS      RESTARTS   AGE
celery-beat-7c67bb87b8-p5vcj     1/1       Running     0          1h
celery-worker-7f4554cbd5-vtxv5   1/1       Running     0          1h
django-6c6b4c979f-lzxg8          1/1       Running     0          1h
django-migrations-fzdsj          0/1       Completed   0          1h
postgres-69c85f5989-fwmkz        1/1       Running     0          1h
redis-dc494cb76-r88dz            1/1       Running     0          1h


$ kubectl get services
NAME               TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
django-service     NodePort       10.99.185.28    <pending>     8000:30236/TCP   50m
kubernetes         ClusterIP      10.96.0.1       <none>        443/TCP          4h
postgres-service   ClusterIP      10.105.67.218   <none>        5432/TCP         50m
redis-service      ClusterIP      10.101.60.2     <none>        6379/TCP         50m

For debugging, we can use:

$ kubectl describe pod celery-beat-559b598c74-fn6sp

$ kubectl logs celery-beat-559b598c74-fn6sp

$ minikube service django-service --url
http://192.168.99.100:32289

Source files - kubernetes_django/minikube-3/

Kubernetes, Local to Production with Django: 4 - Celery with Redis and Flower

Asynchronous Tasks with Celery + Redis in Django

Docker & K8s

1. Docker install on Amazon Linux AMI
2. Docker install on EC2 Ubuntu 14.04
3. Docker container vs Virtual Machine
4. Docker install on Ubuntu 14.04
5. Docker Hello World Application
6. Nginx image - share/copy files, Dockerfile
7. Working with Docker images : brief introduction
8. Docker image and container via docker commands (search, pull, run, ps, restart, attach, and rm)
9. More on docker run command (docker run -it, docker run --rm, etc.)
10. Docker Networks - Bridge Driver Network
11. Docker Persistent Storage
12. File sharing between host and container (docker run -d -p -v)
13. Linking containers and volume for datastore
14. Dockerfile - Build Docker images automatically I - FROM, MAINTAINER, and build context
15. Dockerfile - Build Docker images automatically II - revisiting FROM, MAINTAINER, build context, and caching
16. Dockerfile - Build Docker images automatically III - RUN
17. Dockerfile - Build Docker images automatically IV - CMD
18. Dockerfile - Build Docker images automatically V - WORKDIR, ENV, ADD, and ENTRYPOINT
19. Docker - Apache Tomcat
20. Docker - NodeJS
21. Docker - NodeJS with hostname
22. Docker Compose - NodeJS with MongoDB
23. Docker - Prometheus and Grafana with Docker-compose
24. Docker - StatsD/Graphite/Grafana
25. Docker - Deploying a Java EE JBoss/WildFly Application on AWS Elastic Beanstalk Using Docker Containers
26. Docker : NodeJS with GCP Kubernetes Engine
27. Docker : Jenkins Multibranch Pipeline with Jenkinsfile and Github
28. Docker : Jenkins Master and Slave
29. Docker - ELK : ElasticSearch, Logstash, and Kibana
30. Docker - ELK 7.6 : Elasticsearch on Centos 7
31. Docker - ELK 7.6 : Filebeat on Centos 7
32. Docker - ELK 7.6 : Logstash on Centos 7
33. Docker - ELK 7.6 : Kibana on Centos 7
34. Docker - ELK 7.6 : Elastic Stack with Docker Compose
35. Docker - Deploy Elastic Cloud on Kubernetes (ECK) via Elasticsearch operator on minikube
36. Docker - Deploy Elastic Stack via Helm on minikube
37. Docker Compose - A gentle introduction with WordPress
38. Docker Compose - MySQL
39. MEAN Stack app on Docker containers : micro services
40. MEAN Stack app on Docker containers : micro services via docker-compose
41. Docker Compose - Hashicorp's Vault and Consul Part A (install vault, unsealing, static secrets, and policies)
42. Docker Compose - Hashicorp's Vault and Consul Part B (EaaS, dynamic secrets, leases, and revocation)
43. Docker Compose - Hashicorp's Vault and Consul Part C (Consul)
44. Docker Compose with two containers - Flask REST API service container and an Apache server container
45. Docker compose : Nginx reverse proxy with multiple containers
46. Docker & Kubernetes : Envoy - Getting started
47. Docker & Kubernetes : Envoy - Front Proxy
48. Docker & Kubernetes : Ambassador - Envoy API Gateway on Kubernetes
49. Docker Packer
50. Docker Cheat Sheet
51. Docker Q & A #1
52. Kubernetes Q & A - Part I
53. Kubernetes Q & A - Part II
54. Docker - Run a React app in a docker
55. Docker - Run a React app in a docker II (snapshot app with nginx)
56. Docker - NodeJS and MySQL app with React in a docker
57. Docker - Step by Step NodeJS and MySQL app with React - I
58. Installing LAMP via puppet on Docker
59. Docker install via Puppet
60. Nginx Docker install via Ansible
61. Apache Hadoop CDH 5.8 Install with QuickStarts Docker
62. Docker - Deploying Flask app to ECS
63. Docker Compose - Deploying WordPress to AWS
64. Docker - WordPress Deploy to ECS with Docker-Compose (ECS-CLI EC2 type)
65. Docker - WordPress Deploy to ECS with Docker-Compose (ECS-CLI Fargate type)
66. Docker - ECS Fargate
67. Docker - AWS ECS service discovery with Flask and Redis
68. Docker & Kubernetes : minikube
69. Docker & Kubernetes 2 : minikube Django with Postgres - persistent volume
70. Docker & Kubernetes 3 : minikube Django with Redis and Celery
71. Docker & Kubernetes 4 : Django with RDS via AWS Kops
72. Docker & Kubernetes : Kops on AWS
73. Docker & Kubernetes : Ingress controller on AWS with Kops
74. Docker & Kubernetes : HashiCorp's Vault and Consul on minikube
75. Docker & Kubernetes : HashiCorp's Vault and Consul - Auto-unseal using Transit Secrets Engine
76. Docker & Kubernetes : Persistent Volumes & Persistent Volumes Claims - hostPath and annotations
77. Docker & Kubernetes : Persistent Volumes - Dynamic volume provisioning
78. Docker & Kubernetes : DaemonSet
79. Docker & Kubernetes : Secrets
80. Docker & Kubernetes : kubectl command
81. Docker & Kubernetes : Assign a Kubernetes Pod to a particular node in a Kubernetes cluster
82. Docker & Kubernetes : Configure a Pod to Use a ConfigMap
83. AWS : EKS (Elastic Container Service for Kubernetes)
84. Docker & Kubernetes : Run a React app in a minikube
85. Docker & Kubernetes : Minikube install on AWS EC2
86. Docker & Kubernetes : Cassandra with a StatefulSet
87. Docker & Kubernetes : Terraform and AWS EKS
88. Docker & Kubernetes : Pods and Service definitions
89. Docker & Kubernetes : Service IP and the Service Type
90. Docker & Kubernetes : Kubernetes DNS with Pods and Services
91. Docker & Kubernetes : Headless service and discovering pods
92. Docker & Kubernetes : Scaling and Updating application
93. Docker & Kubernetes : Horizontal pod autoscaler on minikubes
94. Docker & Kubernetes : From a monolithic app to micro services on GCP Kubernetes
95. Docker & Kubernetes : Rolling updates
96. Docker & Kubernetes : Deployments to GKE (Rolling update, Canary and Blue-green deployments)
97. Docker & Kubernetes : Slack Chat Bot with NodeJS on GCP Kubernetes
98. Docker & Kubernetes : Continuous Delivery with Jenkins Multibranch Pipeline for Dev, Canary, and Production Environments on GCP Kubernetes
99. Docker & Kubernetes : NodePort vs LoadBalancer vs Ingress
100. Docker & Kubernetes : MongoDB / MongoExpress on Minikube
101. Docker & Kubernetes : Load Testing with Locust on GCP Kubernetes
102. Docker & Kubernetes : MongoDB with StatefulSets on GCP Kubernetes Engine
103. Docker & Kubernetes : Nginx Ingress Controller on Minikube
104. Docker & Kubernetes : Setting up Ingress with NGINX Controller on Minikube (Mac)
105. Docker & Kubernetes : Nginx Ingress Controller for Dashboard service on Minikube
106. Docker & Kubernetes : Nginx Ingress Controller on GCP Kubernetes
107. Docker & Kubernetes : Kubernetes Ingress with AWS ALB Ingress Controller in EKS
108. Docker & Kubernetes : Setting up a private cluster on GCP Kubernetes
109. Docker & Kubernetes : Kubernetes Namespaces (default, kube-public, kube-system) and switching namespaces (kubens)
110. Docker & Kubernetes : StatefulSets on minikube
111. Docker & Kubernetes : RBAC
112. Docker & Kubernetes Service Account, RBAC, and IAM
113. Docker & Kubernetes - Kubernetes Service Account, RBAC, IAM with EKS ALB, Part 1
114. Docker & Kubernetes : Helm Chart
115. Docker & Kubernetes : My first Helm deploy
116. Docker & Kubernetes : Readiness and Liveness Probes
117. Docker & Kubernetes : Helm chart repository with Github pages
118. Docker & Kubernetes : Deploying WordPress and MariaDB with Ingress to Minikube using Helm Chart
119. Docker & Kubernetes : Deploying WordPress and MariaDB to AWS using Helm 2 Chart
120. Docker & Kubernetes : Deploying WordPress and MariaDB to AWS using Helm 3 Chart
121. Docker & Kubernetes : Helm Chart for Node/Express and MySQL with Ingress
122. Docker & Kubernetes : Deploy Prometheus and Grafana using Helm and Prometheus Operator - Monitoring Kubernetes node resources out of the box
123. Docker & Kubernetes : Deploy Prometheus and Grafana using kube-prometheus-stack Helm Chart
124. Docker & Kubernetes : Istio (service mesh) sidecar proxy on GCP Kubernetes
125. Docker & Kubernetes : Istio on EKS
126. Docker & Kubernetes : Istio on Minikube with AWS EC2 for Bookinfo Application
127. Docker & Kubernetes : Deploying .NET Core app to Kubernetes Engine and configuring its traffic managed by Istio (Part I)
128. Docker & Kubernetes : Deploying .NET Core app to Kubernetes Engine and configuring its traffic managed by Istio (Part II - Prometheus, Grafana, pin a service, split traffic, and inject faults)
129. Docker & Kubernetes : Helm Package Manager with MySQL on GCP Kubernetes Engine
130. Docker & Kubernetes : Deploying Memcached on Kubernetes Engine
131. Docker & Kubernetes : EKS Control Plane (API server) Metrics with Prometheus
132. Docker & Kubernetes : Spinnaker on EKS with Halyard
133. Docker & Kubernetes : Continuous Delivery Pipelines with Spinnaker and Kubernetes Engine
134. Docker & Kubernetes : Multi-node Local Kubernetes cluster : Kubeadm-dind (docker-in-docker)
135. Docker & Kubernetes : Multi-node Local Kubernetes cluster : Kubeadm-kind (k8s-in-docker)
136. Docker & Kubernetes : nodeSelector, nodeAffinity, taints/tolerations, pod affinity and anti-affinity - Assigning Pods to Nodes
137. Docker & Kubernetes : Jenkins-X on EKS
138. Docker & Kubernetes : ArgoCD App of Apps with Heml on Kubernetes
139. Docker & Kubernetes : ArgoCD on Kubernetes cluster
140. Docker & Kubernetes : GitOps with ArgoCD for Continuous Delivery to Kubernetes clusters (minikube) - guestbook