Docker Compose with two containers - Flask REST API service container and an Apache server container

Follow the steps from https://docs.docker.com/engine/installation/linux/ubuntu/.

In my case, Docker CE has been installed.

Version check:

$ docker -v
Docker version 17.03.1-ce, build c6d412e

Follow the steps from https://docs.docker.com/compose/install/.

$ sudo curl -L "https://github.com/docker/compose/releases/download/1.11.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose

Apply executable permissions to the binary:

$ sudo chmod +x /usr/local/bin/docker-compose

Check the version:

$ docker-compose -v
docker-compose version 1.11.2, build dfed245

Using Compose is basically a three-step process:

1. Define app's environment with a Dockerfile so it can be reproduced anywhere.
2. Define the services that make up an app in docker-compose.yml so they can be run together in an isolated environment.
3. Run docker-compose up and Compose will start and run the entire app.

Throughout this, we'll work on Ubuntu 16.04.

Our files look like this:

Flask api (api.py):

# Observatory Service

# Import framework
from flask import Flask
from flask_restful import Resource, Api

# Instantiate the app
app = Flask(__name__)
api = Api(app)

class Observatory(Resource):
    def get(self):
        return {
            'Galaxies': ['Milkyway', 'Andromeda', 
            'Large Magellanic Cloud (LMC)']
        }

# Create routes
api.add_resource(Observatory, '/')

# Run the application
if __name__ == '__main__':
    app.run(host='0.0.0.0', port=80, debug=True)

Dockerfile:

# https://hub.docker.com/r/library/python/tags/
FROM python:3-onbuild  

# Coping source in current directory into the image
# python:3-onbuild expects the source in /usr/src/app
COPY . /usr/src/app

# Commands in a list
CMD ["python", "api.py"]

requirements.txt:

Flask==0.12
flask-restful==0.3.5

docker-compose.yml:

version: '3'  # version of compose format 

services:
  observatory-service:
    build: ./observatory  # path is relative to docker-compose.yml localtion
    volumes:
      - ./observatory:/usr/src/app # mount point
    ports:
      - 5001:80  # host:container

We run the "docker-compose up" in the top directory:

$ docker-compose up
Building observatory-service
Step 1/3 : FROM python:3-onbuild
# Executing 3 build triggers...
Step 1/1 : COPY requirements.txt /usr/src/app/
 ---> Using cache
Step 1/1 : RUN pip install --no-cache-dir -r requirements.txt
 ---> Using cache
Step 1/1 : COPY . /usr/src/app
 ---> d26bdbb8c60e
Removing intermediate container 0a7aa0b401bd
Step 2/3 : COPY . /usr/src/app
 ---> b5e95d302017
Removing intermediate container 20638a1a280a
Step 3/3 : CMD python api.py
 ---> Running in d941e5cd5870
 ---> a980be543d54
Removing intermediate container d941e5cd5870
Successfully built a980be543d54
WARNING: Image for service observatory-service was built because it did not already exist. To rebuild this image you must use `docker-compose build` or `docker-compose up --build`.
Creating flask_observatory-service_1
Attaching to flask_observatory-service_1
observatory-service_1  |  * Running on http://0.0.0.0:80/ (Press CTRL+C to quit)
observatory-service_1  |  * Restarting with stat
observatory-service_1  |  * Debugger is active!
observatory-service_1  |  * Debugger PIN: 649-909-296

Let's type in "localhost:5001 into the browser:

Yes, it gives us json array of Galaxies!

One more thing to know is it reflects our updates on source code since we mounted the volume. So, let's add one more item into our Observatory (api.py):

...
class Observatory(Resource):
    def get(self):
        return {
            'Galaxies': ['Milkyway', 'Andromeda', 
            'Large Magellanic Cloud (LMC)'
            'Small Magellanic Cloud (SMC)'
            ]
        }
...

From the output on the screen, we can see the change has been detected:

...
observatory-service_1  |  * Detected change in '/usr/src/app/api.py', reloading
observatory-service_1  |  * Restarting with stat
...

Refresh the browser:

Press Ctrl+C to stop the container.

Now we want to add another container for a web site.

Let's create a new folder called "web", and write a php file (index.php):

<html>
    <head>
        <title>My Obsertory</title>
    </head>

    <body>
        <h1>Welcome to my observatory</h1>
        <ul>
            <?php
            $json = file_get_contents('http://observatory-service/');
            $obj = json_decode($json);
            $galaxies = $obj->Galaxies;
            foreach ($galaxies as $galaxy) {
                echo "<li>$galaxy</li>";
            }
            ?>
        </ul>
    </body>
</html>

The containers can communicate with each other defined in docker-compose.yml using their host name which matches the service name:

version: '3'  # version of compose format 

services:
  observatory-service:
    build: ./observatory  # path is relative to docker-compose.yml localtion
    volumes:
      - ./observatory:/usr/src/app # mount point
    ports:
      - 5001:80  # host:container

So, we can use observatory-service as hostname in our php script. When we run "docker-compose", that will be resolved to observatory-service container.

Let's modify our compose file:

version: '3'  # version of compose format 

services:
  observatory-service:
    build: ./observatory  # path is relative to docker-compose.yml localtion
    volumes:
      - ./observatory:/usr/src/app # mount point
    ports:
      - 5001:80  # host:container

  website:
    image: php:apache  # pulling image from DockerHub
    volumes:
      - ./website:/var/www/html # mount
    ports:
      - 5000:80  # host:container
    depends_on:
      - observatory-service  # website is not going to work 
                             # unless observatory-service is running

We run the compose again. It will pull up the php image, then start observatory-service, and then itwill start "website":

$ docker-compose up

Go to localhost:5000:

Stop the compose. Now we may want to run in detached mode:

$ docker-compose up -d
Starting flask_observatory-service_1
Starting flask_website_1

Now our containers are running in the background:

$ docker ps
CONTAINER ID        IMAGE                       COMMAND                  CREATED             STATUS              PORTS                  NAMES
250ba770bdd9        php:apache                  "docker-php-entryp..."   11 minutes ago      Up About a minute   0.0.0.0:5000->80/tcp   flask_website_1
f77b1ebd4783        flask_observatory-service   "python api.py"          About an hour ago   Up About a minute   0.0.0.0:5001->80/tcp   flask_observatory-service_1

As we can see our two containers are running. Note the the prefix ("flask") in "flask_observatory-service" and "flask_website_1" is from the name of the top directory: I put all files under "flask" folder.

Now, if we want to stop the container, we can issue the following command:

$ docker-compose stop
Stopping flask_website_1 ... done
Stopping flask_observatory-service_1 ... done

Find the source docker-compose.

This material is based on https://www.youtube.com/watch?v=Qw9zlE3t8Ko

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