Wednesday, March 8, 2017

Docker Build Your Own Image

Before moving forward make sure, you have up and running Docker service

 In this example, I will be using flask-app 

 Ref: https://training.docker.com/user/consume/course_pathway/7c7fcfcb-8e2f-32dc-9531-1db82f671120/92/aa9e230a-6617-3e0b-a8ba-d6f6245aee0a?complete=0&tab=overview

 1) Create directory called flask-app

 mkdir flask-app
cd flask-app
2) Create a file app.py

 cat > app.py

 from flask import Flask, render_template
import random

 app = Flask(__name__)

 # list of cat images
images = [
    "http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr05/15/9/anigif_enhanced-buzz-26388-1381844103-11.gif",
    "http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr01/15/9/anigif_enhanced-buzz-31540-1381844535-8.gif",
    "http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr05/15/9/anigif_enhanced-buzz-26390-1381844163-18.gif",
    "http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr06/15/10/anigif_enhanced-buzz-1376-1381846217-0.gif",
    "http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr03/15/9/anigif_enhanced-buzz-3391-1381844336-26.gif",
    "http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr06/15/10/anigif_enhanced-buzz-29111-1381845968-0.gif",
    "http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr03/15/9/anigif_enhanced-buzz-3409-1381844582-13.gif",
    "http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr02/15/9/anigif_enhanced-buzz-19667-1381844937-10.gif",
    "http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr05/15/9/anigif_enhanced-buzz-26358-1381845043-13.gif",
    "http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr06/15/9/anigif_enhanced-buzz-18774-1381844645-6.gif",
    "http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr06/15/9/anigif_enhanced-buzz-25158-1381844793-0.gif",
    "http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr03/15/10/anigif_enhanced-buzz-11980-1381846269-1.gif"
]

 @app.route('/')
def index():
    url = random.choice(images)
    return render_template('index.html', url=url)

 if __name__ == "__main__":
    app.run(host="0.0.0.0")
#########################
3) Create a file called requirements.txt

 cat > requirements.txt

 Flask =0.10.1
4) Create directory templates and then file index.html in it

 mkdir templates
cat  > templates/index.html

 <html>
  <head>
    <style type="text/css">
      body {
        background: black;
        color: white;
      }
      div.container {
        max-width: 500px;
        margin: 100px auto;
        border: 20px solid white;
        padding: 10px;
        text-align: center;
      }
      h4 {
        text-transform: uppercase;
      }
    </style>
  </head>
  <body>
    <div class="container">
      <h4>Cat Gif of the day</h4>
      <img src="{{url}}" />
      <p><small>Courtesy: <a href="http://www.buzzfeed.com/copyranter/the-best-cat-gif-post-in-the-history-of-cat-gifs">Buzzfeed</a></small></p>
    </div>
  </body>
</html>
5) Write a Dockerfile, create a file called Dockerfile in flask-app directory with following content

 FROM alipine:3.5

 RUN apk add --update py2-pip

 COPY requirements.txt /usr/src/app/
RUN pip install --no-cache-dir -r /usr/src/app/requirements.txt

 COPY app.py /usr/src/app/
COPY templates/index.html /usr/src/app/templates

 EXPOSE 5000

 CMD ["python", "/usr/src/app/app.py"]
6) Verify Dockerfile

 ##out base image
FROM alpine:3.5

 # Install python and pip
RUN apk add --update py2-pip

 # Install python modules needed by the python app
COPY requirements.txt /usr/src/app/
RUN pip install --no-cache-dir -r /usr/src/app/requirements.txt

 # copy files required for the app to run
COPY app.py /usr/src/app/
COPY templates/index.html /usr/src/app/templates/

 # tell the port number the container should expose
EXPOSE 5000

 # run the application
CMD ["python", "/usr/src/app/app.py"]
7) Build the image (make sure you are in flask-app where Dockerfile exists)

 docker build -t manoj/myfirstapp .

 It's output in last lines will be 

 Removing intermediate container 65fce60d1108
Step 8/8 : CMD python /usr/src/app/app.py
 ---> Running in 59d87e1975ed
 ---> af2bf7953190
Removing intermediate container 59d87e1975ed
Successfully built af2bf7953190

 8) Now its time to run your own image

 docker run -p 8888:5000 --name myfirstapp manoj/myfirstapp

 8888 is the port will be running on Docker Host and 5000 port which we exposed in container
Output should be like

  docker run -p 8888:5000 --name myfirstapp manoj/myfirstapp

  * Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)
9) Now try browsing http://docker-host:8888
10) Its time push your repository to Docker Hub if you want

 1st login to docker using command line

 docker login --username=manojXXXX

 this will prompt for password, enter password to connect to you account
11) As login is successful, We can tag our image to our docker username and change its path similar to our docker hub account like

 docker tag manoj/myfirstapp manojXXXX/flask-app
12) Now we can push our image to Docker Hub, with latest tag

 docker push manojsamtani/flask-app:latest

 Output should be like

 The push refers to a repository [docker.io/manojsamtani/flask-app]
806f2b9df705: Pushed 
8b394632d523: Pushed 
decd7faa1c3f: Pushed 
3cb442886a35: Pushed 
f18037a76d54: Pushed 
23b9c7b43573: Pushed 
latest: digest: sha256:5a1f8cf7518c532867a835a225bbe1256cb1baaec06029093ae112089765efd2 size: 1572
13) Now we can stop/remove containers locally

 docker stop myfirstapp

 docker rm myfirstapp

 or

 docker rm -f myfirstapp
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Tuesday, March 7, 2017

Docker : Static Website

Before moving forward make sure, you have up and running Docker service

1) Run a static website in a container

docker run -d seqvence/static-site

So, what happens when you run this command?Since the image doesn't exist on your Docker host, the Docker daemon first fetches it from the registry and then runs it as a containerThe -d flag enables detached mode, which detaches the running container from the terminal/shell and returns your prompt after the container starts

2) Verify if container in running state

docker ps

CONTAINER ID    IMAGE    COMMAND    CREATED   STATUS    PORTS   NAME

Sb3b30fab0bc2        seqvence/static-site   "/bin/sh -c 'cd /u..."   5 seconds ago       Up 4 seconds        80/tcp, 443/tcp     wizardly_hypatia

3) But running container like in step 1) will not expose ports running in container to host machine. So, we need mention following flags for mapping/publish container ports on Docker Host

  • -d will create a container with the process detached from our terminal
  • -P will publish all the exposed container ports to random ports on the Docker host
  • -e is how you pass environment variables to the container
  • --name allows you to specify a container name
  • AUTHOR is the environment variable name and Your Name is the value that you can pass
docker run --name static-site -e AUTHOR="Your Name" -d -P seqvence/static-site

4) Now run below command to see how ports are published on docker host

docker port static-site443/tcp -&gt; 0.0.0.0:3276880/tcp -&gt; 0.0.0.0:32769

5) Try running http://docker-host:32768

6) If we need to map/publish custom host port to the container web server. Try running site 2 at the same time with custom port

docker run --name static-site-2 -e AUTHOR="Manoj Kumar" -d -p 8888:80 seqvence/static-site

docker ps

CONTAINER ID    IMAGE     COMMAND    CREATED       STATUS         PORTS          NAMES
c5d9d6bc66d1        seqvence/static-site   "/bin/sh -c 'cd /u..."   3 seconds ago       Up 3 seconds        443/tcp, 0.0.0.0:8888-&gt;80/tcp                   static-site-2

7) Try running http://docker-host:8888

NOTE: If you have stopped container and trying to start container again with different environment variable, if will through conflict as container already created and in stopped state. If you want to pass more/updated environment variables, 1st remove container and start again



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