# python-app-docker-demo This demo shows two steps: + Install `docker-ce` on Centos 7 + Build and run a simple docker image with a python+flask+gunicorn web application. ## Install docker-ce on Centos 7 Refer to https://docs.docker.com/engine/installation/linux/docker-ce/centos/ You can also find [other OS installation docs from here](https://docs.docker.com/engine/installation). #### Uninstall old versions ``` $ sudo yum remove docker \ docker-common \ docker-selinux \ docker-engine ``` #### Install using repository ``` sudo yum install -y yum-utils device-mapper-persistent-data lvm2 sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo sudo yum install docker-ce sudo systemctl start docker sudo docker run hello-world ``` Other commands: + check docker status ``` sudo systemctl status docker.service ``` + stop docker ``` sudo systemctl stop docker ``` + uninstall docker-ce ``` sudo yum remove docker-ce ``` + remove all images, container, volumes ``` sudo rm -rf /var/lib/docker ``` ## Build/Run a simple python+flask docker web app #### Create the Dockerfile ``` FROM python:2.7 # Creating Application Source Code Directory RUN mkdir -p /usr/src/app # Setting Home Directory for containers WORKDIR /usr/src/app # Installing python dependencies COPY requirements.txt /usr/src/app/ RUN pip install --no-cache-dir -r requirements.txt # Copying src code to Container COPY . /usr/src/app # Application Environment variables #ENV APP_ENV development ENV PORT 8080 # Exposing Ports EXPOSE $PORT # Setting Persistent data VOLUME ["/app-data"] # Running Python Application CMD gunicorn -b :$PORT -c gunicorn.conf.py main:app ``` #### Build your image Normally, image name convention is something like: ` {company/application-name}:{version-number}`. In the demo, I just use `{application-name}:{version-number}` ``` sudo docker build -t my-python-app:1.0.1 . ``` #### check all docker images ``` $ sudo docker images REPOSITORY TAG IMAGE ID CREATED SIZE my-python-app 1.0.1 2b628d11ba3a 22 minutes ago 701.6 MB docker.io/python 2.7 b1d5c2d7dda8 13 days ago 679.3 MB docker.io/hello-world latest 05a3bd381fc2 5 weeks ago 1.84 kB ``` `2b628d11ba3a` is the image ID, some commands based on the ID. + tag ``` sudo docker tag 2b628d11ba3a my-python-app:1.0.1 sudo docker tag 2b628d11ba3a my-python-app:latest ``` + remove image ``` $ sudo docker rmi --force 2b628d11ba3a ``` #### Run your image ``` $ sudo docker run -d -p 8080:8080 my-python-app:1.0.1 ``` You can use `sudo docker ps` to list all running containers. ``` $ sudo docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 4de6041072b7 my-python-app:1.0.1 "/bin/sh -c 'gunicorn" 20 minutes ago Up 20 minutes 0.0.0.0:8080->8080/tcp elegant_kowalevski ``` `4de6041072b7` is the running container id. Some commands below are what you might need. + display logs in running container ``` $ sudo docker logs 4de6041072b7 [2017-10-23 20:29:49 +0000] [7] [INFO] Starting gunicorn 19.6.0 [2017-10-23 20:29:49 +0000] [7] [INFO] Listening at: http://0.0.0.0:8080 (7) [2017-10-23 20:29:49 +0000] [7] [INFO] Using worker: gthread [2017-10-23 20:29:49 +0000] [11] [INFO] Booting worker with pid: 11 [2017-10-23 20:29:49 +0000] [12] [INFO] Booting worker with pid: 12 ``` + stop your container ``` $ sudo docker stop 4de6041072b7 ``` + login inside the container ``` $ sudo docker exec -it 4de6041072b7 /bin/sh # ls /usr/src/app Dockerfile README.md gunicorn.conf.py gunicorn_pid.txt main.py main.pyc requirements.txt # exit ``` #### Test your application ``` $ curl http://localhost:8080 Hello World ``` # python-sample