build_container.md

Build the app’s container image

in order to build the application, we need to use a Dockerfile. A Dockerfile is simply a text-based script of instructions that is used to create a container image

1. Get the app from git

https://github.com/UniCourt/Analytics-Workshop1 ==> clone this repo or download zip

Unzip the file and cd into the app folder.

2. Create a file named Dockerfile in the above folder with the following contents.

FROM python:3.7-alpine

ENV FLASK_APP=app.py
ENV FLASK_RUN_HOST=0.0.0.0

COPY . /app
WORKDIR /app
RUN pip install -r requirements.txt


CMD ["flask", "run"]

Contents of Dockerfile:
a. Get the base image: FROM python:3.7-alpine. This pulls the base python 3.7 image.
b. Declaring environment variables.
c. Copy the custom code into the image by COPY . /app and change working directory.
c. Install required packages in the image. RUN pip install -r requirements.txt.

3. Create a new requirements.txt file with following contents

Flask
psycopg2-binary

This will install Flask and psycopg2-binary, which is required for postgres connection.

4. open a terminal and go to the app directory with the Dockerfile. Now build the container image using the docker build command

docker build -t app-new .

Start an app container

Start your container using the docker run command and specify the name of the image we just created

docker run app-new

Note: Do not panic if you see errors mentioned below in your terminal, this is because we do not have necessary things to connect to db

KeyError: 'POSTGRES_USER'

To view the running container

docker ps

This will list all the running containers.

To stop the running container

docker stop <container if that you see when you run>