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Python Container

Setup​

  1. Create python scripts (e.g. index.py)

  2. In project’s root, add the following files

    1. Dockerfile
    2. docker-compose.yml
    3. .dockerignore

  3. Build Docker container using Docker cli commands or docker-compose

Docker CLI Commands​

Build container​

docker build -t docker-container-name .

Run previously built container​

docker run docker-container-name

Docker Compose Commands​

Build container​

docker-compose up -d --build

Run previously built container​

docker-compose up

Stop running container​

docker-compose stop

Non-Interactive Python Script Example​

Sample package.json​

package.json
{
  "name": "python-docker-example",
  "version": "0.0.0",
  "scripts": {
    "docker-build": "docker build -t python-docker-example .",
    "docker-run": "docker run python-docker-example",
    "dc-build": "docker-compose up -d --build",
    "dc-up": "docker-compose up",
    "dc-stop": "docker-compose stop"
  },
  "private": true
}

index.py​

print ("Hello World")

Dockerfile​

# pull official base image
FROM python

# set working directory
WORKDIR /usr/src/app

# Copy the rest of your app's source code from your host to your image filesystem.
COPY . .

# execute python script
CMD ["python", "./index.py"]

.dockerignore​

.dockerignore
.editorconfig
.git
.gitignore
*.md
Dockerfile
Dockerfile.prod
docker-compose.yml

docker-compose.yml​

version: '3.7'

services:
  python-docker-example:
    container_name: python-docker-example
    build:
      context: .
      dockerfile: Dockerfile
    image: python-docker-example
    volumes:
      - '.:/usr/src/app'

Write to Host​

In this example, the Python script will create and write to a .txt file in a folder named ‘output’.

index.py​

import os
from datetime import datetime

today = datetime.today()
dateFormat = "%m-%d-%Y %H:%M:%S"
generatedFilename = "output/test-generated.txt"

# Remove generated file from output directory if it already exists
if os.path.exists(generatedFilename):
  os.remove(generatedFilename)
  print("Removed existing file from output directory")

# Create file and write to it
with open(generatedFilename, "w") as file:
    file.write("Hello World!\n" + today.strftime(dateFormat))

    # Print some info about the file to the console
    lastModifiedTime = os.path.getmtime(generatedFilename)
    lastModifiedDate = datetime.fromtimestamp(lastModifiedTime)
    print("Created " + generatedFilename + " (" + lastModifiedDate.strftime(dateFormat) + ")")

Dockerfile​

# Create a container based on a parent Python container.
FROM python

# Create a directory to save the Python script's generated file to.
# We'll bind mount this directory when running the container so we have access to the file in the host.
RUN mkdir /output

# Copy the Python script into the root of the container
ADD index.py /

# Execute the Python script
CMD ["python", "./index.py"]

README.md​

README.md
# Basic Python Docker example

## Build the Docker container

`
docker build -t python-write-host .
`

## Run the Docker container with a bind mount so we can get the file created by the Python script

When creating a bind mount (hostDir:containerDir), use the absolute path to the host.

`
docker run -v /Users/jcornwell/workspaces/docker-examples/python-write-to-host/output:/output python-write-host
`

You can also use the --mount param to specify the bind mount on a directory. Using this approach, I was able to specify a relative path on the host.

`
docker run --mount type=bind,source="$(pwd)"/output,target=/output python-write-host
`