Docker compose installing requirements.txt
Question:
In my docker image I am cloning the git master branch to retrieve code. I am using docker-compose for the development environment and running my containers with volumes. I ran across an issue when installing new project requirements from my python requirements.txt file. In the development environment, it will never install new requirements on dev environment because when re-building the image, the latest code is pulled from github.
Below is an example of my dockerfile:
FROM base
# Clone application
RUN git clone repo-url
# Install application requirements
RUN pip3 install -r app/requirements.txt
# ....
Here is my compose file:
myapp:
image: development
env_file: .env
ports:
- "8000:80"
volumes:
- .:/home/app
command: python3 manage.py runserver 0.0.0.0:8000
Is there any way to install newly added requirements after build on development?
Answers:
There are two ways you can do this.
By hand
You can enter the container and do it yourself. Downside: not automated.
$ docker-compose exec myapp bash
2912d2cd9eab# pip3 install -r /home/app/requirements.txt
Using an entrypoint script
You can use an entrypoint script that runs prep work, then runs the command.
Dockerfile:
COPY entrypoint.sh /entrypoint.sh
RUN chmod 755 /entrypoint.sh
# ... probably other stuff in here ...
CMD ["python3", "manage.py", "runserver", "0.0.0.0:8000"]
ENTRYPOINT ["/entrypoint.sh"]
entrypoint.sh:
#!/bin/sh
cd /home/app
pip3 install -r requirements.txt
# May as well do this too, while we're here.
python3 manage.py migrate
exec "$@"
The entrypoint is run like this at container startup:
/entrypoint.sh $CMD
Which expands to:
/entrypoint.sh python3 manage.py runserver 0.0.0.0:8000
The prep work is run first, then at the end of the entrypoint script, the passed-in argument(s) are exec’d. That’s your command, so entrypoint.sh exits and is replaced by your Django app server.
UPDATE:
After taking comments to chat, it came up that it is important to use exec
to run the command, instead of running it at the end of the entrypoint script like this:
python3 manage.py runserver 0.0.0.0:8000
I can’t exactly recall why it matters, but I ran into this previously as well. You need to exec the command or it will not work properly.
The way I solved this is by running two services:
- server: run the server depends on requirements
- requirements: installs requirements prior to running server
And this is how the docker-compose.yml file would look like:
version: '3'
services:
django:
image: python:3.7-alpine
volumes:
- pip37:/usr/local/lib/python3.7/site-packages
- .:/project
ports:
- 8000:8000
working_dir: /project
command: python manage.py runserver
depends_on:
- requirements
requirements:
image: python:3.7-alpine
volumes:
- pip37:/usr/local/lib/python3.7/site-packages
- .:/project
working_dir: /project
command: pip install -r requirements.txt
volumes:
pip37:
external: true
PS: I created a named volume for the pip modules so I can preserve them across different projects. You can create one yourself by running:
docker volume create mypipivolume
In my docker image I am cloning the git master branch to retrieve code. I am using docker-compose for the development environment and running my containers with volumes. I ran across an issue when installing new project requirements from my python requirements.txt file. In the development environment, it will never install new requirements on dev environment because when re-building the image, the latest code is pulled from github.
Below is an example of my dockerfile:
FROM base
# Clone application
RUN git clone repo-url
# Install application requirements
RUN pip3 install -r app/requirements.txt
# ....
Here is my compose file:
myapp:
image: development
env_file: .env
ports:
- "8000:80"
volumes:
- .:/home/app
command: python3 manage.py runserver 0.0.0.0:8000
Is there any way to install newly added requirements after build on development?
There are two ways you can do this.
By hand
You can enter the container and do it yourself. Downside: not automated.
$ docker-compose exec myapp bash
2912d2cd9eab# pip3 install -r /home/app/requirements.txt
Using an entrypoint script
You can use an entrypoint script that runs prep work, then runs the command.
Dockerfile:
COPY entrypoint.sh /entrypoint.sh
RUN chmod 755 /entrypoint.sh
# ... probably other stuff in here ...
CMD ["python3", "manage.py", "runserver", "0.0.0.0:8000"]
ENTRYPOINT ["/entrypoint.sh"]
entrypoint.sh:
#!/bin/sh
cd /home/app
pip3 install -r requirements.txt
# May as well do this too, while we're here.
python3 manage.py migrate
exec "$@"
The entrypoint is run like this at container startup:
/entrypoint.sh $CMD
Which expands to:
/entrypoint.sh python3 manage.py runserver 0.0.0.0:8000
The prep work is run first, then at the end of the entrypoint script, the passed-in argument(s) are exec’d. That’s your command, so entrypoint.sh exits and is replaced by your Django app server.
UPDATE:
After taking comments to chat, it came up that it is important to use exec
to run the command, instead of running it at the end of the entrypoint script like this:
python3 manage.py runserver 0.0.0.0:8000
I can’t exactly recall why it matters, but I ran into this previously as well. You need to exec the command or it will not work properly.
The way I solved this is by running two services:
- server: run the server depends on requirements
- requirements: installs requirements prior to running server
And this is how the docker-compose.yml file would look like:
version: '3'
services:
django:
image: python:3.7-alpine
volumes:
- pip37:/usr/local/lib/python3.7/site-packages
- .:/project
ports:
- 8000:8000
working_dir: /project
command: python manage.py runserver
depends_on:
- requirements
requirements:
image: python:3.7-alpine
volumes:
- pip37:/usr/local/lib/python3.7/site-packages
- .:/project
working_dir: /project
command: pip install -r requirements.txt
volumes:
pip37:
external: true
PS: I created a named volume for the pip modules so I can preserve them across different projects. You can create one yourself by running:
docker volume create mypipivolume