How to add files in docker container volume on build time - docker

Question

I have a python and java app that I want to run inside a container.
I have a folder named pass-hash with:
--h2o-start folder containing Dockerfile that I use to start h2o.jarwhich starts a server for machine learning.
--model-generator folder containing passhash.py and a data.csv file.
The passhash.py app contains h2o.import_file("/var/my-data/data.csv") which takes the data.csv file from the my-data folder I created in the container and generates a POJO file with it.
The h2o-start Dockerfile contains:
FROM openjdk:8
ADD h2o.jar h2o.jar
EXPOSE 54321
EXPOSE 54322
ENTRYPOINT ["java", "-jar", "h2o.jar"]
The model-generator Dockerfile contains:
FROM python:2.7-slim
WORKDIR /model-generator
ADD . /model-generator
RUN mkdir /var/my-data
COPY data.csv /var/my-data
RUN chmod 777 /var/my-data/data.csv
RUN pip install --trusted-host pypi.python.org -r requirements.txt
EXPOSE 8080
ENV NAME World
CMD ["python", "passhash.py"]
The docker-compose.yml file contains:
version: "3"
services:
h2o-start:
image: milanpanic2/h2o-start
build:
context: ./h2o-start
ports:
- "54321:54321"
- "54322:54322"
volumes:
- "home/data"
model-generator:
image: milanpanic2/model-generator
build:
context: ./model-generator
ports:
- "8080:8080"
depends_on:
- "h2o-start"
volumes:
- "csvdata:/var/my-data"
volumes:
csvdata:

Answer 1

Docker Volumes are designed to share folder in between Host Machine and Docker containers. If you copy any file on your host machine (volume location path), it will be automatically going to available inside containers.
The syntax for docker volume is as below:
-v /home/data:/data
In the above syntax /home/data is folder available on the host machine and /data this folder is available inside docker container.
If you copy any file on the host machine inside /home/data folder, it will be automatically going to be available inside container /data folder.
Hope this is clear to you.
If you are using docker-compose then add volume tag as below
volumes:
- /home/data:/data
for example:
version '3'
services:
app:
image: nginx:alpine
ports:
- 80:80
volumes:
- /home/data:/data

Answer 2

I don't know, that is the solution i came up with. Can you tell me the better solution for my problem? My problem is: I have a python app that uses a data.csv file to generate a POJO machine learning model. When I specify a path to this python app to the data file, it gives an exception that the file doen't exist. Also, I have another app written in java, that uses the generated POJO file and it gives predictions based on that data. The java app also updates the data.csv file every day. I want every app (microservice) to run in separate container, but want them both to use the data.csv
To answer this, You need to use volumes.
Try below code.
This is your docker-compose file
version: "3"
services:
h2o-start:
image: milanpanic2/h2o-start
build: context: ./h2o-start
ports:
- "54321:54321" - "54322:54322"
volumes:
- /home/data:/var/my-data
model-generator:
image: milanpanic2/model-generator
build: context: ./model-generator
ports:
- "8080:8080"
depends_on:
- "h2o-start"
volumes:
- /home/data:/var/my-data
This is your docker file
FROM python:2.7-slim
WORKDIR /model-generator
ADD . /model-generator
RUN mkdir /var/my-data
RUN pip install --trusted-host pypi.python.org -r requirements.txt
EXPOSE 8080
ENV NAME World
CMD ["python", "passhash.py"]
And where is your java docker file?
Now just create a default data.csv file and copy it in your host machine location /home/data.
and run application let me know.

Answer 3

If you mean add files when do docker build, take a look at ADD & COPY instructions.