[git] Rebuild Docker container on file changes

For running an ASP.NET Core application, I generated a dockerfile which build the application and copys the source code in the container, which is fetched by Git using Jenkins. So in my workspace, I do the following in the dockerfile:

WORKDIR /app
COPY src src

While Jenkins updates the files on my host correctly with Git, Docker doesn't apply this to my image.

My basic script for building:

#!/bin/bash
imageName=xx:my-image
containerName=my-container

docker build -t $imageName -f Dockerfile  .

containerRunning=$(docker inspect --format="{{ .State.Running }}" $containerName 2> /dev/null)

if [ "$containerRunning" == "true" ]; then
        docker stop $containerName
        docker start $containerName
else
        docker run -d -p 5000:5000 --name $containerName $imageName
fi

I tried different things like --rm and --no-cache parameter for docker run and also stopping/removing the container before the new one is build. I'm not sure what I'm doing wrong here. It seems that docker is updating the image correctly, as the call of COPY src src would result in a layer id and no cache call:

Step 6 : COPY src src
 ---> 382ef210d8fd

What is the recommended way to update a container?

My typical scenario would be: The application is running on the server in a Docker container. Now parts of the app are updated, e.g. by modifying a file. Now the container should run the new version. Docker seems to recommend building a new image instead of modifying a existing container, so I think the general way of rebuilding like I do is right, but some detail in the implementation has to be improved.

Whenever changes are made in dockerfile or compose or requirements , re-Run it using docker-compose up --build . So that images get rebuild and refreshed

You can run build for a specific service by running docker-compose up --build <service name> where the service name must match how did you call it in your docker-compose file.

Example Let's assume that your docker-compose file contains many services (.net app - database - let's encrypt... etc) and you want to update only the .net app which named as application in docker-compose file. You can then simply run docker-compose up --build application

Extra parameters In case you want to add extra parameters to your command such as -d for running in the background, the parameter must be before the service name: docker-compose up --build -d application