Docker container doesn't update when file changes are made on host

Question

I'm using a docker image as my dev environment for a specific version of PHP. I am using PHP for a command line script so every time I make a change to the script I would like it to automatically make changes in the container.

I'm not sure if this is even possible. I assumed it was. I mostly use docker-compose and I can add VOLUMES easily to achieve this, but not in this instance with docker.

My Dockerfile:

FROM php:7.2-cli
COPY ./app /usr/src/app/
WORKDIR /usr/src/app
ENTRYPOINT [ "php" ]
CMD [ "./index.php" ]

I first run:

docker build -t app .

And then

docker run app

Everything works well. But if I change something in index.php I have to run the steps again. Is this expected behaviour or is there any way to have docker watch for changes?

Answer 1

docker run -v /home/user/location:/usr/src/app app

Use a volume so that the files within the container reflect local changes.

https://docs.docker.com/storage/volumes/#choose-the--v-or---mount-flag

Answer 2

If you are editing a file using vim/sublime outside docker in your host, this is normal, because vim/sublime does not simple "edit" that file, but create a new file. see : https://github.com/moby/moby/issues/15793

solution:

After some googling, Sublime text has atomic_save instead so Adding "atomic_save": false to user preferences worked (After a restart). 

if you are using docker-compose, use this command:

$ docker-compose run --build