Sharing a Folder

When you share a folder the base operating system and the running containers will be able to see and consume the files inside it. This is one option for the host machine and the container to interact.


When you go to bind mount a file into a container, you will usually want to bind mount the parent directory/folder. If a bind mount destination does not exist, Docker will create the endpoint as an empty directory rather than a file.

In the section, “Copy the Configuration File using Dockerfile”, you created and copied the configuration file to the /home/shellhttpd/ folder. Purposefully leave the changes you just did because you will share the same folder to see what happens.

Edit the docker-compose.yml file adding the volumes stanza:

gedit shellhttpd/docker-compose.yml


version: '3.2'

#    image: shellhttpd:1.0
    restart: always
      - /var/rootdirs/home/fio/shellhttpd:/home/shellhttpd/
      - 8080:${PORT-8080}
      MSG: "${MSG-Hello world}"

Above, you add the volumes: stanza with the value /var/rootdirs/home/fio/shellhttpd:/home/shellhttpd/. This means that the /var/rootdirs/home/fio/shellhttpd folder from your host machine will be mounted over the container’s /home/shellhttpd folder. The container folder content will be overwritten by the host machine folder content. Thus, as the host machine folder is empty, the shellhttpd.conf you copied in the Dockerfile will disappear in this new setup.

Check your changes, add, commit and push to the server:

git status
git add shellhttpd/docker-compose.yml
git commit -m "Adding shared folder"
git push

Make sure you received your update by checking the latest Target on the Devices tab in your Factory.

Open one terminal connected to your device and check the running containers:

docker ps

Example Output:

CONTAINER ID   IMAGE                               COMMAND                  CREATED          STATUS          PORTS                    NAMES
a2d425490201<factory>/shellhttpd   "/usr/local/bin/http…"   20 minutes ago   Up 20 minutes>8080/tcp   shellhttpd_httpd_1

Monitor the docker logs:

docker logs --follow shellhttpd_httpd_1

Example Output:

MSG=Hello world

Open a second terminal connected to your device and check for the /var/rootdirs/home/fio/shellhttpd folder:

ls /var/rootdirs/home/fio/shellhttpd/

The folder is empty and was automatically created when the Docker image was launched. Let’s create a new configuration file inside that folder and follow the logs from the first terminal:

sudo bash -c 'echo -e "MSG=\"Hello from shared folder\"" > /var/rootdirs/home/fio/shellhttpd/shellhttpd.conf'

And in the first terminal you should see the new MSG value:

Example Output:

MSG=Hello from shared folder

Just to confirm the change, test the container from an external device connected to the same network (e.g. your host machine: the same computer you use to access your device with ssh).

curl <device IP>:8080

Example Output:

Hello from shared folder

At this point, you learned how to share a folder with the Docker container and how to manually update the configuration while the container is running.