Docker Assignments #5: Docker Bind Mount

By using a bind mount, a file or directory on the host machine is mounted into a container

1. Create a folder structure as per above image in your host machine
2. Run an alpine container (name it as 'alpine1')  in interactive-mode and make a note of all files/folders under container "usr" folder
3. delete alpine1 container
4. Run an alpine container (name it as 'alpine1') in interactive-mode by doing bind mount (i.e. “dokcer-bindmount” folder from the host machine ) to container “usr” folder
5. Make a note of all files/folders under "usr" folder of 'alpine1' container
6. Observe what happens to container built-in folder/files under “usr” folder
7.  Change the content in file1.txt file under /usr/folder1/file1.txt
8. Check file1.txt whether changes are reflecting in your host machine or not
9. Change the content in file2.txt file under docker-bindmount/folder2/file2.txt from host machine
10. Check whether same changes are reflecting under container /usr/folder2/file2.txt
11. stop and remove alpine1 container
12. Check whether changes are still exist in host machine
13. Do bind mount to container non-exist folder
14. Implement read-only bind mount
15. Observe the Disadvantage of doing bind mount to container non-empty/built-in folder

Step 2:

     > docker run -it  --name alpine1 alpine sh  

Step 3: 

     > docker rm -f alpine1

Step 4:    

> docker run -it

  --mount type=bind,source=/c/Users/rama/docker-bindmount,target=/usr 

  --name alpine1 alpine sh  (or)

> docker run -it 

  --mount type=bind,source=$(pwd),target=/usr 

  --name alpine1 alpine sh

Step 6: 

     container preexist contents will be hidden and not accessible to host machine

Step 7: 

     append "hello world" message to file1.txt

     > docker exec -it alpine1 sh

     > / # cd /usr/folder1

     > /usr/folder1 # echo "hello world" >> file1.txt

Step 8: 

     file1.txt changes should be reflected in host machine

Step 10: 

     file2.txt changes should be reflected in alpine1 container

Step 11: 

     > docker rm -f alpine1

Step 12: 

     all file changes must remain same

Step 13: 

    directory will be created automatically if not exist in the container   

> docker run -it

  --mount type=bind,source=/c/Users/rama/docker-bindmount,target=/rama 

  --name alpine1 alpine sh  (or)

> docker run -it 

  --mount type=bind,source=$(pwd),target=/rama 

  --name alpine1 alpine sh 

Step 14: 

    By making container read-only, we can't create or modify contents in the container

> docker run -it

  --mount type=bind,source=/c/Users/rama/docker-bindmount,target=/rama,readonly 

  --name alpine1  alpine sh (or)

> docker run --read-only 

  --name alpine1 alpine touch file1.txt ( i.e. file won't be created )

Step 15: 

1. If you bind-mount into a non-empty Linux builtin directory (i.e. bin,usr,tmp and etc ) on the container, the directory’s existing contents are obscured/hidden by the bind mount. So, this results in a non-functioning container

Happy Coding :)