When starting S3Mock in Docker, root folder is not accessible from outside of the container

[ocostello]

I'm attempting to set adobe/S3Mock up on my local machine, so that retainFilesOnExit is enabled and where I've pointed the root folder somewhere that I can view.

My docker-compose.yml looks like so:

services:
  s3mock:
    image: adobe/s3mock:3.5.2
    environment:
      - debug=true
      - retainFilesOnExit=true
      - root=s3container
    ports:
      - 9090:9090
      - 9191:9191

and when I start the server, the logs say that the root folder has been created:

Successfully created "/s3container" as root folder. Will retain files on exit: true

but I can't find it myself. I'm expecting it to appear in the directory I started the server in, and if not there then just at root /s3container but it isn't at either location.

➜  localS3 git:(main) ✗ ls
docker-compose.yml
➜  localS3 git:(main) ✗ docker compose up -d
[+] Running 1/1
 ✔ Container locals3-s3mock-1  Started                                                                                                                 0.0s
➜  localS3 git:(main) ✗ ls
docker-compose.yml
➜  localS3 git:(main) ✗ ls /s3container
ls: /s3container: No such file or directory

Am I seriously misunderstanding this root config, and if so could it be better explained in the docs.

[afranken]

@ocostello

Am I seriously misunderstanding this root config

yes and no.

The property works for the application, but not the Docker container. Since the S3Mock application is running inside Docker, the folder you specify in root will be created inside the Docker container, not on your system.

If you want so see the data in your local file system, you'll have to create a directory and mount it so it's accessible from inside the Docker container, for example:

mkdir tobemounted

services:
  s3mock:
    image: adobe/s3mock:3.5.2
    environment:
      - debug=true
      - retainFilesOnExit=true
      - root=s3container
    ports:
      - 9090:9090
      - 9191:9191
    volumes:
      - ./tobemounted:/s3container

Then, Docker will be able to access your file system.

[afranken]

Example:

 ~/tmp/s3mock-mount-test                                                                                                                                                                                                                                                                                                                                                                                                     at 19:26:40
❯ ls
docker-compose.yml tobemounted

❯ cat docker-compose.yml
services:
  s3mock:
    image: adobe/s3mock:3.5.2
    environment:
      - debug=true
      - retainFilesOnExit=true
      - root=s3container
    ports:
      - 9090:9090
      - 9191:9191
    volumes:
      - ./tobemounted:/s3container

❯ docker-compose up
[...]

❯ curl --request PUT "http://localhost:9090/my-test-bucket/"

^CGracefully stopping... (press Ctrl+C again to force)
[+] Stopping 1/1
 ✔ Container s3mock-mount-test-s3mock-1  Stopped                                                                                                                                                                                                                                                                                                                                                                                     0.1s
canceled

❯ ls tobemounted
my-test-bucket

[ocostello]

Thanks for the swift reply, that works perfectly now.

[afranken]

@ocostello I added this description to the README.md, as it's hopefully helpful for other users as well:
https://github.com/adobe/S3Mock?tab=readme-ov-file#start-using-docker-compose