Add feature to create local folders when mounting

[joaocc]

Hi, Have you thought of adding a feature/flag/mode to allow the creation of folder on the docker host when setting up the container and when mounting volumes? Currently, to use local-persist in docker-compose, I need to make sure the folders exist, which in turns requires an external script. Being able to have the folders create automatically in the docker host, we would have a smoother experience. Thx

[joaocc]

suggestion:

driver_opts:
    mountpoint: /data/my/good/folder
    force_mkdir: true
    mkdir_opts:
        owner: user1
        group: group1
        mode: "u=rwx,o+rX"

[CWSpear]

I don't think Docker can write to the host?

[joaocc]

Hi. I believe that the current version behaves as "mkdir ", while I am kindly requesting for it to behave like "mkdir -p ". Been some time since I last tested this, as I have been waiting for a build with the https://github.com/CWSpear/local-persist/pull/34 to be available. Thx

[CWSpear]

So if you're using the plugin as a docker plugin, there are actually 2 places where the data for a volume lives: on the host and in the Docker local-persist container.

If you see here: https://github.com/CWSpear/local-persist/blob/master/driver.go#L110, it does create (a la Go's mkdir -p) the directory to make sure it exists. This is all that's needed if you run the plugin from the binary directly.

However, if run it as a Docker container, the container can't create volumes on the host, so you're responsible for creating those your self, i.e. the left side of a -v /path/on/host/:/path/on/local-persist/container/ during starting of the local-persist container.

[joaocc]

Now I understand it! :)

This just leaves me with another existential question... (let me know if you want me to add it in a separate ticket). (moved to https://github.com/CWSpear/local-persist/issues/36)

[CWSpear]

I think you've got this part, but gonna just reiterate: there are 2 ways to run this plugin:

Running the binary directly:

+--------------------------------+       +-------------------------+
| Host runs local-persist binary |-------|     App container(s)    |
|  [data needs to persist here]  |       |  [data is mounted here] |
+--------------------------------+       +-------------------------+

The directory gets created here, everything should work out of the box in terms of creating directories, and nothing to worry about here.

But you're running the plugin in a container, which adds a layer:

Running in a container:

+------------------------------+       +-------------------------+       +-------------------------+
|             Host             |-------| local-persist container |-------|     App container(s)    |
| [data needs to persist here] |       | [data is mounted here]  |       |  [data is mounted here] |
+------------------------------+       +-------------------------+       +-------------------------+

Either way, the data has to persist on the host. So when we create the local-persist container, we need to link the actual data to that container so that when we think link a volume to an app container, it is getting the actual data (passed through the container).

Does that make sense...?

So local-persist does create the directories, but in your case, it's creating the directories in the local-persist container, and you still have to create a directory on the host, and make sure those directories are mapped together.

[joaocc]

Thx. The answer you gave me is excellent for my original point. It would be useful for other users to have it in the readme.

As for my 2nd (additional) question, I will create a new issue to make it clearer.!