Docker compose error while creating mount source path

[tylnesh]

I happened upon an old issue with docker distributed in the snap. When using our Dockerfile with volumes defined as such:
volumes: - type: bind source: /opt/something/data target: /opt/something/data bind: create_host_path: true

I get this error:
Error response from daemon: error while creating mount source path '/opt/something/data': mkdir /opt/something: read-only file system

Seems like it's the same issue as here: https://stackoverflow.com/questions/45764477/docker-compose-error-while-creating-mount-source-path

[locnnil]

As snap packages add additional layers of security, the behavior that you listed is expected.

By default, a strictly confined snap (such as the Docker snap) cannot access the entire system. Instead, there are specific data locations where the snapped application is allowed access. Additionally, there are snap interfaces that grant extra permissions, enabling the application inside the snap to function properly.

The applications inside the Docker snap itself uses several of these interfaces, like for dockerd:

docker-snap/snap/snapcraft.yaml

Lines 109 to 116 in ff34705

	- firewall-control
	- home
	- log-observe
	- network-bind
	- network-control
	- privileged
	- support
	- graphics-core22

As well the Docker CLI

docker-snap/snap/snapcraft.yaml

Lines 100 to 103 in ff34705

	- docker-cli
	- network
	- home
	- removable-media

and Docker Compose:

docker-snap/snap/snapcraft.yaml

Lines 123 to 125 in ff34705

	- docker-cli
	- network
	- home

While I understand this setup might not be ideal for development purposes, it’s designed to ensure maximum security and reliability, making it a perfect fit for production scenarios.

Thank you for bringing this up, and I hope this explanation helps clarify things!