As the title states. I am looking to send a file from container A to container B. Both containers are running on separate volumes and are on the same network. Is this possible without temporarily storing the file in the host file system?
I have been reading around and found this solution, however it requires that the file I wish to send is temporarily stored in the host
https://medium.com/#gchudnov/copying-data-between-docker-containers-26890935da3f
Container A has its own volume to which a file is written to. I want to get Container A to send this file to a volume to which Container B is attached. Container B then reads this file.
Thanks
If they are linux containers you can use scp
scp file root#172.17.x.x:/path
Related
I want to know the mechanism of how does docker creates a container on the host. As for how to isolate the container's storage.We know that provisioning a file system for a container is a two-step procedure:1)populate a sub-directory of the host's file system with data and code.2)make the subdirectory the root of the new container.We can use AUFS or overlayfs to do the first step.I always thought that docker use chroot to do the second step. But I recently read a blog that said docker use mount namespace by the call like unshare.
I am confused that how can only use mount namespace to drop access to other host file data?
When I used the command unshare, it surely created a new mount namespace for the process. And it copied identical host's mount points. But it can still read other host file data..I want to know that did I misunderstand the blog's saying..
I have a docker container with an application running inside of it. I am trying to export a text file from the docker container to the host. The problem is the application keeps on writing data into the text file at regular intervals.
Is there a way to directly store the file onto the host and the application inside the docker container keep storing the data to the text file?
Take a look at bind mounts or volumes. They are used to achieve exactly what you asked.
I have been reading about Docker, and one of the first things that I read about docker was that it runs images in a read-only manner. This has raised this question in my mind, what happens if I need users to upload files? In that case where would the file go (are they appended to the image)? or in other words, how to handle uploaded files?
Docker containers are meant to be immutable and replaceable - you should be able to stop a container and replace it with a newer version without any ill effects. It's bad practice to store any configuration or operational data inside the container.
The situation you describe with file uploads would typically be resolved with a volume, which mounts a folder from the host filesystem into the container. Any modifications performed by the container to the mounted folder would persist on the host filesystem. When the container is replaced, the folder is re-mounted when the new container is started.
It may be helpful to read up on volumes: https://docs.docker.com/storage/volumes/
docker containers use file systems similar to their underlying operating system, as it seems in your case Windows Nano Server(windows optimized to be used in a container).
so any uploads to your container will be placed on the corresponding path you provided when uploading the file.
but this data is ephemeral, this means your data will persist until the container is for whatever reason stopped.
to use persistent storage you must provide a volume for your docker container, you can think of volumes as external disks attached to a container that mount on a path inside the container. this will persist data regardless of container state
I have users that each will each have a directory for storing arbitrary php code. Each user can execute their code in a Docker container - this means I don't want user1 to be able to see the directory for user2.
I'm not sure how to set this up.
I've read about bind-mounts vs named-volumes. I'm using swarm-mode so I don't know on which host a particular container will run. This means I'm not sure how to connect the container to the volume mount and subdirectory.
Any ideas?
Have you considered having an external server for storage and mounting it on each Docker host?
If you need the data to exist and you don't want to mount external storage you can try looking into something like Gluster for syncing files across multiple hosts
As for not wanting users to share directories you can just set the rights on the folder.
I am using the docker HTTP API described here.
Suppose I get a volume ID using the GET /volumes API endpoint. Is it possible for me to inspect the contents of this volume (list files, read files)?
I understand that I could create a container that mounts this volume and then use the /containers/(id)/archive endpoint to download files from it, but this seems like a rather expensive operation when all I wish to do is inspect the contents of a single file on the volume.
I think the right thing is too execute the scripts you want to execute in a container with the volumes mounted, but you can just list the files and folders in the volume folder here : /var/lib/docker/volumes/.
This path is gonna change if you tweak a bit docker, but your volumes are always stored somewhere, just go inside the folder corresponding at your volume ID.
See ya !