Does docker container get the same band-width as the host container? Or do we need to configure min and(or) max. I 've noticed that we need to override default RAM(which is 2 GB) and Swap space configuration if we need to run CPU intensive jobs. Also do we need to configure the disk-space ? Or does it by default get as much space as the actual hard disk.
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Memory and CPU are controlled using cgroups by docker. If you do not configure these, they are unrestricted and can use all of the memory and CPU on the docker host. If you run in a VM, which includes all Docker for Desktop installs, then you will be limited to that VM's resources.
Disk space is usually limited to the disk space available in /var/lib/docker. For that reason, many make this a different mount. If you use devicemapper for docker's graph driver (this has been largely deprecated), created preallocated blocks of disk space, and you can control that block size. You can restrict containers by running them with read-only root filesystems, and mounting volumes into the container that have a limited disk space. I've seen this done with loopback device mounts, but it requires some configuration outside of docker to setup the loopback device. With a VM, you will again be limited by the disk space allocated to that VM.
Network bandwidth is by default unlimited. I have seen an interesting project called docker-tc which monitors containers for their labels and updates bandwidth settings for a container using tc (traffic control).
BMitch
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Does docker container get the same band-width as the host container?
Yes. There is no limit imposed on network utilization. You could maybe impose limits using a bridge network.
Also do we need to configure the disk-space ? Or does it by default get as much space as the actual hard disk.
It depends on which storage driver you're using because each has its own options. For example, devicemapper uses 10G by default but can be configured to use more. The recommended driver now is overlay2. To configure start docker with overlay2.size.
jcragun
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Note on `overlay2.size`: "It is supported only when the backing fs is xfs and mounted with pquota mount option." – BMitch Feb 20 '19 at 12:56
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This depends some on what your host system is and how old it is.
In all cases network bandwidth isn't explicitly limited or allocated between the host and containers; a container can do as much network I/O as it wants up to the host's limitations.
On current native Linux there isn't a desktop application and docker info will say something like Storage driver: overlay2 (overlay and aufs are good here too). There are no special limitations on memory, CPU, or disk usage; in all cases a container can use up to the full physical host resources, unless limited with a docker run option.
On older native Linux there isn't a desktop application and docker info says Storage driver: devicemapper. (Consider upgrading your host!) All containers and images are stored in a separate filesystem and the size of that is limited (it is included in the docker info output); named volumes and host bind mounts live outside this space. Again, memory and CPU are not intrinsically limited.
Docker Toolbox and Docker for Mac both use virtual machines to provide a Linux kernel to non-Linux hosts. If you see a "memory" slider you are probably using a solution like this. Disk use for containers, images, and named volumes is limited to the VM capacity, along with memory and CPU. Host bind mounts generally get passed through to the host system.
David Maze
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