I'm trying to learn some things about Docker. Right now, I'm asking myself, if a Docker container can communicate with something like a camera from the host.
Can anyone answer me that, and say how to pls?
Since Docker 1.2.0, you can use --device flag in docker run to access to host devices.
This is used this way:
docker run ... --device=/dev/ttyUSB0 ...
Related
Is it possible to make sure that my containers are running with specific docker option.
I need to run my container with the --device option. I cannot use device plugin because I am running a windows container and device manager does not seems implemented for windows.
Thank you for your help
I want to build a cassandra cluster with docker. The documentation already tells you how to this so this is not the problem I have.
However I am currently using Docker on Windows 10 and obviously it cannot execute the nested command in docker run --name some-cassandra2 -d -e CASSANDRA_SEEDS="$(docker inspect --format='{{ .NetworkSettings.IPAddress }}' some-cassandra)" cassandra:tag which results in an empty seed list for the container.
How can I nest a command like this in Windows or - if this is not possible - get a workaround for this?
I managed to fix it thanks to a docker-compose.yml by Jason Giedymin. It should work in v1 as well as v2 of docker-compose. By doing it this way you just let docker do the linking from the get go and tell cassandras about other seeds with the environment variable the container already gives you.
The sleep 30 part is pretty smart as well as it makes sure that the second container doesn't try to connect on a container that isn't fully up yet.
One thing I would recommend though, is using external_links instead of links. This way other containers don't rely on all of the cassandra containers to be up to start/work. This would defeat the purpose of a distributed database.
I still don't know how to nest Windows cmd commands into each other so I would still be thankful for some tips.
I wanted to start the docker daemon with an open TCP address like this: docker daemon -H tcp://0.0.0.0:2375, but the terminal suggested that I use dockerd instead, which is apparently not a program that comes with the Docker Client for mac. Is there a way I can either
A - get some form of dockerd on my mac machine.
B - get around the use of dockerd by some other method.
?
Install socat command: brew install socat
Choose a port: (in the example 8099)
Run: socat -d -d TCP-L:8099,fork UNIX:/var/run/docker.sock
and then use tcp://localhost:8099 as API URL
works for me, hope this helps
Finally I found the config of mac docker like dockerd.
Click the docker icon in the menu bar, preferences, advanced
get around the use of dockerd by some other method. (2016)
Note that in 2022, you can go without dockerd/Docker Desktop entirely.
See Batuhan Apaydin's article "A modern toolkit to start working with container images on macOS that meets your needs without requiring a Docker Daemon or even Docker Desktop".
It uses lima+nerdctl
The nerdctl tool is designed as a drop-in replacement for the Docker client
And Lima is a hypervisor that launches Linux virtual machines with automatic file sharing, port forwarding, and containerd.
The name of lima comes from an abbreviation of the first two capital letters of LInux MAchines.
The design of Lima is similar to WSL2, but Lima focuses on macOS as the primary target host.
Lima uses QEMU, which is a generic and open source machine emulator and virtualizer, as a hypervisor under the hood to achieve the virtualization thing.
Lima can also work with other container engines such as Podman and even for non-container applications.
By default, when lima launches a VM, it runs buildkitd and containerd in a rootless way and also downloads necessary client tooling around them such as buildctl, nerdctl.
Everything will be set up for us. So, all that’s left is building, pulling, and running containers
For buildkit, Batuhan proposes developer-guy/buildkit-machine
buildkit-machine allows you to make buildkitd daemon accessible in your macOS environment.
To do so, it uses lima, which is a Linux subsystem for macOS, under the hood.
lima spins up a VM that runs buildkitd daemon in a rootless way which means that sock file of the buildkitd daemon is now be able to accessible from /run/user/<USERID>/buildkit/buildkitd.
So: no more Docker Desktop / dockerd, and use container in a rootless mode!
For more, see Bret Fisher's video "Free Docker Desktop Alternatives: DevOps and Docker Live Show (Ep 156)" (Jan. 2022)
I have found a workaround for this in the official forum
https://forums.docker.com/t/using-pycharm-docker-plugin-with-docker-beta/8617/9
$socat TCP-LISTEN:2376,reuseaddr,fork UNIX-CLIENT:/var/run/docker.sock
That workaround opens port 2376 to the world... as TLS isn't enabled, this is a bad idea as anyone on the same network can hijack your docker daemon
It is not supported to run dockerd on Mac. From this issue:
I think on Darwin it should never suggest to run dockerd. The daemon runs in a Linux virtual machine, so you do not need to (and cannot) run it manually.
If you want to do any specific configuration on mac, you might have already installed Docker Desktop. Docker desktop supports configuration using UserInterface shown below in the screenshot.
I'm very new to kubernetes and trying to conceptualize it as well as set it up locally in order to try developing something on it.
There's a confound though that I am running on a windows machine.
Their "getting started" documentation in github says you have to run Linux to use kubernetes.
As docker runs on windows, I was wondering if it was possible to create a kubernetes instance as a container in windows docker and use it to manage the rest of the cluster in the same windows docker instance.
From reading the setup instructions, it seems like docker, kubernetes, and something called etcd all have to run "in parallel" on a single host operating system... But part of me thinks it might be possible to
Start docker, boot 'default' machine.
Create kubernetes container - configure to communicate with the existing docker 'default' machine
Use kubernetes to manage existing docker.
Pipe dream? Wrongheaded foolishness? I see there are some options around running it in a vagrant instance. Does that mean docker, etcd, & kubernetes together in a single VM (which in turn creates a cluster of virtual machines inside it?)
I feel like I need to draw a picture of what this all looks like in terms of physical hardware and "memory boxes" to really wrap my head around this.
With Windows, you need docker-machine and boot2docker VMs to run anything docker related.
There is no (not yet) "docker for Windows".
Note that issue 7428 mentioned "Can't run kubernetes within boot2docker".
So even when you follow instructions (from a default VM created with docker-machine), you might still get errors:
➜ workspace docker run --net=host -d -v /var/run/docker.sock:/var/run/docker.sock gcr.io/google_containers/hyperkube:v0.14.2 /hyperkube kubelet --api_servers=http://localhost:8080 --v=2 --address=0.0.0.0 --enable_server --hostname_override=127.0.0.1 --config=/etc/kubernetes/manifests
ee0b490f74f6bc9b70c1336115487b38d124bdcebf09b248cec91832e0e9af1d
➜ workspace docker logs -f ee0b490f74f6bc9b70c1336115487b38d124bdcebf09b248cec91832e0e9af1d
W0428 09:09:41.479862 1 server.go:249] Could not load kubernetes auth path: stat : no such file or directory. Continuing with defaults.
I0428 09:09:41.479989 1 server.go:168] Using root directory: /var/lib/kubelet
The alternative would be to try on a full-fledge Linux VM (like the latest Ubuntu), instead of a boot2docker-like VM (based on a TinyCore distro).
All k8s components can be raised up with hyperkube, which helps you bring up a containerized one.
If you're able to run docker on windows, it would probably work. I haven't tried it on windows personally.
I installed boot2docker as explained on the docker website. Here are some command runs to show that I have things installed correctly:
$$:~ kv$ boot2docker start
Waiting for VM and Docker daemon to start...
...................ooo
Started.
Writing /Users/kvantum/.boot2docker/certs/boot2docker-vm/ca.pem
Writing /Users/kvantum/.boot2docker/certs/boot2docker-vm/cert.pem
Writing /Users/kvantum/.boot2docker/certs/boot2docker-vm/key.pem
Your environment variables are already set correctly.
$$:~ kv$ docker images
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
ubuntu 14.04 b39b81afc8ca 11 days ago 188.3 MB
hello-world latest e45a5af57b00 3 weeks ago 910 B
After this, I ran the following command:
docker run -t -i ubuntu:14.04 /bin/bash
Inside the container, I installed zeromq, and started a zeromq server on port 5555 using tcp.
My questions are following:
If I exit out of the container, will it save all the work I do inside it?
I have no idea how to connect to the server running on port 5555. I read something about exposing a port, but I am not sure how to go about doing that. I did an ifconfig inside the container, and tried to connect to the server from the host like this:
$$:~ kv$ ./zmq_client tcp://container_ip:5555
This did not work. Can someone please lists the steps I need to take in order to connect to the server running within the container.
For completion sake, I am providing the list of my environment variables:
TERM_PROGRAM=Apple_Terminal
TERM=xterm-256color
SHELL=/bin/bash
TMPDIR=/var/folders/km/5kbpdx4s7cg4rmyc6d5q9l9r0000gq/T/
DOCKER_HOST=tcp://192.168.109.103:2376
Apple_PubSub_Socket_Render=/tmp/launch-1tWMHJ/Render
TERM_PROGRAM_VERSION=326
OLDPWD=/Users
TERM_SESSION_ID=262CBC8B-0A74-4B70-9F28-D9FA51FF713C
USER=kv
SSH_AUTH_SOCK=/tmp/launch-ZTWNGL/Listeners
__CF_USER_TEXT_ENCODING=0x1F7:0:0
DOCKER_TLS_VERIFY=1
__CHECKFIX1436934=1
PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/opt/X11/bin
PWD=/Users/kv
DOCKER_CERT_PATH=/Users/kv/.boot2docker/certs/boot2docker-vm
HOME=/Users/kv
SHLVL=1
LOGNAME=kv
LC_CTYPE=UTF-8
DISPLAY=/tmp/launch-rco9zt/org.macosforge.xquartz:0
_=/usr/bin/env
One last question I have is about code performance. So within my Mac OS X, I have a docker container running (which runs Ubuntu). If I run the application, like a zeromq based server inside the container, will it not be slower as compared to running it on Mac OS X directly. Please explain the benefits of using docker in such a scenario..
You should really do some more reading and research before turning to SO, then ask about anything you can't figure out. But:
No. If the container is "exited" you can restart it and your files will still be there, but once it is removed your files are gone. You can use docker commit to save them to an image, but the best bet is to use a Dockerfile.
docker run -p 5000:8000 image will expose port 8000 in the container as port 5000 on the host.
Yes, it will be slower due to the boot2docker VM. It would not be slower if you were running on a Linux host. The advantage is that zeromq is now running in an isolated container with all its dependencies.