`docker run` on a remote host
is it possible (using the docker command or the docker-py API directly) to start a container from a remote host?
Lets assume I have two machines that have different architectures: - A is an x86 machine - B is an ARM machine
I would like to run a container on the B machine using my A machine. At first, I thought it was possible using this command:
[A]$> DOCKER_HOST=$MACHINE_B_IP:$MACHIN_B_PORT docker run hello-from-B
But this command actually pulls the image hello-from-B and tries to run it on the machine A which ends up on some exec format error cause obviously you can't run images that are specific to ARM to an x86 machine.
Communication between machine A and B is working well. I can run commands like images or ps and it gives me the expected results:
[A]$> DOCKER_HOST=$MACHINE_B_IP:$MACHIN_B_PORT docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
hello-from-B <none> fd5059044831 13 hours ago 1.26GB
I've heard about docker-machine and haven't tried it yet, but from my understanding, this won't solve my problem.
Is there any way to achieve that using docker directly. A workaround might be to using ssh to connect to the remote host and use the docker client directly from the remote host, but I'd like to avoid this solution as much as possible.
Thanks in advance,
TL;DR;
How can DOCKER_HOST=... docker run something runs something on the DOCKER_HOST rather than running it on my local machine.
if your targeted machine B could be created on one of these platform then I guess docker-machine would serve your needs. you would create your machine using docker-machine create --driver <..driver setup..> MACHINE_B then you activate it using eval $(docker-machine env MACHINE_B) . docker-machine env MACHINE_B will print out some export statements:
export DOCKER_TLS_VERIFY="1"
export DOCKER_HOST="tcp://...."
export DOCKER_CERT_PATH="/..."
export DOCKER_MACHINE_NAME="MACHINE_B"
once your machine is active, you can use the docker command as you would locally to act remotely on MACHINE_B.
This article explains the concept very well: https://docs.docker.com/engine/reference/commandline/dockerd/#bind-docker-to-another-hostport-or-a-unix-socket
Considering the huge warning on the page, I suggest you resort to using a secure connection via SSH ie. ssh user@host 'docker run hello-from-B'
Warning: Changing the default docker daemon binding to a TCP port or Unix docker user group will increase your security risks by allowing non-root users to gain root access on the host. Make sure you control access to docker. If you are binding to a TCP port, anyone with access to that port has full Docker access; so it is not advisable on an open network.
With -H it is possible to make the Docker daemon to listen on a specific IP and port. By default, it will listen on unix:///var/run/docker.sock to allow only local connections by the root user. You could set it to 0.0.0.0:2375 or a specific host IP to give access to everybody, but that is not recommended because then it is trivial for someone to gain root access to the host where the daemon is running.
Similarly, the Docker client can use -H to connect to a custom port. The Docker client will default to connecting to unix:///var/run/docker.sock on Linux, and tcp://127.0.0.1:2376 on Windows.
-H accepts host and port assignment in the following format:
tcp://[host]:[port][path] or unix://path
You can use multiple -H, for example, if you want to listen on both TCP and a Unix socket
# Run docker in daemon mode
$ sudo <path to>/dockerd -H tcp://127.0.0.1:2375 -H unix:///var/run/docker.sock &
# Download an ubuntu image, use default Unix socket
$ docker pull ubuntu
# OR use the TCP port
$ docker -H tcp://127.0.0.1:2375 pull ubuntu
As you said the connectivity is available between the servers, you can make use of Docker rich APIs.
There are 2 ways in configuring the docker daemon port
1) Configuring at /etc/default/docker file :
DOCKER_OPTS="-H tcp://127.0.0.1:5000 -H unix:///var/run/docker.sock"
2) Configuring at /etc/docker/daemon.json :
{
"hosts": ["tcp://127.0.0.1:5000", "unix:///var/run/docker.sock"]
}
For more details on configuring docker daemon port, refer configure-docker-daemon-port
Once the Docker ports are configured, you can access the Docker APIs in the remote host.
JSON input file:
#cat container_create.json
{
"AttachStdin": true,
"AttachStdout": true,
"AttachStderr": true,
"ExposedPorts": {
"property1": {},
"property2": {}
},
"Tty": true,
"OpenStdin": true,
"StdinOnce": true,
"Cmd": null,
"Image": "ubuntu:14.04",
"Volumes": {
"additionalProperties": {}
},
"Labels": {
"property1": "string",
"property2": "string"
}
}
API to create a container:
curl -X POST http://192.168.56.101:6000/containers/create -d @container_create.json --header "Content-Type: application/json" | jq .
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 602 100 90 100 512 1737 9883 --:--:-- --:--:-- --:--:-- 10039
{
"Warnings": null,
"Id": "f5d3273e48350d606bd8b9d2a5bd876dc5c2d1a73183f876a1dd56473cad8940"
}
The ID generated is the container ID and status will not be active/running.
API for starting the created container.
# curl -X POST http://192.168.56.101:6000/containers/f5d3273e48350/start | jq . % Total % Received % Xferd Average Speed Time Time Time Current
API to check the status/inspect the container:
# curl -X GET http://192.168.56.101:6000/containers/f5d3273e48350/json | jq .
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 4076 0 4076 0 0 278k 0 --:--:-- --:--:-- --:--:-- 306k
{
"NetworkSettings": {
"Networks": {
"bridge": {
"MacAddress": "02:42:ac:11:00:03",
"GlobalIPv6PrefixLen": 0,
"GlobalIPv6Address": "",
"IPv6Gateway": "",
"IPAMConfig": null,
"Links": null,
"Aliases": null,
"NetworkID": "689d6b65ce1b06c93b2c70f41760a3e7fb2b50697d71cd9c1f39c64c865e5fa6",
"EndpointID": "76bf1f8638d1ff0387e6c3fe89e8ccab1670c709ad550f9acc6f46e559654bee",
"Gateway": "172.17.0.1",
"IPAddress": "172.17.0.3",
"IPPrefixLen": 16
}
},
"MacAddress": "02:42:ac:11:00:03",
"SecondaryIPAddresses": null,
"SandboxKey": "/var/run/docker/netns/24a031d9dfda",
"Ports": {
"0/tcp": null
},
"LinkLocalIPv6PrefixLen": 0,
"LinkLocalIPv6Address": "",
"HairpinMode": false,
"SandboxID": "24a031d9dfda70026a875f4841269c5e790b12ccafcc11869111faa240020b99",
"Bridge": "",
"SecondaryIPv6Addresses": null,
"EndpointID": "76bf1f8638d1ff0387e6c3fe89e8ccab1670c709ad550f9acc6f46e559654bee",
"Gateway": "172.17.0.1",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"IPAddress": "172.17.0.3",
"IPPrefixLen": 16,
"IPv6Gateway": ""
},
},
"AttachStderr": true,
"AttachStdout": true,
"AttachStdin": true,
"User": "",
"Domainname": "",
"Hostname": "f5d3273e4835",
"OpenStdin": true,
"StdinOnce": true,
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
],
"Cmd": [
"/bin/bash"
],
"ArgsEscaped": true,
"Image": "ubuntu:14.04",
<*************REMOVING THE OUTPUT CONTENT********>
"ExecIDs": null,
"HostnamePath": "/var/lib/docker/containers/f5d3273e48350d606bd8b9d2a5bd876dc5c2d1a73183f876a1dd56473cad8940/hostname",
"ResolvConfPath": "/var/lib/docker/containers/f5d3273e48350d606bd8b9d2a5bd876dc5c2d1a73183f876a1dd56473cad8940/resolv.conf",
"Image": "sha256:132b7427a3b40f958aaeae8716e0cbb2177658d2410554ed142e583ef522309f",
"State": {
"FinishedAt": "0001-01-01T00:00:00Z",
"StartedAt": "2017-06-09T06:53:45.120357144Z",
"Error": "",
"Status": "running",
"Running": true,
"Paused": false,
"Restarting": false,
"Path": "/bin/bash",
"Created": "2017-06-09T06:52:51.820429355Z",
"Id": "f5d3273e48350d606bd8b9d2a5bd876dc5c2d1a73183f876a1dd56473cad8940",
"HostsPath": "/var/lib/docker/containers/f5d3273e48350d606bd8b9d2a5bd876dc5c2d1a73183f876a1dd56473cad8940/hosts",
"LogPath": "/var/lib/docker/containers/f5d3273e48350d606bd8b9d2a5bd876dc5c2d1a73183f876a1dd56473cad8940/f5d3273e48350d606bd8b9d2a5bd876dc5c2d1a73183f876a1dd56473cad8940-json.log",
"Name": "/objective_bartik",
"RestartCount": 0,
"Driver": "aufs",
"MountLabel": "",
"ProcessLabel": "",
"AppArmorProfile": "docker-default"
}
Refer this for more info:
DOCKER APIs
How to build an Image using Docker API?
How to commit Docker Container using API
Hope this info will he helpful.
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