I have a few micro-services deployed as a stack on docker swarm, with each micro-service running in a separate container.
How do I give commands to the swarm from within one of the services running inside a container on the swarm manager host? e.g running "docker service update" command from within a container to update one of the services in the swarm.
I read somewhere that it can be done by bind mounting the docker socket using:
-v /var/run/docker.sock:/var/run/docker.sock
But this does not work for me. I get docker not found error upon trying to run docker command from within the container.
Related
Is it possible to spawn Docker Services within a container running on Docker swarm? This would allow containers to dynamically maintain the components running in the swarm.
Currently I am able to run containers within other containers on the host machine by mounting the /var/run/docker.sock into the container while using the docker-py SDK.
docker run -v /var/run/docker.sock:/var/run/docker.sock master
Inside the container I have a python script that runs the following:
container = docker.from_env().containers.run('worker', detach=True, tty=True, volumes=volumes, network='backend-network', mem_limit=worker.memory_limit)
Is something similar to this possible in Docker Swarm, not just vanilla Docker?
You can mount the Docker socket and use the docker module as you're doing now, but create a service, assuming you're on a manager node.
some_service = docker.from_env().services.create(…)
https://docker-py.readthedocs.io/en/stable/services.html
I have docker on my host machine with a container running. I was wondering if it's possible, and what the best approach would be, to "trigger" a container creation from the running container.
Let's say my machine is host and I have a container called app (with id 123456789) running on host.
root#host $ docker contain ls
123456789 app_mage .... app
I would like to create a container on host from within app
root#123456789 $ docker run --name app2 ...
root#host docker container ls
123456789 app_mage .... app
12345678A app_mage .... app2
What I need is for my app to be running on docker and to run arbitrary applications in an isolated environment (but I'd rather avoid docker-in-docker)
A majority of the Docker community will veer away from these types of designs, however it is very doable.
Similar to Starting and stopping docker container from other container you can simply mount the docker.sock file from the host machine into the container, giving it privilege to access the docker daemon.
To make things more automated, you could use the docker-py sdk to start containers from inside a container, which would in turn access the Docker deamon on the host machine hosting the container that you are spawning more containers from.
For example:
docker run -v /var/run/docker.sock:/var/run/docker.sock image1 --name test1
----
import docker
def create_container():
docker.from_env().containers.run("image2", name="test2")
This example starts container test1, and runs that method inside the newly created container, which in turn creates a new container test2 running on the same host as test1.
I am creating a Spring Boot monitoring agent that collects docker metrics. The agent can be attached through POM dependency to any client Spring Boot application that runs inside a docker container.
In the agent, I am trying to programatically run docker stats
But, it fails to execute because the docker container doesn't have docker client installed in it.
So how can I run docker commands in docker container? Please note, I can't make changes to the Dockerfile of client.
You may execute docker commands within the container by defining the docker socket in the container.
run the container and mount the 'docker.sock' in the following manner:
docker run -v /var/run/docker.sock:/var/run/docker.sock ...
so mainly you have to mount docker.sock to order to run docker commands within container.
I'm running a gitlab/gitlab-ce container on docker. Then , inside it, i want to run a gitlab-runner service, by providing docker as runner. And every single command that i run (e.g docker ps, docker container ..), i get this error:
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is
the docker daemon running
P.s: i've tried service docker restart, reinstal docker and gitlab-runner.
By default it is not possible to run docker-in-docker (as a security measure).
You can run your Gitlab container in privileged mode, mount the socket (-v /var/run/docker.sock://var/run/docker.sock) and try again.
Also, there is a docker-in-docker image that has been modified for docker-in-docker usage. You can read up on it here and create your own custom gitlab/gitlab-ce image.
In both cases, the end result will be the same as docker-in-docker isn't really docker-in-docker but lets your manage the hosts docker-engine from within a docker container. So just running the Gitlab-ci-runner docker image on the same host has the same result and is a lot easier.
By default the docker container running gitlab does not have access to your docker daemon on your host. The docker client uses a socket connection to communicate to the docker daemon. This socket is not available in your container.
You can use a docker volume to make the socket of your host available in the container:
docker run -v /var/run/docker.sock:/var/run/docker.sock gitlab/gitlab-ce
Afterwards you will be able to use the docker client in your container to communicate with the docker daemon on the host.
I am very new to docker , just started venturing into this. I read online about this. I came to know of the following commands of docker which is: docker run and docker service. As I understood , with docker run we are spinning a new container. However I am not clear what docker service do? Does it spin container in a Swarm?
Can anyone help understand in simple to understand?
The docker run command creates and starts a container on the local docker host.
A docker "service" is one or more containers with the same configuration running under docker's swarm mode. It's similar to docker run in that you spin up a container. The difference is that you now have orchestration. That orchestration restarts your container if it stops, finds the appropriate node to run the container on based on your constraints, scale your service up or down, allows you to use the mesh networking and a VIP to discover your service, and perform rolling updates to minimize the risk of an outage during a change to your running application.
Docker Run vs Docker service
docker run:
we can create number of containers with different images.
docker service:
we can create number of containers with same image in a single command line.
SYNTAX:
docker service create --name service-name --network network-name --replicas number-of-containers image-name
EXAMPLE:
docker service create --name service1 --network swarm-net --replicas 5 redis