I am debugging a Kubernetes cluster which deploys Docker containers.
How can I see the results and exit code of docker run executed by Kubernetes?
Kubernetes does not execute docker run command, it works with an API, usualy via default docker endpoint unix:///var/run/docker.sock
Related
I am running kubernetes cluster on AWS using Kops. We deploy Jenkins on it and we want to run docker, kubectl commands inside jenkins pods and want output to show of kubernetes clusters nodes, pods, and containers. We are able to achieve this via dockerfile or docker compose. We tried to mount docker socket as volume but didn't workout.
The regular jenkins image does not ship with the docker command.
Check out this jenkins image, it contains the docker and docker-compose commands:
https://hub.docker.com/r/trion/jenkins-docker-client
I found the solution, i need to mount docker socket and docker binary inside jenkins container and it will workout like charm.
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 am really confused, I had being learning kubernetes with minikube creating services and other things.
The problem comes in the following shape:
I run the following commands after a fresh install of minikube:
eval $(minikube docker-env)
The reason is because I want to get an image from my computer to be used with minikube. My understanding is that with this command I am in the same context for minikube and docker, so I can access my local images. "Please correct me if I am wrong here".
minikube start
So I get up and running the cluster, and ready to start creating things.
I want to pull the following container:
docker pull nginx/nginx-ingress
Because I want to try an ingress controller to work with my services.
But then I get this weird message:
Using default tag: latest
Warning: failed to get default registry endpoint from daemon (Cannot connect to the Docker daemon at tcp://192.168.99.101:2376. Is the docker daemon running?). Using system default: https://index.docker.io/v1/
Cannot connect to the Docker daemon at tcp://192.168.99.101:2376. Is the docker daemon running?
I run:
docker ps
And no results with a hang out.
I go to another terminal, I run the docker ps and it works like a charm.
Please if someone can bring some light to me of the impact of the command:
eval $(minikube docker-env)
And if you know why in my current Term with minikube running cannot access to my docker machine would help a lot.
minikube starts a dedicated virtual machine as a single-node Kubernetes cluster. If you have other Docker environments (a separate Docker Machine VM, the Docker Toolbox VM, the Docker for Mac or Docker for Windows environments, or a Linux-native Docker) these are separate from the Docker in the VM. You can't share images or containers between these environments.
If you have private images that aren't published to a registry, you'll have to re-docker build them when you switch to the Minikube environment. You otherwise don't specifically have to docker pull things that you're using, when you reference them in a Kubernetes pod spec Kubernetes will pull them for you.
I have a setup which runs my Docker container like this.
run-docker.sh
docker build -t wordpress-gcloud
container=$(docker run -d wordpress-gcloud)
ipOfContainer=$(docker inspect "$container" | jq -r '.[0].NetworkSettings.IPAddress')
But now I have setup a Docker Swarm (1 manager + 2 workers).
How should I convert the above bash script to run the container on the swarm?
Typically, you can access your Swarm cluster via Swarm APIs, which is similar with Docker API. To access Swarm APIs, you can use -H parameter with docker commands. For example, if you have a swarm manager running on your local machine, and the port number is 3376, then you can get your swarm cluster info with:
docker -H 127.0.0.1:3376 info
You can also inspect the swarm cluster containers by:
docker -H 127.0.0.1:3376 inspect <container ID>
More details about communciate with Swarm cluster can be found here: https://docs.docker.com/swarm/install-manual/#/step-6-communicate-with-the-swarm
But in your case, I think that docker build command could be a problem. In my understanding, Swarm will find a random node from your cluster to execute this docker build process, so if the Dockerfile is not existing on the node where docker build has been executed, you will get error. My idea is to consider to build your image in a certain place, and push the image to a image registry, then pull and run the image in any place you want.
I'm using the Kubernetes Jenkins plugin to orchestrate jenkins slaves
I want to run all the jobs in Docker (build docker images and execute tests/builds in docker).
example jenkins job:
docker run -e NEXUS_USERNAME=${NEXUS_USERNAME} -e NEXUS_PASSWORD=${NEXUS_PASSWORD} common-dropwizard:latest mvn deploy
I am using the jenkinsci/jnlp-slave from here: https://hub.docker.com/r/jenkinsci/jnlp-slave/
Unfortunately, the slave image doesn't appear to support running docker. My question is what is the best approach to accomplish this?
thanks
You need to install docker client and mount the docker socket so you can access the Docker host. Then you can interact with that Docker host
https://jpetazzo.github.io/2015/09/03/do-not-use-docker-in-docker-for-ci/
https://github.com/jenkinsci/docker-workflow-plugin/tree/master/demo