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How to Access Docker Container’s Network Namespace from Host

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This post is to illustrate how to access the docker container's network namespace. 1. Identify the docker container id you want to access and run below command as root on host. # docker ps 2. Get docker container's PID: # pid=$(docker inspect -f '{{.State.Pid}}' ${container_id}) 3. Create netns directory: # mkdir -p /var/run/netns/ 4. Create the name space softlink: # ln -sfT /proc/$pid/ns/net /var/run/netns/[container_id] 5. Run ip netns command to access this name … [Read more...] about How to Access Docker Container’s Network Namespace from Host

How To Change The Time Zone For A Docker Container

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The goal of this post is to set up the timezone on the container to match the same timezone on the Docker server, this will allow users to see the same time in both instances (Docker Server and Container). Most of the time Containers do not use the same time as the Docker server, this post will show how to configure this. This is how this looks like before making the changes. Container Time: # docker exec 15c0c99b5c65 date Wed Aug 23 15:40:24 UTC 2019 Docker Server Time: # date Wed … [Read more...] about How To Change The Time Zone For A Docker Container

How To Access Kubernetes Dashboard Externally

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Following is an alternative workaround to access Dashboard externally. 1. kubernetes-dashboard is a service file which provides dash-board functionality, to edit this we need to edit dashboard service and change service "type" from ClusterIP to NodePort: [root@kubeXXXX]# kubectl -n kube-system edit service kubernetes-dashboard # Please edit the object below. Lines beginning with a '#' will be ignored, # and an empty file will abort the edit. If an error occurs while saving this file will … [Read more...] about How To Access Kubernetes Dashboard Externally

New User Failed Run Kubectl with Error “The connection to the server xxx.xxx.xxx was refused – did you specify the right host or port?”

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The Problem When run kubectl from a new created user, failed with error: The connection to the server xxx.xxx.xxx was refused - did you specify the right host or port? The Solution A newly created user has no KUBECONFIG configured. Setup kubernetes configuration for the new user: # mkdir -p $HOME/.kube # sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config # sudo chown $(id -u):$(id -g) $HOME/.kube/config … [Read more...] about New User Failed Run Kubectl with Error “The connection to the server xxx.xxx.xxx was refused – did you specify the right host or port?”

How to schedule master node running pod/service as a worker node

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Question: How can I schedule master node running pod/service as worker node? By deafult, only worker node could run the pod, master only response for the scheduler/configuration. $ kubectl get nodes -o json | jq .items[].spec.taints [ { "effect": "NoSchedule", "key": "node-role.kubernetes.io/master" } ] $ kubectl get nodes -o json | grep master "node-role.kubernetes.io/master": "" "key": … [Read more...] about How to schedule master node running pod/service as a worker node

Troubleshooting kubectl Error: The connection to the server x.x.x.x:6443 was refused – did you specify the right host or port?

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This document describes steps to troubleshoot kubectl error: The connection to the server x.x.x.x:6443 was refused - did you specify the right host or port? 1. The kubectl should be executed on the Master Node. 2. Current user must have Kubernetes cluster configuration environment variable (Details of how to are listed under section Preparing to Use Kubernetes as a Regular User), e.g.: $ env | grep -i kube KUBECONFIG=/root/.kube/config 3. The docker service must be running: $ … [Read more...] about Troubleshooting kubectl Error: The connection to the server x.x.x.x:6443 was refused – did you specify the right host or port?

“docker dead but subsys locked” – error while starting docker

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The Problem The docker engine package was upgraded. After that the user is not able to start the docker service, and revert back with error "docker dead but subsys locked" on verifying the status of the service. Under normal circumstances, the general solution would be to remove the lock file and the dead files of the service. This is not applicable in this condition. # rm /var/run/docker/execdriver/native/ # rm /var/lock/subsys/docker # docker info Cannot connect to the Docker daemon. Is … [Read more...] about “docker dead but subsys locked” – error while starting docker

How to check the status and space used by images and containers

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This post objective is to find out the stats of running container, system information related to space used by images and containers on /var/lib/docker. 1. 'docker stats' command used to check the containers stats on system like CPU usage, IO usage, Memory usage. Below example is for 2 running containers dockerweb and webserver2. # docker stats dockerweb webserver2 CONTAINER ID NAME CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS e33f00e0e3ce dockerweb … [Read more...] about How to check the status and space used by images and containers

6 Bash Shell Command Line Chaining Operators in Linux

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Introduction In this article, I will explain you 6 Bash shell command line Chaining Operators (Linux operator). Now let’s discuss what is chaining operator. Chaining operator is something which helps to run multiple commands at once like we execute a script and task completes automatically. Usually, people use Bash shell command line Chaining Operators (Linux operator) in shell scripting but also we can use these operators on shell prompt. Here we are going to discuss on below Bash shell … [Read more...] about 6 Bash Shell Command Line Chaining Operators in Linux