Kubernetes 101 - Part12 - Debug pod

While troubleshooting application connectivity and name resolution issues in Kubernetes we often have to access utilities like ping, nslookup, dig, traceroute, etc. Here is a container image that you can use in those cases. Following are some of the utilities that are pre-installed on this container image:

• ping
• dig
• nslookup
• traceroute
• curl
• wget
• nc
• netstat
• ifconfig
• route
• host
• arp
• iostat
• top
• free
• vmstat
• pmap
• mpstat
• python3
• pip

 

Run as a pod on Kubernetes

❯ kubectl run debug --image=vineethac/debug -n default -- sleep infinity

 

Exec into the debug pod

❯ kubectl exec -it debug -n default -- bash 
root@debug:/# ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=46 time=49.3 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=45 time=57.4 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=46 time=49.4 ms
^C
--- 8.8.8.8 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2003ms
rtt min/avg/max/mdev = 49.334/52.030/57.404/3.799 ms
root@debug:/#
root@debug:/# nslookup google.com
Server:		10.96.0.10
Address:	10.96.0.10#53

Non-authoritative answer:
Name:	google.com
Address: 142.250.72.206
Name:	google.com
Address: 2607:f8b0:4005:80c::200e

root@debug:/# exit
exit
❯

 

Reference

https://github.com/vineethac/Docker/tree/main/debug-image

Hope it was useful. Cheers!

Kubernetes 101 - Part10 - Plugins I use for managing K8s clusters

Following are some of the kubectl plugins that I use on a daily basis: 

• kubectx

• kail

• kubectl tree

• kubectl images

• kubectl allctx

• kubectl view-cert -A -E

• kubectl get-all

• kubectl neat
  

You can find many useful kubectl plugins here: https://krew.sigs.k8s.io/plugins/

Docker 101 - Part5 - Push container image to docker hub repository

Docker 101 - Part4 - Creating images using dockerfile

In this article, I will briefly explain how to create your own image using Dockerfile. For example, I will be creating an FIO image. FIO is a storage stress test tool and this image can be used for container storage IO benchmarking/ testing.

• Login to the CentOS docker host.
• Create a file named "Dockerfile".
• # vi Dockerfile
• Add the below two lines and save it.

• # docker build ./

• Once the build is complete, it returns the IMAGE ID as shown below.
• You can use the "docker tag" command to mention a repository and tag to the image. 

• At this stage, as shown in the above screenshot, the FIO image is created with repository "vineethac/fio_image" and tagged as "latest".
• You can run this image as given below.

• # docker run -dit --name FIO_test01 --mount source=disk_data,target=/vol vineethac/fio_image fio --name=RandomReadTest1 --readwrite=randread --rwmixwrite=0 --bs=4k --invalidate=1 --direct=1 --filename=/vol/newfile --size=10g --time_based --runtime=300 --ioengine=libaio --numjobs=2 --iodepth=1 --norandommap --randrepeat=0 --exitall

• The above command will start a container with FIO application running inside it. FIO will use "/vol/newfile" for IO tests. "/vol" is using "disk_data" directory which is inside "/var/lib/docker/volumes". Once the test is complete, the container will exit.

Hope it was useful. Cheers!

Related posts

Docker 101 - Part3 - Persisting data using volumes

Docker 101 - Part2 - Basic operations

Docker 101 - Part1 - Installation