Rename and Remount LVM Logical Volume

A usual scenario where rename and remount of LVM logical volume are needed, is when you install a box with a CentOS, and use the default LVM based partitioning scheme. This scheme will take 50G for your / partition, and the rest will be allocated to your /home, which is not practical. In this example, we will be remounting logical volume originally mounted to /home, to /var/lib/elasticsearch, renaming it along the way.

The original partition scheme 

# df -Th

Filesystem                   Type      Size  Used Avail Use% Mounted on

/dev/mapper/cl-root          xfs        50G  3.0G   48G   6% /

/dev/sda1                    xfs      1014M  179M  836M  18% /boot

/dev/mapper/cl-home xfs       965G   42G  924G   5% /home

Stop the service that might be using the partition that we are going to change

# systemctl stop elasticsearch

Rename the original directory to other name

# mv /var/lib/elasticsearch /var/lib/elasticsearch-old

Create a new directory to replace the one we already renamed above

# mkdir /var/lib/elasticsearch

Unmount /home

# umount /home

Check the name of volume group and logical volume

# lvs

Rename the logical volume to the one we desired. This is totally optional. You can use -t flag to test out the renaming process before proceeding

# lvrename -t cl home elasticsearch

# lvrename cl home elasticsearch

Change /etc/fstab to reflect on the new logical volume name and mount point. Test it out without the  -i option, before permanently make the change using the -i option

# sed 's/cl-home/cl-elasticsearch/g;s/\/home/\/var\/lib\/elasticsearch/g' /etc/fstab

# sed -i 's/cl-home/cl-elasticsearch/g;s/\/home/\/var\/lib\/elasticsearch/g' /etc/fstab

Mount it

# mount -a

Check to see if your new directory and logical volume mounted properly

# df -Th

Filesystem                   Type      Size  Used Avail Use% Mounted on

/dev/mapper/cl-root          xfs        50G  3.0G   48G   6% /

/dev/sda1                    xfs      1014M  179M  836M  18% /boot

/dev/mapper/cl-elasticsearch xfs       965G   42G  924G   5% /var/lib/elasticsearch

Move the content of /var/lib/elasticsearch to /home

# mv /var/lib/elasticsearch/* /home

Move the content of /var/lib/elasticsearch-old to /var/lib/elasticsearch

# mv /var/lib/elasticsearch-old/* /var/lib/elasticsearch

Remove /var/lib/elasticsearch-old

# rmdir /var/lib/elasticsearch-old

Set proper permission for /var/lib/elasticsearch

# chmod 750 -R /var/lib/elasticsearch

# chown -R elasticsearch.elasticsearch /var/lib/elasticsearch

Start your service

# systemctl start elasticsearch

Done.

Run an Application with GUI with Docker

There are a few ways to achieve this, like vnc and ssh X forwarding. But in this post, I will show how to run firefox by sharing the .Xauthority file with the docker instance.

First, create a Dockerfile in a directory called docker that use an ubuntu image from dockerhub, and install the firefox application

$ mkdir docker

$ cd docker

$ cat > Dockerfile

FROM ubuntu

RUN apt update && apt install -y firefox

CMD ["/usr/bin/firefox"]

Press ctrl-d to save the file

Next, build an image using the above Dockerfile

$ sudo docker build --tag=firefox-app docker/

Then, run the image, with additional options of --network and --env, and sharing our host .Xauthority file with the container that we are going to run 

$ sudo docker run --network=host --env="DISPLAY" --volume="$HOME/.Xauthority:/root/.Xauthority:rw" --name=firefox1 firefox-app

You should be able to get a working firefox, running from a docker container, separated from the current firefox that you have in your current machine

Credit: https://medium.com/@SaravSun/running-gui-applications-inside-docker-containers-83d65c0db110