Docker series (Part 12): Database upgrade with named volume

Tasks we will do are:

Let's start:

1. First we went to dockerhub and searched for postgres

1. After that we are going to filter from tags for 9.6.1

You may look into it

1. We can see the volume path here

We will use it while creating the container

1. Lets create the container

docker container run -d --name psql -v psql:/var/lib/postgresql/data postgres:9.6.1

basically we have used -d to detach the container and get the container ID

--name is used to name the container the name "psql"

-v is used to set the volume and "psql:" is used to give it a name and "/var/lib/postgresql/data" is given to set the volume address .

after that we have used postgress:9.6.1 to use the image of "postgres" and its version is 9.6.1

1. NOw we will monitor our container logs live

docker container logs -f psql

-f is given s we can keep watching as it runs

Now we can see that

LOG:  autovacuum launcher started
LOG:  database system is ready to accept connections

That means we are ready to work

Now, lets stop it using Ctrl+c

1. Lets stop this container

docker container stop psql

We have used the container name here (psql)

1. Now lets create a container having version 9.6.2

docker container run -d --name psql-2 -v psql:/var/lib/postgresql/data postgres:9.6.2

1. Now lets see the list of containers

docker container ps -a

to see the whole history of containers we created or are running

You can see the postgres:9.6.2 is running but postgres:9.6.1 has exited as we stopped it few moments back.

1. Check the volume list

docker volume ls

Here you can see "psql" volume used . Note: for the version 9.6.1 & 9.6.2 we used the same volume psql

How?
Check out this commands

docker container run -d --name psql -v psql:/var/lib/postgresql/data postgres:9.6.1

docker container run -d --name psql-2 -v psql:/var/lib/postgresql/data postgres:9.6.2

We have psql:/var/lib/postgresql/data both the times where "psql" was the volume name and "/var/lib/postgresql/data" was the location of the volume

OH! By the way, don't forget that we set this volume location after checking the official image's volume location

Let's check the logs for this container

docker container logs <container name or, container id>

This time we did not see live logs...You can do it using

docker container logs -f <container name or, container id>