DevOps Classroomnotes 23/Nov/2022

Docker Volumes Contd..

• Generally for stateful application containers, its a good idea to create a VOLUME as part of Dockerfile.
• Experiment:
  • Create a volume for mysql data and mount that into mysql container
    
    
  • insert some data into it
    
  • delete the container
  • Create a new mysql container and reuse the same volume and verify if the data is present or not.
    
    
    
  • To interact with mysql container Refer Here
  • To create the container we have used docker container run --name mysql-primary -d -P --mount "source=mysql-employee-vol,target=/var/lib/mysql" -e "MYSQL_ROOT_PASSWORD=rootroot" -e "MYSQL_USER=qtdevops" -e "MYSQL_PASSWORD=qtdevops" -e "MYSQL_DATABASE=employee" mysql
  • To login into mysql prompt docker container exec -it mysql-primary mysql -u root -p
  • To create a table
    use employee;
CREATE TABLE authors (id INT, name VARCHAR(20), email VARCHAR(20));
INSERT INTO authors (id,name,email) VALUES(1,"Vivek","xuz@abc.com");
INSERT INTO authors (id,name,email) VALUES(2,"Priya","p@gmail.com");
INSERT INTO authors (id,name,email) VALUES(3,"Tom","tom@yahoo.com");
select * from authors;
• Tmpfs mount: This gets mounted to the RAM/memory into container. This is useful only for applications which require preset data to be present in memory

Networking

• Every container is getting an ip address
• Docker has a subcommand for network
  
• lets see what are the networks available
  
• Two possible Networing options identified
• Share the same network of docker host to the container
  
• Create a new network on the docker host and make it available to the containers. Connect the network created by docker host to the network docker host is connected by using a bridge
  
• Experiment:
  • Created a linux vm and verified network interfaces. we had two interfaces
    • loopback (lo) => 127.0.0.1/localhost
    • eth0
  • We had installed docker on the linux machine and one more interface got created
    • docker0
  • Now we have create a docker container and verified the network interfaces we got two interfaces
    • loopback (lo)
    • eth0