Uly.me

cloud engineer

docker

Run MySQL in a Docker container

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How to run MySQL commands in a Docker container.

#!/bin/bash
set -a; source <(cat .env | sed -e '/^#/d;/^\s*$/d' -e "s/'/'\\\''/g" -e "s/=\(.*\)/='\1'/g"); set +a
docker exec wp_db mysql -uroot -p${MYSQL_PASSWORD} -e " \
use db1; \
select * from wp_options where option_name='siteurl'; \
select * from wp_options where option_name='home';" 2>/dev/null
  • The first command loads the content of .env to environment variables.
  • The MySQL password can then be used using the ${MYSQL_PASSWORD} variable.
  • I’m using sed to get around the special characters in the password.
  • The second command runs docker exec on wp_db container.
  • The last 3 commands are the actual sql commands.
  • We are selecting to use the db1 database.
  • Then we run select statements from the wp_options table.
  • Finally, 2>/dev/null suppresses errors and warning to null.

Rebuild Docker containers

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How to rebuild your application from scratch using Docker.

#!/bin/bash
docker-compose down -v
docker rmi $(docker images -a -q)
docker-compose up -d
docker-compose restart -t 10

Steps

  • Purge the containers.
  • Delete docker images.
  • Reinitiate docker.
  • Restart docker.

Install Docker on Amazon Linux 2

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Steps how to install Docker and Docker Compose on Amazon Linux 2.

Install Docker

$ sudo amazon-linux-extras install docker
$ sudo service docker start
$ sudo usermod -a -G docker ec2-user

Start at boot.

$ sudo chkconfig docker on

Install git (optional).

$ sudo yum install -y git

Install Docker Compose

$ sudo curl -L https://github.com/docker/compose/releases/latest/download/docker-compose-$(uname -s)-$(uname -m) \
-o /usr/bin/docker-compose
$ sudo chmod +x /usr/local/bin/docker-compose

Check

docker --version
docker-compose --version

Stop and remove all Docker containers

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How to stop and remove all Docker containers.

Stop all containers

$ docker kill $(docker ps -q)

Remove all containers

$ docker rm $(docker ps -a -q)

Delete all docker images

$ docker rmi $(docker images -q)

Docker container logs

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How to check Docker container logs. Look for the container ID.

$ docker ps -a
3e2c1193915f

To view the logs for the container.

docker logs 3e2c1193915f
# or
docker container logs 3e2c1193915f

Rocky Linux in a Container

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Here’s how to run Rocky Linux in a Docker container.

Download the image.

docker pull rockylinux/rockylinux

Create a Rocky Linux container called bullwinkle.

docker run -it --name bullwinkle -d rockylinux/rockylinux

Login to the container using bash.

docker exec -it --user root bullwinkle /bin/bash

When done, stop and delete the container.

docker ps -a
docker stop container_ID
docker rm container_ID

Terraform in a Docker Container

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Run Terraform in a Docker container.

docker run --rm -it --name terraform -v ~/.aws:/root/.aws -v $(pwd):/workspace -w /workspace hashicorp/terraform:latest

Create an alias.

alias terraform='docker run --rm -it --name terraform -v ~/.aws:/root/.aws -v $(pwd):/workspace -w /workspace hashicorp/terraform:latest'

Run the command

terraform --version
Terraform v1.0.2
on linux_amd64