Category: Docker – ServerOK

How to install Docker on CentOS 8

Posted on September 15, 2021 (September 15, 2021) by ServerOk

RHEL replaced Docker on RHEL 8 (CentOS 8) with podman. To install Docker on CentOS, you can do the fallowing steps. Install yum-utils

yum install -y yum-utils

1	yum install -y yum-utils

Add Docker repository

yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

1	yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

Install Docker with

yum install docker-ce docker-ce-cli containerd.io

1	yum install docker-ce docker-ce-cli containerd.io

Enable docker to start on boot

systemctl enable docker

1	systemctl enable docker

Start docker

systemctl start docker

1	systemctl start docker

Check the status of the docker

systemctl status docker

1	systemctl status docker

Back to docker […]

podman

Posted on August 17, 2021 (August 17, 2021) by ServerOk

Podman is a daemonless, open source, Linux native tool designed to make it easy to find, run, build, share and deploy applications using Open Containers Initiative (OCI) Containers and Container Images. It is compatible with docker cli, so you can alias podman to docker. To install podman on Oracle Linux 8, run

dnf install podman

1	dnf install podman

Once installed, […]

How to check if running inside Docker?

Posted on July 16, 2021 by ServerOk

To check if you are inside a docker container, run the command

cat /proc/1/cgroup | grep --color  docker

1	cat /proc/1/cgroup \| grep --color docker

If you get some result with docker in it, you are inside a docker container. Example See Docker […]

Create Dockerfile From Image

Posted on June 12, 2021 by ServerOk

If you have a docker image and don’t have the Dockerfile used to create the image, dfimage can help you re-create Dockerfile. To find information about an image, you can use the command “docker history IMAGE_ID”. History command will show all actions taken on the image, including the commands used. You can use this information […]

Build a docker container with Apache

Posted on April 26, 2021 (April 26, 2021) by ServerOk

To create a docker container with Apache, create a Dockerfile

mkdir my-app
cd my-app
vi Dockerfile

mkdir my-app

cd my-app

vi Dockerfile

Paste following content into the Dockerfile

from ubuntu:20.04

ARG DEBIAN_FRONTEND=noninteractive

RUN apt-get update && apt-get install -y apache2

RUN echo 'Hello World!' > /var/www/html/index.html

RUN echo '. /etc/apache2/envvars' > /root/run_apache.sh && \
 echo 'mkdir -p /var/run/apache2' >> /root/run_apache.sh && \
 echo 'mkdir -p /var/lock/apache2' >> /root/run_apache.sh && \ 
 echo '/usr/sbin/apache2 -D FOREGROUND' >> /root/run_apache.sh && \ 
 chmod 755 /root/run_apache.sh

EXPOSE 80

CMD /root/run_apache.sh

from ubuntu:20.04

ARG DEBIAN_FRONTEND=noninteractive

RUN apt-get update && apt-get install -y apache2

RUN echo 'Hello World!' > /var/www/html/index.html

RUN echo '. /etc/apache2/envvars' > /root/run_apache.sh && \

echo 'mkdir -p /var/run/apache2' >> /root/run_apache.sh && \

echo 'mkdir -p /var/lock/apache2' >> /root/run_apache.sh && \

echo '/usr/sbin/apache2 -D FOREGROUND' >> /root/run_apache.sh && \

chmod 755 /root/run_apache.sh

EXPOSE 80

CMD /root/run_apache.sh

Now build an image with command

docker build -t sevrerok/okapache:1.0 .

1	docker build -t sevrerok/okapache:1.0 .

Once image is build, you can see it using docker images command

[root@instance-20210426-0136 my-app]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
sevrerok/okapache   1.2                 c3832b03b548        8 minutes ago       214MB
sevrerok/okapache   1.1                 d1a86f0eb69a        37 minutes ago      214MB
ubuntu              20.04               7e0aa2d69a15        2 days ago          72.7MB
sevrerok/okapache   1.0                 7e0aa2d69a15        2 days ago          72.7MB
[root@instance-20210426-0136 my-app]#

[root@instance-20210426-0136 my-app]# docker images

REPOSITORY TAG IMAGE ID CREATED SIZE

sevrerok/okapache 1.2 c3832b03b548 8 minutes ago 214MB

sevrerok/okapache 1.1 d1a86f0eb69a 37 minutes ago 214MB

ubuntu 20.04 7e0aa2d69a15 2 days ago 72.7MB

sevrerok/okapache 1.0 7e0aa2d69a15 2 days ago 72.7MB

[root@instance-20210426-0136 my-app]#

To start a container with the image, run

docker container run -d -p 80:80 sevrerok/okapache:1.0

1	docker container run -d -p 80:80 sevrerok/okapache:1.0

See docker build […]

Install Odoo using Docker

Posted on September 13, 2020 by ServerOk

Odoo is an open source ERP and CRM software written in python. To install Odoo using docker, first install docker using

wget -qO- https://get.docker.com/ | sh

1	wget -qO- https://get.docker.com/ \| sh

Odoo use PostgreSQL server to store database. Lets create a postgres docker container.

docker run -d -e POSTGRES_USER=odoo -e POSTGRES_PASSWORD=your-password-here -e POSTGRES_DB=postgres --name odoo-db postgres:10

1	docker run -d -e POSTGRES_USER=odoo -e POSTGRES_PASSWORD=your-password-here -e POSTGRES_DB=postgres --name odoo-db postgres:10

In above command, replace your-password-here with a secure password. Create a Odoo container with

docker run -d -p 127.0.0.1:8069:8069 -p 127.0.0.1:8072:8072 --name odoo --link odoo-db:db -t odoo

1	docker run -d -p 127.0.0.1:8069:8069 -p 127.0.0.1:8072:8072 --name odoo --link odoo-db:db -t odoo

If container did not […]

Docker delete container after running

Posted on January 1, 2020 by ServerOk

When you run a docker image, it create a container and run it. After docker container stop, container stays, so you can use it again if required. Some times, you need to delete docker container after it is run. This is useful if your docker container is just a command line executable. In my case, […]

Run PostgreSQL in Docker

Posted on June 30, 2019 (June 30, 2019) by ServerOk

To run PostgreSQL on docker, create a directory for saving the data presistant

mkdir -p /opt/my-postgresql

1	mkdir -p /opt/my-postgresql

run docker container

docker run --name my-postgresql \
    -p 5432:5432 \
    -e POSTGRES_PASSWORD=serverok123 \
    -e POSTGRES_USER=serverok \
    -e POSTGRES_DB=serverok \
    -v /opt/my-postgresql:/var/lib/postgresql/data \
    -d postgres

docker run --name my-postgresql \

-p 5432:5432 \

-e POSTGRES_PASSWORD=serverok123 \

-e POSTGRES_USER=serverok \

-e POSTGRES_DB=serverok \

-v /opt/my-postgresql:/var/lib/postgresql/data \

-d postgres

In above, change the value for POSTGRES_DB, POSTGRES_USER and POSTGRES_PASSWORD as needed. Connect to PostgreSQL server To connect to PostgreSQL server, run

docker container exec -ti my-postgresql bash

1	docker container exec -ti my-postgresql bash

Now you are inside PostgreSQL conainer, to login, run

psql -U serverok -W

1	psql -U serverok -W

It will ask for […]

Docker compose start container on boot

Posted on March 3, 2019 by ServerOk

I have a docker container, that i need to start on server boot. The docker-compose.yml file i used to create this docker container is

[root@cp03 serverok-rubycms]# cat docker-compose.yml 
version: '3'
services:
  web:
    image: serverok/rubycms:1.0
    command: bash -c "rm -f tmp/pids/server.pid && cd /myapp && source /etc/profile.d/rvm.sh && script/server -e production"
    volumes:
      - /home/naiwnyc/cms:/myapp
    ports:
      - "3000:3000"
[root@cp03 serverok-rubycms]#

[root@cp03 serverok-rubycms]# cat docker-compose.yml

version: '3'

services:

web:

image: serverok/rubycms:1.0

command: bash -c "rm -f tmp/pids/server.pid && cd /myapp && source /etc/profile.d/rvm.sh && script/server -e production"

volumes:

- /home/naiwnyc/cms:/myapp

ports:

- "3000:3000"

[root@cp03 serverok-rubycms]#

With above docker-compose.yml file. i have to start docker container manually after server reboot. To make it auto start, add the line

    restart: always

1	restart: always

Here is the modified docker-compose.yml file.

[root@cp03 serverok-rubycms]# cat docker-compose.yml 
version: '3'
services:
  web:
    image: serverok/rubycms:1.0
    restart: always
    command: bash -c "rm -f tmp/pids/server.pid && cd /myapp && source /etc/profile.d/rvm.sh && script/server -e production"
    volumes:
      - /home/naiwnyc/cms:/myapp
    ports:
      - "3000:3000"
[root@cp03 serverok-rubycms]#

[root@cp03 serverok-rubycms]# cat docker-compose.yml

version: '3'

services:

web:

image: serverok/rubycms:1.0

restart: always

command: bash -c "rm -f tmp/pids/server.pid && cd /myapp && source /etc/profile.d/rvm.sh && script/server -e production"

volumes:

- /home/naiwnyc/cms:/myapp

ports:

- "3000:3000"

[root@cp03 serverok-rubycms]#

[…]

docker-compose: error while loading shared libraries

Posted on March 3, 2019 by ServerOk

When running docker-compose on CentOS 7, i get following error

[root@cp03 serverok-rubycms]# docker-compose up 
docker-compose: error while loading shared libraries: libz.so.1: failed to map segment from shared object: Operation not permitted
[root@cp03 serverok-rubycms]#

[root@cp03 serverok-rubycms]# docker-compose up

docker-compose: error while loading shared libraries: libz.so.1: failed to map segment from shared object: Operation not permitted

[root@cp03 serverok-rubycms]#

To fix the error, do the following

mv /usr/local/bin/docker-compose /usr/local/bin/docker-compose-bin

1	mv /usr/local/bin/docker-compose /usr/local/bin/docker-compose-bin

Now create a new file

vi /usr/local/bin/docker-compose

1	vi /usr/local/bin/docker-compose

Add following content

#!/bin/bash

export TMPDIR=/opt/compose-tmp
/usr/local/bin/docker-compose-bin "$@"

#!/bin/bash

export TMPDIR=/opt/compose-tmp

/usr/local/bin/docker-compose-bin "[email protected]"

Make it executable

chmod 755 /usr/local/bin/docker-compose

1	chmod 755 /usr/local/bin/docker-compose

Create temp folder

mkdir -p /opt/compose-tmp

1	mkdir -p /opt/compose-tmp

Now docker-compose will work. […]