Greetings, IT Enthusiasts! Welcome to my blog, your go-to destination for all things. Whether you’re a seasoned developer, admin or a curious beginner, we’ve got something for everyone.
I’ll try to provide information and examples in a pill-like form, avoiding unnecessary complications at every level.
Enable repository and install newest gcc with following commands.
yum install centos-release-scl yum install devtoolset-9-gcc devtoolset-9-gcc-c++ devtoolset-9-binutils
Activate it and check version.
scl enable devtoolset-9 bash gcc --version
For make activation permanent add “scl enable devtoolset-9 bash” to end of the the /etc/profile file.
Ok.That’s it!
We will be disabling IPv6 in kernel module.
First, check IPv6 is enabled or not
ifconfig -a | grep inet6
if you see inet6 in the output, you have IPv6.
Let’s disable it. Edit /etc/default/grub file and add ” ipv6.disable=1″ to GRUB_CMDLINE_LINUX
GRUB_TIMEOUT=5 GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)" GRUB_DEFAULT=saved GRUB_DISABLE_SUBMENU=true GRUB_TERMINAL_OUTPUT="console" GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet" GRUB_DISABLE_RECOVERY="true" GRUB_CMDLINE_LINUX="ipv6.disable=1 crashkernel=auto rhgb quiet"
Recreate a GRUB configuration file with command:
grub2-mkconfig -o /boot/grub2/grub.cfg
Now we can restart the server and verify no line “inet6” in the ifconfig/ip command output.
init 6 ifconfig -a | grep inet6
Ok, that’s it!
I assume that you have already installed ansible. If not, please check my blog.
We have a couple of things to do on both the ansible server site and the remote Windows machine.
Let’s start with Windows machine. With most version of Windows, Winrm ships in the box but not turned on by default.
There is a script you can run on the remote Windows machine in PowerShell console as an Administrator. Please download it from link below. Please “Set-ExecutionPolicy Bypass” before executing the script.
, I assume that you have already installed Tomcat, Tomcat System Service, and Ansible. If you have not, please check my blog for instructions.
First we need a inventory file. Let’s create /etc/ansible/hosts file copying foloowing lines. You need to use your tomcat sever ip and user information.
[tomcat] 192.168.1.160 ansible_connection=ssh ansible_ssh_user=tomcat ansible_ssh_pass=tomcat
Now we can check the connection
Here is the fresh installation of docker on CentOS. You can change the docker-compose verison to the latest.
Just create a yml file with following lines.
- name: install docker on fresh server
hosts: localhost
gather_facts: false
tasks:
- name: Get some utils installed and repo added
shell: yum install -y yum-utils; yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
- name: install docker/git
yum:
name:
- docker-ce
- docker-ce-cli
- containerd.io
- git
state: latest
- name: kill firewall
service:
name: firewalld
enabled: no
state: stopped
- name: Enable service
service:
name: docker
enabled: yes
state: started
- name: Grab docker compose
shell: curl -L "https://github.com/docker/compose/releases/download/1.27.4/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose; chmod +x /usr/local/bin/docker-compose
Save it and execute like below.
ansible-playbook install_docker.yml
You can login to a remote Linux machine without entering a password.
First, we need to create public and private keys using ssh-key-gen on the localhost.
ssh-keygen
Now, we have two files in the .ssh directory “id_rsa” as private key file and “id_rsa.pub” as public key file.
If you want to start Tomcat automatically when system boots up, you need to configure it as a system service.
Let’s create a new file tomcat11.service in /etc/systemd/system
[Unit] Description=Apache Tomcat11 After=network.target [Service] Type=forking Environment="JAVA_HOME=/home/tomcat/jdk-21.0.1" Environment="CATALINA_PID=/home/tomcat/apache-tomcat-11.0.0-M14/temp/tomcat.pid" Environment="CATALINA_HOME=/home/tomcat/apache-tomcat-11.0.0-M14" Environment="CATALINA_BASE=/home/tomcat/apache-tomcat-11.0.0-M14" Environment="CATALINA_OPTS=-Xms512M -Xmx1024M -server -XX:+UseG1GC" Environment="JAVA_OPTS=-Djava.awt.headless=true -Djava.security.egd=file:/dev/./urandom" ExecStart=/home/tomcat/apache-tomcat-11.0.0-M14/bin/startup.sh ExecStop=/home/tomcat/apache-tomcat-11.0.0-M14/bin/shutdown.sh User=tomcat Group=tomcat UMask=0007 RestartSec=10 Restart=always [Install] WantedBy=multi-user.target
you need to set your own environment JAVA_HOME, CATALINA_HOME, CATALINA_BASE, CATALINA_PID and ExecStart, ExecStop parameters.
After saving tomcat11.service file, we need to reload systemd daemon with
First we need java. Tomcat11 requires Java Development Kit(JDK) 21 or later versions. You can download and install with following link https://www.oracle.com/java/technologies/downloads
After the installaton you can check version.
java -version
Please note that, if you have multiple java installed in your sever. You need to set JAVA_HOME environment parameter to set correct version.
Download the tomcat11 installation file
wget https://downloads.apache.org/tomcat/tomcat-11/v11.0.0-M14/bin/apache-tomcat-11.0.0-M14.tar.gz
After download create tomcat user in linux and copy tar file to tomcat user home directory and change ownership
First, we need to ensure that python3.9 and pip are available.
if not available, please read my install pyhon3.9 post below.
if so, pip is available proceed installation step but please note that do not install ansible on root user.
pip3.9 install ansible
Verifying ansible installation.
ansible --version
As you can see, the executable location is under the $HOME/.local/bin directory. You can add it to the PATH environment variable in the bash_profile.
Now, we can create configuration file.
sudo mkdir /etc/ansible sudo chown ansible:ansible /etc/ansible ansible-config init --disabled -t all > /etc/ansible/ansible.cfg
Let’s try a simple ansible playbook to test without creating inventory file. We will be using localhost.
create a test.yml file with below lines and save it.
- hosts: localhost
tasks:
- name: Get user name
shell: whoami
register: theuser
- name: Get host name
shell: hostname
register: thehost
- debug: msg="I am {{ theuser.stdout }} at {{ thehost.stdout }}"
Execute with following command.
ansible-playbook test.yml
Ok, that’s it!
Firstly, install the requsite packages.
sudo yum install gcc openssl-devel bzip2-devel libffi-devel zlib-devel
Once that is done, download python3.9 or newer version.
wget https://www.python.org/ftp/python/3.9.6/Python-3.9.6.tgz
Extract it.
tar -xvf Python-3.9.6.tgz
Move into the directory and configure with following command.