To run Ansible playbook in multiple hosts via SSH.
SOLUTION
Configuring SSH environment
Ensure SSH keypair exists on the current machine (ex: ~/.ssh/id_rsa for private key and ~/.ssh/id_rsa.pub for public key). If you do not have one, create one:
ssh-keygen
Copy the public key (ex: ~/.ssh/id_rsa.pub) to each remote host’s ~/.ssh/authorized_keys. If this file doesn’t exist, create it.
Ensure the current machine’s .ssh/ directory and file have correct permission.
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys
In the current machine’s /etc/hosts, add all remote hosts.
In each remote host, enable the remote login and grant yourself the access to this service.
Enabling Remote Login on Mac
Test SSH connection to remote host to ensure they work first before working on Ansible playbook.
ssh user@donkeykong
ssh user@supermario
Creating Ansible Playbook
Create ansible.cfg and define the location of inventory file.
[defaults]
inventory = inventory.yml
Create inventory.yml and define both localhost and remote hosts.
all:
hosts:
localhost:
ansible_connection: local
donkeykong:
ansible_user: user
ansible_ssh_private_key_file: ~/.ssh/id_rsa
supermario:
ansible_user: user
ansible_ssh_private_key_file: ~/.ssh/id_rsa
Run a test to ensure the connection to remote hosts are successful.
ansible all -i inventory.yml -m ping
If successful, the output looks something like this:
You have a shiny Mac laptop running macOS Big Sur. This laptop is connected to an old external monitor via HDMI. The screen quality looks pixelated and fuzzy.
Running font smoothing (as below) doesn’t fix the problem:
The usage of HDMI seems to fool macOS Big Sur, thinking your old monitor is a glorious new TV. This causes macOS to use YPbPr instead of RGB mode.
The fix is to perform Extended Display Identification Data (EDID) override to force macOS to use RGB mode.
Some instructions on the web are inaccurate. There’s no need to reboot into Recovery Mode to disable System Integrity Protection (SIP) via csrutil first.
When running the Docker container interactively (ex: docker run --rm -it myimage), you want to run a startup script every time.
SOLUTION
For Ubuntu, Debian and Centos images, write the startup script to /root/.bashrc:
# UBUNTU
FROM ubuntu:latest
RUN echo "echo 'Welcome!'" >> /root/.bashrc
WORKDIR /home
# DEBIAN
FROM debian:latest
RUN echo "echo 'Welcome!'" >> /root/.bashrc
WORKDIR /home
# CENTOS
FROM centos:latest
RUN echo "echo 'Welcome!'" >> /root/.bashrc
WORKDIR /home
For Alpine image, it’s a little different because it uses Ash shell. Besides writing the startup script to /root/.profile, you also need to set that path to an environment variable called ENV:
FROM alpine:latest
ENV ENV=/root/.profile
RUN echo "echo 'Welcome!'" > $ENV
WORKDIR /home
