Kubernetes (k8s) – Open-source container orchestration platform that automates many of the manual processes involved in deploying, managing, and scaling containerized applications. Namespaces – Virtual cluster backed by the same physical cluster. Namespaces are the way to separate and organize objects such as pods and containers in your cluster Role-Based Access Control (RBAC) – Method…
Category: TUTORIALS
TUTORIALS
Ansible Vault
The ansible vault allows file encryption and requires a password to unencrypt Command: ansible-vault encrypt <file> The ansible-vault rekey command will allow you to re–encrypt a file and reset the password To supply the vault password during play execution, you must use either of the –ask-vault-password or –ask-vault-file flags Ansible 2.4 introduces the –vault-id feature…
Ansible Parallelism
It is possible to control the number of hosts acted upon at once tie by Ansible. The Ansible process will create forks to execute actions in parallel. Parallelism is the word used for Ansible default ability to interact with multiple hosts at the same time. The parallel processes spawned by Ansible are known as forks…
Ansible Galaxy
Ansible Galaxy (https://galaxy.ansible.com/) is essentially a large public repository for sharing and downloading community developed ansible roles. Roles ship with readmes detailing role use and available variables. Galaxy contains a large number of roles that are constantly evolving and increasing. Galaxy can use git allowing for other role sources such as GitHub. The ansible-galaxy utility…
Ansible Roles
Roles The default location for roles is /etc/ansible/roles Roles provide a way to automatically load certain vars_files, tasks and handlers based on a known file structure Roles expect a particular directory structure Directories not being used may be excluded Each directory in use contains a main.yml with relevant content Roles Directories Tasks – Contains the…
Ansible Variables and Templates
Variables can contain letters, numbers and underscore, but must begin with a letter Can be stored as dictionaries which map keys to values. Dictionary variables can be refenced using bracket notation or dot notation, ex: dictionary_name [‘filed’] or dictionary.field Variables stored as a list (array) may be accessed by putting the element number in brackets:…
Ansible Error Handling
ignore_errors – Ignore any errors force_handlers – Force previously notified handler to run failed_when – Define failure conditions changed_when – Override the “changed” status result any_errors_fatal – Abort an entire play if any task fails block / rescue / always – Implement a block in order to logically group tasks and provide error handling
CentOS/RHEL 8 Boot Loader File
Grub Parameter File : /boot/grub2/grubenv # GRUB Environment Block saved_entry=82c1b57e69f343e28fe48516f70a9866-4.18.0-193.28.1.el8_2.x86_64 kernelopts=root=/dev/mapper/cl-root ro console=ttyS0,115200n8 no_timer_nvme_core.io_timeout=4294967295 nvme_core.max_retries=10 crashkernel=auto resume=/dev/mapper/cl-swap rd.lvm.lv=cl/root rd.lvm.lv=cl/swap boot_success=0 boot_indeterminate=0 ON BIOS (Basic Input/Output System) Systems : /boot/grub2/grub.cfg On Systems with UEFI (Unified Extensible Firmware Interface) : /boot/efi/EFI/centos/grub.cfg OR /boot/efi/EFI/rhel/grub.cfg To Generate Grub config file : grub2-mkconfig -o /boot/efi/EFI/centos/grub.cfg
Virtual Data Optimizer (VDO)
What – Virtual Data Optimizer (VDO) is a device mapper module which adds data reduction capabilities to the Linux block storage stack. VDO is a block virtualization technology that combines: Data Compression (Compress Remaining Blocks) Data Deduplication (Eliminate Duplicate Blocks) Thin provisioning (Eliminate Zero Blocks) Data Deduplication is a technique for eliminating duplicate copies of repeating…
Ansible and Core Components
There are several IT automations tools like Chef, Puppet, Salt, Rundeck etc. Ansible is one of them and its very popular. Same as other tools, it can configure systems, deploy software, and orchestrate more advanced IT tasks such as continuous deployments or zero downtime rolling updates etc. Ansible Tower by RedHat is a commercial (free…