Ansible – Linux Book Center

Unreachable Host: port unreachable

Unreachable Host: port unreachable : port unreachable

I do have access to ssh into the destination machine, and it works, but whenever I run this playbook, I get this error output:

sudo ansible-playbook test.yml PLAY [web] ***************************************************************************************************************************************************************************************** TASK [Gathering Facts] *********************************************************************************************************************************************************************************** fatal: [machine]: UNREACHABLE! => {"changed": false, "msg": "Failed to connect to the host via ssh: Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password,keyboard-interactive).\r\n", "unreachable": true} to retry, use: --limit @/ansible-play/test.retry PLAY RECAP *********************************************************************************************************************************************************************************************** machine : ok=0 changed=0 unreachable=1 failed=0

Solution 1:

Try to check the SSH arguments and I used below, and it helps me sometime.

#ansible-playbook --user=brines -vvv test.yml

Solution 2:

Invalid SSH Configuration also may lead this issue. So, hvae to fix the SSH configuration issue or copy & paste the ssh keys on concern hosts.

#cd /root/.ssh 
#ssh-keygen -t rsa

save key under the name of id_rsa

#cat id_rsa.pub

copy the entire key and paste in file (of master node located at path: /.ssh/ or /root/.ssh) as:

#vi authorized_keys

Then run this to check:

#ansible all -m ping -u brines

Output should be like this:

master-node | SUCCESS => { "changed": false, "ping": "pong" }

How to create Incident in Service Now using ansible?

Overview

Faster delivery can result in improved support and for stakeholder satisfaction, faster delivery and improved productivity will be the most important thing while automating any service and it is very much satisfied here.

We can do below operations in Service Now using ansible

Updating incidents, problems, and change requests

Updating the Service Now configuration management database (CMDB)

Using the CMDB as an inventory source

In this post will demonstrate, how to manage incidents.

First, we need install the collation to handle any service and here we need to install.

servicenow.itsm collection to manage service servicenow through ansible.

Install Service Now collection using below command:

$ ansible-galaxy collection install servicenow.itsm

Once the collection installed, then we have access to below modules:

servicenow.itsm.incident for managing incident tickets
servicenow.itsm.problem for interacting with problems
servicenow.itsm.change_request for handling changes
servicenow.itsm.configuration_item for managing the CMDB
servicenow.itsm.now Inventory plugin and it allows us to use CMDB as an inventory source.

To display the documents of each module use below command

$ ansible-doc servicenow.itsm.incident

Credentials and Service Now declaration:

Before managing incident, we should tell ansible where our ServiceNow instance available and what credentials to be used.

Create inc_vars.yml file and mention instance & credentials as variables like below

---
#snow_record variables
sn_username: admin
sn_password: mypassword@123
sn_instance: snow_host

#data variables
sn_severity: 2
sn_priority: 2

Now that we have our credentials variables ready to use in playbook and we need to create a playbook to create new incident.

Create inc_new.yml and add below codes and save & exit

---
- host: localhost
  gather_facts: false
  tasks:
    - name: create new incident
      servicenow.itsm.incident
        state: new
        username: "{{ sn_username }}"
        password: "{{ sn_password }}"
        instance: "{{ sn_instance }}"
        
        data:
          severity: "{{ sn_severity }}"
          priority: "{{ sn_priority }}"
          short_description: demo incident
   register: new_incident
 - debug:
     var: new_incident.record

Now run this playbook using below  and it will create a new incident

#ansible-playbook inc_new.yml

How to patch linux servers using ansible

Ansible is opensource automation tool and will see how to patch linux servers using ansible in this post.

We are going to use RedHat Linux 7.3 Operating System in this practical.

Requirements:
1. Linux Host Installed with Ansible and Yum repository configured with httpd.
2. Linux Host Installed with RHEL 7.4 -> Node machine
3. Since Ansible requires SSH enabled between ansible master and node and don’t have node package, Make sure SSH connection established between Master and node.

Configuring yum repository for patching:

browse https://access.redhat.com/ and login with valid credentials.
Click on Security -> Security Advisories and downlod the necessary packages.
Copy those packages to yum repository where all existing packages are available in Linux host. I downloaded and copied kernel update in my repository.

 
# yum list all | grep 3.10.0-1062.el7
kernel.x86_64                            3.10.0-1062.el7                @yum_repo
kernel-headers.x86_64                    3.10.0-1062.el7          yum_repo
kernel-devel.x86_64                      3.10.0-1062.el7          yum_repo
kernel-tools.x86_64                      3.10.0-1062.el7          yum_repo
kernel-tools-libs.x86_64                 3.10.0-1062.el7          yum_repo

4. Run createrepo, “yum clean all” & “yum makecache” commands to update the repository along with new RPM’s.

Now the repository is ready for patching.

Ansible playbook for Linux patching:

#cd /etc/ansible

2. create playbook called “patching.yml” with below content

# vi patching.yml
---
- name: Patch Linux system
  hosts: Linux_Servers
  become: true
  ignore_errors: yes
  tasks:
- name: Copy the Kernel Patch Repo File
  copy:
    src: /etc/yum.repos.d/yum.repo
    dest: /etc/yum.repos.d/
- name: Apply patches
  yum:
     name: kernel
     state: latest

3. Edit /etc/ansible/hosts file and provide Linux hosts which needs to be patched and mention group as “Linux_Servers” for those hosts. Host group name has been mentioned in playbook in “hosts: Linux_Servers” portion.

# cat /etc/ansible/hosts
[Linux_Servers]
client.lbc.com

4. Now run the playbook from Ansible host and make SSH connection established between master and client.

# ansible-playbook patching.yml

Before kernel patching:

# uname -a
Linux client.lbc.com 3.10.0-862.el7.x86_64 #1 SMP Wed Mar 21 18:14:51 EDT 2018 x86_64 x86_64 x86_64 GNU/Linux

After kernel Patching:

# uname -a
Linux client.lbc.com 3.10.0-1062.el7.x86_64 #1 SMP Thu Jul 18 20:25:13 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

We successfuly completed kernel patching. Reference:

How to install Ansible on RHEL7/ CentOS7

We are going to see how to install Ansible on RHEL7/ CentOS7 in this post.

Control node needs to install Python 2.6 or latest version and windows doesn’t support for control node.

Since the ansible agentless tool, on Managed hosts no need to install any specific agent/client. And need to install python 2.4 or latest version on managed hosts.

Installing Ansible on RHEL7/ CentOS7:

To install the Ansible we should have Enabled EPEL repository on our server already

Once enable EPEL Repo, then we can start installing Ansible using yum.

[root@localhost ~]# yum install ansible -y

Post installation of ansible will check the version of Ansible by using below command

[root@localhost ~]# ansible --version
ansible 2.7.9
 config file = /etc/ansible/ansible.cfg
 configured module search path = [u'/root/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
 ansible python module location = /usr/lib/python2.7/site-packages/ansible
 executable location = /usr/bin/ansible
 python version = 2.7.5 (default, Aug 2 2016, 04:20:16) [GCC 4.8.5 20150623 (Red Hat 4.8.5-4)]
[root@localhost ~]#

Finally, we installed ansible over our machine which we are going to take it as a control node.

Hereafter if we want to deploy or manage any remote hosts(Managed Host) from the control node, SSH authentication is mandatory. So, We should copy and paste the SSH keys to the remote hosts to make the communication available between the control and managed node.

Reference: Ansible documented site

Architecture of Ansible

we are going to see the Architecture of Ansible in this post.

Communication:

Communication established between control node(Server) and Managed hosts(Client machines) using SSH Protocol.

A normal user will be sufficient for communication between Control and Managed hosts.

A normal user can able to perform a few tasks but for other tasks, we need administrators user or other users who have sudo access to perfom that tasks.

complete Architecture detail of Ansible:

This will explain how the ansible working and what are all the things contains as architecture.

As we can see the above diagram ansible automation engine will interact directly with the person who writes playbooks to do tasks.

It also interacts with the cloud(public/private) directly. Basically its CMDB(Configuration Management Data Base).

Also, it contains the below components:

Inventory
Modules
API
Plugins

Inventory:

Inventory will contain the List of Host or IP Address of Host/ Wildcards where we are going to do automation tasks using ansible.

default ansible inventory path: /etc/ansible/hosts

We can specify the different inventory path using -i option.

Modules:

Ansible has more 1000 readymade playbooks in it and we should use those modules in paybooks to do automation tasks. Modules will be copied from Control node to managed hosts while executing the tasks and it will run the program based on playbook and Module then will give back us the output.

Also, the user can create custom playbooks based on their needs.

We should mention the modules in playbooks and modules will be directly executed in remote hosts through playbooks and will get the output.

API:

Ansible uses API as transport for Cloud services.

Plugins:

Plugins will enhance the features ansible.

Plugins will allow executing the task on build stat. Its a piece of code.

Using ansible we can automate the tasks on different types of network.

Introduction of Ansible automation tool

We are going to see Introduction of Ansible automation tool in this post. By reading the future post you can learn full ansible automation and it’s purely based on RedHat Linux.

Ansible is written by Micheal DeHaan

What is Ansible?

It’s a simple IT automation and powerful configuration management tool which is written in python.

It’s an open source configuration management tool.

We can standardize our environment configuration from one server to all other remote servers using ansible by creating the playbooks to complete that task.

Mainly it’s agentless automation tool. Work is pushed to the remote host when the ansible executed.

What we can do:

Configuration of Servers
Application Deployments
Continuous testing of existing application
Provisioning
Orchestration
Automating our administration tasks

What we cannot do:

We cannot install the initial minimum installation of the system.
We cannot monitor the servers
It will not track what changes are made over the files on the system.

How the Ansible work:

Ansible Syntax (or) ansible adhoc command:

Ex:

#Ansible -m command -a "uptime" Test

Ansible:- Keyword

m:- Module

command:- Module Name

uptime:- OSCommand

Test:- Target server Group

Ansible Features:

Easy to learn
Written in python
Agentless
YAML based playbooks
Ansible Galaxy

Ansible Modules:

It’s having 1375 modules. For each and every operation we need to use modules to run the commands.

So we should understand the modules to do automation.