Personal stuff created to prepare to my EX294 exam.

Disclaimer:

• The tasks described below are on the same level of what you would find on the certification exam. Although I executed 95% of the test without problems and testing the applied configs, I didn't pass the exam and the only report received by them was:

    OBJECTIVE: SCORE
    Understand core components of Ansible: 59%
    Install and configure Ansible: 100%
    Run ad-hoc Ansible commands: 0%
    Use Ansible modules for system administration tasks: 56%
    Create Ansible plays and playbooks: 67%
    Create and use templates to create customized configuration files: 100%
    Work with Ansible variables and facts: 100%
    Create and work with roles: 67%
    Download and use roles with Ansible Galaxy: 0%
    Use Ansible Vault in playbooks to protect sensitive data: 43%
  

Not sure why but well, that's how they do things.

Feel free to use if you like but don't take this as a course for the certification. Probably what they want is to sell their 2k USD prep course, where they might give the "correct" answers for the test.

========== pre tasks ==========

1. Lab Setup:

• Centos8

• 5 vms:

  • 1 control node
  • 4 managed nodes with:
    • Centos8, minimal install
    • disk: 30GB
      • /boot: 300MiB
      • /home: 10GiB
      • /: 12GiB
      • 7.71 GiB free
    • mem: 1GB

• I used the 192.168.1.0/24 network on my tests and then added the appropriate mhost entries in /etc/hosts.

192.168.1.200  mhost_base
192.168.1.201	mhost1
192.168.1.202	mhost2
192.168.1.203	mhost3
192.168.1.204	mhost4

2. Structure

• Playbooks: ~ansible/tasks/playbooks
  • Every command should br executed from ~ansible/tasks directory.
• Scripts: ~ansible/tasks/scripts
• Roles: ~ansible/tasks/roles

3. Tips:

• Keep in mind the 'ansible-doc <module_name>' command.
• Use the setup module to check the available facts, keeping in mind:
  • Use the -b option to gather all variables, when needed.
  • Consider using 'gather_subset' when possible, this will create less overhead on the execution.
  • The filter option will work only for second level variables and further values would be ignored. This only applies when running ad-hoc commands. During playbook execution this restriction doesn't exist.
• When running playbooks, keep in mind the options:
  • --syntax-check
  • --step
  • --start-at-task
  • --force-handlers
  • --list-tasks

Ex: This will show the 'ansible_default_ipv4' dictionary.

$ ansible -b mhost1 -m setup -a 'gather_subset=network filter=ansible_default_ipv4'
mhost1 | SUCCESS => {
    "ansible_facts": {
        "ansible_default_ipv4": {
            "address": "192.168.1.201",
            "alias": "ens33",
            "broadcast": "192.168.1.255",
            "gateway": "192.168.1.1",
            "interface": "ens33",
            "macaddress": "00:0c:29:f9:b2:70",
            "mtu": 1500,
            "netmask": "255.255.255.0",
            "network": "192.168.1.0",
            "type": "ether"
        },
        "discovered_interpreter_python": "/usr/libexec/platform-python"
    },
    "changed": false

This won't return any fact.

$ ansible -b mhost1 -m setup -a 'gather_subset=network filter=ansible_default_ipv4.address'
mhost1 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/libexec/platform-python"
    },
    "changed": false
}

========== tasks ==========

1. Create ansible.cfg.

• Must be in tasks dir, inside ~ansible.
• Roles path should be ~ansible/tasks/roles and default path should also be considered.
• Inventory file should be ~ansible/tasks/mnodes.
• Remote port 22 for SSH connection.
• User ansible should be used to connect to remote hosts.
• Privilege escalation must be disabled.
• Default module must be "command".
• Ansible should start 5 forks.

Solution: ansible.cfg

Test (check the 'config file' line):

$ ansible --version

2. Create mnodes inventory file as follows:

• mhost1 must be part of the host group prod1.
• mhost2 must be part of the host group prod2.
• mhost3 and mhost4 must be part of webservers group.
• prod1 and prod2 must be part of prod group.
• group linux should include all managed hosts.

Solution: mnodes

Test:

$ ansible --list prod
$ ansible --list webservers
$ ansible --list linux
$ ansible --list all
$ ansible -u root -k -m ping all -o

- Tasks using only ad-hoc commands

--- using the root user (-u root on ansible ad-hoc commands)

3. Configure mhost4 to listen on non-default ssh port 555

• ansible should connect to the other hosts on port 22.
• update the inventory file to tell ansible to use port 555 to mhost4.

Solution:

$ ansible -u root -k mhost4 -m lineinfile -a "path=/etc/ssh/sshd_config regexp='^#Port 22' line='Port 555'" 
$ ansible -u root -k mhost4 -m firewalld -a "port=555/tcp permanent=true immediate=true state=enabled"
$ ansible -u root -k mhost4 -m seport -a "ports=555 proto=tcp setype=ssh_port_t state=present"

Change the inventory file adding on the end of the mhost4 line 'ansible_port=555'

Test:

$ ansible -u root -k -m ping all -o

Usefull commands that can be used to troubleshoot:

firewall-cmd --list-ports
semanage port -l
semanage port -a -t ssh_port_t -p tcp 555
semanage port -d -p tcp 555

4. Create ansible user and distribute ssh key using ad-hoc commands

• use ad-hoc command to create user ansible on all managed nodes (password '123').
• create a key pair (if you don't already have one).

ssh-keygen -t rsa

• copy the pub key to the managed nodes.
• add user to sudoers file, allowing privilege escalation.

Solution:

$ ansible -u root -k all -m user -a "name=ansible password='{{'123' | password_hash('sha512')}}'"
$ ansible -u root -k all -m authorized_key -a "user=ansible state=present key='{{ lookup('file', '/home/ansible/.ssh/id_rsa.pub') }}'"

OBS.: Another option to copy the key would be to use the 'copy' module

$ ansible -u root -k all -m copy -a "dest=/home/ansible/.ssh/id_rsa.pub src=/home/ansible/.ssh/id_rsa.pub mode='0400'"

Test:

$ ansible -m ping all -o

--- from this point onwards, use 'ansible' user

5. Configuring MOTD with ad-hoc commands

Add the text: 'Ansible managed host'.

Solution: a. Using the lineinfile module

$ ansible -b -m lineinfile -a "path=/etc/motd line='Ansible managed host'"

b. Using the copy module

$ ansible -b -m copy -a "dest=/etc/motd content='Ansible managed host'"

6. Configure managed hosts to use BaseOS and AppStream yum repos with ad-hoc commands (disable gpg check)

• Pre task: mount or copy cdrom contents to /srv.
• Repo 1: name "BaseOS", description "DNF BaseOS Repo", baseurl=file:///srv/BaseOS, gpgcheck "1", gpgkey "/etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial", enabled "1".
• Repo 2: name "AppStream", description "DNF AppStream Repo", baseurl "file:///srv/AppStream", gpgcheck "1", gpgkey "/etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial", enabled "1".

Solution:

$ ansible all -b -m mount -a "path=/srv src=/dev/cdrom fstype=iso9660 state=mounted"
$ ansible all -b -m yum_repository -a "name='BaseOS' description='DNF BaseOS repo' baseurl='file:///srv/BaseOS' gpgcheck='1' gpgkey='/etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial' enabled='1'"
$ ansible all -b -m yum_repository -a "name='AppStream' description='DNF AppStream repo' baseurl='file:///srv/AppStream' gpgcheck='1' gpgkey='/etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial' enabled='1'"

- Tasks using playbooks and ad-hoc commands

7. Create the services.yaml playbook to:

• Install, start and enable httpd on webservers.
• Install, start and enable mariadb on prod.

Solution: services.yaml

$ ansible-playbook playbooks/services.yaml --syntax-check
$ ansible-playbook playbooks/services.yaml

Test: As we didn't allow inbout http traffic yet, tests should be executed from within each host.

a. testing webservers

$ ansible webservers -m uri -a "url=http://localhost"
$ ansible -b webservers m shell -a 'ss -natp | grep *:80'

b. testing db servers

$ ansible -b prod m shell -a 'ss -natp | grep *:3306'
$ ansible prod -o -m mysql_info -a "login_user=root filter=version"

OBS.: to use the mysql_info module, you must have PyMySQL installed on the nodes

8. Create the user01_user.yaml playbook to add the correspondent user to all managed nodes.

• Username 'user01', password 'password', sha512 as hash algorithm.

Solution: user01_user.yaml

$ ansible-playbook playbooks/user01_user.yaml --syntax-check
$ ansible-playbook playbooks/user01_user.yaml

9. Create the user01_file.yaml playbook that will create the /root/user01_file in all managed nodes

• User and group should be set to user01.
• User rwx, group rw, others no permission.
• Set gid bit.

Solution: user01_file.yaml

$ ansible-playbook playbooks/user01_file.yaml --syntax-check
$ ansible-playbook playbooks/user01_file.yaml

Tests:

$ ansible -b all -a 'ls -l /root/user01_file'

10. Create the /root/file1.txt file with ad-hoc command on all managed nodes

• Content of the file: 'This file was created with Ansible'.
• Remove all permissions for others on the file.

Solution:

$ ansible -b -m copy -a "dest=/root/file1.txt content='This file was created with Ansible' mode=o-rwx" all

Tests:

$ ansible -b -a "ls -l /root/file1.txt"
$ ansible -b -a "cat /root/file1.txt"

11. Create the archive.yaml playbook to:

• Execute playbook on webservers.
• Archive the contents of /etc in /root/etc-<hostname>.tar.bz2 you may use ansible_facts or magic variables (I'm using the second option).
• Compress with bzip2.
• Copy the files to the local /tmp directory on the ansible controler.

Solution: archive.yaml

$ ansible-playbook playbooks/archive.yaml --syntax-check
$ ansible-playbook playbooks/archive.yaml

Tests: On the local machine (ansible controler node), execute:

ls -l /tmp/*etc.tar.bz2

12. Create the cronjobs.yaml playbook to schedule the below tasks:

• Restart rsyslog service at 23h and 6h on prod nodes every day.
• Restart rsyslog service at 2h on webservers on every monday.

Solution: cronjobs.yaml

$ ansible-playbook playbooks/cronjobs.yaml --syntax-check
$ ansible-playbook playbooks/cronjobs.yaml

Alternative solution using magic variables with conditionals: cronjobs_magicvars

Tests:

$ ansible -b all -a 'crontab -l'

13. Create the update_prod1.yaml playbook to update all packages on prod1 node

Solution: update_prod1.yaml

$ ansible-playbook playbooks/update_prod1.yaml --syntax-check
$ ansible-playbook playbooks/update_prod1.yaml

14. Create the httpd_configs.yaml playbook to:

• Change the httpd DocumentRoot directory from /var/www/html to /var/web/html.
• Set it's selinux context type to 'httpd_sys_content_t' (use the sefcontext module, making it persistent - 'ansible-doc sefcontext' for help).
• Create a custom index.html file at new location.
• Allow inbound traffic for http protocol.
• Setting should be persistent.
• Reload both services by making usage of handlers.
• Playbook should be executed on webservers only.

Solution: httpd_configs.yaml

$ ansible-playbook playbooks/httpd_configs.yaml --syntax-check
$ ansible-playbook playbooks/httpd_configs.yaml 

Tests:

curl http://mhost3
curl http://mhost3
$ ansible webservers -b -a 'ls -lZd /var/web'

15. Create the create_testing_networks_groups.yaml playbook to perform the below tasks:

• Create group 'testing' on webservers, gid=3030.
• Create group 'networks' on prod nodes, gid=4040.
• Use magic variables to diferentiate between the groups.

Solution: create_testing_networks_groups.yaml

$ ansible-playbook playbooks/create_testing_networks_groups.yaml --syntax-check
$ ansible-playbook playbooks/create_testing_networks_groups.yaml 

Tests:

$ ansible prod -a 'grep ^networks\: /etc/group'
$ ansible webservers -a 'grep ^testing\: /etc/group'

16. Create the parted.yaml playbook to:

• Create an extended partition on all managed nodes.
• Use all remaining space for extended partition.
• Create one logical partition of size 200 MB on all managed nodes

Solution: parted.yaml

$ ansible-playbook playbooks/parted.yaml --syntax-check
$ ansible-playbook playbooks/parted.yaml

Tests:

$ ansible -b -m shell -a 'dumpe2fs /dev/sda5 | head -1 || echo "invalid fs"' all
$ ansible -b -m parted -a 'device=/dev/sda5 unit=MiB' all

17. Create the mount.yaml playbook to:

• Format the /dev/sda5 device with 'ext4' filesystem.
• Create /opt/tmp.
• Mount the fs in /opt/tmp.
• Make sure to add entry to fstab.

Solution: mount.yaml

$ ansible-playbook playbooks/mount.yaml --syntax-check
$ ansible-playbook playbooks/mount.yaml

Tests:

$ ansible all -a 'grep /opt/tmp /etc/fstab'
$ ansible all -a 'df /opt/tmp'

18. Create the file.sh shell script to execute the following tasks using ad-hoc commands:

• Create the /root/redhat/ex294/results file on prod nodes.
• Give full permissions to group and read/execution to others.
• Set mark as owner and group.
• Create a symbolic link in /root with the default name.

Solution: file.sh

$ bash scripts/file.sh

Tests:

$ ansible prod -b -a 'find /root -name results -ls'

19. Create the user.sh shell script to execute the following tasks using ad-hoc commands:

• Create the 'ex294' group.
• Create user 'rhce' on all nodes:
  • Password should be: 'rhce_pass' using sha512 to generate the password hash.
  • UID: 2021.
  • 'ex294' group as secondary.

Solution: user.sh

$ bash scripts/user.sh

Tests:

$ ansible all -k -u rhce -m ping
$ ansible all -k -u rhce -a 'id'

20. Create the motd_with_condition.yaml playbook to configure motd on:

• Set "hosts: all" in the playbook as the selection must be made based on contitions.
• webservers with "This is a webserver node\n".
• prod1 with "This is a prod1 node\n".

Solution: motd_with_conditionals.yaml

$ ansible-playbook playbooks/motd_with_conditionals.yaml --syntax-check
$ ansible-playbook playbooks/motd_with_conditionals.yaml

Tests:

$ ansible all -a "grep 'This is a' /etc/motd"

21. Create the packages.yaml playbook to install:

• Set "hosts: all" in the playbook as the selection should be made based on contitions.
• httpd-manual on webservers.
• mariadb-test on prod nodes.

Solution: packages_with_conditionals.yaml

$ ansible-playbook playbooks/packages_with_conditionals.yaml --syntax-check
$ ansible-playbook playbooks/packages_with_conditionals.yaml

Tests:

$ ansible all -a 'rpm -q mariadb-test'
$ ansible all -a 'rpm -q httpd-manual'

22. Create the firewall_config.yaml playbook to:

• Set "hosts: all" in the playbook as the selection should be made based on contitions.
• Configure webservers to accept https and ntp inbound traffic.
• Configure prod nodes to accept traffic on port range 400-404/tcp and 3306/tcp.
• Firewall rules should be persistent and service must be reloaded (don't use the immediate option on firewalld module).

Solution: firewall_config.yaml

$ ansible-playbook playbooks/firewall_config.yaml --syntax-check
$ ansible-playbook playbooks/firewall_config.yaml

Tests:

$ ansible prod -b -a 'firewall-cmd --list-port'
$ ansible webservers -b -a 'firewall-cmd --list-service'

23. Create the create_users.yaml playbook to create users, based on:

• 'userdetails.yaml' should contain user information.
  • username, department, age (below).

---
users:
  - username: lisa
    department: software developer
    age: 32
  - username: bob
    department: testing
    age: 38
  - username: lara
    department: hr
    age: 28
...

• 'passwords.yaml' should contain the user passwords (format, user_password: passwords).

---
all_users_pass: wadda
...

• Create users:
  • webservers when user's department is 'software developer', and assign 'testing' group as suplementary to it.
  • prod nodes when user's department is 'testing' and assign 'network' group as suplementary to it.
  • all managed nodes when user's department is HR.
  • The password should be the one defined on password.yaml adding '_username' to it (wadda_lara, to user lara for example).

Solution: create_users.yaml

$ ansible-playbook playbooks/create_users.yaml --syntax-check
$ ansible-playbook playbooks/create_users.yaml

Tests: try to login to the nodes using the created users accordingly

24. Create the vgroup.yaml playbook to:

• Install lvm2 package on all nodes.
• webservers: Create a 1GiB logical partition.
• prod1 nodes: create a 600MiB logical partition.
• On webservers and prod1 nodes, create the 'vgroup' volume group with using the newly created partition.
• Use conditionals to select the appropriate nodes.

Solution: vgroup.yaml

$ ansible-playbook playbooks/vgroup.yaml --syntax-check
$ ansible-playbook playbooks/vgroup.yaml

Tests:

$ ansible -b -m shell -a 'fdisk -l /dev/sda | tail -1'
$ ansible -b -a 'vgscan' all
$ ansible -b -a 'vgdisplay' all

25. Create the logvol.yaml playbook to:

• Create logical volume of size 800MiB if vgroup has enough free space (> 800MiB).
• Create logical volume of size 500MiB if vgroup has less than 800MiB.
• The name of the logical volume should be 'lvm'.
• Message 'vol group does not exist' should be displayed if vgroup wasn't created on node.
• Use 'lvs' with ansible ad-hoc commands to verify.

Solution: logvol.yaml

$ ansible-playbook playbooks/logvol.yaml --syntax-check
$ ansible-playbook playbooks/logvol.yaml

Tests:

$ ansible -b -a 'lvscan' all

26. Create the volume.yaml playbook to:

• Create a logical volume with name 'vol' on managed nodes, using the remaining space on vgroup.
• Display 'vgroup does not exist' in case the vg wasn't created on a given node.

Solution: volume.yaml

$ ansible-playbook playbooks/volume.yaml --syntax-check
$ ansible-playbook playbooks/volume.yaml

Tests:

$ ansible -b -a 'lvscan' all

27. Create the mount_vol.yaml playbook to:

• Create the '/volume/lvm' directory to serve as mount point.
• Create a xfs filesystem on lv 'vol'.
• Mount it on '/volume/lvm', in a persistent way.

Solution: mount_vol.yaml

$ ansible-playbook playbooks/mount_vol.yaml --syntax-check
$ ansible-playbook playbooks/mount_vol.yaml

Tests:

$ ansible -a 'df /volume/lvm' all

- Some jinja2 theory

28. Jinja2 if example.

• Create the j2if.yaml playbook with if, elif, else conditions to validade hosts in groups.
• Do not enclose variables on quotation marks, only the strings.

Solution: j2if.yaml

$ ansible-playbook playbooks/j2if.yaml --syntax-check
$ ansible-playbook playbooks/j2if.yaml

29. Jinja2 for example.

• Create the j2for.yaml playbook to iterate over the hosts from the play.

Solution: j2for.yaml

$ ansible-playbook playbooks/j2for.yaml --syntax-check
$ ansible-playbook playbooks/j2for.yaml

30. Create the host_list.yaml playbook to:

• Set "hosts: all" in the playbook as the selection should be made based on conditions.
• Create the /root/host_list.txt file on prod1 nodes with a list of all managed hosts.
• The playbook should use the host_list.j2 template to generate this list.

Solution: host_list.yaml host_list.j2

$ ansible-playbook playbooks/host_list.yaml --syntax-check
$ ansible-playbook playbooks/host_list.yaml

Tests:

$ ansible -b -a 'cat /root/host_list.txt' prod1

31. Create the partition_size_report.yaml playbook to:

• Set "hosts: all" in the playbook as the selection should be made based on contitions.
• Collect partition size information and add it to the /root/partition_size_report.txt file on prod2 nodes.
• Each line should show the hostname to identify the host which the partition belongs.
• The playbook should use the partiton_size_report.j2 template to get disk information.

Solution: partition_size_report.yaml partition_size_report.j2

$ ansible-playbook playbooks/partition_size_report.yaml --syntax-check
$ ansible-playbook playbooks/partition_size_report.yaml

Tests:

$ ansible -b -a 'cat /root/partition_size_report.txt' prod2

32. Create the etc_hosts.yaml playbook to:

• Execute on all managed nodes.
• Create appropriate entries for the hosts on /etc/hosts file.
• The playbook should use the etc_hosts.j2 template.
  • Use a for statement to loop through the hosts.
  • Use a if statement to check if the interface is present on the managed nodes.

Solution: etc_hosts.yaml etc_hosts.j2

$ ansible-playbook playbooks/etc_hosts.yaml --syntax-check
$ ansible-playbook playbooks/etc_hosts.yaml

Tests:

$ ansible -b -a 'cat /etc/hosts' all

33. Create the sysinfo.yaml template to:

• Collect below details from managed nodes:
  • hostname.
  • size of vgroup.
  • size of 'lvm' logical volume.
  • Ansible OS family.
• Store the information on each remote node, in the /root/sysinfo-<hostname>.txt file.
• Use the sysinfo.j2 template to gather the requested details.

Solution: sysinfo.yaml sysinfo.j2

$ ansible-playbook playbooks/sysinfo.yaml --syntax-check
$ ansible-playbook playbooks/sysinfo.yaml

Tests:

$ ansible -b -m shell -a 'cat /etc/sysinfo*' all

- Ansible vault theory

Encrypt a variable and get it's value while executing the playbook

• Create the encrypted value for the variable.

$ ansible-vault encrypt_string --name '<var name>' '<password>' --ask-vault-pass

• Copy the variable with the value. Ex.:

password: !vault |
          $ANSIBLE_VAULT;1.1;AES256
          32623463386364616635363132366566666235646565306633306432616434366162626464303866
          3731666561303763663362313933336631303930303162650a303661323665336638636131316135
          33383261653532653462376232646162343265383434626166383966303162626337626634346137
          3866643431303363310a353733316632666630343838333763353965666362613866643135376333
          3836

• Create the vault_encrypt_var.yaml playbook, adding the variable with the encrypted value generated on the last step.
• Run the playbook providing the vault password used to generate the encrypted value for the variable.

$ ansible-playbook playbooks/vault_encrypt_var.yaml --ask-vault-pass

Encrypt a playbook and a variable inside the same playbook

• Encrypt the variable, adding an id to it.

$ ansible-vault encrypt_string --vault-id '<id name>'@prompt --name '<variable name>' '<password>'

• Encrypt the playbook, ading a different id to it.

$ ansible-vault encrypt --vault-id '<id name>'@prompt '<playbook or file>'

• Run the playbook:

$ ansible-playbook <playbook> --vault-id '<first id>'@prompt --vault-id '<second id>'@prompt

- Ansible roles and ansible-galaxy

• Use the ansible-galaxy init <role name> command to create a default directory and files structure.

• Downloading roles:

  • ansible-galaxy install <user>.<role>
  • It's also possible to create a requirements file on YAML format to download several roles at once. Ex:

- src: http://some/url/here/
  version: master
  name: role_name_in_disk
- src: geerlingguy.apache
  version: master
  name: my_apache_role
- src: geerlingguy.docker
  version: master

• Then execute ansible-galaxy install -r <requirements file>.yaml
• To list the roles, execute ansible-galaxy list

linux system roles

• Install the rhel-system-roles package.
• Administrative roles will be placed under /usr/share/ansible/roles/ directory.
• Example playbooks will be at ``/usr/share/doc/rhel-system-roles/``` directory.
• Example of roles on this package:
  • network
  • timesync
  • storage
  • selinux

Using the timesync role to sync the nodes via ntp

• On control node, allow the service to receive requests from the nodes, adjusting /etc/chrony.conf file, on the below line.

allow 192.168.1.0/24 

• Check if chronyd is enabled and running. If so, restart it.

# systemctl restart chronyd

• Check the execution of the daemon.

# chronyc sources -v

• Make sure there's a firewall rule allowing the access to this service (port 123/udp) and if not, create the rule.

# firewall-cmd --list-ports
# firewall-cmd --zone=public --add-port=123/udp --permanent
# firewall-cmd --reload

OBS.: Of course all this could be done using ansible ad-hoc commands or even a simple playbook.

• Check on managed nodes the time and date configuration.

$ ansible all -a 'timedatectl status'