09-backups

Lab 9

The goal of this and the next lab is to configure the backups for your infrastructure.

In this lab we'll prepare the backup documentation and set up the connection with the backup server.

In the next lab we will set up automatic backups themselves, and improve the documentation accordingly.

Current infrastructure

This is what we have built so far:

Teachers have also prepared a backup server for you. It is located in the same network with all your virtual machines, so consider it an on-site resource. See task 1 for more details.

For simplicity you can assume that all the data from this server is also copied to another storage outside of our infrastructure perimeter, and whatever backup you'll upload to this server will also get an off-site copy automatically -- so you don't need to worry about the -1- part of the 3-2-1 rule.

Task 1

Configure your DNS server to resolve the backup server name in your domain.

Backup server IP address is 192.168.42.132. Note that this address may change in future, so do not hard-code it in DNS zone file but store as the Ansible variable instead.

Once done, each of your virtual machines should be able to resolve backup server name. You can check it by running this command on any of your VMs (replace foo.bar with your domain you have set up in lab 5):

host backup.foo.bar.

You should receive something like this in response:

backup.foo.bar has address 192.168.42.132

Task 2

Backups will be uploaded from your managed hosts to the backup server over SSH. More details will be provided in the next lab, but first we'll need to get this SSH connection working. Of course we'll use SSH keys for user authentication.

For that we'll need a separate user account on every managed host, and also a few more SSH keypairs.

Remember -- different users should have different private SSH keys!

Add Ansible role backup with the tasks that will

1. Create a user named backup on every managed host
2. Generate a new SSH key pair for this user

Requirements:

1. User backup home directory should be /home/backup
2. User backup public SSH key should be located at /home/backup/.ssh/id_rsa.pub

Note that there may be user named backup created already on the managed host so you will need to modify it to match the requirements above. Your Ansible code will be the same for both cases.

Make sure to generate a new keypair for the user backup; Ansible module user has an option to do it automatically -- check the module documentation.

DO NOT upload YOUR OWN SSH private key (used for GitHub) to managed hosts!

If you feel that SSH keys are still unclear topic for you please refer to lecture 2 slides that covered it.

Add this backup role to Init play created in lab 4 and run Ansible to apply the changes:

ansible-playbook infra.yaml

You can focus on the next task so far, and check the result later.

Task 3

Add backup server SSH key to the list of known hosts for user backup.

Backups server public key is

ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIEu6pFFWyuRrl4WGFPQGElYN9txwTGm2wSntcpVAaN90

You can check it by running any of these comman on your managed host (you should see the same key printed):

ssh-keyscan -t ed25519 backup
ssh-keyscan -t ed25519 backup.<your-domain>

Add this key to the /home/backup/.ssh/known_hosts file; this file should be owned by user backup, group backup and contain these three lines:

{{ backup_server_ip }} {{ backup_server_ssh_key }}
backup {{ backup_server_ssh_key }}
backup.{{ domain }} {{ backup_server_ssh_key }}

Adjust the variable names as needed. Yes, this file is allowed to contain IP address, but this should come from the variable!

This will "acknowledge" the backup server key for the user backup: with known_hosts file added as described above user backup will be able to establish the SSH connection with the backup server without asking to verify the server key.

Task 4

Once the user is created and SSH keypair is generated for it (task 2) the public key will be authorized on the backup server automatically within some time (usually 15 minutes). A separate account will be created for your backups, account name will match your GitHub username.

Once the key is authorized on the backup server the backup user you've just created should be able to log in there. You can test it by running this command manually on the managed host:

sudo -u backup ssh <your-github-username>@backup.<your-domain> id

Example for GitHub username elvis and domain demo.tld (modify for your names accordingly):

sudo -u backup ssh [email protected] id

Note that user account names are different:

• on your managed host (which is only yours) it is backup
• on the backup server (which is a shared resource) it matches your GitHub username

If the key was authorized successfully you should get something like this in response:

uid=1042(elvis) gid=1042(elvis) groups=1042(elvis)

Numbers will be different but the username should match your GitHub username.

If you are getting this prompt:

The authenticity of host 'backup (192.168.42.132)' can't be established.
ECDSA key fingerprint is SHA256:38L1IHYS4QwFRgaAeynjaOlHjf4LPjElh8aBtSgy68c.
Are you sure you want to continue connecting (yes/no/[fingerprint])?

it means that you didn't add the backups server key correctly. Although accepting the key manually may seem a simple solution, please don't do it -- it'll hide the problem instead of solving it, and prevent your backups from working automatically later. Please go back to task 3 and fix your solution -- user backup should be able to lo in to the backup server without any interactive prompts.

If you are getting this error:

Permission denied (publickey).

then please

1. make sure you are running the command from the correct server: your managed host
2. make sure you are running the command as the correct user: backup
3. make sure that user backup home directory is /home/backup: can be checked with echo ~backup
4. make sure that /home/backup/.ssh/id_rsa.pub file is there
5. if the problem is still there, contact the teachers for help

Task 5

Create a free-text file named backup_sla.md in the root of your Ansible repository.

In that file describe the backup approach for:

• Database servers
• InfluxDB
• Ansible repository

This document should contain the information about:

• Backup coverage -- what is backed up and what is not
• RPO (recovery point objective)
• Versioning and retention -- how many backup versions are stored and for how long
• Usability checks -- how is backup usability verified
• Restoration criteria -- when should backup be restored
• RTO (recovery time objective)

Note that you don't need to backup each and every service. In case of disaster recovery it makes more sense to re-create some service from scratch than restore it from the backup (Nginx, AGAMA, Grafana, Bind). But for other services backups are must (MySQL and InfluxDB contain data that cannot be restored with Ansible).

If you are missing some information to complete backup documentation (list of responsible IT staff, amount of data, value of information, acceptable data loss) -- make it up! Be creative, but try to keep it adequate and somewhat related to real life.

Expected result

Your repository contains these files and directories:

ansible.cfg
backup_sla.md
infra.yaml
roles/backup/tasks/main.yaml

Your repository also contains all the required files from the previous labs.

Backup user is configured as required on every your managed host by running this command:

ansible-playbook infra.yaml