2.3. Preparing Cleveland server

Note : In this tutorial , we will install barman 3.16

2.3.1 Install Barman-cli and update /etc/hosts – on both Chicago and Boston

where: on both chicago and boston
as user: vagrant

Bash
# Step 1: Add the official PGDG repository to access PostgreSQL-specific tools

sudo dnf install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-9-x86_64/pgdg-redhat-repo-latest.noarch.rpm
Bash
# Step 2: List all available barman-cli versions to find our specific target
sudo dnf --showduplicates -y list barman
Bash
# Step 3: Install version 3.16.0 specifically to allow for a future upgrade demonstration
sudo dnf install -y barman-cli-3.16.0-42PGDG.rhel9
Bash
#  Step 4: Verify the installation
barman-wal-archive --version
Bash
#  Step 5: update the host ip addresses in /etc/hosts 
sudo bash -c 'cat << EOF >> /etc/hosts
192.168.56.140 chicago
192.168.56.141 boston
192.168.56.142 cleveland
EOF'
Bash
# Step 6:: Display the contents of public key 
sudo cat /var/lib/pgsql/.ssh/id_rsa.pub
2.3.2 Install Barman and update /etc/hosts on cleveland (barman)

where: on Cleveland (Barman) server
as user: Vagrant

Bash
# Step 1: Add the official PGDG repository to access PostgreSQL-specific tools
sudo dnf install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-9-x86_64/pgdg-redhat-repo-latest.noarch.rpm
Bash
# Step 2 : Update /etc/hosts with IP address of Chicago and Boston
sudo bash -c 'cat << EOF >> /etc/hosts
192.168.56.140 chicago
192.168.56.141 boston
192.168.56.142 cleveland
EOF'
Bash
# Step 3 : List the available Barman versions 
sudo dnf list barman --showduplicates
Bash
# Step 4 : Install Barman specific version
sudo dnf install -y barman-3.16.2-42PGDG.rhel9
Bash
# Step 5: Verify the installed barman version
sudo barman --version
screenshot
2.3.3 Enable SSH setup to cleveland from chicago and boston

where: on Cleveland (Barman) server
as user: barman

Bash
# Step 1 : switch to barman user in Cleveland server
sudo -i -u barman
Bash
# Step 2: Generate the ssh keys - accept the defaults - Hit enter whenever you see prompts
ssh-keygen -t rsa

Note: Hit enter – 3 times by accepting the defaults .

Copy the contents from section 2.3.1 – Step 6 (from above) – output of both chicago and boston and paste it in cleveland

Bash
# Step 3: edit the authorized_keys file in barman server(cleveland) to paste the public key of chicago and boston
vi /var/lib/barman/.ssh/authorized_keys
screenshot

save the file

Note: the public keys are sensitive information and not to be shared / documented in the real world. This demo is purely carried out in local sandbox and most of the best practices in security terms is not considered to give the readers the screenshots at the time of implementation.

Bash
# Step 4 : cat the contents of public key on barman server
cat /var/lib/barman/.ssh/id_rsa.pub

2.3.4 Enable SSH setup to chicago and boston from cleveland

where: on both chicago and boston
as user: postgres

Bash
# Step 1: switch to postgres user in both chicago and boston
sudo -i -u postgres

copy the output of step 4 from section 2.3.3 in both chicago and boston as postgres user and save the file

Bash
# Step 2 : copy the public key of barman user from cleveland (section 2.3.3 step 4)
vi /var/lib/pgsql/.ssh/authorized_keys
screenshot
Bash
# Step 3: ssh to barman
ssh barman@cleveland

Note on both chicago and boston : accept the defaults – and enter Yes when prompted.

screenshot

Step 4 is to switch back to postgres user on the DB server(chicago and boston) from cleveland

Now we are connected to cleveland server as barman user.
lets try to switchback to postgres user of both chicago and boston without password prompt.
Accept the defaults , hit Yes when prompted,
see the below screenshot for reference

screenshot

Congratulations, You have successfully completed barman and ssh setup.

2-2-installing-repmgr-from-packages
chapter-3-quick-start-guide

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