Step 8 - Using PGD CLI v5

Using PGD CLI

The PGD CLI command uses a configuration file to work out the hosts to connect to. There are options that allow you to override this to use alternative configuration files or explicitly point at a server. But, by default, PGD CLI looks for a configuration file in preset locations.

The connection to the database is authenticated in the same way as other command line utilities, like the psql command, are authenticated.

Unlike other commands, PGD CLI doesn't interactively prompt for your password. Therefore, you must pass your password using one of the following methods:

• Adding an entry to your .pgpass password file, which includes the host, port, database name, user name, and password
• Setting the password in the PGPASSWORD environment variable
• Including the password in the connection string

We recommend the first option, as the other options don't scale well with multiple database clusters, or they compromise password confidentiality.

Configuring and connecting PGD CLI

• Ensure PGD CLI is installed.
  • If PGD CLI was already installed, move to the next step.
  • For any system, repeat the configure repositories step on that system.
  • Then run the package installation command appropriate for that platform.
    • RHEL and derivatives: sudo dnf install edb-pgd5-cli
    • Debian, Ubuntu, and derivatives: sudo apt-get install edb-pgd5-cli
• Create a configuration file.
  • This is a YAML file that specifies the cluster and endpoints for PGD CLI to use.
• Install the configuration file.
  • Copy the YAML configuration file to a default config directory /etc/edb/pgd-cli/ as pgd-cli-config.yml.
  • Repeat this process on any system where you want to run PGD CLI.
• Run pgd-cli.

Use PGD CLI to explore the cluster

• Check the health of the cluster with the cluster show --health command.
• Show the nodes in the cluster with the nodes list command.
• Show the groups in the cluster with the groups list command.
• Set a group option with the group set-option command.
• Switch write leader with the group set-leader command.

For more details about these commands, see the worked example that follows.

Also consult the PGD CLI documentation for details of other configuration options and a full command reference.

Worked example

Ensure PGD CLI is installed

In this worked example, you configure and use PGD CLI on host-one, where you've already installed Postgres and PGD. You don't need to install PGD CLI again.

Create a configuration file

The PGD CLI configuration file is similar to the PGD Proxy configuration file. It's a YAML file that contains a cluster object. This has two properties:

• The name of the PGD cluster's top-level group (as name)
• An array of endpoints of databases (as endpoints)

cluster:
  name: pgd
  endpoints:
    - host=host-one dbname=bdrdb port=5444
    - host=host-two dbname=bdrdb port=5444
    - host=host-three dbname=bdrdb port=5444

Note that the endpoints in this example specify port=5444. This is necessary for EDB Postgres Advanced Server instances. For EDB Postgres Extended and community PostgreSQL, you can omit this.

Install the configuration file

Create the PGD CLI configuration directory:

sudo mkdir -p /etc/edb/pgd-cli

Then, write the configuration to the pgd-cli-config.yml file in the /etc/edb/pgd-cli directory.

For this example, you can run this on host-one to create the file:

cat <<EOF | sudo tee /etc/edb/pgd-cli/pgd-cli-config.yml
cluster:
  name: pgd
  endpoints:
    - host=host-one dbname=bdrdb port=5444
    - host=host-two dbname=bdrdb port=5444
    - host=host-three dbname=bdrdb port=5444
EOF

You can repeat this process on any system where you need to use PGD CLI.

Run PGD CLI

With the configuration file in place, and logged in as the enterprisedb system user, you can run pgd-cli. For example, you can use the nodes list command to list the nodes in your cluster and their status:

pgd nodes list

Node Name Group Name   Node Kind Join State Node Status
---------  ----------- --------- ---------- -----------
node-one   dc1         data      ACTIVE     Up         
node-three dc1         data      ACTIVE     Up         
node-two   dc1         data      ACTIVE     Up 

Using PGD CLI to explore the cluster

Once PGD CLI is configured, you can use it to get PGD-level views of the cluster.

Check the health of the cluster

The cluster show --health command provides a quick way to view the health of the cluster:

pgd cluster show --health

Connections
-----------
Checks if all BDR nodes are accessible.

Result: Ok, all BDR nodes are accessible


Raft
----
Raft Consensus status. Checks if all data and witness nodes are participating
in raft and have the same leader.

Result: Ok, raft Consensus is working correctly


Replication Slots
-----------------
Checks if all PGD replication slots are working correctly.

Result: Ok, all PGD replication slots are working correctly


Clock Skew
----------
Clock drift between nodes. Uses raft leader as reference node to calculate
clock drift. High clock drift can affect conflict resolution and potentially
cause inconsistency.

Result: Ok, clock drift is within permissible limit


Versions
--------
Checks if all nodes are running the same PGD version.

Result: Ok, all nodes are running the same PGD version

Show the nodes in the cluster

As previously seen, the nodes list command lists the nodes in the cluster:

pgd nodes list

Node Name  Group Name  Node Kind Join State Node Status
---------- ----------- --------- ---------- -----------
node-one   dc1         data      ACTIVE     Up         
node-three dc1         data      ACTIVE     Up         
node-two   dc1         data      ACTIVE     Up  

This view shows the group the node is a member of and its current status. To find out what versions of PGD and Postgres are running on the nodes, use nodes list --versions:

pgd nodes list --versions

Node Name BDR Version                   Postgres Version                
---------- ---------------------------  --------------------------------
node-one   5.7.0 (snapshot e2534db6d)   16.6 (Debian 16.6-1EDB.bullseye)
node-three 5.7.0 (snapshot e2534db6d)   16.6 (Debian 16.6-1EDB.bullseye)
node-two   5.7.0 (snapshot e2534db6d)   16.6 (Debian 16.6-1EDB.bullseye)

Show the groups in the cluster

Finally, the groups list command for PGD CLI shows which groups are configured, and more:

pgd groups list

Group Name   Parent Group Name Group Type Nodes
------------ ----------------- ---------- -----
pgd                            global     0    
dc1          pgd               data       3    

This command shows:

• The groups
• Their types
• Their parent group
• The number of nodes in each group

Set a group option

You can set group options using PGD CLI, too, using the group set-option command. If you wanted to set the dc1 group's location to London, you would run:

pgd group dc1 set-option location London

Status Message                      
------ -----------------------------
OK     Command executed successfully

You can verity the new location using the group get-option command:

pgd group dc1 get-option location

Option Name Option Value
----------- ------------
location    London  

Set the write leader

If you need to change write leader in a group, to enable maintenance on a host, PGD CLI offers the group set-leader command. You enter a group name after group and the name of the node you want to switch to after set leader:

pgd group dc1 set-leader node-two

Status Message                      
------ -----------------------------
OK     Command executed successfully

You can verify the write leader using the group show command with the --summary option:

pgd group dc1 show --summary

Group Property    Value       
----------------- ------------
Group Name        dc1
Parent Group Name pgd
Group Type        data        
Write Leader      node-two
Commit Scope                 

More details on the available commands in PGD CLI are available in the PGD CLI command reference.