Secure Methods for Scripting PostgreSQL psql Connections

PostgreSQL is a powerful open-source relational database management system (RDBMS) used for storing and managing data.

What is psql?

psql is a command-line tool that lets you interact with PostgreSQL databases. You can use it to run SQL queries, create and manage databases, and perform other administrative tasks.

Scripting psql Execution with Password

There are generally three ways to provide the password for psql in a script:

1. Password Prompt: This is the simplest method, but less secure for scripts. You can run psql with the appropriate options for hostname, username, and database, and psql will prompt you to enter the password.

psql -h hostname -U username -d database

export PGPASSWORD=yourpassword
psql -h hostname -U username -d database

Security Considerations

While storing the password in a script (either .pgpass file or environment variable) is more secure than prompting for it each time, it's still not ideal. If someone gains access to your script, they will also have access to the password. Consider these alternatives for increased security:

• Connection pooling: Connection pools can manage database connections and credentials securely.
• Password management tools: Tools like Kubernetes Secrets or HashiCorp Vault can securely store and manage database credentials.

#!/bin/bash

# This script prompts the user for the password (not recommended)
psql -h hostname -U username -d database

echo "Finished executing psql commands."

Using a pgpass file (More Secure):

Important Note: This example doesn't show creating the .pgpass file itself. Remember to create it with the following format (replace placeholders with your details):

hostname:port:database:username:password

Permissions on the .pgpass file must be set to read/write by you only (use chmod 600 ~/.pgpass).

#!/bin/bash

# This script uses the .pgpass file for password

psql -h hostname -U username -d database

echo "Finished executing psql commands."

Using PGPASSWORD environment variable (More Secure):

#!/bin/bash

# Set the PGPASSWORD environment variable before running the script (not shown here)
export PGPASSWORD=yourpassword

psql -h hostname -U username -d database

echo "Finished executing psql commands."

# Unset the PGPASSWORD environment variable after use (optional but recommended)
unset PGPASSWORD

psql allows specifying connection details in a single string format instead of separate options. This string can be constructed within the script without including the password directly.

Here's an example:

#!/bin/bash

# Construct connection string with username but not password
connection_string="host=${hostname} user=${username} dbname=${database}"

# Execute psql with the connection string
psql -c "SELECT * FROM my_table" "$connection_string"

echo "Finished executing psql commands."

In this example, the password is not stored anywhere in the script. You'll need to provide it through another secure method during execution, like prompting the user or using a dedicated password prompting tool.

Service Accounts (if applicable):

If you're running PostgreSQL in a containerized environment like Kubernetes, you can leverage service accounts to grant access to the database without needing a password. This approach involves creating a service account with the necessary permissions and mounting it as a volume within the container running the script.

Password Management Tools:

External password management tools like HashiCorp Vault or AWS Secrets Manager can securely store and retrieve database credentials. The script can interact with these tools to obtain the password at runtime without storing it directly.

SSH Tunneling:

If your script runs on a separate server from the database, you can establish an SSH tunnel to securely connect to the database. The tunnel encrypts the communication, eliminating the need for the password to be exposed in the script.

Choosing the Right Method:

The best method depends on your specific environment and security requirements.

• Connection string offers a balance between ease of use and security if you can provide the password securely at runtime.
• Service accounts are ideal for containerized environments with proper access control mechanisms.
• Password management tools provide a centralized and secure way to manage credentials across different applications.
• SSH tunneling is useful when connecting to a remote database server securely.