Connect to PostgreSQL from Domino

This topic describes how to connect to PostgreSQL from Domino.

PostgreSQL is an open-source relational database that can run on a wide variety of local systems and clouds.

Connect to Postgres with Domino Data Sources

The easiest way to connect to an Postgres instance from Domino is to use a :doc:`Domino Data Source </reference/data/external_data/domino_data_sources>`.

Configuration

To create a Postgres Data Source select Postgres as the Data Source type from the New Data Source wizard and specify the relevant parameters.

Authentication

Specify the credentials that will be used to connect to Postgres.

Currently, the only authentication mechanism supported is Username and Password. The credentials will be securely stored in the Domino secret store backed by HashiCorp Vault.

Python and psycopg2

Domino recommends the psycopg2 library for interacting with PostgreSQL databases from Python.

Environment setup

Use the following Dockerfile instruction to install psycopg2 in your environment.

This instruction assumes you already have pip installed.

USER root
RUN pip install psycopg2
USER ubuntu

Credential setup

There are several environment variables you must set up to store secure information about your PostgreSQL connection. Set the following as Domino environment variables on your user account:

POSTGRES_HOST

Hostname where your DB is running. Make sure your PostgreSQL DB and network firewall are configured to accept connections from Domino.
POSTGRES_USER

The PostgreSQL user you want to authenticate as.
POSTGRES_PASSWORD

The password for the user chosen above.

Read Environment variables for secure credential storage to learn more about Domino environment variables.

Usage

Read the psycopg2 documentation for detailed information about how to use the package. Below is a simple example for connecting to PostgreSQL with psycopg2 where:

You have set up environment variables noted above with the hostname, username, and password
Your user has access to a database named db1 in the target PostgreSQL instance
The database contains a table named metrics

import psycopg2
import os

# fetch values from environment variables and set the target database
hostname = os.environ['POSTGRES_HOST']
username = os.environ['POSTGRES_USER']
password = os.environ['POSTGRES_PASSWORD']
dbname = 'db1'

# set up a connection object with parameters for your database
conn = psycopg2.connect(
  host=hostname,
  port=5432,
  user=username,
  password=password,
  database=dbname, )

# create a cursor in your connection
cur = conn.cursor()

# execute a query on the metrics table and store the response
cur.execute("SELECT * FROM metrics;")
results = cur.fetchall()

# display the contents of the response
print(results)

The results object created in the example above is a Python array of entries from the queried table.

R and RPostgreSQL

Domino recommends the RPostgreSQL library for interacting with PostgreSQL databases from R.

Environment setup

Use the following Dockerfile instruction to add RPostgreSQL to your environment.

USER root
RUN R -e 'install.packages("RPostgreSQL")'
USER ubuntu

Credential setup

There are several environment variables you must set up to store secure information about your PostgreSQL connection. Set the following as Domino environment variables on your user account:

POSTGRES_HOST

Hostname where your DB is running. Make sure your PostgreSQL DB and network firewall are configured to accept connections from Domino.
POSTGRES_USER

The PostgreSQL user you want to authenticate as.
POSTGRES_PASSWORD

The password for the user chosen above.

Read Environment variables for secure credential storage to learn more about Domino environment variables.

Usage

Read the RPostgreSQL documentation for detailed information about how to use the package. Below is a simple example for connecting to PostgreSQL with RPostgreSQL where:

You have set up environment variables noted above with the hostname, username, and password
Your user has access to a database named db1 in the target PostgreSQL instance
The database contains a table named metrics`

# load the library
library(RPostgreSQL)

# fetch values from environment variables and set the target database
hostname <- Sys.getenv['POSTGRES_HOST']
username <-  Sys.getenv['POSTGRES_USER']
password <- Sys.getenv['POSTGRES_PASSWORD']
database <- 'db1'

# set up a driver and use it to create a connection to your database
drv <- dbDriver("PostgreSQL")
conn <- dbConnect(
  drv,
  host=hostname,
  port=5432,
  user=username,
  password=password,
  dbname=database )

# run a query and load the response into a dataframe
df_postgres <- dbGetQuery(conn, "SELECT * from metrics;")

# close your connection when finished
dbDisconnect(conn)