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Build a Python application

Yugabyte Cloud requires SSL

Are you using Yugabyte Cloud? Install the prerequisites, then go to the Use Python with SSL section.

The following tutorial creates a simple Python application that connects to a YugabyteDB cluster using the psycopg2 database adapter, performs a few basic database operations — creating a table, inserting data, and running a SQL query — and prints the results to the screen.

Prerequisites

This tutorial assumes that you have satisfied the following prerequisites.

YugabyteDB is up and running. If you are new to YugabyteDB, you can have YugabyteDB up and running within five minutes by following the steps in Quick start.
Python 3, or later, is installed.
Psycopg 2, the popular PostgreSQL database adapter for Python, is installed.

To install a binary version of psycopg2, run the following pip3 command:
```
$ pip3 install psycopg2-binary
```
For details about using this database adapter, see Psycopg documentation.

Create a sample Python application

Create a file yb-ysql-helloworld.py and add the following content:

import psycopg2

# Create the database connection.

conn = psycopg2.connect("host=127.0.0.1 port=5433 dbname=yugabyte user=yugabyte password=yugabyte")

# Open a cursor to perform database operations.
# The default mode for psycopg2 is "autocommit=false".

conn.set_session(autocommit=True)
cur = conn.cursor()

# Create the table. (It might preexist.)

cur.execute(
  """
  DROP TABLE IF EXISTS employee
  """)

cur.execute(
  """
  CREATE TABLE employee (id int PRIMARY KEY,
                         name varchar,
                         age int,
                         language varchar)
  """)
print("Created table employee")
cur.close()

# Take advantage of ordinary, transactional behavior for DMLs.

conn.set_session(autocommit=False)
cur = conn.cursor()

# Insert a row.

cur.execute("INSERT INTO employee (id, name, age, language) VALUES (%s, %s, %s, %s)",
            (1, 'John', 35, 'Python'))
print("Inserted (id, name, age, language) = (1, 'John', 35, 'Python')")

# Query the row.

cur.execute("SELECT name, age, language FROM employee WHERE id = 1")
row = cur.fetchone()
print("Query returned: %s, %s, %s" % (row[0], row[1], row[2]))

# Commit and close down.

conn.commit()
cur.close()
conn.close()

Run the application

To run the application, type the following:

$ python3 yb-ysql-helloworld.py

You should see the following output:

Created table employee
Inserted (id, name, age, language) = (1, 'John', 35, 'Python')
Query returned: John, 35, Python

Use Python with SSL

The client driver supports several SSL modes, as follows:

SSL mode	Client driver behavior
disable	Supported
allow	Supported
prefer (default)	Supported
require	Supported
verify-ca	Supported
verify-full	Supported

By default, the driver supports the prefer SSL mode. And in the require mode, a root CA certificate isn't required to be configured.

To enable verify-ca or verify-full, you need to provide the path to the root CA certificate in the connection string using the sslrootcert parameter. The default location is ~/.postgresql/root.crt. If the root certificate is in a different file, specify it in the sslrootcert parameter:

conn = psycopg2.connect("host=<hostname> port=5433 dbname=yugabyte user=<username> password=<password> sslmode=verify-full sslrootcert=/Users/my-user/Downloads/root.crt")

The difference between verify-ca and verify-full depends on the policy of the root CA. If you're using a public CA, verify-ca allows connections to a server that somebody else may have registered with the CA. Because of this behavior, you should always use verify-full with a public CA. If you're using a local CA, or even a self-signed certificate, using verify-ca may provide enough protection, but the best security practice is to always use verify-full.

Create a sample Python application with SSL

Create a file yb-ysql-helloworld-ssl.py and copy the following content to it, replacing the values in the conn object as appropriate for your cluster:

import psycopg2

# Create the database connection.

conn = psycopg2.connect("host=<hostname> port=5433 dbname=yugabyte user=<username> password=<password> sslmode=verify-full sslrootcert=<path>")

# Open a cursor to perform database operations.
# The default mode for psycopg2 is "autocommit=false".

conn.set_session(autocommit=True)
cur = conn.cursor()

# Create the table. (It might preexist.)

cur.execute(
 """
 DROP TABLE IF EXISTS employee
 """)

cur.execute(
 """
 CREATE TABLE employee (id int PRIMARY KEY,
                        name varchar,
                        age int,
                        language varchar)
 """)
print("Created table employee")
cur.close()

# Take advantage of ordinary, transactional behavior for DMLs.

conn.set_session(autocommit=False)
cur = conn.cursor()

# Insert a row.

cur.execute("INSERT INTO employee (id, name, age, language) VALUES (%s, %s, %s, %s)",
           (1, 'John', 35, 'Python + SSL'))
print("Inserted (id, name, age, language) = (1, 'John', 35, 'Python + SSL')")

# Query the row.

cur.execute("SELECT name, age, language FROM employee WHERE id = 1")
row = cur.fetchone()
print("Query returned: %s, %s, %s" % (row[0], row[1], row[2]))

# Commit and close down.

conn.commit()
cur.close()
conn.close()

Run the application

To run the application, type the following:

$ python3 yb-ysql-helloworld-ssl.py

You should see the following output:

Created table employee
Inserted (id, name, age, language) = (1, 'John', 35, 'Python + SSL')
Query returned: John, 35, Python + SSL