how to fix “OperationalError: (psycopg2.OperationalError) server closed the connection unexpectedly”

Question

Services

My service based on flask + postgresql + gunicorn + supervisor + nginx

When deploying by docker, after running the service, then accessing the api

Answer 1

Building on the Solution in the answer and the info from @MaxBlax360's answer. I think the proper way to set these config values in Flask-SQLAlchemy is by setting app.config['SQLALCHEMY_ENGINE_OPTIONS']:

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
# pool_pre_ping should help handle DB connection drops
app.config['SQLALCHEMY_ENGINE_OPTIONS'] = {"pool_pre_ping": True}  
app.config['SQLALCHEMY_DATABASE_URI'] = \
    f'postgresql+psycopg2://{POSTGRES_USER}:{dbpass}@{POSTGRES_HOST}:{POSTGRES_PORT}/{POSTGRES_DBNAME}'
db = SQLAlchemy(app)

See also Flask-SQLAlchemy docs on Configuration Keys