---
id: a97ac519-d24f-4c31-bd98-bcdd12368514
---

# PostgreSQL database connection refused.
---

This incident type occurs when a software system is unable to establish a connection to a PostgreSQL database due to the database server refusing the connection. This can be caused by a variety of factors such as network issues, incorrect credentials, or the database server being unavailable. This can lead to the system being unable to perform necessary database operations, which can impact the functionality of the software system.

### Parameters
```shell
export POSTGRES_PORT="PLACEHOLDER"

export POSTGRESQL_CONF_FILE="PLACEHOLDER"

export POSTGRES_DATABASE="PLACEHOLDER"

export POSTGRES_USER="PLACEHOLDER"

export POSTGRES_HOST="PLACEHOLDER"

export POSTGRES_LOG_FILE="PLACEHOLDER"
```

## Debug

### Check if PostgreSQL service is running
```shell
systemctl status postgresql.service
```

### Check if the PostgreSQL server is listening to incoming connections on the correct port
```shell
ss -nlt | grep ${POSTGRES_PORT}
```

### Check if the PostgreSQL server is listening on the correct IP address
```shell
cat ${POSTGRESQL_CONF_FILE} | grep listen_addresses
```

### Try to connect to the PostgreSQL database using the psql client and the correct credentials
```shell
psql -h ${POSTGRES_HOST} -p ${POSTGRES_PORT} -U ${POSTGRES_USER} -d ${POSTGRES_DATABASE}
```

### Check the PostgreSQL server logs for errors or messages related to connection issues
```shell
tail -n 50 ${POSTGRES_LOG_FILE}
```

### Check the PostgreSQL server configuration file for any settings that may be causing connection issues
```shell
cat ${POSTGRESQL_CONF_FILE}
```

### Network connectivity issues such as firewall blocking the database connection port or DNS resolution failure.
```shell


#!/bin/bash



# Define variables

DB_HOST=${POSTGRES_HOST}

DB_PORT=${POSTGRES_PORT}



# Check if the database port is accessible

nc -zv $DB_HOST $DB_PORT



# Check if DNS resolution is successful

ping -c 1 $DB_HOST


```

## Repair

### Allow traffic from the PostgreSQL port in iptables
```shell


#!/bin/bash



# Define variables

POSTGRESQL_PORT=${POSTGRES_PORT}



# Allow traffic from PostgreSQL port in iptables

iptables -A INPUT -p tcp --dport $POSTGRESQL_PORT -j ACCEPT

iptables-save > /etc/sysconfig/iptables



# Check if iptables rules have been updated

iptables -L



echo "PostgreSQL port $POSTGRESQL_PORT has been allowed in iptables."


```

### Restart the PostgreSQL server
```shell


#!/bin/bash



# Restart the PostgreSQL service

sudo systemctl restart postgresql



# Wait for the service to restart

sleep 5



# Verify that the service is running

sudo systemctl status postgresql


```

This incident type occurs when a software system is unable to establish a connection to a PostgreSQL database due to the database server refusing the connection. This can be caused by a variety of factors such as network issues, incorrect credentials, or the database server being unavailable. This can lead to the system being unable to perform necessary database operations, which can impact the functionality of the software system.


This incident type refers to a situation where a SQLServer database goes offline, which can potentially cause disruptions in software or applications that rely on it. The incident is triggered by a monitoring system that detects the database's state is not available. A prompt response is necessary to resolve the issue and prevent any adverse impact on the system.


Database Offline (SQLServer)

This incident type refers to a situation where Redis, a popular in-memory data structure store, has rejected connections. This could happen due to various reasons such as server overload, network issues, or misconfiguration. When this occurs, it can cause disruptions in the performance of applications that rely on Redis for data storage or caching. Thus, it requires immediate attention and resolution to minimize the impact on the applications and users.


Redis Rejected Connections Incident

This incident type occurs when there are too many locks acquired on a Postgresql database instance. This can cause issues with database performance and functionality. It may be necessary to adjust the max\_locks\_per\_transaction setting in Postgresql to prevent this issue from occurring.


Postgresql too many locks acquired

This incident type refers to a situation where the Postgresql database has a high rollback rate, which means that a high percentage of transactions are being aborted compared to the committed ones. This can cause issues with data consistency and performance, and may require investigation and resolution by the responsible team. The incident details may include information about the affected database instance, the service or system impacted, the urgency level, and any related alerts or escalations.


Postgresql high rollback rate incident

This incident type refers to a scenario where there is a high rate of statement timeouts in a Postgresql database instance. This can lead to degraded performance and potentially impact the availability of the database. It is important to quickly identify and address the underlying cause of the timeouts to ensure the stability of the system.


Postgresql high rate statement timeout incident.

```shell
export POSTGRES_PORT="PLACEHOLDER"

export POSTGRESQL_CONF_FILE="PLACEHOLDER"

export POSTGRES_DATABASE="PLACEHOLDER"

export POSTGRES_USER="PLACEHOLDER"

export POSTGRES_HOST="PLACEHOLDER"

export POSTGRES_LOG_FILE="PLACEHOLDER"
```


### Check if PostgreSQL service is running

```shell
systemctl status postgresql.service
```

### Check if the PostgreSQL server is listening to incoming connections on the correct port

```shell
ss -nlt | grep ${POSTGRES_PORT}
```

### Check if the PostgreSQL server is listening on the correct IP address

```shell
cat ${POSTGRESQL_CONF_FILE} | grep listen_addresses
```

### Try to connect to the PostgreSQL database using the psql client and the correct credentials

```shell
psql -h ${POSTGRES_HOST} -p ${POSTGRES_PORT} -U ${POSTGRES_USER} -d ${POSTGRES_DATABASE}
```

### Check the PostgreSQL server logs for errors or messages related to connection issues

```shell
tail -n 50 ${POSTGRES_LOG_FILE}
```

### Check the PostgreSQL server configuration file for any settings that may be causing connection issues

```shell
cat ${POSTGRESQL_CONF_FILE}
```

### Network connectivity issues such as firewall blocking the database connection port or DNS resolution failure.

```shell


#!/bin/bash



# Define variables

DB_HOST=${POSTGRES_HOST}

DB_PORT=${POSTGRES_PORT}



# Check if the database port is accessible

nc -zv $DB_HOST $DB_PORT



# Check if DNS resolution is successful

ping -c 1 $DB_HOST


```


### Allow traffic from the PostgreSQL port in iptables

```shell


#!/bin/bash



# Define variables

POSTGRESQL_PORT=${POSTGRES_PORT}



# Allow traffic from PostgreSQL port in iptables

iptables -A INPUT -p tcp --dport $POSTGRESQL_PORT -j ACCEPT

iptables-save > /etc/sysconfig/iptables



# Check if iptables rules have been updated

iptables -L



echo "PostgreSQL port $POSTGRESQL_PORT has been allowed in iptables."


```

### Restart the PostgreSQL server

```shell


#!/bin/bash



# Restart the PostgreSQL service

sudo systemctl restart postgresql



# Wait for the service to restart

sleep 5



# Verify that the service is running

sudo systemctl status postgresql


```


PostgreSQL database connection refused.

Overview

Parameters

Debug

Check if PostgreSQL service is running

Check if the PostgreSQL server is listening to incoming connections on the correct port

Check if the PostgreSQL server is listening on the correct IP address

Try to connect to the PostgreSQL database using the psql client and the correct credentials

Check the PostgreSQL server configuration file for any settings that may be causing connection issues

Network connectivity issues such as firewall blocking the database connection port or DNS resolution failure.

Repair

Allow traffic from the PostgreSQL port in iptables

Restart the PostgreSQL server

Learn more

Related Runbooks

Database Offline (SQLServer)

Redis Rejected Connections Incident

Postgresql too many locks acquired

Postgresql high rollback rate incident

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