Troubleshoot connection issues to Azure Cosmos DB for PostgreSQL
APPLIES TO: Azure Cosmos DB for PostgreSQL (powered by the Citus database extension to PostgreSQL)
Connection problems may be caused by several things, such as:
- Firewall settings
- Connection time-out
- Incorrect sign in information
- Connection limit reached for cluster
- Issues with the infrastructure of the service
- Service maintenance
- The coordinator node failing over to new hardware
Generally, connection issues to Azure Cosmos DB for PostgreSQL can be classified as follows:
- Transient errors (short-lived or intermittent)
- Persistent or non-transient errors (errors that regularly recur)
Troubleshoot transient errors
Transient errors occur for a number of reasons. The most common include system Maintenance, error with hardware or software, and coordinator node vCore upgrades.
Enabling high availability for cluster nodes can mitigate these types of problems automatically. However, your application should still be prepared to lose its connection briefly. Also other events can take longer to mitigate, such as when a large transaction causes a long-running recovery.
Steps to resolve transient connectivity issues
- Check the Microsoft Azure Service Dashboard for any known outages that occurred during the time in which the application was reporting errors.
- Applications that connect to a cloud service such as Azure Cosmos DB for PostgreSQL should expect transient errors and react gracefully. For instance, applications should implement retry logic to handle these errors instead of surfacing them as application errors to users.
- As the cluster approaches its resource limits, errors can seem like transient connectivity issues. Increasing node RAM, or adding worker nodes and rebalancing data may help.
- If connectivity problems continue, or last longer than 60 seconds, or happen more than once per day, file an Azure support request by selecting Get Support on the Azure Support site.
Troubleshoot persistent errors
If the application persistently fails to connect to Azure Cosmos DB for PostgreSQL, the most common causes are firewall misconfiguration or user error.
- Coordinator node firewall configuration: Make sure that the server firewall is configured to allow connections from your client, including proxy servers and gateways.
- Client firewall configuration: The firewall on your client must allow connections to your database server. Some firewalls require allowing not only application by name, but allowing the IP addresses and ports of the server.
- User error: Double-check the connection string. You might have mistyped parameters like the server name. You can find connection strings for various language frameworks and psql in the Azure portal. Go to the Connection strings page in your cluster. Also keep in mind that clusters have only one database and its predefined name is citus.
Steps to resolve persistent connectivity issues
- Set up firewall rules to allow the client IP address. For temporary testing purposes only, set up a firewall rule using 0.0.0.0 as the starting IP address and using 255.255.255.255 as the ending IP address. That rule opens the server to all IP addresses. If the rule resolves your connectivity issue, remove it and create a firewall rule for an appropriately limited IP address or address range.
- On all firewalls between the client and the internet, make sure that port 5432 is open for outbound connections (and 6432 if using connection pooling).
- Verify your connection string and other connection settings.
- Check the service health in the dashboard.
- Learn the concepts of Firewall rules in Azure Cosmos DB for PostgreSQL
- See how to Manage firewall rules for Azure Cosmos DB for PostgreSQL
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