Tutorial: Migrate offline from an Azure VM or an on-premises PostgreSQL server to Azure Database for PostgreSQL with the migration service

This article guides you in migrating an Azure virtual machine (VM) or an on-premises PostgreSQL server to an Azure Database for PostgreSQL flexible server with the migration service using the Azure portal and Azure CLI.

The migration service in Azure Database for PostgreSQL is a fully managed service integrated into the Azure portal and Azure CLI. It's designed to simplify your migration journey to the Azure Database for PostgreSQL flexible server.

• Prerequisites
• Perform the migration
• Monitor the migration
• Check the migration when completed

Prerequisites

To begin the migration, you need the following prerequisites:

Before starting the migration with the Azure Database for PostgreSQL migration service, it is important to fulfill the following prerequisites, specifically designed for offline migration scenarios.

• Verify the source version
• Configure target setup
• Configure network setup
• Enable extensions
• Check server parameters
• Check users and roles
• Disable high availability (reliability) and read replicas in the target

Verify the source version

The source PostgreSQL server version must be 9.5 or later.

If the source PostgreSQL version is less than 9.5, upgrade it to 9.5 or higher before you start the migration.

Configure target setup

Before you begin the migration, you must set up an Azure Database for PostgreSQL in Azure.

The SKU chosen for the Azure Database for PostgreSQL should correspond with the specifications of the source database to ensure compatibility and adequate performance.

Configure network setup

Network setup is crucial for the migration service to function correctly. Ensure that the source PostgreSQL server can communicate with the target Azure Database for PostgreSQL server. The following network configurations are essential for a successful migration.

For information about network setup, visit Network guide for migration service.

• Additional networking considerations:

pg_hba.conf Configuration: To facilitate connectivity between the source and target PostgreSQL instances, it's essential to verify and potentially modify the pg_hba.conf file. This file includes client authentication and must be configured to allow the target PostgreSQL to connect to the source. Changes to the pg_hba.conf file typically require a restart of the source PostgreSQL instance to take effect.

The pg_hba.conf file is located in the data directory of the PostgreSQL installation. This file should be checked and configured if the source database is an on-premises PostgreSQL server or a PostgreSQL server hosted on an Azure VM.

Enable extensions

To ensure a successful migration with the migration service in Azure Database for PostgreSQL, you might need to verify extensions to your source PostgreSQL instance. Extensions provide additional functionality and features that might be required for your application. Make sure to verify the extensions on the source PostgreSQL instance before initiating the migration process.

Enable supported extensions identified in the source PostgreSQL instance on the target Azure Database for PostgreSQL flexible server.

For more information about extensions, visit Extensions in Azure Database for PostgreSQL.

Note

A restart is required when there are any changes to the shared_preload_libraries parameter.

Check server parameters

These parameters aren't automatically migrated to the target environment and must be manually configured.

• Match server parameter values from the source PostgreSQL database to the Azure Database for PostgreSQL by accessing the "Server parameters" section in the Azure portal and manually updating the values accordingly.

• Save the parameter changes and restart the Azure Database for PostgreSQL to apply the new configuration if necessary.

Check users and roles

When migrating to Azure Database for PostgreSQL, it's essential to address the migration of users and roles separately, as they require manual intervention:

• Manual Migration of Users and Roles: Users and their associated roles must be manually migrated to the Azure Database for PostgreSQL. To facilitate this process, you can use the pg_dumpall utility with the --globals-only flag to export global objects such as roles and user accounts. Execute the following command, replacing <<username>> with the actual username and <<filename>> with your desired output file name:

  pg_dumpall --globals-only -U <<username>> -f <<filename>>.sql
  

• Restriction on Superuser Roles: Azure Database for PostgreSQL doesn't support superuser roles. Therefore, users with superuser privileges must have those privileges removed before migration. Ensure that you adjust the permissions and roles accordingly.

By following these steps, you can ensure that user accounts and roles are correctly migrated to the Azure Database for PostgreSQL without encountering issues related to superuser restrictions.

Disable high availability (reliability) and read replicas in the target

• Disabling high availability (reliability) and reading replicas in the target environment is essential. These features should be enabled only after the migration has been completed.

• By following these guidelines, you can help ensure a smooth migration process without the added variables introduced by HA and Read Replicas. Once the migration is complete and the database is stable, you can proceed to enable these features to enhance the availability and scalability of your database environment in Azure.

Perform the migration

You can migrate by using the Azure portal or the Azure CLI.

Portal

This article guides you using the Azure portal to migrate your PostgreSQL database from an Azure VM or an on-premises PostgreSQL server to an Azure Database for PostgreSQL. The Azure portal allows you to perform various tasks, including database migration. Following the steps outlined in this tutorial, you can seamlessly transfer your database to Azure and take advantage of its powerful features and scalability.

Configure the migration task

The migration service comes with a simple, wizard-based experience on the Azure portal.

1. Open your web browser and go to the portal. Enter your credentials to sign in. The default view is your service dashboard.

2. Go to your Azure Database for the PostgreSQL flexible server.

3. In the Overview tab of the flexible server, on the left menu, scroll down to Migration and select it.

   

4. Select the Create button to migrate to a flexible server from on-premises or Azure VMs.

   Note

   The first time you use the migration service, an empty grid appears with a prompt to begin your first migration.

   If migrations to your flexible server target have already been created, the grid now contains information about attempted migrations.

5. Select the Create button to go through a wizard-based series of tabs to perform a migration.

   

Setup

The user needs to provide multiple details related to the migration, like the migration name, source server type, option, and mode.

• Migration name is the unique identifier for each migration to this Flexible Server target. This field accepts only alphanumeric characters and doesn't accept any special characters except a hyphen (-). The name can't start with a hyphen and should be unique for a target server. No two migrations to the same Flexible Server target can have the same name.

• Source Server Type - Depending on your PostgreSQL source, you can select Azure Database for PostgreSQL Single Server, Azure VM, or on-premises.

• Migration Option - Allows you to perform validations before triggering a migration. You can pick any of the following options

  • Validate - Checks your server and database readiness for migration to the target.
  • Migrate - Skips validations and starts migrations.
  • Validate and Migrate—Performs validation before triggering a migration. If there are no validation failures, the migration is triggered.

Choosing the Validate or Validate and Migrate option is always a good practice for performing premigration validations before running the migration.

To learn more about the premigration validation, visit premigration.

• Migration mode allows you to pick the mode for the migration. Offline is the default option.

Select the Next: Connect to source button.

Runtime Server

The Migration Runtime Server is a specialized feature within the migration service in Azure Database for PostgreSQL, designed to act as an intermediary server during migration. It's a separate Azure Database for PostgreSQL - Flexible Server instance that isn't the target server but is used to facilitate the migration of databases from a source environment that is only accessible via a private network.

For more information about the Runtime Server, visit the Migration Runtime Server.

Connect to source

The Connect to Source tab prompts you to give details related to the source selected in the Setup Tab, which is the source of the databases.

• Server Name - Provide the Hostname or the IP address of the source PostgreSQL instance

• Port - Port number of the Source server

• Server admin login name - Username of the source PostgreSQL server

• Password - Password of the source PostgreSQL server

• SSL Mode - Supported values are preferred and required. When the SSL at the source PostgreSQL server is OFF, use the SSLMODE=prefer. If the SSL at the source server is ON, use the SSLMODE=require. SSL values can be determined in postgresql.conf file.

• Test Connection—Performs the connectivity test between the target and source. Once the connection is successful, users can proceed to the next step; they need to identify the networking issues between the target and source and verify the username/password for the source. Establishing a test connection takes a few minutes.

After the successful test connection, select the Next: Select Migration target button.

Select migration target

The select migration target tab displays metadata for the Flexible Server target, such as the subscription name, resource group, server name, location, and PostgreSQL version.

• Admin username - Admin username of the target PostgreSQL server

• Password - Password of the target PostgreSQL server

• Test Connection - Performs the connectivity test between target and source. Once the connection is successful, users can proceed with the next step. Otherwise, we need to identify the networking issues between the target and the source and verify the target's username/password. Test connection takes a few minutes to establish a connection between the target and source

After the successful test connection, select the Next: Select Database(s) for Migration

Select databases for migration

Under the Selected database for migration tab, you can choose a list of user databases to migrate from your source PostgreSQL server.

After selecting the databases, select the Next: Summary.

Summary

The Summary tab summarizes all the source and target details for creating the validation or migration. Review the details and select the Start Validation and Migration button.

Monitor the migration

After you select the Start Validation and Migration button, a notification appears in a few seconds to say that the validation or migration creation is successful. You're automatically redirected to the flexible server's Migration page. The entry is in the InProgress state and PerformingPreRequisiteSteps substate. The workflow takes 2-3 minutes to set up the migration infrastructure and check network connections.

The grid that displays the migrations has these columns: Name, Status, Migration mode, Migration type, Source server, Source server type, Databases, **Duration, and Start time. The entries are displayed in the descending order of the start time, with the most recent entry on the top. You can use the refresh button to refresh the status of the validation or migration run.

Migration details

Select the migration name in the grid to see the associated details.

In the Setup tab, we have selected the migration option as Validate and Migrate. In this scenario, validations are performed first before migration starts. After the PerformingPreRequisiteSteps substrate is completed, the workflow moves into the substrate of Validation in Progress.

• If validation has errors, the migration moves into a Failed state.

• If validation is complete without error, the migration starts, and the workflow moves into the substate of Migrating Data.

Validation details are available at the instance and database level.

• Validation at Instance level
  • Contains validation related to the connectivity check, source version, that is, PostgreSQL version >= 9.5, and server parameter check, whether the extensions are enabled in the server parameters of the Azure Database for PostgreSQL—flexible server.
• Validation at Database level
  • It contains validation of the individual databases related to extensions and collations support in Azure Database for PostgreSQL, a flexible server.

You can see the validation and the migration status under the migration details page.

Some possible migration states:

Migration states

State	Description
InProgress	The migration infrastructure setup is underway, or the actual data migration is in progress.
Canceled	The migration is canceled or deleted.
Failed	The migration has failed.
Validation Failed	The validation has failed.
Succeeded	The migration has succeeded and is complete.
WaitingForUserAction	Applicable only for online migration. Waiting for user action to perform cutover.

Migration substates

Substate	Description
PerformingPreRequisiteSteps	Infrastructure setup is underway for data migration.
Validation in Progress	Validation is in progress.
MigratingData	Data migration is in progress.
CompletingMigration	Migration is in the final stages of completion.
Completed	Migration has been completed.
Failed	Migration has failed.

Validation substates

Substate	Description
Failed	Validation has failed.
Succeeded	Validation is successful.
Warning	Validation is in warning.

Cancel the migration using the portal

You can cancel any ongoing validations or migrations. The workflow must be in the InProgress state to be canceled. You can't cancel a validation or migration in the Succeeded or Failed state.

• Canceling a validation stops further validation activity, and the validation moves to a Canceled state.
• Canceling a migration stops further migration activity on your target server and moves to a Canceled state. The cancel action returns all changes the migration service makes on your target server.

CLI

This article explores using the Azure CLI to migrate your PostgreSQL database from an Azure virtual machine or an on-premises PostgreSQL instance to an Azure Database for PostgreSQL. The Azure CLI provides a powerful and flexible command-line interface that allows you to perform various tasks, including database migration. Following the steps outlined in this article, you can seamlessly transfer your database to Azure and take advantage of its powerful features and scalability.

To learn more about Azure CLI with the migration service, visit How to set up Azure CLI for the migration service.

Once the CLI is installed, open the command prompt and log into your Azure account using the below command.

az login

Configure the migration task

To begin the migration, create a JSON file with the migration details. The JSON file contains the following information:

• Edit the below placeholders << >> in the JSON lines and store them in the local machine as <<filename>>.json where the CLI is being invoked. In this tutorial, we have saved the file in C:\migration-CLI\migration_body.json

{
"properties": {
"SourceDBServerResourceId": "<<source hostname or IP address>>:<<port>>@<<username>>",
        "SecretParameters": {
            "AdminCredentials": {
                "SourceServerPassword": "<<Source Password>>",
                "TargetServerPassword": "<<Target Password>>"
            },
			"targetServerUserName": "<<Target username>>"
        },
        "DBsToMigrate": "<<comma separated list of databases in a array like - ["ticketdb","timedb","inventorydb"]>>",
        "OverwriteDBsInTarget": "true",
        "sourceType": "OnPremises",
        "sslMode": "Prefer"
    }
}

Note

When configuring the JSON properties for the migration to Azure Database for PostgreSQL Flexible Server, if your source environment is an Azure Virtual Machine, you can specify the source type using the "sourceType":"AzureVM" property. This helps the migration service understand the environment from which the data is being migrated.

• Run the following command to check if any migrations are running. The migration name is unique across the migrations within the Azure Database for PostgreSQL flexible server target.

  az postgres flexible-server migration list --subscription 11111111-1111-1111-1111-111111111111 --resource-group my-learning-rg --name myflexibleserver --filter All
  

• In the above steps, there are no migrations performed so we start with the new migration by running the following command

  az postgres flexible-server migration create --subscription 11111111-1111-1111-1111-111111111111 --resource-group my-learning-rg --name myflexibleserver --migration-name migration1 --migration-mode offline --migration-option ValidateAndMigrate --properties "C:\migration-cli\migration_body.json"
  

• Run the following command to initiate the migration status in the previous step. You can check the status of the migration by providing the migration name

  az postgres flexible-server migration show --subscription 11111111-1111-1111-1111-111111111111 --resource-group my-learning-rg --name myflexibleserver --migration-name migration1
  

• The status of the migration progress is shown in the Azure CLI.

• You can also see the status of the Azure Database for PostgreSQL flexible server in the Azure portal.

• You can cancel any ongoing migration attempts using the cancel command. This command stops the particular migration attempt and rolls back all changes on your target server. Here's the CLI command to delete a migration:

  az postgres flexible-server migration update cancel --subscription 11111111-1111-1111-1111-111111111111 --resource-group my-learning-rg --name myflexibleserver --migration-name migration1
  

Check the migration when complete

After completing the databases, you need to manually validate the data between source and target and verify that all the objects in the target database are successfully created.

After migration, you can perform the following tasks:

• Verify the data on your flexible server and ensure it's an exact copy of the source instance.

• Post verification, enable the high availability option on your flexible server as needed.

• Change the SKU of the flexible server to match the application needs. This change needs a database server restart.

• If you change any server parameters from their default values in the source instance, copy those server parameter values in the flexible server.

Copy other server settings, such as tags, alerts, and firewall rules (if applicable), from the source instance to the flexible server.

• Make changes to your application to point the connection strings to a flexible server.

• Monitor the database performance closely to see if it requires performance tuning.

Related content

• Migration service
• Migrate from AWS RDS
• Best practices
• Known Issues and limitations
• Network setup
• Premigration validations