Demo 1 - Migrate from PostgreSQL to Alloy DB using Database Migration Service

Overview

In this lab, you will learn how to migrate a self-managed PostgreSQL database to AlloyDB for PostgreSQL using Database Migration Service like the diagram below.

Objectives

1. Configure VPC Peering between source VPC and destination VPC
2. Create a Database Migration Service Job to migrate the self-managed PostgreSQL database to Alloy DB for PostgreSQL cluster.
3. After the migration completed, promote the Alloy DB cluster as Primary Database

Prerequisite

• Google Cloud Project and an Account with Editor IAM Role

Setup guide

1. Clone "cloud-solutions" repo from Github with bellow command.

   git clone https://github.com/GoogleCloudPlatform/cloud-solutions.git
   

2. Change directory to root of the lab you want to try like example command.

   cd cloud-solutions/projects/mmb-datacloud/phase1
   

3. Deploy the lab environment using terraform command to Google Cloud Project.

   terraform apply
   

4. Confirm that the lab environment correctly deployed with terraform command.

   terraform state list
   

   You will get a list of states like below.

   data.google_compute_image.debian_image
   google_compute_firewall.vpc_1_allow_icmp_internal
   google_compute_firewall.vpc_1_allow_postgres_internal
   google_compute_firewall.vpc_1_allow_ssh
   google_compute_firewall.vpc_2_allow_icmp_internal
   google_compute_firewall.vpc_2_allow_ssh
   google_compute_instance.self_managed_postgres_vm
   google_compute_network.vpc_1
   google_compute_network.vpc_2
   google_compute_subnetwork.vpc_1_subnet
   google_compute_subnetwork.vpc_2_subnet
   google_project_service.apis["aiplatform.googleapis.com"]
   google_project_service.apis["alloydb.googleapis.com"]
   google_project_service.apis["cloudresourcemanager.googleapis.com"]
   google_project_service.apis["compute.googleapis.com"]
   google_project_service.apis["servicenetworking.googleapis.com"]
   

Task 1. Migration Preparation

Create a VPC Peering between VPC 1 and VPC 2

In this task, create a VPC peering between VPC 1 where the self-managed PostgreSQL database deployed and VPC 2 where new Alloy DB Cluster will be created.

1. From the Cloud Shell, use below gcloud command to create a VPC Peering between VPC 1 to VPC 2

   gcloud compute networks peerings create vpc1-to-vpc2 \
      --network=vpc-1 \
      --peer-network=vpc-2 \
      --auto-create-routes
   

2. Create another VPC Peering from VPC2 to VPC1

   gcloud compute networks peerings create vpc2-to-vpc1 \
      --network=vpc-2 \
      --peer-network=vpc-1 \
      --auto-create-routes
   

3. Verify VPC Peering has been created correctly.

   gcloud compute networks peerings list --network=vpc-1
   gcloud compute networks peerings list --network=vpc-2
   

   Check that result of command shows similar output as below.

   NAME          NETWORK  PEER_PROJECT                  PEER_NETWORK  STACK_TYPE  PEER_MTU  IMPORT_CUSTOM_ROUTES  EXPORT_CUSTOM_ROUTES  UPDATE_STRATEGY  STATE   STATE_DETAILS
   vpc1-to-vpc2  vpc-1    qwiklabs-gcp-00-0eaff2ed73b0  vpc-2         IPV4_ONLY             False                 False                 INDEPENDENT      ACTIVE  [2026-03-26T02:02:24.666-07:00]: Connected.
   NAME          NETWORK  PEER_PROJECT                  PEER_NETWORK  STACK_TYPE  PEER_MTU  IMPORT_CUSTOM_ROUTES  EXPORT_CUSTOM_ROUTES  UPDATE_STRATEGY  STATE   STATE_DETAILS
   vpc2-to-vpc1  vpc-2    qwiklabs-gcp-00-0eaff2ed73b0  vpc-1         IPV4_ONLY             False                 False                 INDEPENDENT      ACTIVE  [2026-03-26T02:02:24.666-07:00]: Connected.
   

Enable Database Migration API

1. In the Google Cloud Console, click the search bar or press / key and search Database Migration and click the Database Migration menu from Search Result.

2. On the Product details page, click the Enable button to enable Database Migration API.

3. After the API is enabled, search Database Migration again from the search bar and click the Database Migration from the Search Result.

4. On Database Migration page, click the Migration jobs menu from the left menu bar and click the Create migration job button.

Task 2. Database Migration Service

Create a migration job

1. On Create a Database Migration job page’s 1st Get started step, please enter Migration job name as self-managed-to-allydb. Migration Job ID will automatically add the same as the job name.

2. Choose PostgreSQL as Source database engine from Source database engine list.

3. Choose AlloyDB for PostgreSQL as the destination database engine from Destination database engine list.

4. Leave Destination region as us-central1 and Migration job type as Continuous as automatically added value after choosing the source database engine.

5. On Before you continue, review the prerequisites page, click the Open button to check the prerequisites for PostgreSQL source and Connectivity. After reading through the prerequisites click the Save & continue button to go to the next step.

Define a source

1. On the Define your source page, click the Select source connection profile combo box and click the Create a connection profile button.

2. On Create connection profile section, please input self-managed-cp as Connection profile name and it will automatically populate same value at Connection profile ID.

3. On the Define connection configurations section, click the Define button inside of the PostgreSQL to PostgreSQL box.

4. Please keep the PostgreSQL to PostgreSQL page open and collect pre-configured values from the Cloud Shell environment using below commands.

   • Hostname or IP address

   gcloud compute instances describe self-managed-postgres-vm \
      --zone=us-central1-a \
      --format="value(networkInterfaces.networkIP)"
   

   • Port: 5432
   • Username: pgadmin
   • Password: Check further steps

5. The password of pgadmin user is generated inside of the self-managed-postgres-vm and can be figured out with the below command.

gcloud compute ssh self-managed-postgres-vm \
   --zone=us-central1-a \
   --command='cat /var/log/pgadmin_password.log'

1. You can get a similar output as below when executed the previous command.

gcloud compute ssh self-managed-postgres-vm --zone=us-central1-a --command='cat /var/log/pgadmin_password.log'
pgadmin password: <RANDOM PASSWORD>

1. Back to the PostgreSQL to PostgreSQL page and input the configuration with reference to what you discover from previous steps. And click Save button.

2. Check the connection configurations from Define connection configurations page and click Create button.

3. On "Define your source" page, check the Select source connection profile dropdown menu has selected self-managed-cp and click Save & continue

Define a destination

1. On Define a destination page, select New cluster from Type of destination cluster dropdown menu.

2. On Configure your cluster page, Enter ** managed-alloydb-cluster at Cluster ID input box and click the Generate button to generate random password for postgres user. Select PostgreSQL 16 compatible from database version dropdown menu.

Note: Please make a copy of the password for further steps

1. On the Networking section, change the Network value from default to vpc-2 and leave the Automatic at the Allocated IP range. And click the Confirm network setup button from Network setup confirmation required section.

2. After network setup completed, you can see the green notice box at Networking section that indicate Private services access connection created for vpc-2 successfully.

3. On Configure your primary instance page, check the Instance ID configured as managed-alloydb-cluster-primary and change Zonal availability from Multiple zones to Single zone.

4. From the Machine section, change Machine Type to 2 vCPU, 16 GB and leave other configurations as default.

5. Click the Save & continue button below Network Security section.

6. On Create destination database? popup window, click the Create Destination & Continue button to create an AlloyDB database. It will take 5 ~ 10 mins to complete the creation task.

Define connectivity method

1. From the Define connectivity method section, choose Proxy via cloud-hosted VM - TCP option from the Connectivity method dropdown menu.

2. From Enter parameters for the Compute Engine VM section, enter tcp-proxy-vm as name in Compute Engine VM instance name input box and choose vpc-2-subnet as Subnetwork where the instance will deployed. And click the Continue button.

3. Middle of Generate a script and run it section, click the View script button.

4. From the View script side panel, click the Copy Icon button at the top right corner of the codeblock.

5. Save the file in Cloud Shell as deploy-tcp-proxy.sh file and execute the the script file to configure the TCP Proxy VM between VPC1 and VPC2.

6. The execution of the script will yield results comparable to the example provided below. From the script output, ascertain and record the value corresponding to INTERNAL_IP.

WARNING: The option to deploy a container during VM creation using the container startup agent is deprecated. Use alternative services to run containers on your VMs. Learn more at https://cloud.google.com/compute/docs/containers/migrate-containers.
Created [https://www.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/instances/tcp-proxy-vm].
WARNING: Some requests generated warnings:
- You are creating a container VM. The option to deploy a container during VM instance creation that relies on a container startup agent will be discontinued. Use alternative services to run containers on your VMs. Learn more at https://cloud.google.com/compute/docs/containers/migrate-containers

NAME: tcp-proxy-vm
ZONE: us-central1-b
MACHINE_TYPE: n1-standard-1
PREEMPTIBLE:
INTERNAL_IP: 10.20.0.2
EXTERNAL_IP: 34.134.20.45
STATUS: RUNNING
Creating firewall...working..Created [https://www.googleapis.com/compute/v1/projects/PROJECT_ID/global/firewalls/tcp-proxy-vm-firewall].
Creating firewall...done.
NAME: tcp-proxy-vm-firewall
NETWORK: vpc-2
DIRECTION: INGRESS
PRIORITY: 1000
ALLOW: tcp:5432
DENY:
DISABLED: False
networkInterfaces:
- networkIP: 10.20.0.2

1. Open the Database migration job create page again and click the Continue button from bottom of Generate a script and run it section.

2. Enter the value of INTERNAL_IP in the TCP Proxy private IP input box and click the Configure & continue button.

Configure migration databases

1. From Select objects to migrate section, leave the default value All databases in Database to migrate and click the Save & continue button.

Test and create migration job

1. Review all the configurations from Test and create your migration job page and click the Create & start job button to start the migration.

2. From the Create & start migration job popup window, click the Create & start button.

3. On Migration jobs page, click self-managed-to-alloydb migration job from the list and check that Status is Running from job information section.

Task 3. Verify a migration

1. While the migration job is running, open another Google Cloud Console tab and search for AlloyDB and click the AlloyDB for PostgreSQL menu item from the search result.

2. On AlloyDB for PostgreSQL page, click the managed-alloydb-cluster destination AlloyDB cluster from the resource table on the right side.

3. On AlloyDB cluster detail page, click the AlloyDB Studio menu from the left side.

4. Enter the values below in the Log into your database popup window. Click the Authenticate button to login.

Database	fraud_detection
User	postgres
Password	The password generated from previous Define a destination step.

Note: If you lost the password while you created the Migration Job, you can reset the password of postgres user by below gcloud command.

gcloud alloydb users set-password postgres \
 --password='NEW PASSWORD' \
 --cluster=managed-alloydb-cluster \
 --region=us-central1

1. On SQL editor, type SELECT * FROM transactions LIMIT 100; and (Win/Linux) Control + Enter or (Mac) Command + Enter to run the SQL command to check the migrated table and values.

2. (Optional) Check the total size of the transactions table using the SQL command. Total table size will be approximately 846MB when the migration is completed.

SELECT pg_size_pretty(pg_total_relation_size('transactions'));

Task 4. Promote a migration

After verifying the migration, promote AlloyDB as your new primary database.

1. Open Database migration job page that previously opened. Check all databases are Running status and 0 B values on the Replication delay column. If all Replication delay values are 0 B then click the Promote button at the top menu bar.

2. On Promote migration job? popup window, click the Promote button.

3. Check that the status of all databases are changed to Completed and show the Migration promoted successfully banner at the bottom of the page.

Congratulations

You have successfully migrated from the self-managed PostgreSQL database to fully managed AlloyDB for PostgreSQL service using Database Migration Service.