Using a dump file to set up replication from external databases

This page describes the process for setting up replication when you have a dump file that you created from your external server.

You must complete all the steps on this page. When finished, you can administer and monitor the source representation instance the same way as you would any other Cloud SQL instance.

Before you begin

Before you start, you should have configured the external server, created the source representation instance, and set up the Cloud SQL replica.

Updating permissions for the replication user

The replication user on the external server is configured to accept connections from any host (%). You should update this user account so that it can only be used with the Cloud SQL replica. Open a terminal on the external server and enter these commands:

mysql Client

    UPDATE mysql.user
      SET Host='NEW_HOST'
      WHERE Host='OLD_HOST'
      AND User='USERNAME';
      GRANT REPLICATION SLAVE, EXECUTE
      ON *.* TO 'GCP_USERNAME'@'HOST';
    FLUSH PRIVILEGES;

example

UPDATE mysql.user
  SET Host='192.0.2.0'
  WHERE Host='%'
  AND User='replicationUser';
  GRANT REPLICATION SLAVE, EXECUTE
  ON *.* TO 'gcp_user'@'gmail.com';
FLUSH PRIVILEGES;
Property Description
NEW_HOST Specify the outgoing IP of the Cloud SQL replica.
OLD_HOST The current value assigned to Host that you want to change.
USERNAME The replication user account on the external server.
GCP_USERNAME The username for the GCP user account.
HOST The hostname for the GCP user account.

Exporting data to a Google Cloud bucket

You can populate a Cloud SQL replica with a mysqldump file located in a Google Cloud bucket. These conditions apply:

  • You must use the mysqldump utility bundled with MySQL.
  • While mysqldump is running, do not perform any DDL operations on the external server. Doing so could cause inconsistencies in the export file.

To upload your data to a bucket, follow these steps:

  1. In Google Cloud, create a bucket.
  2. Open a terminal a client connecting to the external database server and run the command below.

mysqldump

    mysqldump \
        --host=EXTERNAL_HOST \
        --port=EXTERNAL_PORT \
        --user=USERNAME\
        --password=PASSWORD \
        --databases=DATABASE_LIST  \
        --hex-blob \
        --source-data=EXTERNAL_DATA  \
        --no-autocommit \
        --default-character-set=utf8mb4 \
        --single-transaction \
        GTID_PURGED \
        ADD_DROP_TABLE \
        ROUTINES \
        COMPRESS \
        GZIP \
        | gsutil cp - gs://BUCKET/DUMP_FILENAME

example

    mysqldump \
        --host=192.0.2.1 \
        --port=3306 \
        --user=replicationUser \
        --password \
        --databases guestbook journal \
        --hex-blob \
        --master-data=1 \
        --no-autocommit \
        --default-character-set=utf8mb4 \
        --single-transaction \
        --compress \
        | gzip \
        | gsutil cp - gs://replica-bucket/external-database.sql.gz
Property Description
EXTERNAL_HOST The IPv4 or DNS address for the external server.
EXTERNAL_PORT The port for the external server. If the external server is hosted on Cloud SQL, this is 3306.
USERNAME The name of the replication user account or user account on the external server that has database read permissions.
PASSWORD Replication user password.
DATABASE_LIST Space-separated list of all databases on the external server, except for the system databases (sys, mysql, performance_schema, and information_schema). Use the SHOW DATABASES MySQL command to list your databases.
EXTERNAL_DATA If your external server does not support GTID, and you have permission to access the global read lock on it, use --master-data=1. Otherwise, don't use this property.
GTID_PURGED If your external server supports GTID, use --set-gtid-purged=on; otherwise, don't use this property.
ADD_DROP_TABLE If you want to add a DROP TABLE statement before each CREATE TABLE statement, include --add-drop-table.
ROUTINES If you want to show stored routines, such as procedures and functions, in the output for dumped databases, include --routines.
COMPRESS If you want to compress all information sent between the Cloud SQL replica and the external server, use --compress.
GZIP If you want to compress the dump file even more, use | gzip. If your database contains data that does not compress well, such as binary incompressible data or JPG images, don't use this.
BUCKET The name of the bucket you created in Step 1 to contain the dump file.
DUMP_FILENAME A file with this name is created in your bucket. This file contains the contents of the database on your external server.

Updating the source representation instance with the Cloud Storage bucket file path

After you set up the Cloud SQL replica, you need to update your source representation instance with the file path of your Cloud Storage bucket.

REST

    gcloud auth login
    ACCESS_TOKEN="$(gcloud auth print-access-token)"
    curl --header "Authorization: Bearer ${ACCESS_TOKEN}" \
         --header 'Content-Type: application/json' \
         --data @JSON_PATH \
  -X PATCH \
 https://sqladmin.googleapis.com/sql/v1beta4/projects/PROJECT-ID/instances/SOURCE_REPRESENTATION_INSTANCE

example

    gcloud auth login
    ACCESS_TOKEN="$(gcloud auth print-access-token)"
    curl --header "Authorization: Bearer ${ACCESS_TOKEN}" 
--header 'Content-Type: application/json'
--data @./source.json
-X PATCH
https://sqladmin.googleapis.com/sql/v1beta4/projects/MyProject/instances/cloudsql-source-instance

Property Description
JSON_PATH The path to the JSON file that contains the request data for the source representation instance.
PROJECT_ID The ID of your project in Google Cloud.
SOURCE_REPRESENTATION_INSTANCE The name of the source representation instance.

Verifying your replication settings

After your setup is complete, ensure that the Cloud SQL replica can replicate from the external server.

First, ensure that your external sync settings are correct. To do this, use the commands below to verify:

  • Connectivity between the Cloud SQL replica and external server
  • Replication user privileges
  • Version compatibility
  • The Cloud SQL replica is not already replicating
  • Binlogs are enabled on the external server
  • GTID is enabled if you are trying to do an external sync from an RDS external server and are using a Google Cloud bucket

Open a terminal and enter these commands to verify external sync settings are correct:

curl

gcloud auth login
ACCESS_TOKEN="$(gcloud auth print-access-token)"
curl --header "Authorization: Bearer ${ACCESS_TOKEN}" \
     --header 'Content-Type: application/json' \
     --data '{
         "syncMode": "SYNC_MODE",
         "skipVerification": "SKIP_VERIFICATION"
       }' \
     -X POST \
     https://sqladmin.googleapis.com/sql/v1beta4/projects/PROJECT_ID/instances/REPLICA_INSTANCE/verifyExternalSyncSettings

example

gcloud auth login
ACCESS_TOKEN="$(gcloud auth print-access-token)"
curl --header "Authorization: Bearer ${ACCESS_TOKEN}" \
     --header 'Content-Type: application/json' \
     --data '{
         "syncMode": "online",
       }' \
     -X POST \
     https://sqladmin.googleapis.com/sql/v1beta4/projects/myproject/instances/myreplica/verifyExternalSyncSettings
Property Description
SYNC_MODE verifyExternalSyncSettings verifies that you can keep the Cloud SQL replica and external server in sync after replication is set up. Sync modes include EXTERNAL_SYNC_MODE_UNSPECIFIED, ONLINE, and OFFLINE.
SKIP_VERIFICATION Whether or not to skip the built-in verification step before syncing your data. Only recommended if you have already verified your replication settings.
PROJECT_ID The ID of your project in Google Cloud.
REPLICA_INSTANCE The ID of your Cloud SQL replica.

Starting replication on the external server

After you have verified that you can replicate from the external server, you are ready to perform the replication. Expect the replica to import about 25-50 GB per hour.

During the initial import process, do not perform any DDL operations on the external server. Doing so could cause inconsistencies during the import. After the import process completes, the replica uses the binary logs on the external server to catch up to the current state of the external server.

Open a terminal, log in using gcloud, then enter the curl command to replicate from the external server.

gcloud auth login
ACCESS_TOKEN="$(gcloud auth print-access-token)"
curl --header "Authorization: Bearer ${ACCESS_TOKEN}" \
     --header 'Content-Type: application/json' \
     --data '{
         "syncMode": "SYNC_MODE",
         "skipVerification": "SKIP_VERIFICATION"
       }' \
     -X POST \
     https://sqladmin.googleapis.com/sql/v1beta4/projects/PROJECT_ID/instances/REPLICA_INSTANCE/startExternalSync

example

gcloud auth login
ACCESS_TOKEN="$(gcloud auth print-access-token)"
curl --header "Authorization: Bearer ${ACCESS_TOKEN}" \
     --header 'Content-Type: application/json' \
     --data '{
         "syncMode": "online",
         "skipVerification": false
       }' \
     -X POST \
     https://sqladmin.googleapis.com/sql/v1beta4/projects/MyProject/instances/replica-instance/startExternalSync
Property Description
SYNC_MODE Verifies that you can keep the Cloud SQL replica and external server in sync after replication is set up.
SKIP_VERIFICATION Whether or not to skip the built-in verification step before syncing your data. Only recommended if you have already verified your replication settings.
PROJECT_ID The ID of your project in Google Cloud.
REPLICA_INSTANCE The ID of your Cloud SQL replica.

Cleaning up your storage

If you replicated from a file in a bucket, you can remove this file and bucket. See the Cloud Storage documentation for Deleting Objects and Deleting Buckets.

Proceeding with replication

Once you start replication from the external server, you need to monitor replication and then complete your migration. To learn more, see Monitoring replication.

Troubleshooting

Click the links in the table for details:

Issue Troubleshooting
Lost connection to MySQL server during query when dumping table. The source may have become unavailable, or the dump contained packets too large.

Make sure the external primary is available to connect, or use mysqldump with the max_allowed_packet option.

To learn more about using mysqldump flags for managed import migration, see Allowed and default initial sync flags

The initial data migration was successful, but no data is being replicated. One possible root cause could be your source database has defined replication flags which result in some or all database changes not being replicated over.

Make sure the replication flags such as binlog-do-db, binlog-ignore-db, replicate-do-db or replicate-ignore-db are not set in a conflicting way.

Run the command show master status on the primary instance to see the current settings.

The initial data migration was successful but data replication stops working after a while. Things to try:

  • Check the replication metrics for your replica instance in the Cloud Monitoring section of the Google Cloud Console.
  • The errors from the MySQL IO thread or SQL thread can be found in Cloud Logging in the mysql.err log files.
  • The error can also be found when connecting to the replica instance. Run the command SHOW SLAVE STATUS, and check for the following fields in the output:
    • Slave_IO_Running
    • Slave_SQL_Running
    • Last_IO_Error
    • Last_SQL_Error
mysqld check failed: data disk is full. The data disk of the replica instance is full.

Increase the disk size of the replica instance. You can either manually increase the disk size or enable auto storage increase.

Reviewing your replication logs

When you verify your replication settings, logs are produced. You can view these logs by following these steps:

  • Go to the Logs Viewer in the Google Cloud Console.

    Go to the Logs Viewer

  • Select the Cloud SQL replica from the Instance dropdown.
  • Select the replication-setup.log log file.
  • If the Cloud SQL replica is unable to connect to the external server, confirm the following:

    • Any firewall on the external server is configured to allow connections from the Cloud SQL replica's outgoing IP address.
    • Your SSL/TLS configuration is correct.
    • Your replication user, host, and password are correct.

What's next