Chapter 3. Migrating from Internal Satellite Databases to External Databases

When you install Red Hat Satellite, the satellite-installer command installs MongoDB and PostgreSQL databases on the same server as Satellite. If you are using the default internal databases but want to start using external databases to help with the server load, you can migrate your internal databases to external databases. Depending on your requirements, you can use external databases for either MongoDB or PostgreSQL database, or both.

To confirm whether your Satellite Server has internal or external databases, you can query the status of your databases:

For PostgreSQL, enter the following command:

# satellite-maintain service status --only postgresql

For MongoDB, enter the following command:

# satellite-maintain service status --only rh-mongodb34-mongod

Use MongoDB as an External Database Considerations and PostgreSQL as an External Database Considerations to decide if you want to use external databases for your Satellite deployment.

Red Hat does not provide support or tools for external database maintenance. This includes backups, upgrades, and database tuning. You must have your own database administrator to support and maintain external databases.

To migrate from the default internal databases to external databases, you must complete the following procedures:

  1. Section 3.3, “Preparing a Host for External Databases”. Prepare a Red Hat Enterprise Linux 7 server to host the external databases.
  2. Section 3.4, “Installing MongoDB”. Prepare MongoDB with user pulp owning the pulp_database
  3. Section 3.5, “Installing PostgreSQL”. Prepare PostgreSQL with databases for Satellite and Candlepin and dedicated users owning them.
  4. Section 3.6, “Migrating to External Databases”. Edit the parameters of satellite-installer to point to the new databases, and run satellite-installer.

3.1. MongoDB as an External Database Considerations

Pulp uses the MongoDB database. If you want to use MongoDB as an external database, the following information can help you decide if this option is right for your Satellite configuration. Satellite supports MongoDB version 3.4.

Advantages of External MongoDB

  • Increase in free memory and free CPU on Satellite
  • Flexibility to tune the MongoDB server’s system without adversely affecting Satellite operations

Disadvantages of External MongoDB

  • Increase in deployment complexity that can make troubleshooting more difficult
  • An external MongoDB server is an additional system to patch and maintain
  • If either the Satellite or the Mongo database server suffers a hardware or storage failure, Satellite is not operational
  • If there is latency between the Satellite and the external database server, performance can suffer

FIPS-related Restrictions

  • You cannot use an external MongoDB with Satellite in FIPS mode.

3.2. PostgreSQL as an External Database Considerations

Foreman, Katello, and Candlepin use the PostgreSQL database. If you want to use PostgreSQL as an external database, the following information can help you decide if this option is right for your Satellite configuration. Satellite supports PostgreSQL version 9.2.

Advantages of External PostgreSQL:

  • Increase in free memory and free CPU on Satellite
  • Flexibility to set shared_buffers on the PostgreSQL database to a high number without the risk of interfering with other services on Satellite
  • Flexibility to tune the PostgreSQL server’s system without adversely affecting Satellite operations

Disadvantages of External PostgreSQL

  • Increase in deployment complexity that can make troubleshooting more difficult
  • The external PostgreSQL server is an additional system to patch and maintain
  • If either Satellite or the PostgreSQL database server suffers a hardware or storage failure, Satellite is not operational
  • If there is latency between the Satellite server and database server, performance can suffer

If you suspect that the PostgreSQL database on your Satellite is causing performance problems, use the information in Satellite 6: How to enable postgres query logging to detect slow running queries to determine if you have slow queries. Queries that take longer than one second are typically caused by performance issues with large installations, and moving to an external database might not help. If you have slow queries, contact Red Hat Support.

3.3. Preparing a Host for External Databases

Install a freshly provisioned system with the latest Red Hat Enterprise Linux 7 server to host the external databases.

Subscriptions for Red Hat Software Collections and Red Hat Enterprise Linux do not provide the correct service level agreement for using Satellite with external databases. You must also attach a Satellite subscription to the base operating system that you want to use for the external databases.

Prerequisites

Procedure

  1. Use the instructions in Attaching the Satellite Infrastructure Subscription to attach a Satellite subscription to your server.
  2. Disable all repositories and enable only the following repositories:

    # subscription-manager repos --disable '*'
    # subscription-manager repos --enable=rhel-server-rhscl-7-rpms \
    --enable=rhel-7-server-rpms

3.4. Installing MongoDB

You can install only the same version of MongoDB that is installed with the satellite-installer tool during an internal database installation. You can install MongoDB using Red Hat Software Collections (RHSCL) repositories or from an external source, as long as the version is supported. Satellite supports MongoDB version 3.4.

Procedure

  1. To install MongoDB, enter the following command:

    # yum install rh-mongodb34 rh-mongodb34-syspaths
  2. Start and enable the rh-mongodb34 service:

    # systemctl start rh-mongodb34-mongod
    # systemctl enable rh-mongodb34-mongod
  3. Create a Pulp user on MongoDB for database pulp_database:

    # mongo pulp_database \
    --eval "db.createUser({user:'pulp',pwd:'pulp_password',roles:[{role:'dbOwner', db:'pulp_database'},{ role: 'readWrite', db: 'pulp_database'}]})"
  4. In the /etc/opt/rh/rh-mongodb34/mongod.conf file, specify the bind IP:

    bindIp: your_mongodb_server_bind_IP,::1
  5. Edit the /etc/opt/rh/rh-mongodb34/mongod.conf file to enable authentication in the security section:

    security:
      authorization: enabled
  6. Restart the rh-mongodb34-mongod service:

    # systemctl restart rh-mongodb34-mongod
  7. Open port 27017 for MongoDB:

    # firewall-cmd --add-port=27017/tcp
    # firewall-cmd --runtime-to-permanent
  8. From Satellite Server, test that you can access the database. If the connection succeeds, the command returns 1.

    # scl enable rh-mongodb34 " mongo --host mongo.example.com \
    -u pulp -p pulp_password --port 27017 --eval 'ping:1' pulp_database"

3.5. Installing PostgreSQL

You can install only the same version of PostgreSQL that is installed with the satellite-installer tool during an internal database installation. You can install PostgreSQL using Red Hat Enterprise Linux Server 7 repositories or from an external source, as long as the version is supported. Satellite supports PostgreSQL version 9.2.

Procedure

  1. To install PostgreSQL, enter the following command:

    # yum install postgresql-server
  2. To initialize, start, and enable PostgreSQL service, enter the following commands:

    # postgresql-setup initdb
    # systemctl start postgresql
    # systemctl enable postgresql
  3. Edit the /var/lib/pgsql/data/postgresql.conf file:

    # vi /var/lib/pgsql/data/postgresql.conf
  4. Remove the # and edit to listen to inbound connections:

    listen_addresses = '*'
  5. Edit the /var/lib/pgsql/data/pg_hba.conf file:

    # vi /var/lib/pgsql/data/pg_hba.conf
  6. Add the following line to the file:

      host  all   all   Satellite_ip/24   md5
  7. Restart PostgreSQL service to update with the changes:

    # systemctl restart postgresql
  8. Open the postgresql port on the external PostgreSQL server:

    # firewall-cmd --add-service=postgresql
    # firewall-cmd --runtime-to-permanent
  9. Switch to the postgres user and start the PostgreSQL client:

    $ su - postgres -c psql
  10. Create two databases and dedicated roles, one for Satellite and one for Candlepin:

    CREATE USER "foreman" WITH PASSWORD 'Foreman_Password';
    CREATE USER "candlepin" WITH PASSWORD 'Candlepin_Password';
    CREATE DATABASE foreman OWNER foreman;
    CREATE DATABASE candlepin OWNER candlepin;
  11. Exit the postgres user:

    # \q
  12. From Satellite Server, test that you can access the database. If the connection succeeds, the commands return 1.

    # PGPASSWORD='Foreman_Password' psql -h postgres.example.com  -p 5432 -U foreman -d foreman -c "SELECT 1 as ping"
    # PGPASSWORD='Candlepin_Password' psql -h postgres.example.com -p 5432 -U candlepin -d candlepin -c "SELECT 1 as ping"

3.6. Migrating to External Databases

Back up and transfer existing data, then use the satellite-installer command to configure Satellite to connect to external MongoDB and PostgreSQL databases.

Prerequisites

  • You have installed and configured MongoDB and PostgreSQL databases on a Red Hat Enterprise Linux server.

Procedure

  1. On Satellite Server, stop the satellite-maintain services:

    # satellite-maintain service stop
  2. Start the postgreSQL and mongod services:

    # systemctl start postgresql
    # systemctl start mongod
  3. Back up the internal databases:

    # satellite-maintain backup online --skip-pulp-content --preserve-directory -y /var/migration_backup
  4. Transfer the data to the new external databases:

    PGPASSWORD='Foreman_Password' pg_restore -h postgres.example.com -U foreman -d foreman < /var/migration_backup/foreman.dump
    PGPASSWORD='Candlepin_Password' pg_restore -h postgres.example.com -U candlepin -d candlepin < /var/migration_backup/candlepin.dump
    mongorestore --host mongo.example.com --db pulp_database --username pulp_user --password pulp_password /var/migration_backup/mongo_dump/pulp_database/
  5. Use the satellite-installer command to update Satellite to point to the new databases:

    satellite-installer --scenario satellite \
        --foreman-db-host postgres.example.com \
        --foreman-db-password Foreman_Password \
        --foreman-db-database foreman \
        --foreman-db-manage false \
        --katello-candlepin-db-host postgres.example.com \
        --katello-candlepin-db-name candlepin \
        --katello-candlepin-db-password Candlepin_Password \
        --katello-candlepin-manage-db false \
        --katello-pulp-db-username pulp \
        --katello-pulp-db-password pulp_password \
        --katello-pulp-db-seeds mongo.example.com:27017 \
        --katello-pulp-db-name pulp_database \
        --katello-pulp-manage-db false