Managing databases

Overview

We currently support the following databases, with no need for additional configuration after deployment.

• MySQL (or Percona if configured via Manifest
• Postgres
• MongoDB
• Redis
• InfluxDB
• SQLite (only in development environments)

How to deploy databases with Cloud 66

When creating a Cloud 66 application, you can add as many databases as you need in your service configuration during the application build.

After you have analyzed your code, ensure that your desired database type is displayed in the About your app section of the analysis results.

Adding databases after initial deployment

You can add databases to an existing application either by using Database Groups for physical databases, or by adding logical databases to your existing physical database(s)

Database authentication

When we deploy a database we automatically generate the required users and passwords to allow authentication. You can find these values via your Dashboard in the detail page of any database server. They will be available as environment variables and your application will be configured to use them.

MySQL and Postgres databases managed by Cloud 66 automatically have the following users created:

• a Database Application user
• a Database Admin user
• a Database Replication user (where replication is required)

The Application and Replication users always have the same password. The associated Linux users for these will differ depending on database type.

Connecting your container to your DB

Databases in Cloud 66 run as separate components and aren't containerized. Even though they may be running on the same private network as your cluster servers, you will not be able to connect to them via localhost because of the nature of containers (which are, by definition, abstracted from operating the system).

Instead, we we automatically create a Kubernetes services for each DB that connects out from your cluster to the database server(s). To see these on your cluster, you can list the namespaces and then select your namespace and list the services associated with it with the following commands:

$ kubectl get namespaces
$ kubectl -n <your-namespace> get svc

This will show you all the services running, some of which will be your databases.

Service names for database groups

If your application has two or more database groups, your Kubernetes database services will inherit those names. For example, if you have three MySQL database groups named main, spare and archive then the Kubernetes services will be named:

• mysql-main
• mysql-spare
• mysql-archive

If one of these groups is set as your "primary" then it will use the default service name (mysql) instead of its group-specific name.

Connection strings

A typical connection string might have:

• The protocol
• The username and password (where required)
• The name of the Kubernetes service, including database groups (e.g. mongodb-spare)
• The name of the DB server (e.g. mongo_production_1)

So to connect to a MongoDB server named mongo_production_1 and running in your app namespace as mongodb-spare you would use something like:

$ mongodb://mongodb-spare/mongo_production_1

A similar setup for a Postgres server would look something like this:

$ postgresql://username:password@service_name/database

Connecting your app to your DB in Cloud 66 Container Service V1

To connect to a database in Version 1 of Cloud 66 Container Management Service (CSv1), you should use its ElasticDNS address. Please read our full guide on ElasticDNS for more details.

Database deployment types

No database (external)

This option allows you to deploy your application without a database managed by Cloud 66, and is ideal for externally hosted databases.

You can also configure an external database via your Manifest file by specifying the server node as external.

Please note that if there is no connectivity to your external database, or your external database host is not configured correctly, the deployment will fail.

Local database

This option deploys your chosen database to the same server as your web server - this is intended primarily for development, as running your database locally in production is not advised. In this case, your application database configuration will be amended to target your local database server. If you scale up your web server, these settings will also be amend automatically to reflect your database configuration.

Dedicated database

This option will automatically create a new server for your database and configure your application accordingly.

Upgrading your database

Cloud 66 will not do in-place database upgrades, because this process may cause your application to stop working or may not be possible automatically.

You have two options for upgrading your database through Cloud 66:

1. Using Database Groups
2. Cloning your entire application

These options are described in full below.

Upgrading databases using Groups

To upgrade your database(s) using Groups:

1. Add a new Database Group to your application - this will automatically create a Group with the latest version of your chosen engine
2. Migrate your data from your existing database to your new Group - using database backups is usually the quickest and easiest way
3. Test that your application can connect to and read your new database
4. Switch your application configuration to use the new Group
5. Remove the old Database Group

Cloning your application

You can make a new instance of your application by cloning it. We will provision new components for your application, which will use the latest versions by default. Be sure to check that you have not locked any component versions using your Manifest file.

Once the new application is created, you can migrate data from your old application to your new application.

How to run database schema migrations

If you’ve made structural changes to your databases, you will typically need to run migration commands during your build process, so that those changes are applied to your live database. The nature of these commands depend on your framework.

To do this in Cloud 66, you should add the commands to your service.yml file using the following syntax:

deploy_command: <migration commands for your app>

So, for example, the service definition for a Django app with a migration enabled might look as follows:

version: 2
services:
  helloworld:
    git_url: git@github.com:my-account/my-repo.git
    git_branch: master
    deploy_command: python manage.py migrate
    ports:
    - :container: 5000
      :http: 80
databases:
- mysql

Customize your database configuration

You can customize the database configuration on your servers using CustomConfig. CustomConfig is available for MySQL, Postgres, Redis and MongoDB.

Editing and committing your database CustomConfig will perform the following steps on every database server in your application, one by one, sequentially:

• Check your template for Liquid syntax errors
• Determine the correct server configuration and prepare general variables
• Prepare custom variables for your database type (e.g. server_state)
• Compile the database configuration based on the information from the server and database type
• Upload the configuration to the server
• Restart your database

Database customization variables

There are a number of variables available for use in your database CustomConfig. Some are general for all database types, while others are database specific.

Global variables

The following variables are available to any database CustomConfig.

MySQL variables

The following variables are only available in the MySQL CustomConfig.

*It is 0 for standalone servers, 1 for master servers and a number greater than 1 for slave servers

Postgres variables

The following variables are only available in the Postgres CustomConfig.

Redis variables

The following variables are only available in the Redis CustomConfig.

Migrating to an external database

If you need to migrate a database managed by Cloud 66 to an external provider, you should bear in mind the following:

• Updating your Manifest file will not be sufficient to reconfigure your application - you will need to connect your application manually to your new database servers, including authentication credentials, ideally via your app’s environment variables.
• Your existing database servers will need to be manually removed from your application after you have migrated. They will not be automatically removed or deleted.

The exact migration process will differ widely depending on both the database used, and the host to which you are migrating your data, but all of them share the following steps:

1. Switch off your application (maintenance mode is useful here)
2. Migrate your data to the new host
3. Set up authentication credentials and connection details
4. Add a firewall rule to allow your app to reach the new data host (and vice versa)
5. Turn your application back on
6. Delete your defunct Cloud 66 database servers