Percona Everest installation and workflow

This section provides an overview of how Percona Everest is installed, the components involved, and the workflow, from operator installation to database provisioning, backups, and restores.

Percona Everest installation workflow

Starting from Percona Everest v1.4.0, the CLI installation is a wrapper around the helm charts:

• everest-core

• everest-db-namespace.

The installation flow is as follows:

1. The everest-core helm chart is installed:

   This step deploys all the core components required for Percona Everest to function.

   Component category	Namespace	Components
   OLM components	everest-olm	olm-operator, catalog-operator, package-server, everest-catalog
   Monitoring stack	everest-monitoring	vm-operator, kube-state-metrics
   Everest components	everest-system	everest-server, everest-operator

2. The everest-db-namespace chart is installed in the everest namespace. This chart handles the deployment of database operators using the following workflow:

   1. Creates OLM subscriptions for each of the selected database operators (by default, all supported operators are selected).
   2. OLM reconciles the subscriptions and creates an install plan for each operator.
   3. A Helm hook creates the everest-operators-installer job that waits for the OLM install plan to be created and approves it once created.
   4. OLM reconciles the approved install plan and creates a cluster-service-version for each database operator. The CSV includes all the manifests needed to install the operator. OLM automatically applies these manifests, and the operator is installed.

Configurable installation options

Percona Everest supports several configuration flags for customizing the installation.

Namespace configuration

Flag	Description
--namespaces everest	By default, the everest namespace is used, and all the database operators (PXC, PSMDB, and PG) are installed.
--namespaces n1,n2	Deploy database operators in custom namespaces.
--skip-db-namespace	Skip creation of database namespaces.

Example

You can provision multiple database namespaces simultaneously by providing a comma-separated list with the --namespaces flag.

everestctl install --namespaces n1,n2

Operator installation flags

If you want to skip the installation of certain operators, you can use the following flags:

Flag	Description
--operator.mongodb=false	Skip installing MongoDB operator.
--operator.postgresql=false	Skip installing PostgreSQL operator.
--operator.xtradb-cluster=false	Skip installing PXC operator.

Manage namespaces

You can manage database namespaces after the initial installation using the following commands:

everestctl namespaces add [NAMESPACE]
everestctl namespaces update [NAMESPACE]
everestctl namespaces remove [NAMESPACE]

For detailed information on managing namespaces, see the Namespaces management section.

The helm installation method provides an identical flow to the one described above, with similar configuration options. Refer to the helm chart documentation for a full list of available configuration options.

Percona Everest server and operator workflow

Database creation workflow

Here’s the database creation workflow in Percona Everest:

1. The Percona Everest user is authenticated and logged in and a JWT Token is provided.
2. The user creates a database, either through the frontend UI or everestctl or via the APl.
3. The Percona Everest API is invoked to create a create a Custom Resource Definition (CRD). The Percona Everest server then creates a custom resource DatabaseCluster.
4. In the everest-operator reconciliation loop, once the DatabaseCluster object is recognized, an appropriate custom resource for the database is created, for example if it’s PXC , PerconaXtraDBCluster is created.

5. The database operator takes over the task of creating the database and the necessary objects to manage it.

   Note

   Other actions, such as creating backups, restores ,monitoring or deleting the objects follows a similar flow except the objects involved may differ.

   All the custom resources connected to Percona Everest follow a similar flow except the DatabaseEngine.

Database engine workflow

Here’s the workflow for the database engine in Percona Everest:

1. The user installs the everest db namespace chart either as part of initial installation or as a separate step.
2. Subscriptions are created for the operators chosen while installing the helm chart.
3. OLM reconciles the Subscriptions and creates an InstallPlan.
4. The helm chart creates a kubernetes job called everest-operators-installer that waits for the InstallPlan to be created and approves it.
5. OLM detects that the InstallPlan has been approved and creates a ClusterServiceVersion, deploying all components that make up the database operator.

6. The Percona operator detects the deployment resource of the database operator and reconciles the DatabaseEngine CR of the corresponding type.

7. During the reconciliation process, the Percona operator detects the installed version and queries Percona’s Version Service to fetch supported engine versions.

   Example

   Check Percona.com to get the engine versions supported by that operator. To check which MongoDB versions are supported by PSMDB operator v1.19.0, visit:

   🔗 Supported MongoDB versions – PSMDB Operator v1.19.0.

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