Security

Security for EDB Postgres Distributed for Kubernetes is analyzed at three layers: code, container, and cluster.

Code

Source code of EDB Postgres Distributed for Kubernetes is systematically scanned for static analysis purposes, including security problems. EDB uses a popular open-source linter for Go called GolangCI-Lint directly in the CI/CD pipeline. GolangCI-Lint can run several linters on the same source code.

One of these is Golang Security Checker, or gosec. gosec is a linter that scans the abstract syntactic tree of the source against a set of rules aimed at discovering well-known vulnerabilities, threats, and weaknesses hidden in the code. These threads include hard-coded credentials, integer overflows, SQL injections, and others.

Container

Every container image that's part of EDB Postgres Distributed for Kubernetes is built by way of CI/CD pipelines following every commit. Such images include not only those of the operator but also of the operands, specifically every supported PostgreSQL version. In the pipelines, images are scanned with:

• Dockle for best practices in terms of the container build process
• Clair for vulnerabilities found in both the underlying operating system and libraries and applications that they run

The following guidelines and frameworks were taken into account for container-level security:

• The Container Image Creation and Deployment Guide, developed by the Defense Information Systems Agency (DISA) of the United States Department of Defense (DoD)
• The CIS Benchmark for Docker, developed by the Center for Internet Security (CIS)

Cluster

Security at the cluster level takes into account all Kubernetes components that form both the control plane and the nodes as well as the applications that run in the cluster, including PostgreSQL.

Role-based access control (RBAC)

The operator interacts with the Kubernetes API server with a dedicated service account called pgd-operator-controller-manager. In Kubernetes this account is installed by default in the pgd-operator-system namespace. A cluster role binds between this service account and the pgd-operator-controller-manager cluster role that defines the set of rules, resources, and verbs granted to the operator.

RedHat OpenShift directly manages the operator RBAC entities by way of Operator Lifecycle Manager (OLM). OLM allows you to grant permissions only where they're required, implementing the principle of least privilege.

The following are some examples and, most importantly, the reasons why EDB Postgres Distributed for Kubernetes requires full or partial management of standard Kubernetes namespaced resources.

jobs : The operator needs to handle jobs to manage different PGDGroup phases.

poddisruptionbudgets : The operator uses pod disruption budgets to make sure enough PGD nodes are kept active during maintenance operations.

pods : The operator needs to manage PGD nodes as a Cluster resource.

secrets : Unless you provide certificates and passwords to your data nodes, the operator adopts the "convention over configuration" paradigm by self-provisioning random-generated passwords and TLS certificates and by storing them in secrets.

serviceaccounts : The operator needs to create a service account to enable the PGDGroup recovery job to retrieve the backup objects from the object store where they reside.

services : The operator needs to control network access to the PGD cluster from applications and properly manage failover/switchover operations in an automated way.

statefulsets : The operator needs to manage PGD proxies.

validatingwebhookconfigurations and mutatingwebhookconfigurations : The operator injects its self-signed webhook CA into both webhook configurations, which are needed to validate and mutate all the resources it manages. For more details, see the Kubernetes documentation.

To see all the permissions required by the operator, you can run kubectl describe clusterrole pgd-operator-manager-role.

EDB Postgres Distributed for Kubernetes internally manages the PGD nodes using the Cluster resource as defined by EDB Postgres for Kubernetes. See the EDB Postgres for Kubernetes documentation for the list of permissions used by the EDB Postgres for Kubernetes operator service account.

Calls to the API server made by the instance manager

The instance manager, which is the entry point of the operand container, needs to make some calls to the Kubernetes API server to ensure that the status of some resources is correctly updated and to access the config maps and secrets that are associated with that Postgres cluster. Such calls are performed through a dedicated ServiceAccount created by the operator that shares the same PostgreSQL Cluster resource name.

See the EDB Postgres for Kubernetes documentation for more information on the instance manager.

Pod security policies

A pod security policy is the Kubernetes way to define security rules and specifications that a pod needs to meet to run in a cluster. For InfoSec reasons, every Kubernetes platform must implement them.

EDB Postgres Distributed for Kubernetes doesn't require privileged mode for containers execution. The PostgreSQL containers run as the postgres system user. No component requires running as root.

Likewise, volumes access doesn't require privileged mode or root privileges. Proper permissions must be assigned by the Kubernetes platform or administrators. The PostgreSQL containers run with a read-only root filesystem, that is, no writable layer.

The operator explicitly sets the required security contexts.

On Red Hat OpenShift, Cloud Native PostgreSQL runs in the restricted security context constraint, the most restrictive one. The goal is to limit the execution of a pod to a namespace allocated UID and SELinux context.

Exposed ports

EDB Postgres Distributed for Kubernetes exposes ports at operator, instance manager, and operand levels, as shown in the table.

PGD

The current implementation of EDB Postgres Distributed for Kubernetes creates passwords for the postgres superuser and the database owner.

As far as encryption of passwords is concerned, EDB Postgres Distributed for Kubernetes follows the default behavior of PostgreSQL: starting with PostgreSQL 14, password_encryption is by default set to scram-sha-256. On earlier versions, it's set to md5.

You can disable management of the postgres user password using secrets by setting enableSuperuserAccess to false in the cnp section of the spec.

Storage

EDB Postgres Distributed for Kubernetes delegates encryption at rest to the underlying storage class. For data protection in production environments, we highly recommend that you choose a storage class that supports encryption at rest.

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