CloudNativePG

CloudNativePG (CNPG) is an operator to run PostreSQL on Kubernetes
Makes it easy to run production Postgres on K8S
Supports streaming replication, backups, PITR, TLS, monitoring...
Open source
Accepted to CNCF on January 21, 2025 at the Sandbox maturity level

(https://www.cncf.io/projects/cloudnativepg/)

A few examples

EphemeraSearch

personal project, ~200 GB database, tiny budget
Sellsy

40,000 databases across 50 clusters, Talos, Proxmox VE
MistralAI

30 production clusters, each from a few GB to a few TB size

→ CNPG works for environments with small, big, and many clusters!

Typical operation

Decide what kind of storage we want to use

(cloud, local, distributed, hyperconverged...)
Decide on backup strategy

(typically object store, e.g. S3-compatible)
Set up StorageClass if needed
Install CNPG
Deploy Postgres cluster(s) with YAML manifests
Profit!

Local vs remote storage

Local storage can feel less safe

(compared to a SAN, cloud block device, distributed volume...)
However, it can be much faster

(much lower latency, much higher throughput)
If we're using replication, losing a local volume is no problem
Distributed storage can also fail

(or be unavailable for a while)

CNPG installation

Example with Helm:

helm upgrade --install --namespace cnpg-system --create-namespace \
  --repo https://cloudnative-pg.io/charts/ \
  cloudnative-pg cloudnative-pg \
  --version 1.25.1

Interesting options to add, to integrate with Prometheus Operator:

--set monitoring.podMonitorEnabled=true
--set monitoring.grafanaDashboard.create=true
--set monitoring.grafanaDashboard.namespace=prom-system

Minimal Postgres cluster

apiVersion: postgresql.cnpg.io/v1
kind: Cluster
metadata:
  name: minimal
spec:
  instances: 2
  storage:
    size: 10G

Note: this is missing (notably) resource requests and backups!

`kubectl` plugin

There is a kubectl-cnpg plugin
Install it (e.g. with krew)
Check commands like:

k cnpg status

k cnpg psql

k cnpg backup

k cnpg promote

Production clusters

Check the following YAML manifest:

https://github.com/jpetazzo/pozok/blob/main/cluster-production.yaml

If you want to test this, you need an S3-compatible object store.

Set the required variables:

$CLUSTER_NAME, $AWS_ACCESS_KEY_ID, $AWS_SECRET_ACCESS_KEY, $AWS_DEFAULT_REGION, $BUCKET_NAME, $AWS_ENDPOINT_URL
Then envsubst < cluster-production.yaml | kubectl apply -f-
Cluster comes up; backups and WAL segments land in the S3 bucket!

Automated switchover

CNPG detects when we kubectl cordon a node
It assumes "cordon = maintenance"
If the node hosts a primary server, it initiates a switchover
It also uses Pod Disruption Budgets (PDB) to collaborate with evictions

(the PDB prevents the eviction of the primary until it gets demoted)

Benchmarking

Postgres has pgbench
Step 1: execute e.g. pgbench -i -s 10 to prepare the database

(-s is an optional "scaling factor" for a bigger dataset)
Step 2: execute pgbench -P1 -T10 to run the benchmark

(-P1 = report progress every second, -T10 = run for 10 seconds)
These commands can be executed in the pod running the primary, e.g.:

kubectl exec minimal-1 -- pgbench app -i -s 10

kubectl exec minimal-1 -- pgbench app -P1 -T60

CNPG lab 1

Install CNPG on a managed cluster with a default StorageClass
Provision a CNPG cluster (primary+replica)
Run a pgbench (e.g. 60 seconds)
Note the number of transactions / second
Install another StorageClass (e.g. rancher/local-path-provisioner)
Provision another CNPG cluster with that storage class
Run a benchmark and compare the numbers
Discuss!

CNPG lab 2

This one requires access to an S3-compatible object store
Deploy a cluster sending backups to the object store
Run a benchmark (to populate the database)
Trigger a backup (e.g. with k cnpg backup)
Create a new cluster from the backup
Confirm that the numbers of rows (e.g. in pgbench_history) is the same

???

:EN:- Deploying Postgres clusters with CloudNativePG :FR:- Déployer des clusters Postgres avec CloudNativePG

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