This document provides an overview of running PostgreSQL in Kubernetes. It defines common Kubernetes concepts like clusters, masters, nodes, pods, services, persistent volumes, and deployments. It also discusses design patterns for running PostgreSQL on Kubernetes, including in a single node or high availability configuration. Finally, it covers deploying to Kubernetes with tools like kubectl and Helm and considerations for monitoring PostgreSQL performance on Kubernetes.

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Zero to Hero
Running Postgres in Kubernetes
Taylor Graham : Field CTO
Twitter: @thecloudslayer
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WHO IS RUNNING K8S ON LAPTOP?

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WHO
2019 Container Adoption Survey - Diamanti

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WHAT
2019 Container Adoption Survey - Diamanti

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WHERE
2019 Container Adoption Survey - Diamanti

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WHY
• Business: Kubernetes is a system for deploying applications that
can save money because it takes less IT manpower to manage
and helps more efficiently utilize the infrastructure. It helps
make your apps a more portable, so you can move them more
easily between different clouds and internal environments or
laptop to laptop.
• Tech: Agility in development, deployment, and operations

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BASIC CONCEPTS

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CLUSTER
• Doc: I could not find a
definition.
• Taylor: A Kubernetes
cluster is everything.

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MASTER
• DOC: The Kubernetes Master is a collection of three processes
that run on a single node in your cluster, which is designated as
the master node. Those processes are: kube-apiserver, kube-
controller-manager and kube-scheduler.The Kubernetes master
is responsible for maintaining the desired state for your cluster.
• Taylor: I would call it the
brains / command and control.
I would think of it like vCenter
coming from that world.

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CLUSTER COMMANDS
Kubectl cluster-info
Kubectl version

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NAMESPACE
• Doc: Namespaces are a way to divide
cluster resources between multiple users.
Namespace provide a scope for names.
Names of resources need to be unique
within a namespace, but not across
namespaces. Namespaces can not be
nested inside one another and each
Kubernetes resource can only be in one
namespace.
• Taylor: It’s a good way not to blow
everything up ASAP.

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NAMESPACE COMMANDS
helm install edb-2.4.2.tgz -f myvalues.yaml –namespace anotherfailwhale
Kubectl create namespace anotherfailwhale

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NODES
• Doc: A node is a worker machine in Kubernetes, previously known
as a minion. A node may be a VM or physical machine, depending
on the cluster. Each node contains the services necessary to
run pods and is managed by the master components. The services
on a node include the container runtime, kubelet and kube-proxy
• Taylor: The physical server
or virtual machine running
all the magic.

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NODE COMMANDS
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NODE COMMANDS
Kubectl get nodes

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POD
• Doc: A Pod is the basic execution unit of a Kubernetes
application–the smallest and simplest unit in the
Kubernetes object model that you create or deploy. A Pod
represents processes running on your Cluster.
• Taylor: Because they
share a local host with
all containers in pod I
think of it like docker-
compose on your
laptop.

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POD COMMANDS

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AND MORE POD COMMANDS
kubectl describe pod

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SERVICE
• Doc: a Service is an abstraction which defines a
logical set of Pods and a policy by which to
access them. The set of Pods targeted by a
Service is usually determined by a selector.
• Taylor: what the doc said….

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PV/PVC
• Doc: A PersistentVolume (PV) is a piece of storage in the cluster that
has been provisioned by an administrator or dynamically provisioned
using Storage Classes. A PersistentVolumeClaim (PVC) is a request
for storage by a user. It is similar to a pod. Pods consume node
resources and PVCs consume PV resources.
• Taylor: LUN and VMDK

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PV

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DEPLOYMENT / REPLICASET
• A Deployment controller provides declarative updates
for Pods and ReplicaSets.
• A ReplicaSet’s purpose is to maintain a stable set of replica Pods
running at any given time. As such, it is often used to guarantee the
availability of a specified number of identical Pods.
• Taylor:

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STATEFULSET
• Doc: StatefulSet is the workload API object used to manage
stateful applications. Manages the deployment and scaling
of a set of Pods , and provides guarantees about the
ordering and uniqueness of these Pods.
• Taylor: Where you run a
database.
Stable, unique network identifiers. $(statefulset name)-$(ordinal)
Stable, persistent storage.
Ordered, graceful deployment and scaling.
Ordered, automated rolling updates.

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DESIGN PATTERNS

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SINGLE NODE
Postgres
Data
Application Database
Stand alone Postgres server
basic configuration
Containers
Pods

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metrics
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HA REFERENCE ARCHITECTURE
Postgres
HA
Agent
Proxy
Mon
Agent
Data
Application
EDB-Service
Postgres
HA
Agent
Mon
Agent
Data
Postgres
HA
Agent
DR
Tool
Proxy
Mon
Agent
Data
Admin
Tool
read/write
readread
redundant
streaming
replication
streaming
replication
Shared or Local Storage
Database, Tools, Agents
Containers
Pods
Application Application
Master Standby 2Standby 1
Proxy
Postgres cluster
with application scale-out
Backup

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metrics
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On-Prem In-Memory Compute Nodes
Postgres
HA
Agent
Proxy
Mon
Agent
EDB-Service
Postgres
HA
Agent
Mon
AgentPostgres
HA
Agent
DR
Tool
Proxy
Mon
Agent
Admin
Tool
read/write
readread
redundant
streaming
replication
Database, Tools, Agents
Containers
Pods
Master Standby 2Standby 1
Proxy
NODE POOL DB PREFORMANCE NODE 2 NODE 3
Volume Claim Volume Claim Volume Claim
Data Data DataBackup
Nodes
ApplicationApplication Application
streaming
replication
17k TPS
PgBench

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OK LETS DEPLOY

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KUBECTL

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HELM
• helm install edb-2.4.2.tgz -f myvalues.yaml

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OPENSHIFT

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RANDOM THOUGHTS

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MONITORING THOUGHTS
Old way
Utilization (U): The percentage of time a resource is in use.
Saturation (S): The amount of work the resource must (the “queue” of work).
Errors (E): A count of errors.
RED methodology
Rate (R): The number of requests per second.
Errors (E): The number of failed requests.
Duration (D): The amount of time to process a request.
RED is actually derived from The Four Golden Signals
Latency: The time it takes to service a request.
Traffic: A measure of how much demand on the system.
Errors: The rate of failed requests.
Saturation: A measure of how “full” a service is, often measured by latency.
OOM KILLER

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EVERYTHING ELSE

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QUESTIONS & DISCUSSION
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THANK YOU
info@enterprisedb.com
www.enterprisedb.com
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