Scaling Microservices
with Kubernetes

Deivid Hahn Fração
Web Developer

Containers

Microservices
Challenges
▸ Infrastructure complexity
▸ Scaling
▸ Service discovery and routing
▸ Monitoring and logging

Solution

What is
Kubernetes?
"Kubernetes is an open-source
system for automating
deployment, scaling, and
management of containerized
applications."

What is
Kubernetes?
▸ Also known as k8s
▸ Inspired by the Google Borg system
▸ V1.0 released in July 2015
▸ Google donated it to the Cloud
Native Computing Foundation

Kubernetes
is...
▸ Portable: public, private, hybrid,
multi-cloud
▸ Extensible: modular, pluggable,
hookable, composable
▸ Self-healing: auto-placement,
auto-restart, auto-replication,
auto-scaling

Architecture

Kubectl
▸ Command line interface for running
commands against Kubernetes
clusters

Dashboard

Minikube
▸ Minikube is a tool that makes it
easy to run Kubernetes locally
▸ It runs a single-node
Kubernetes cluster inside a VM

Components

Master
Components

▸ Exposes the Kubernetes API
▸ REST operations
▸ It is the front-end for the
Kubernetes control plane
kube-apiserver

▸ Kubernetes’ backing store
▸ All cluster data is stored
here
▸ A multi-node cluster in
production and back it up
periodically is
recommended.
etcd

▸ Watches newly created
pods that have no node
assigned
▸ Selects the best node
option for them to run
kube-scheduler

▸ Run controllers that handle
routine tasks
kube-controller-manager
cloud-controller-manager
▸ Run controllers that interact
with cloud providers

Node
Components

▸ It watches for pods that
have been assigned to its
node
▸ Runs the pod and mount
required volumes
▸ Downloads the pod’s
secrets
▸ Reports the status of the
node back to the rest of the
system
kubelet

▸ Maintain network rules
kube-proxy

Concepts

Desired
State
▸ Very important concept in
the Kubernetes model
▸ It is Kubernetes’
responsibility to make sure
that the current state
matches the desired state

Pod
▸ It contains one or more
application containers,
tightly coupled
▸ Containers within a pod
share an IP address and port
space, and can find each
other via localhost

Pod
▸ Pods are considered to be
relatively ephemeral
▸ Normally used with
controllers

How to
create
a Pod?

How to
create
a Pod?

How to
create
a Pod?

Describing
a Pod

Describing
a Pod

Describing
a Pod

Label
▸ Labels are key/value pairs
that are attached to objects,
such as pods
▸ Labels can be used to
organize and to select
subsets of objects

Liveness
Probe
▸ The kubelet uses liveness
probes to know when to
restart a Container

Liveness
Probe

Readiness
probe
▸ The kubelet uses readiness
probes to know when a
Container is ready to start
accepting traffic
▸ A Pod is considered ready
when all of its Containers are
ready
▸ When a Pod is not ready, it is
removed from Service load
balancers

Readiness
probe

Readiness
/ liveness
probe
fields
▸ initialDelaySeconds: Number
of seconds after the
container has started before
liveness or readiness probes
are initiated
▸ periodSeconds: How often
(in seconds) to perform the
probe

Readiness
/ liveness
probe
fields
▸ successThreshold: Minimum
consecutive successes for
the probe to be considered
successful after having
failed
▸ failureThreshold: Minimum
consecutive failures for the
probe to be considered
unhealthy

▸ Pods are mortal
▸ Each Pod has a unique IP
address, but those IPs are
not exposed outside the
cluster.
▸ A service defines a logical
set of Pods and a policy by
which to access them
Services

▸ ClusterIP (default): Exposes
the Service on an internal IP
in the cluster
▸ NodePort: Exposes the
Service on the same port of
each selected Node in the
cluster
Services
- Types

▸ LoadBalancer - Creates an
external load balancer in the
current cloud (if supported)
and assigns a fixed, external
IP to the Service
▸ ExternalName - Exposes the
Service using an arbitrary
name (e.g.
test.example.com)
Services
- Types

Services

Replication
Controller
▸ Replication Controller
ensures that a specified
number of pod replicas are
running at any one time
▸ If there are too many pods,
the ReplicationController
terminates the extra pods. If
there are too few, the
ReplicationController starts
more pods.

Replication
Controller

Replication
Controller

Replication
Controller

Replication
Controller

Replica
Set
▸ Next-generation Replication
Controller
▸ The difference between a
ReplicaSet and a Replication
Controller right now is the
selector support

Replica
Set

Replica
Set

Replica
Set

Deployments
▸ A Deployment controller
provides declarative updates
for Pods and ReplicaSets
▸ Recommended way

Deployments

Deployments

Deployments

Deployments

Deployments

Deployments

Namespace
▸ Namespaces are intended
for use in environments with
many users spread across
multiple teams, or projects
▸ Names of resources need to
be unique within a
namespace, but not across
namespaces

Namespace

Secrets
▸ Passwords, OAuth tokens,
and ssh keys
▸ A secret can be used with a
pod in two ways: as files in a
volume mounted on one or
more of its containers, or
used by kubelet when pulling
images for the pod

Secrets

Secrets in
a Pod

Using Secrets
as
Environment
Variables

ConfigMap
▸ Key-value pairs of
configuration data that can
be consumed in pod
▸ ConfigMap is similar to
Secrets, but it do not contain
sensitive information

THANKS!