An Akka and a Kubernetes expert walk into a bar. They order drinks and try to figure out what is better for building distributed applications. Does Akka Cluster have a place in the age of Kubernetes? Does Kubernetes bring any value to those who are building applications using Akka? Akka Cluster is a mature choice to achieve full elasticity for your distributed JVM services. The Kubernetes orchestrator offers a growing set of features - think resilience or custom scaling metrics - that ultimately overlap with Akka's. This talk explores integration patterns between the two. Friends or foes?

1. Akka Cluster vs Kubernetes
Clustering Solutions Showdown

2. About us
Fabio Tiriticco
@ticofab
Scala & Akka consultant Kubernetes consultant
Ádám Sándor
@adamsand0r

3. Reactive
Distributed
Systems
Reactive Programming
Actors
Async Messaging
Non-blocking IO
Deployment
Streaming
Transparent clustering
Resource Provisioning
Zero-downtime deployments
Networking
Docker Containers
Service Discovery
Microservices
Reactive Community Kubernetes Community
Development+ +

4. @ticofab
@adamsand0rQuestions we try to answer
1. Can Kubernetes make an application reactive?
2. If so, what value does Akka Cluster provide on top of Kubernetes?
3. Is Akka Cluster suitable for a microservice architecture?
4. How can Akka Cluster and Kubernetes work together?

5. @ticofab
@adamsand0r
Reactive Systems

6. @ticofab
@adamsand0rThe Reactive Manifesto
2013, J. Boner, R. Kuhn, D. Farley, M. Thompson
VALUE
MEANS
FORM

7. @ticofab
@adamsand0rThe key to Elasticity is Distribution
Scale UP
Scale OUT
Limited by the
speed of light!
🌍

8. The key to Distribution is Location Transparency
MESSAGE DRIVEN
=
LOCATION TRANSPARENCY

9. @ticofab
@adamsand0r
Fault Tolerance Resilience
“The component is being hit
but keeps going, possibly
with reduced functionality”
“Upon failure, a component
is able to jump back to a
fully functional fresh state”
What is Resilience?

10. @ticofab
@adamsand0r
Akka

11. @ticofab
@adamsand0rWhat is Akka?
Reactive
Principles
Reactive
Design
Patterns
Reactive
Building
Blocks
JVM / application level

12. @ticofab
@adamsand0rHow does Akka help us achieve elasticity?
T1000
Actor
“John”
“John”
target?
• contains its own state
• can only communicate
via async messaging
t1000.getTarget()
Single JVMJVM 1
JVM 2
• unit of computation
Akka’s building
blocks are Actors
target:
Sarah
Actor
• contains behaviour

13. @ticofab
@adamsand0rAkka Cluster
JVM
JVM
JVMJVM
JVM

14. @ticofab
@adamsand0rHow does Akka help us achieve resilience?
Supervisor Actor
Actor
Every actor:
is created by a supervisor,
to whom failure handling is
delegated
USING A COMPONENT
≠
HANDLING ITS FAILURES

15. @ticofab
@adamsand0rHow does Akka help us achieve resilience?
Skynet
actor
T1000
actor
TooManyHolesException
X
Fresh
restart
try {
walk();
} catch (OutOfLegsException e) {
}
legsAvailable = false;
pullWithArms();
T800
instance
walk();

16. @ticofab
@adamsand0r
Kubernetes and its significance

17. @ticofab
@adamsand0rWhat is Kubernetes?
11.8.2.12
11.8.2.4
11.8.2.1
11.8.2.7
11.8.2.6 11.8.2.5
11.8.2.8
11.8.2.3
11.8.2.2
11.8.2.10
11.8.2.11
VM VM VMVM

18. @ticofab
@adamsand0rK8s creates nodes and helps form cluster
JVM JVM
pod-1 pod-2 pod-3 pod-4
vm-1 vm-2
Actor Actor ActorActor Actor ActorActors
JVM
Akka Cluster node
Pods
VM
Kubernetes node
JVMJVM

19. @ticofab
@adamsand0rLots of cloud providers
Google Kubernetes Engine
GKE
Azure Kubernetes Service
AKS
Elastic Container
Service for Kubernetes
EKS
( )

20. @ticofab
@adamsand0r
Can Kubernetes make an
application reactive?
Question 1

21. 11.8.2.12
11.8.2.4
11.8.2.1
11.8.2.7
11.8.2.6 11.8.2.5
11.8.2.8
11.8.2.3
11.8.2.2
11.8.2.9
11.8.2.10
11.8.2.11
UI 11.8.2.22
backend
11.8.2.23
processing
11.8.2.24
Does Kubernetes help us achieve elasticity?

22. 11.8.2.12
11.8.2.4
11.8.2.1
11.8.2.7
11.8.2.6
11.8.2.8
11.8.2.3
11.8.2.2
11.8.2.9
11.8.2.10
11.8.2.11
UI 11.8.2.22
backend
11.8.2.23
processing
11.8.2.24
Does Kubernetes help us achieve resilience?
11.8.2.5
11.8.2.18

23. @ticofab
@adamsand0r
What value does Akka Cluster
provide on top of Kubernetes?
Question 2

24. Fabio’s first journey in the Reactive World (2013)

25. @ticofab
@adamsand0rDevice matching use case (1)

26. @ticofab
@adamsand0rDevice matching use case (2)

27. @ticofab
@adamsand0rDevice matching use case (3)

28. @ticofab
@adamsand0rEngine requirements
🔄 Allow a FAST bi-directional channel between paired devices
👥 Manage many devices concurrently
📱 Hold state for each device (location, matched devices..)
21

29. @ticofab
@adamsand0rStateless Microservice Architecture
Phone
1
Phone
Service
instance 1
Websocket
Listener
1
2
3
Phone
Service
instance 2
Phone
Service
instance 3
Phone
3

30. @ticofab
@adamsand0rActor-based architecture (single node)
WS
Listener
Phone
Manager
1
Phone 1
Phone 2
Phone 3
2
3
match 3 match 1
New phone
connected!
New phone
connected!
Do you match
with phone 2 ?
Do you match
with phone 3 ? Do you match
with phone 3 ?
New phone
connected!
You matched
with me!

31. @ticofab
@adamsand0rActor-based architecture (multi node)
WS
Listener
Phone
Manager
Phone 1
Phone 2
Phone 3
1
6
3
Phone
Manager
Phone 4
Phone 5
Phone 6
Phone
Manager
Phone 7
Phone 8
Phone 9
9
match 9
You matched
with me!
match 6

32. @ticofab
@adamsand0r
Phone service
instance 2
Phone service
instance 1
Stateful Microservice Architecture
Gateway service instance Actor messaging
Phone
1
Phone
3
1
2
3
Akka Cluster

33. @ticofab
@adamsand0rDistributed workload
Worker 1
Master
Worker 2
Worker N
….
Master

34. @ticofab
@adamsand0rDistributed workload
Akka Cluster
Deployment
Deployment
• Less performance (HTTP)
• Multiple technologies
• High performance (actor msg)
• Actor programming model
• Mono-technology
Worker 1 (pod)
Master
(pod) Worker 2 (pod)
Worker N (pod)
….
Deployment
Deployment
Worker 1 (pod)
Master
(pod) Worker 2 (pod)
Worker N (pod)
….
Service
Master
(pod)
Master
(pod)

35. @ticofab
@adamsand0r
Is Akka Cluster suitable for a
microservice architecture?
Question 3

36. @ticofab
@adamsand0rConfusion
https://doc.akka.io/docs/akka/current/cluster-usage.html
https://tech.iheart.com/why-we-picked-akka-cluster-as-
our-microservice-framework-bbf3019a3217
iHeart blog post, 2016
Akka docs, summer 2018

37. @ticofab
@adamsand0r

38. @ticofab
@adamsand0r
Actor
in Akka Cluster
Microservice
on Kubernetes
Location transparency ✅ ✅
Resilience ✅ ✅
Scalability ✅ ✅
Independently deployable ❌ ✅

39. @ticofab
@adamsand0rOne codebase - One cluster
Device
1
1
2
3 WS
GW
Device
3
Device
2
Device
4
Phone Service Instance 1 (pod)
Phone
1
WS
Gateway
Phone
3
Phone
2
Phone
4
Phone Service Instance 2 (pod)
Phone
5
WS
Gateway
Phone
7
Phone
6
Phone
8
Akka Cluster

40. @ticofab
@adamsand0rSeparate codebase - One cluster
1
2
3
Actor
Messaging
WS GW
Instance 2 (pod)
WS
Gateway
WS GW
Instance 1 (pod)
WS
Gateway
Phone Service Instance 1 (pod)
Phone
1
Phone
3
Phone
2
Phone
4
Phone Service Instance 2 (pod)
Phone
5
Phone
7
Phone
6
Phone
8
Akka Cluster

41. @ticofab
@adamsand0rSeparate codebase - Separate clusters
Actor
Messaging
Phone Service Instance 1 (pod)
Phone
1
Phone
3
Phone
2
Phone
4
Akka Cluster
Phone Service Instance 2 (pod)
Phone
5
Phone
7
Phone
6
Phone
8
WS GW
Instance 1 (pod)
WS
Gateway
WS GW
Instance 1 (pod)
WS
Gateway
Akka Cluster
Actor
Messaging
HTTP /
event queue
HTTP /
event queue
1
2
3

42. @ticofab
@adamsand0r
How can Akka Cluster and
Kubernetes work together?
Question 4

43. @ticofab
@adamsand0r
K8S
API
K8s creates nodes and helps form cluster
11.8.2.1
Node 3
cluster: mycluster
11.8.2.6
Node 2
cluster: mycluster
11.8.3.2
Node 4
cluster: mycluster
Node 1
cluster: mycluster
11.8.3.3

44. @ticofab
@adamsand0rCluster on top of cluster
?BOTH

45. @ticofab
@adamsand0r
Pod 1
Deployment
Controller
Pod 2
Resilience at different levels
Actor 2
Supervisor
Actor 1
Restart
💀
👀
Restart
💀
👀

46. @ticofab
@adamsand0rScale of resilience
JVM Exceptions JVM Errors Hardware failure
Skynet attack
Meteorite hits
Akka
Actors{ } Kubernetes[ ]Akka
Cluster{ }

47. @ticofab
@adamsand0rLocation transparency at different levels
VM 1
VM 2
No need to know VM IP address
Actor 2Actor 1
Pod 2
Pod 1
Pod 3

48. @ticofab
@adamsand0rConclusions
Kubernetes is a great
infrastructure choice for your
clustered application
⚙
It provides location
transparency with cluster
formation
🖇
It introduces resilience at
an infrastructure level
+
Akka has a great
programming model, ready
to scale up from day 1
📬
Akka Cluster enables direct
communication between
stateful services
📟
And resilience is
built in your service
.

49. @ticofab
@adamsand0rConclusion
Akka & Kubernetes together give you superpowers.
Superman is a ™ of DC Comics

50. @ticofab
@adamsand0rReferences
Jonas Bonér: Reactive Microservices Architecture (O'Reilly)
Sam Newman: Building Microservices (O’Reilly)
Jamie Allen, “Reactive is a Product”, React Sphere 2018
Akka docs (https://goo.gl/MJ1o41)
iHeart blog post (https://goo.gl/h2eN7X)
Wade Waldron, Cognitive Class, Introduction to Reactive Systems

51. Q&A
Thanks!
@ticofab
@adamsand0r

52. @ticofab
@adamsand0rDevice matching use case (4) - 2018
😓

53. • Watch the video and see where we can shorten (50 min is too long)
• Add a couple of cases where Akka Cluster can be superseded by K8S
(like if you need distributed working with stateless services).
• See if we can have an equal amount of speaking time and maybe
rebalance
• Add more jokes
• Microservices architecture from Neal Ford slides
• Add 3d-thing “cluster on top of cluster”
• Remove the solar system
• Remove one of the CloudMatch videos
•