1.
Testing Java Microservices Apps without Cooking
Your Laptop: Using Docker & Telepresence
Daniel Bryant
@danielbryantuk

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@danielbryantuk
tl;dr
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• The inner dev/test loop can be painful with microservices & Kubernetes
• The pain increases as the number of services within your system increase
• You have options with +/- : mocks, service virtualisation, remocal tools
• Telepresence enables remote-to-local “remocal” development
• Choose your dev/test approach wisely!

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@danielbryantuk
3

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Setting the Scene
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@danielbryantuk
Inner and outer dev loops
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Hat tip to Mitch Denny (now 404): https://mitchdenny.com/the-inner-loop/
http://jorgemoral.es/posts/2020_03_17-develop_apps…

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@danielbryantuk
You are building microservices, right?
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@danielbryantuk
SOA: There’s just more stu
ff
(and dependencies)
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@danielbryantuk
So, let’s run everything locally…
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@danielbryantuk
tl;dr
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“My laptop only has 16GB
RAM and you’re asking it
to run Kubernetes and a
JVM and a database???”

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@danielbryantuk
Okay, let’s run everything remotely…
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@danielbryantuk
Inner and outer dev loops with K8s
can be the same
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• Write code
• Build container
• Push to registry
• Deploy to cluster
• Test
And can be …. SLOW.

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@danielbryantuk
Automation can help…
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@danielbryantuk
tl;dr
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But you want a really fast inner loop (no docker build/push) …

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@danielbryantuk
tl;dr
14 And you want to use your own tools.

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@danielbryantuk
tl;dr
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And you want to avoid the “works on my machine”
production vs local dev debacle

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Options and Tradeo
ff
s
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@danielbryantuk
What are your options?
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• Mocks
• Mockito, PowerMock(Ito), EasyMock, JMockit
• Service virtualisation
• TestContainers
• Hoverfly, WireMock
• Remocal tooling
• Telepresence
• Devspaces, Okteto

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@danielbryantuk
Mocks
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https://site.mockito.org/

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@danielbryantuk
Mocks
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• Good
• Idiomatic (familiar language constructs etc)
• Quick and cheap
• Can help build your mental model (TDD-like)
• Bad
• Implicit assumptions coded in (“the three realities conundrum”)
• Di
ff
icult to keep up to date and share/coordinate
• Needs a test runner

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@danielbryantuk
Service virtualisation
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https://livebook.manning.com/book/testing-java-microservices/chapter-9/47

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@danielbryantuk
Service virtualisation
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https://livebook.manning.com/book/testing-java-microservices/chapter-9/47

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@danielbryantuk
TestContainers
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@danielbryantuk
Service virtualisation
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• Good
• More realistic than mocks (can be the “real thing”, albeit resource constrained)
• Enables (wire-level) deterministic test of failure scenarios
• Easy to use large(r) amounts of data
• Bad
• Slower than mocks to initialise
• Can be tricky to configure
• Challenging to keep up to date and share (unless you use dedicated tooling/SaaS)

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@danielbryantuk
Remocal tooling
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@danielbryantuk
Remocal tooling
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• Good
• Enables testing against (and poking of) the real thing
• Data sets can be large scale (as resources can be scaled on remote cluster)
• No need to build mental model of dependency (both good and bad!)
• Bad
• Need a solid network connection
• Mutating remote shared state can be an issue
• Lack of language bindings

26.
@danielbryantuk
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@danielbryantuk
What is Telepresence
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• “Fancy Kubernetes VPN for development”
• “kubectl port-forward on steroids”
• “kubectl proxy all-the-things”
• A network bridge between your laptop and the Kubernetes cluster

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@danielbryantuk
Telepresence: Local-to-Remote bridge
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@danielbryantuk
Telepresence: Local-to-Remote bridge
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www.youtube.com/watch?v=W_a3aErN3NU

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Demo Time!
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@danielbryantuk
Telepresence: Local-to-Remote bridge
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telepresence connect
• Open a tunnel to the remote cluster; exposes “in-cluster” services/network/DNS
telepresence intercept my-service —port 3000
• Re-routes (intercepts) tra
ff
ic to my-service in the remote cluster to my local machine
telepresence login & telepresence intercept
• Create preview URL to isolate and share results of the intercept

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@danielbryantuk
Telepresence: Local-to-Remote bridge
$ telepresence intercept dataprocessingnodeservice --port 3000
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Using deployment dataprocessingnodeservice
intercepted
State : ACTIVE
Destination : 127.0.0.1:3000
Intercepting: HTTP requests that match all of:
header("x-telepresence-intercept-id") ~= regexp ("76a1e848-1829-74x-1138-e3294c1e9119:dataprocessingnodeservice")
Preview URL : https://[random-subdomain].preview.edgestack.me
www.youtube.com/watch?v=W_a3aErN3NU

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@danielbryantuk
Preview URLs, Personal Intercepts
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Docker Desktop Extension for Telepresence
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getambassador.io/testing-with-telepresence-and-docker

35.
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Wrapping up
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@danielbryantuk
What to use, when
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Mocks Service virtualization Remocal
Unit tests ✅
Integration tests ✅ ✅
Component tests ✅ ✅ ✅
End-to-end tests ✅ ✅
Poking around an
existing API
✅
Building an API ✅ ✅

38.
@danielbryantuk
Conclusion
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• The inner dev/test loop can be painful with microservices & Kubernetes
• The pain increases as the number of services within your system increase
• You have options with +/- : mocks, service virtualisation, remocal tools
• Telepresence enables remote-to-local “remocal” development
• Choose your dev/test approach wisely!

39.
@danielbryantuk
Thank you! Questions?
39
getambassador.io/products/telepresence
getambassador.io/testing-with-telepresence-and-docker
Easy Debugging of Spring Boot Microservices Running on
Kubernetes
AL Developer O
ff
ice Hours
db@datawire.io / @danielbryantuk