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Debugging Microservices with Telepresence:
Local-to-Remote "Hot Reload"
Daniel Bryant

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@danielbryantuk
tl;dr
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• The inner development loop can be painful with microservices & Kubernetes
• Telepresence “proxies” your local machine into the cluster, increasing fast feedback
• Telepresence supports several workflows, from small to large systems
• Please support this CNCF project — get involved!

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@danielbryantuk
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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
Inner and outer loop 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
9 And you want to use your own tools.

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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
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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
Preview URLs, Personal Intercepts
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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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The Good, the Bad, and the
“Don’t Try this at Home”
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@danielbryantuk
Benefits
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• Use any tool that runs on your laptop: IDE, profiler, debugger, …
• Connect to cloud-based resources
• Same network namespace (e.g., nslookup works)
• Very fast inner loop!

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@danielbryantuk
Requirements
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• Network connection
• kubectl access to cluster
• Mac, Linux, or WSL2

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@danielbryantuk
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@danielbryantuk
tl;dr
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• Capturing DNS and routing selectively to the
cluster is tricky
• Maintaining proxy connections can be
challenging
• Kubernetes has many resource types
• No two laptops are alike
• No two clusters are alike
• And more

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@danielbryantuk
Telepresence is a CNCF project, with a wide variety of users
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Workflows
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@danielbryantuk
Simple Workflow (YOLO)
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• One (production) cluster for single-source-of-truth microservices
• Developer checks out code and works on microservices
• Intercepts services on demand using Telepresence + IDE
• Once code is done, microservices are built and deployed via pipeline
Testing in production can be… scary (and personal intercepts help a lot!)

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@danielbryantuk
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@danielbryantuk
Typical Workflow (SME)
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• One shared (dev) cluster for single-source-of-truth microservices
• Developers check out one of the microservices (and coordinate with other devs)
• Watch for coupled service/API evolution
• Take care with mutating shared state
• Developers intercept and work on services via Telepresence + IDE
• Pipeline is used to run tests, build, and deploy to staging and prod
https://www.youtube.com/watch?v=75soljoqhjY

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@danielbryantuk
Advanced Workflow
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• One cluster with multiple namespaces for all single-source-of-truth microservices
• Developers check out one of the microservices
• Developers use Bazel + Telepresence + IDE
• Telepresence (1) is used in container mode with Bazel images
• Once code is done, Jenkins is used to run tests, build, and deploy
https://www.youtube.com/watch?v=tD0FIlxO1AQ

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Wrapping up
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@danielbryantuk
Conclusion
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• The inner development loop can be painful with microservices & Kubernetes
• Telepresence “proxies” your local dev machine into the cluster, increasing fast feedback
• Telepresence supports several workflows, from small to large systems
• Please support this CNCF project — get involved!

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@danielbryantuk
Contributing to Telepresence
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• Documentation and workflows
• Explain how you integrate Telepresence into your development workflow
• Let us know if you’re a user!
• Triage
• Lots of folks use GitHub for support, which doesn’t scale well
• Join Slack to help other users https://a8r.io/slack #telepresence

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@danielbryantuk
Thank you! Questions?
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Easy Debugging of Spring Boot Microservices
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ff
ice Hours
db@datawire.io / @danielbryantuk