This document presents an overview of application configuration in Kubernetes, specifically focusing on the Spring framework and Spring Cloud Config Server. It discusses various challenges in managing configurations across applications, proposing a solution through centralized management that combines git-backed configmaps and secrets. The presentation emphasizes the importance of versioning, auditing, and integrating different configuration management approaches within cloud-native environments.

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Modern Application
Configuration in
Kubernetes
Craig Walls
Engineer, VMware Tanzu
September 1, 2021

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This presentation may contain product features or functionality that are
currently under development.
This overview of new technology represents no commitment from
VMware to deliver these features in any generally available product.
Features are subject to change, and must not be included in contracts,
purchase orders, or sales agreements of any kind.
Technical feasibility and market demand will affect final delivery.
Pricing and packaging for any new features/functionality/technology
discussed or presented, have not been determined.
The information in this presentation is for informational purposes only
and may not be incorporated into any contract. There is no commitment
or obligation to deliver any items presented herein.
Disclaimer

3. ©2021 VMware, Inc.
Live in Colorado
Enjoy board games and all things Disney
Author of Spring in Action and Spring Boot in Action
(and also Build Talking Apps for Alexa)
Member of Spring Engineering Team
Developer Spring Cloud Services &
Application Configuration Service on Kubernetes
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About me…

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Let’s talk about configuration…

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How do you configure your Spring apps?
application.yml application.properties
Environment
Variables
JVM System
Properties
Command Line Args?
!

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How do you configure your Spring apps?
!

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The Spring Environment abstraction

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Captures properties from multiple sources…

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…Avails them for property placeholders
e.g., ${someProperty}

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…And Spring Boot Config Props
e.g., @ConfigurationProperties-annotated classes

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However…

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application.properties / application.yml
is packaged into deployment artifact

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(But it could be in the filesystem)

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Difficult to manage across multiple apps/instances
"

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Difficult to audit
"

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Environment variables tricky to manage
"

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Also tricky to audit
"

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Command line arguments and JVM system properties
Not practical as a main configuration source
#

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Spring Environment abstraction is extensible
$

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What if config came from somewhere central?
!

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Spring Cloud Config Server

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Configuration can be managed in Git…
(and Vault, CredHub, DB, S3, etc)
$

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…and served via REST
$

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Configuration can be versioned
$

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Configuration can be rolled back
$

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Configuration can be audited
(e.g., git log and git blame)
$

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Applications just need to read from Config Server…
"

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…and somehow merge configuration into Environment
"

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Spring Cloud Config Server client library

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Problem solved!

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But wait…

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What about non-Spring or non-Java apps?
(Let’s not talk about that right now…)
!

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Then came Kubernetes
%

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Spring Cloud Config Server runs fine in K8s
$

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Applications running in K8s can still
be Config Server Clients
$

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But wait…

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What about non-Spring or non-Java apps?
(I said…Let’s not talk about that right now…)
!

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The configuration
elephant in the K8s
room

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What about ConfigMaps?
(Okay…I guess we should talk about that)
!

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ConfigMaps are K8s resources

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…hold configuration data

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Can be consumed as env vars…or…

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…mounted as files in the pod’s filesystem

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Secrets are also K8s resources
&

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Secrets are like ConfigMaps
(just more secret)

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Do not require any special client library
$

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Work with any K8s workload…Spring, Java, or otherwise
$

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Problem solved!

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But wait…

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Spring Cloud Config Server != ConfigMaps/Secrets

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Spring Cloud Config Server
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K8s ConfigMaps and Secrets
Central-management of properties
Can be versioned
Can be audited
HTTP-based property consumption
Probably should be secured
Requires client-side library or code
Doesn’t require special client code
K8s-native
Not centrally managed
Versioning/auditing not built-in
Can leverage K8s-native security

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WHAT IF…?

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…we bring them together?

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Application Configuration Service for VMware Tanzu

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Git-backed ConfigMaps and Secrets!
$

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Same Git-hosted properties
$

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Written to ConfigMaps and/or Secrets

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Best of both worlds!
'

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Problem solved!

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How does it work?

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Configuration Source
(defines where configuration lives)

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Configuration Slice
(defines the desired configuration subset )

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Source + Slice = ConfigMap/Secret

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Let’s see it in action…
(

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Azure Spring Cloud Enterprise Tier w/VMware Tanzu

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Cloud-Native, Spring, and K8s
•Next-Generation Cloud Native Apps with Spring Cloud and
Kubernetes
•Application Modernization: Migrating Mainframe Apps to the
Cloud Using Spring
Azure Spring Cloud
•Rapid Development with Azure Spring Cloud
•Enable Authentication and Authorization with Azure Active
Directory and Spring Security
•Accelerate Spring Apps to Cloud at Scale—Discussion with Azure
Spring Cloud Customers
You may also be interested in…

67. Thank You
©2021 VMware, Inc.
See you in the Q&A session!