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What is Micro service Architecture?

"Loosely coupled service oriented architecture with bounded context"

Micro-services with Spring Cloud Release march 2015

Why are popular?

  • Desire for faster changes
  • Need for greater availability - less time to recover
  • Motivation for fine grained scaling (scale service wise), while in Monolothic - scale DB, message tier, Application tier
  • Compatible with a DevOps mindset

Characteristics?

  • Components exposed as services
  • Tied to a specific domain
  • Loosely coupled
  • Built to tolerate failure
  • Delivered continuously via automation
  • Built an run by independent services

Frequent Questions:

  1. Should every application be turned into a set of micro-services?
  • NO
  1. How do I find my service if URIs can change?
  • Service catalogue is the answer - Eureka server
  1. How am I supposed to ship changes continuously?
  • As services are independent of each other, easy to ship changes continuously
  1. How do services maintain consistent configurations at scale?
  • cloud configurations
  1. Is there a single Technology stack for these systems?
  • No, there are multiple opinions available and you can choose according to your requirement
  1. How do I keep a poor-performing service form taking everything down
  • circuit breaker, ZipKin Spring cloud sleuth
  1. What is the right way to secure services
  • Spring cloud security
  1. How do I troubleshoot problems
  • Sleuth
  1. Is not Monolith simpler
  • Depend on the case to case.

Boot:

  • opinionated runtime for Spring

  • Convention not configurations

  • "Opinions can be overridden"

  • Handles Boilerplate set-up

  • simple dependency management

  • Embeds application server in executable jar

  • Built in endpoints for health metrics - Actuator framework

  • spring.io -> start.spring.io - spring InitialiZr -> STS

Application we will develop Toll station

  1. First part Toll station systems | | Toll Rate service | | Config server ---> Git server

  2. Second Part Internal Web Application

A. Toll Process Job B. Toll Usage Service(Secured) C. Driver Profile Service ---create graph | | | | | | Task Processor ---> Task history AuthZ Server Zipkin Server ---> Message Bus

Goals:

  • Understand modern micro-services pattern
  • Get comfortable starting Spring boot and cloud projects
  • Explore core capabilities of spring cloud
  • learn how to configure and extend spring cloud

Overview:

  • Role of configuration in micro-services
  • problems with status quo
  • Creating a config server
  • Consuming configurations in application

Role of configuration in micro-services

  • Removing 'settings' from compiled code
  • Change runtime behaviours
  • Enforce consistency across elastic services
  • Cache values to reduce load on databases

Problems with status quo (current/existing solutions)

  • Local config files fall out of sync
  • No history of changes with env variables
  • Configuration changes require restart
  • Challenges with sensitive information
  • Inconsistent usage aross team

Spring Cloud Config:

  • Http Access to git or file based configurations

Creating config server:

  • Choose a config store
  • Add config files
  • build the spring projects
  • secure the configurations

Setting up config files:

  • Native support for YML, Property files
  • Can serve out any text file
  • File name contain app, optionally profile
  • Nested folders supported
  • All Matching files returned

Creating config server: Spring boot projects

  1. use start.spring.io/STS to generate scaffolding
  2. See POM dependency on "spring-cloud-config-server" and "spring-boot-starter-actuator"
  3. Add @EnableConfigServer annotation to class
  4. Create Application property (or .yml file) with server port, app name and profile

Create Spring starter projects

  • Annotate the main class with @EnableConfigServer annotation
  • set application properties - default path is resources/config can be configured to something else as well
  • add local configuration files - to folder resources/config app1.properties, app2.properties, app3.properties
  • Run as spring boot application
  • Query for configurations : localhost:8888/app1/default, localhost:8888/app2/default, localhost:8888/app3/default

creating the config server : application.yml spring: cloud: config: server: encrypt: enabled: false git: uri: https://github.com/girirajvyas/spring-cloudconfig-pune-tolls : Point to Git Location search-paths: - 'station*' : pattern to search sun directories repos: : points to alternate repos perf: pattern: - "/perf" : pattern to go to alternate repo uri: https://github.com/girirajvyas/spring-cloudconfig-pune-tolls-perfs search-paths: - 'station'

creating the config server: Endpoints
https://github.com/girirajvyas/spring-cloudconfig-pune-tolls / {application} / {profile} / [/label] branch:master required required optional | |-application.properties - default (always returned) | |-station1
| - s1rates-dev.properties - exact match for dev profile | - s1rates-qa.properties | - s1rates.properties - default for app name s1rates |-station2
- s2rates-dev.properties - s2rates.properties - default for app name s2rates

{application} - name of application spring.application.name value or spring cloud config name value spring.cloud.config.name or spring.application.name {profile} - spring profile (default,dev, qa) spring.cloud.config.env {label} - version marker in config source, it could be branch name tag name or even git commit hash spring.cloud.config.label or config sevrers default label

Examples Appname - s1rates /s1rates/default - application.properties, s1rates.properties /s1rates/dev - application.properties, s1rates.properties, s1rates-dev.properties (in case same property is available in all 3 files, -dev 1 would take precedence) /s2rates/qa - application.properties, s2rates.properties /s3rates/default - application.properties

Demo:

  • create github repo with files
  • Create a spring starter projects
  • Annotate the main class
  • set git url in application YAML
  • Run as spring boot
  • Experiment with search paths

Test:

  • localhost:8888/s1rates/default
  • localhost:8888/s1rates/perf - to fetch data from alternate repository
  • localhost:8888/s1rates.json/.yml/.properties

Consuming Configurations

  • Spring Apps use Config servers as a property source
  • Loads values based on a. app name, b. Spring profile, c. Label
  • Annotate code with @Value attributes
  • Can consume form non-spring apps via URL

Demo:

  • Create spring starter projects
  • Add application and bootstrap files
  • Create controller with annotations
  • Return values derived from properties
  • Experiment with different name, profiles