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Configuration management

TL;DR: What are you going to learn in this chapter?

Important

This chapter covers the following topics:

  1. Pinpoint Configuration management issues due to API Versioning
  2. Exposing the two versions on the API Gateway

Preamble

You can configure your services either during deployment using CI tooling, such as Gitlab Environments, or any other Infra As Code tool (Istio, Ansible,...) or using a configuration server. For this workshop, all the configuration items will be provided by Spring Cloud Config.

We will illustrate in this chapter the impacts of versioning in the configuration management.

Here are the issues to fix in this chapter:

  • Specify a different port number for the new rest-book version
  • Specify a new version number on all the layers
  • Apply different parameters for the number of results of the /books API, timeout,...

Warning

Now you MUST stop all your Spring apps.

Configuration server version management

For this workshop, we will only carry out a simple version management based on Spring profiles.

Copy / paste the rest-book.yml to rest-book-v1.yml and rest-book-v2.yml.

In the latter, UPDATE the properties server.port and server.servet.context-path:

server:
  port: 8083
  servlet:
    context-path: /v2

You can also remove the book.find.limit property in the first version and modify the booknumbers.api.timeout_sec property in the second one.

Now, start your config server, RUN:

./gradlew clean bootRun -p config-server

Test it using these HTTP requests:

http :8888/rest-book/v1 --print b | jq ' .propertySources[0].source' | jq '."server.servlet.context-path"'

You MUST get this output:

    "/v1"

and

http :8888/rest-book/v2 --print b | jq ' .propertySources[0].source."server.servlet.context-path"'

You MUST get this output:

    "/v2"

Rest-book configuration management

First, UPDATE the application.properties files to specify the current profile:

In the V1:

spring.profiles.active=v1

And in the V2:

spring.profiles.active=v2

OpenAPI

CHECK the rest-book v1 OpenAPI description file to specify the new version:

openapi: 3.0.0
info:
  title: OpenAPI definition
  version: "v1"
servers:
  - url: http://localhost:8082/v1

UPDATE the rest-book v2 OpenAPI description file to specify the new version:

openapi: 3.0.0
info:
  title: OpenAPI definition
  version: "v2"
servers:
  - url: http://localhost:8083/v2

Test it

First, stop the config server, and build the whole application:

./gradlew clean build

The build MUST be successful.

Start your backends (we assume your Docker infrastructure is still up).

In the first shell, RUN:

./gradlew bootRun -p config-server

In the second shell, RUN:

./gradlew bootRun -p rest-book-2

In the third shell, RUN:

./gradlew bootRun -p rest-book

In the fourth shell, RUN:

./gradlew bootRun -p rest-number

Now, reach your APIs (without using the gateway):

RUN for the V1:

http :8082/v1/books

and the V2, RUN:

http :8083/v2/books

Rest-number

This service doesn't really need to be versioned now. To put in place the whole infrastructure and the same behaviour of rest-book module, we will apply the same configuration:

./gradlew bootRun -p config-server

spring.profiles.active=v1
  • RUN then the rest-number module:
./gradlew bootRun -p rest-number

Gateway configuration

Now, we will expose both versions in the gateway.

UPDATE the gateway configuration file, adding the following content:

        # HTTP HEADER VERSIONING
        - id: rewrite_v2
          uri: http://127.0.0.1:8083
          predicates:
            - Path=/books/{segment}
            - Header=X-API-VERSION, v2
          filters:
            - RewritePath=/books/(?<segment>.*),/v2/books/$\{segment}
        - id: rewrite_v2
          uri: http://127.0.0.1:8083
          predicates:
            - Path=/books
            - Header=X-API-VERSION, v2
          filters:
            - RewritePath=/books,/v2/books
        - id: rewrite_v2
          uri: http://127.0.0.1:8081
          predicates:
            - Path=/isbns
            - Header=X-API-VERSION, v2
          filters:
            - RewritePath=/isbns,/v1/isbns
        # HTTP ACCEPT MEDIA TYPE HEADER VERSIONING
        - id: rewrite_accept_v2
          uri: http://127.0.0.1:8083
          predicates:
            - Path=/books
            - Header=accept, application/vnd.api\.v2\+json
          filters:
            - RewritePath=/books,/v2/books
        - id: rewrite_accept_v2
          uri: http://127.0.0.1:8083
          predicates:
            - Path=/books/{segment}
            - Header=accept, application/vnd.api\.v2\+json
          filters:
            - RewritePath=/books/(?<segment>.*),/v2/books/$\{segment}
        - id: rewrite_accept_v2
          uri: http://127.0.0.1:8081
          predicates:
            - Path=/isbns
            - Header=accept, application/vnd.api\.v2\+json
          filters:
            - RewritePath=/isbns,/v1/isbns
        # URI PATH VERSIONING
        - id: path_route
          uri: http://127.0.0.1:8083
          predicates:
            - Path=/v2/books
        - id: path_route
          uri: http://127.0.0.1:8083
          predicates:
            - Path=/v2/books/{segment}
        - id: path_route
          uri: http://127.0.0.1:8081
          predicates:
            - Path=/v2/isbns
          filters:
            - RewritePath=/v2/isbns,/v1/isbns

To propose a cohesive and coherent API to our customer, we chose to publish all our API endpoints with a v1 and v2 prefix. Although rest-number only provides ONE version (i.e., the v1), we will expose both on the gateway.

UPDATE the configuration file adding this configuration:

        - id: path_route
          uri: http://127.0.0.1:8081
          predicates:
            - Path=/v2/isbns
          filters:
            - RewritePath=/v2/isbns,/v1/isbns

Test it

Restart your gateway and test it:

./gradlew clean bootRun -p gateway

You can now use the scripts files. For every script (e.g., countBooks.sh), you have one which reach the V2 endpoints (e.g., countBooks-v2.sh)

Here is an example for the countBooks.sh script file copied to countBooks-v2.sh.

http :8080/v2/books/count

This action is voluntary simple. Feel free to add an argument to the existing script files if you want ;-).

Note

In this chapter, we have seen one part of the impacts of API versioning in configuration management. The most important part is done before, both in the GIT configuration and the release management.

Go then to chapter 5