Externalized configuration Pattern in Node.js

Examples of how to manage external configurations in a microservice scenario, here are some ways on how to do it. I'm following the spec from this doc. https://microservices.io/patterns/externalized-configuration.html

There are differents situations of external configuration scenarios:

• From a S3 bucket
• From a Api-rest
• From a git repository
• From AWS parameter store

Benefits:

• Hot configuration changes.

Change hot settings.

Some interesting benefits of this patter is that, you can make changes in the config, without redeploy the services. In the projects there are a file ./configChange.js with a mechanism to detect changes in configuration and reset the services, to apply this new changes. So is important to run the script using a process agent example nodemon or pm2 to detect when the process finish and restart it.

From a S3 bucket.

In this scenario I use a S3 bucket to get the configuration when the server start. There are two mock service loan and payments, and there are a config folder in each service with only the s3 bucket path.

Link: https://github.com/damiancipolat/externalized_configuration_nodejs/tree/master/s3-external-config

Architecture diagram

Many instances of differents services fetching the config from the s3 files.

The services retrieves config from json files stored in a s3 bucket.

loanService.json

{
    "port":"8080",
    "base":{
        "dollars":10,
        "ars":30,
        "eur":50
    }
}

paymentService.json

{
    "port":"8080",
    "base":{
        "dollars":10,
        "ars":30,
        "eur":50
    }
}

Install and run:

cd paymentService
npm install
cd ..

cd loanService
npm install
cd ..

From a configuration service.

In this scenario there is a service that work as a exclusive api rest for configuration. I'm using https://www.mocky.io/ to mock an api-rest.

Link: https://github.com/damiancipolat/externalized_configuration_nodejs/tree/master/api-external-config

Install and run:

cd loanService
npm install
npm start

From a GITHUB repository.

In this scenario we extract the configurations from a github central configuration "file" so is very easy to make changes in this configurations. To make this the service use the GITHUB-API to can fetch the file, in the config/default.json there are the github credentials.

The service use this the file https://github.com/damiancipolat/externalized_configuration_nodejs/tree/master/git-external-config/loanService/config, only for a example purpose I'm using the same repo, but in a production scenario is better to use a configuration repository for the services.

Link: https://github.com/damiancipolat/externalized_configuration_nodejs/tree/master/git-external-config

How to get the Github api token, go to this link: https://help.github.com/en/github/authenticating-to-github/creating-a-personal-access-token-for-the-command-line#creating-a-token

cd loanService
npm install
npm start

From a AWS Parameter Store.

In this scenario we extract the configurations from a aws parameter store service

Link: https://github.com/damiancipolat/externalized_configuration_nodejs/tree/master/aws-parameter-store-config/lambda