Description
Semantic versioning
How to authenticate using Istio and JWT
How to sync mongodb & elasticsearch (via mongodb change streams)
Kafka connector to elasticsearch

Description

User service provides endpoints to receive data related to users.

This microservice is connected with another microservice via service registry pattern. A key advantage of a microservices architecture is the ability to create new instances of each service to meet the current load, respond to failures and roll out upgrades. One side effect of this dynamic server-side environment is that IP address and port of a service instances change constantly. In order to route an API request to a particular service, the client or API gateway needs to find out the address of the service instance it should use. Whereas in the past it might have been feasible to record these locations in a config file, in a dynamic environment where instances are added and removed on the fly, an automated solution is needed. Service discovery provides a mechanism for keeping track of the available instances and distributing requests across them.

Circuite breaker pattern is also implemented there. Use of the Circuit Breaker pattern can allow a microservice to continue operating when a related service fails, preventing the failure from cascading and giving the failing service time to recover. You wrap a protected function call in a circuit breaker object, which monitors for failures. Once the failures reach a certain threshold, the circuit breaker trips, and all further calls to the circuit breaker return with an error, without the protected call being made at all.

Semantic versioning

Github action (docker.yml) creates tag via https://github.com/mathieudutour/github-tag-action and then docker image with this generated tag is pushed to dockerhub.
When deploying app to kubernetes set image version in ./src/infra/minikube.sh to TAG variable

How to authenticate using Istio and JWT

If you don't have private and public keys:

1. Set your data to payload variable in ./src/infra/istio/rsa-jwt-generator/generate-keys-and-tokens-using-python.py
2. To generate private & public keys and token run

python ./src/infra/istio/rsa-jwt-generator/generate-keys-and-tokens-using-python.py

3. Set issuer and generated public key to ./src/infra/istio/request-auth.yaml
4. Apply changed to kubernetes

kubectl apply -f ./src/infra/istio/request-auth.yaml

5. Add Authorization header to your request with Bearer <generated_token>

If you have private and public keys:

1. Set your private & public keys in ./src/infra/istio/rsa-jwt-generator/generate-token.py
2. To generate token run

python ./src/infra/istio/rsa-jwt-generator/generate-token.py

3. Set issuer and generated public key to ./src/infra/istio/request-auth.yaml
4. Apply changed to kubernetes

kubectl apply -f ./src/infra/istio/request-auth.yaml

5. Add Authorization header to your request with Bearer <generated_token>
   
   

How to sync mongodb & elasticsearch (via mongodb change streams)

Without docker:

1. Start mongodb replica set using ./docker-compose.yaml
   (To create replica set image created via ./src/infra/mongo-rs/Dockerfile is used)
2. Start elasticsearch using ./docker-compose.yaml
3. Add 127.0.0.1 mongodb line to the hosts file on your machine
4. Run npm instal in ./src/infra/mongodb-elasticsearch
5. Run node index.js in ./src/infra/mongodb-elasticsearch

Using docker:

1. Start mongodb replica set, elasticsearch and synchronizer using ./docker-compose.yaml
   

CAUTION: without docker set mongodb and elasticsearch domains as localhost, otherwise set their service names

Kafka connector to elasticsearch

1. Start kafka-connect container using ./docker-compose.yaml
   
2. Create kafka-connector by sending a POST request to http://localhost:8083/connectors url
   with body like in src/infra/kafka-connect-elastic/kafka-elastic-connector.json example
   (kafka topic and elasticsearch index will have the same name mentioned in topics field)
   Kafka connector also transforms some fields names (! kafka connector is unable to transform nested fields !)
3. Create mapping for elasticsearch by sending a PUT request to http://localhost:9200/syncmongoelastic url
   with body like in src/infra/kafka-connect-elastic/elastic-mapping.json example
   
4. Send messages to kafka

To list all connectors make a GET request to http://localhost:8083/connectors
To delete a connecter make a DELETE-request to http://localhost:8083/connectors/<connector-name>
To get connector status make a GET request to http://localhost:8083/connectors/<connector-name>/tasks/0/status

To get index mapping make a GET request to http://localhost:9200/<index-name>/_mapping

CAUTION: if you want to change your connector config (after you already created it),
you have to delete the existing one and create a new one with changed configs and !!! necessarily a new name !!!
(even if you have deleted kafka-connect container, new kafka-connector name is required!)