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Example use case of using Consul KV to retrieve Configuration values to have a stateless micro service.

Python based:

• • Consul agent running at <consul_ip>.
  • Django based micro service.
  • Manage DB configuration in settings.py of the micro service.

Steps:

Add database configuration key values to Consul:

curl -X PUT -d 'django.db.backends.mysql' http://<consul_ip>:8500/v1/kv/<service_name>/database/engine
curl -X PUT -d '<DB_NAME>' http://<consul_ip>:8500/v1/kv/<service_name>/database/name
curl -X PUT -d '<DB_IP>' http://<consul_ip>:8500/v1/kv/<service_name>/database/ip
curl -X PUT -d 3306 http://<consul_ip>8500/v1/kv/<service_name>/database/port
curl -X PUT -d '<DB_USERNAME>' http://<consul_ip>:8500/v1/kv/<service_name>/database/username
curl -X PUT -d '<DB_PASSWORD>' http://<consul_ip>:8500/v1/kv/<service_name>/database/password

In settings.py of Django, retrieve the DB configuration values as:

import envconsul

ENV_CONSUL = envconsul.EnvConsul(
 service_name='<service_name>',
 host='<consul_ip>',
 port=8500,
)

DB_ENGINE = ENV_CONSUL.get_str('/database/engine')
DB_NAME = ENV_CONSUL.get_str('/database/name')
DB_IP = ENV_CONSUL.get_str('/database/ip')
DB_PORT = ENV_CONSUL.get('/database/port')
DB_USERNAME = ENV_CONSUL.get_str('/database/username')
DB_PASSWORD = ENV_CONSUL.get_str('/database/password')

# Use the values obtained from Consul in DATABASES config of Django.

DATABASES = {
 'default': {
 'ENGINE': DB_ENGINE,
 'NAME': DB_NAME,
 'HOST': DB_IP,
 'PORT': DB_PORT,
 'USER': DB_USERNAME,
 'PASSWORD': DB_PASSWORD,
 },
}

This way, DB configuration can easily be passed to all the micro services.

...

2.  

Example show is using python-envconsul to fetch KVs. Need to use better library such as python-consul which provides capabilities to fetch KV as notifications whenever there are changes in the values. 

Java based:

<TODO>