What is service discovery?

• A key problem in deployment is getting services to be able to find each-other

• A database might be at 10.1.1.1:6543 while the webserver is at 10.1.1.2:8080

Level 1 Service Descovery: Baiscs

• Everything is manually configured

You'll know you should start caring about service discovery when you start seeing one of the following:

1. You want "zero downtime deployments" or to use other, more complex deploy strategies

2. You have more than a couple of microservices

3. You are deploying to several environments (dev, staging, prod) and it's getting unwieldy

Lever 2: Service Discovery via hash table

• A straightforward approach: Store the service IPs in a hash table

• The hash table in question in the config is here:

In simple term:

• All you need to do is update your frontend to set the keys in the hash table to be the forntend's IP

• Then make the backend do the same for the backend

Problems with this approach

• It's complex

• It's error prone

• It requires to write custom config files

Level 3 Service Discovery via DNS

• The idea for DNS is just to map hostnames to IPs. This is the industry standard

• It would be ideal if we could connect to "http://frontend" from our reverse proxy and having DNS respond with the IP for the correct versions of the frontend

• So instead of the first example where you use the IP

• You would use mongo where mongo is a key in the key:value pairs