How to send data to corresponding region's instance server? - load-balancing

Question

Let's say I have three regions(eu,us,asia) that host the same app on the respective instance. I will register only one domain name for those same apps.
When a user requests from eu , I like to send data to eu region app server and vice versa.
Eg: user -> request -> example.com (from eu) -> send data to eu app
Eg: user -> request -> example.com (from us) -> send data to us app
Eg: user -> request -> example.com (from asia) -> send data to asia app
Can I set up like that by Load Balancer or something else?

Answer 1

Yes, you can do this with OCI DNS and traffic management via geolocation traffic steering policies. The steering policy should filter or prioritize DNS answers based on a query's continent geokey.
Example of a POST /steeringPolicies request body using the ROUTE_BY_GEO template:
{
"compartmentId": "ocid1...",
"displayName": "Geolocations mapped to answer pools",
"ttl": 30,
"healthCheckMonitorId": "ocid1...",
"template": "ROUTE_BY_GEO",
"answers": [
{
"name": "US Server 1",
"rtype": "A",
"rdata": "192.168.0.2",
"pool": "US"
},
{
"name": "US Server 2",
"rtype": "A",
"rdata": "192.168.0.3",
"pool": "US"
},
{
"name": "EU Server 1",
"rtype": "A",
"rdata": "192.168.0.4",
"pool": "EU"
},
{
"name": "EU Server 2",
"rtype": "A",
"rdata": "192.168.0.5",
"pool": "EU"
},
{
"name": "rest of world 1",
"rtype": "A",
"rdata": "203.0.113.2",
"pool": "Global"
},
{
"name": "rest of world 2",
"rtype": "A",
"rdata": "203.0.113.3",
"pool": "Global"
}
],
"rules": [
{
"ruleType": "FILTER",
"defaultAnswerData": [
{
"answerCondition": "answer.isDisabled != true",
"shouldKeep": true
}
]
},
{
"ruleType": "HEALTH"
},
{
"ruleType": "PRIORITY",
"cases": [
{
"caseCondition": "query.client.geoKey in (geoKey '6255149')",
"answerData": [
{
"answerCondition": "answer.pool == 'US'",
"value": 1
},
{
"answerCondition": "answer.pool == 'EU'",
"value": 2
},
{
"answerCondition": "answer.pool == 'Global'",
"value": 3
}
]
},
{
"caseCondition": "query.client.geokey in (geokey '6255148')",
"answerData": [
{
"answerCondition": "answer.pool == 'EU'",
"value": 1
},
{
"answerCondition": "answer.pool == 'US'",
"value": 2
},
{
"answerCondition": "answer.pool == 'Global'",
"value": 3
}
]
},
{
"answerData": [
{
"answerCondition": "answer.pool == 'Global'",
"value": 1
},
{
"answerCondition": "answer.pool == 'US'",
"value": 2
},
{
"answerCondition": "answer.pool == 'EU'",
"value": 3
}
]
}
]
},
{
"ruleType": "LIMIT",
"defaultCount": 1
}
]
}
-- Traffic Management Steering Policies API Guide, Create Steering Policies Using Templates