Services in one project connect over an internal network. No ports open to the internet, and internal traffic is not billed.
Why it matters
Services within a project can access each other. Services from other projects cannot, automatic isolation.
Services reach each other by service name on internal DNS, not through public internet addresses.
Internal traffic is not charged bandwidth costs. Save money on high-traffic applications.
Use service names as hostnames. No need to hardcode IP addresses.
Steps
Create services within the same project, backend, database, cache, etc.
Connect services using service names as hostnames (e.g., mongodb:27017).
Database and cache services don't need exposed ports to the internet. More secure and efficient.
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