FIELD NOTE · E8 · Com2us Platform · Feb 2023 – Feb 2026

Moving a live game between clouds without stopping it

80 servers, 20 databases, about one week, zero downtime

1 Week · 0 Downtime · 80 Servers / 20 DBs

In one line: Moved the GCP infrastructure of Summoners War: Chronicles (80 servers, 20 databases) to Tencent Cloud in about one week with zero downtime.
Highlights: Decided to move firewalls before servers
Migration tool plus private validation
The entire migration captured in Terraform code
Tech: GCP · Tencent Cloud · Migration · Terraform

Below the islands, the code: gcp.tf → tencentcloud.tf

Problem: A live service on GCP (80 servers, 20 databases) had to move to Tencent Cloud. Downtime was not acceptable.
Judgment: The biggest risk was security policy going missing or changing during the move. So I moved the network and firewall first, before any server.
What I did: Firewall rules were built on Tencent Cloud to match GCP first, then servers moved with Online Migration. Before cutover, the dev team and I checked for issues in private validation.
Result: After validation the service was cut over. The migration finished in about one week with zero downtime.
What I learned: When you move clouds, make the security standard move with you. The migration also stayed in Terraform code, which made later operations and changes easier.

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