Infrastructure

Add a read replica

Copy a database server continuously to another one that serves reads, and promote it if the primary fails.

1. 1

   Create the replica server

   Create another database server with the same engine (MySQL or PostgreSQL), ideally with the same provider and region so the copy uses the private network. Anything already on it is moved aside.

2. 2

   Add it

   Open the primary database server → Replicas, choose the new server under Add a read replica, and type its name to confirm. The primary gets a replication login for that server only and opens its database port to it; the replica takes a full copy and then follows every change.

3. 3

   Send reads to it

   Once the replica shows Streaming, point read-only queries and reports at it. In Laravel, the Replicas tab shows the read and write hosts to put in config/database.php.

4. 4

   Watch the lag

   Every five minutes the replica is checked and the tab shows how many seconds it’s behind. If it stops copying, the account’s owners are emailed with the reason.

5. 5

   Promote it

   If the primary fails, open the replica → Replicas → Promote to a standalone server. It stops following the primary and accepts writes, keeping everything copied; then point your applications at it.

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