Architecture
text
Region A (Primary)                    Region B (Secondary)
+-----------------------+             +-----------------------+
| GKE Cluster           |             | GKE Cluster           |
| +-- Digest pods       |             | +-- Kafka brokers     |
| +-- UI pods           |             | +-- cert-manager      |
| +-- Ingest pods       |             | +-- humio-operator    |
| +-- Kafka brokers     |             |     (0 replicas)      |
| +-- cert-manager      |             |                       |
|                       |             | NOT running:          |
|                       |             | - LogScale pods       |
|                       |             |   (epoch conflict if  |
|                       |             |    started prematurely)|
|                       |             |                       |
| GCS Bucket (R/W)      |             | GCS Bucket (own, R/W) |
| dr-primary-...        |             | dr-secondary-...      |
+-----------------------+             +-----------------------+
         |                                     |
         |  Without bucket replication:        |
         +--- read-only cross-region access ---+
         |    (secondary reads primary bucket) |
         |                                     |
         |  With bucket replication:           |
         |    (secondary reads local copy,     |
         |     set GCP_RECOVER_FROM_REPLACE_   |
         |     BUCKET to rewrite paths)        |
         |                                     |
         +------ Global LB (health check) -----+
         +------ Cloud DNS (failover) ---------+

Key points:

  • The secondary cluster's GCS bucket is its own; it does not write to the primary's bucket.

  • The secondary reads the primary's bucket only during recovery (snapshot restore).

  • The GLB health check determines which backend receives traffic. When the primary fails, traffic shifts to the secondary.

  • Cloud DNS failover routing provides an alternative (or complementary) mechanism for DNS-level redirection.