Serving traffic by region

Each server has a region. Pyo spreads a service's replicasOne running copy of a service. More replicas share the traffic and keep it up if one stops. across regions, and answers each request from the closest healthy replica.

A server's regionCopy Anchor Link

Pyo detects each server's region from its address, like Singapore, and shows it with its country's flag.

To group servers your own way, rename the region. For example, call two servers in different US cities US East. Choose Change region from a server's menu on the cluster's Servers tab, or on the server's page. A name can be up to 40 characters, and Pyo suggests regions your team already uses. Detect automatically puts the detected region back.

The same region is used everywhere: to spread replicas, to route traffic, in the traffic view, and to pin a service to a region.

How replicas spreadCopy Anchor Link

Replicas spread evenly across regions, then across the servers in each region. For example, 4 replicas on servers in Singapore and the US run as 2 in each.

The spread is a preference, not a rule. If a region is full or down, replicas still start in another one.

Existing services pick up regions at their next deploy.

How traffic is routedCopy Anchor Link

While the cluster accepts public traffic, each server answers the requests that reach it, through Pyo Gateway. Build-only servers don't. Where the server sends them is set on the cluster's Settings tab, under Traffic routing:

• Local: keep traffic on the same server. Requests go to a replica on the server they reached, otherwise to any healthy replica. It needs an agent that supports it, and shows as disabled otherwise.
• Regional (the default): keep traffic within the same region. Requests go to a replica in the region, otherwise to any healthy replica.
• Global: distribute traffic across all servers. Requests go to any healthy replica.

In every mode, replicas are placed across regions the same way. Only where requests go changes. A change applies to the cluster's services straight away, without a redeploy. Team owners and admins can change it, and each change is recorded in Activity.

Point visitors at the right regionCopy Anchor Link

Which server a visitor reaches is up to your DNS, or a load balancer in front of your servers. Point each region's domains at the servers in that region. Pyo doesn't do this for you today.

See where traffic goesCopy Anchor Link

A service's Overview has a Traffic card, below the Analytics card. It shows the path the service's requests take, in three columns from left to right.

• Domains: each domain, with a badge saying whether its DNS points at your servers. Hover over a domain to see its DNS records and which server each address belongs to. An address that isn't one of your servers is shown too.
• Entry servers: the servers that answer requests, in a box for each region. A region's box shows how many of its replicas are healthy, its requests, error rate and p95The time 95 out of 100 requests finished within. The slowest 5 took longer. response time, and a small chart of requests over the last 24 hours. The numbers need observability. Each server shows its share of the requests. Servers that don't answer requests are marked: build-only servers, or every server while the cluster's public traffic is off.
• Replicas: grouped by the server they run on, each marked healthy or not.

Lines show where requests go. A thicker line carries a bigger share. A red line leads to something that isn't healthy, and a dashed amber line leads to an address that isn't one of your servers. A legend in the corner explains them.

The card's header shows whether the cluster's traffic routing is Local, Regional or Global, and links to the cluster's settings. Drag to move around, use the zoom buttons or Fit, and click a server to open it.

When something looks wrong, a line above the canvas says how many problems it found. Open it to see the list. For example:

• A domain points at an address that isn't one of the cluster's servers, or at a server that doesn't answer requests.
• A domain points at one region, but replicas run in several, so visitors everywhere still reach that one region.
• A region takes traffic but has no healthy replica, so its requests go to another region.
• Replicas aren't spread evenly, usually because a region was full or offline. Redeploy once it has room.

Cron jobs don't have a Traffic card.