The Fly Platform gets close to users by running applications in datacenters close to users. These datacenters are identified by region.

The platform works out which region an application should be running in based on the incoming connection from a client. It then starts the application in that region and completes the connection.

This means that an application does not need to know which region it is running in.

There are a set of Fly capabilities available to applications, such as region-local Redis databases, that are tied to a region.

Discovering your Application's Region

When an application is started, a three-character value is set in the environment variable FLY_REGION reflecting the region it is running in.

Region ID Region Location
ams Amsterdam, Netherlands
atl Atlanta, Georgia (US)
cdg Paris, France
dfw Dallas, Texas (US)
ewr Parsippany, NJ (US)
fra Frankfurt, Germany
gru Sao Paulo, Brazil
hkg Hong Kong
iad Ashburn, Virginia (US)
lax Los Angeles, California (US)
lhr London, United Kingdom
maa Chennai (Madras), India
nrt Tokyo, Japan
ord Chicago, Illinois (US)
scl Santiago, Chile
sea Seattle, Washington (US)
sin Singapore
sjc Sunnyvale, California (US)
syd Sydney, Australia
yyz Toronto, Canada

FLY_REGION is just one of the range of Runtime Enviroment information available to applications.