Routing

Manual overrides

Since an automatically generated routing table can only be changed with a service deployment additional routing commands can be stored manually in the consul KV store which get appended to the automatically generated routing table. This allows fine-tuning and fixing of problems without a deployment.

The routing commands are also stored in the KV store.

Config Language

The routing table is configured with the following commands:

route add <svc> <src> <dst>[ weight <w>][ tags "<t1>,<t2>,..."][ opts "k1=v1 k2=v2 ..."]

Add route for service svc from src to dst with optional weight, tags and options. Valid options are:

Option	Description
strip=/path	Forward /path/to/file as /to/file
proto=tcp	Upstream service is TCP, dst must be :port
proto=https	Upstream service is HTTPS
tlsskipverify=true	Disable TLS cert validation for HTTPS upstream
host=name	Set the Host header to name. If name == 'dst' then the Host header will be set to the registered upstream host name

route del <svc>[ <src>[ <dst>]]

Remove route matching svc, src and/or dst.

route del <svc> tags "<t1>,<t2>,..."

Remove all routes of service matching svc and tags.

route del tags "<t1>,<t2>,..."

Remove all routes matching tags.

route weight <svc> <src> weight <w> tags "<t1>,<t2>,..."

Route w% of traffic to all services matching svc, src and tags.

route weight <src> weight <w> tags "<t1>,<t2>,..."

Route w% of traffic to all services matching src and tags.

route weight <svc> <src> weight <w>

Route w% of traffic to all services matching svc and src.

route weight service host/path weight w tags "tag1,tag2"

Route w% of traffic to all services matching service, host/path and tags.

• w is a float > 0 describing a percentage, e.g. 0.5 == 50%
• w <= 0: means no fixed weighting. Traffic is evenly distributed
• w > 0: route will receive n% of traffic. If sum(w) > 1 then w is normalized.
• sum(w) >= 1: only matching services will receive traffic

Note that the total sum of traffic sent to all matching routes is w%.

The order of commands matters but routes are always ordered from most to least specific by prefix length.

Routing rules

The routing table contains first all routes with a host sorted by prefix length in descending order and then all routes without a host again sorted by prefix length in descending order.

For each incoming request the routing table is searched top to bottom for a matching route. A route matches if either host/path or - if there was no match - just /path matches.

The matching route determines the target URL depending on the configured strategy. rnd and rr are available with rnd being the default.

Example

The auto-generated routing table is

route add service-a www.mp.dev/accounts/ http://host-a:11050/ tags "a,b"
route add service-a www.kjca.dev/accounts/ http://host-a:11050/ tags "a,b"
route add service-a www.dba.dev/accounts/ http://host-a:11050/ tags "a,b"
route add service-b www.mp.dev/auth/ http://host-b:11080/ tags "a,b"
route add service-b www.kjca.dev/auth/ http://host-b:11080/ tags "a,b"
route add service-b www.dba.dev/auth/ http://host-b:11080/ tags "a,b"

The manual configuration under /fabio/config is

route del service-b www.dba.dev/auth/
route add service-c www.somedomain.com/ http://host-z:12345/

The complete routing table then is

route add service-a www.mp.dev/accounts/ http://host-a:11050/ tags "a,b"
route add service-a www.kjca.dev/accounts/ http://host-a:11050/ tags "a,b"
route add service-a www.dba.dev/accounts/ http://host-a:11050/ tags "a,b"
route add service-b www.mp.dev/auth/ http://host-b:11080/ tags "a,b"
route add service-b www.kjca.dev/auth/ http://host-b:11080/ tags "a,b"
route add service-c www.somedomain.com/ http://host-z:12345/ tags "a,b"