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Routing

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Frank Schröder edited this page Oct 25, 2017 · 7 revisions

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 commands in the language specified below.

Comments

Blank lines and lines starting with # or // are ignored.

route add

Add a route for a service svc for the src (e.g. /path or :port) to a dst (e.g. URL or host:port).

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

Options

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

Example

# route traffic for product-svc to 1.2.3.4:8000 and :9000
route add product-svc /product http://1.2.3.4:8000
route add product-svc /product http://1.2.3.4:9000

route del

Remove one or more routes which match the given criteria.

route del <svc>[ <src>[ <dst>]]
route del <svc> tags "<t1>,<t2>,..."
route del tags "<t1>,<t2>,..."

Example

# remove all routes for 'product-svc'
route del product-svc

# remove all routes for 'product-svc' and /path
route del product-svc /path

# remove single route
route del product-svc /path http://1.2.3.4:8000

# remove all routes for 'product-svc' matching a tag
route del product-svc tags "green"

# remove all routes matching a tag
route del tags "yesterday"

route weight

Directs a certain amount of traffic to instances matching certain criteria.

The weight w is expressed as follows:

  • 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.

route weight <svc> <src> weight <w> tags "<t1>,<t2>,..."
route weight <src> weight <w> tags "<t1>,<t2>,..."
route weight <svc> <src> weight <w>
route weight service host/path weight w tags "tag1,tag2"

Example

# Route 5% of the traffic to product-svc:/path with tags "green"
route weight product-svc /path weight .05 tags "green"

# Route 5% of the traffic to '/path' to the Go implementation.
# Route the rest (95%) to the other implementation
route weight /path weight .05 tags "lang=go"

# Route 5% of the traffice to '/path' on the product-svc-go
route weight product-svc-go /path weight .05

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"
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