The information on this page is written for Vamp v0.9.1
Gateways are dynmic runtime entities in the Vamp eco-system. They represent load balancer rules to deployment, cluster and service instances. There are two types of gateways:
- Internal gateways are created automatically for each deployment cluster and updated using the gateway/deployment API
- External gateways are explicitly declared either in a deployment blueprint or using the gateway API
Example - automatically created gateway
The below gateway is for deployment
sava and port
The cluster contains two services
sava:1.1.0, each with two running instances.
--- name: vamp/sava/port # name port: 40000/http # port, either http or tcp, assigned by Vamp active: true # is it running - not in case of non (yet) existing routes sticky: none routes: # routes vamp/sava/sava:1.0.0/port: weight: 50% instances: - name: vamp_6fd83b1fd01f7dd9eb7f.cda3c376-ae26-11e5-91fb-0242f7e42bf3 host: default port: 31463 - name: vamp_6fd83b1fd01f7dd9eb7f.cda2d915-ae26-11e5-91fb-0242f7e42bf3 host: default port: 31292 vamp/sava/sava:1.1.0/port: weight: 50% instances: - name: vamp_2e2fc6ab8a1cdbe79dc3.caa3c9e4-ae26-11e5-91fb-0242f7e42bf3 host: default port: 31634 - name: vamp_2e2fc6ab8a1cdbe79dc3.caa37bc3-ae26-11e5-91fb-0242f7e42bf3 host: default port: 31826
The gateway API allows for programmable routing. External gateways give an entry point to clusters (optionally specified in deployment blueprints), and allow for canary releasing and A/B testing across deployments.
A gateway defines a set of rules for routing traffic between different services within the same cluster. Vamp allows you to determine this in three ways:
conditionwill target specific traffic. Read more about conditions
for example, IOS users
condition_strengthtargets a percentage of traffic matching a condition
for example, 10% of IOS users
weightfor each available route (%) defines the distribution of all remaining traffic (not matching or not targetted by a condition)
for example, 100% of all traffic, except the targetted 10% of IOS users
Routes, condition-strength and weights
Each route can have a weight and one or more conditions (see boolean expression in conditions). Each condition has a condition-strength.
Routing is calculated as followed:
- Find the first
conditionthat matches the request. Read more about conditions
for example, IOS users
- If the route exists, send the request to it depending on the
for example, 10% of IOS users are sent to the route
- If, based on
condition strength, the request should not follow that route, then send request to one from all routes based on their
for example, all non-IOS traffic and 90% of IOS users are routed according to route weight
Vamp has to account for all traffic.
When defining weights, the total weight of all routes must always add up to 100%. This means that in a straight three-way split one service must be given 34% as
33%+33%+33%=99%. 1% can be a lot of traffic in high volume environments.
Example - Route all
Firefox and only
Firefox users to route
service_A: weight: 100% service_B: weight: 0% condition_strength: 100% condition: user-agent == Firefox
Example - Route half of
Firefox users to
service_B, other half to
service_A (80%) or
Firefox requests will be just sent to
service_A (80%) or
service_A: weight: 80% service_B: weight: 20% condition_strength: 50% condition: user-agent == Firefox
Example - A/B test two deployments using route weight
Below is a basic example, similar to putting both deployments (
sava:1.1.0) in the same cluster.
It is easy to imagine having an older legacy application and the new one and doing a full canary release (or A/B testing) in seamless way by using gateways like this.
--- name: sava:1.0 gateways: 9050/http: sava/port clusters: sava: services: - breed: name: sava:1.0.0 deployable: magneticio/sava:1.0.0 ports: port: 8080/http scale: cpu: 0.2 memory: 256MB instances: 2
--- name: sava:1.1 gateways: 9060/http: sava/port clusters: sava: services: - breed: name: sava:1.1.0 deployable: magneticio/sava:1.1.0 ports: port: 8080/http scale: cpu: 0.2 memory: 256MB instances: 2
Gateway (90% / 10%):
--- name: sava port: 9070/http routes: sava:1.0/sava/port: weight: 90% # condition can be used as well sava:1.1/sava/port: weight: 10%
URL path rewrite
Vamp supports URL path rewrite. This can be a powerful solution in defining service APIs (e.g. RESTful) outside of application service. Path rewrite is defined in the format
path: NEW_PATH if CONDITION, where:
NEW_PATHnew path to be used; HAProxy variables are supported, e.g.
CONDITIONcondition using HAProxy directives, e.g. matching path, method, headers etc.
routes: web/port1: rewrites: - path: a if b web/port2: weight: 100%
Vamp managed and external routes
Vamp managed routes are in the format:
gateway- pointing to another gateway, e.g. it is possible to chain gateways
deployment/cluster- pointing to deployment cluster, i.e. services are not ‘visible’
deployment/cluster/service- pointing to specific service within deployment cluster
All examples above cover only Vamp managed routes.
It is also possible to route traffic to specific IP or hostname and port.
In that case IP or hostname and port need to be specified between brackets, e.g.
[hostname:port] (and double quotes due to Yaml syntax).
name: mesos port: 8080/http sticky: route routes: "[192.168.99.100:5050]": weight: 50% "[localhost:5050]": weight: 50%