vulcand / vulcand-docs

Vulcand documentation

Vulcand

Vulcand is a programmatic extendable proxy for microservices and API management. It is inspired by Hystrix and powers Mailgun microservices infrastructure.

Focus and priorities

Vulcand is focused on microservices and API use-cases.

Features

• Uses etcd as a configuration backend.
• API and command line tool.
• Pluggable middlewares.
• Support for canary deployments, realtime metrics and resilience.

Project info

documentation	https://vulcand.github.io/
status	Used in production@Mailgun on moderate workloads. Under active development.
discussions	https://groups.google.com/d/forum/vulcan-proxy
roadmap	roadmap.md
build status

Opentracing Support

Vulcand has support for open tracing via the Jaeger client libraries. Users who wish to use tracing support should use the --enableJaegerTracing flag and must either run the Jaeger client listening on localhost:6831/udp or set the environment variables JAEGER_AGENT_HOST and JAEGER_AGENT_POST. (See the Jaeger client libraries for all available configuration environment variables.)

When enabled vulcand will create 2 spans: one span called vulcand which covers the entire downstream request and another span called middleware which only spans the processing of the middleware before the request is routed downstream.

Aliased Expressions

When running vulcand in a kubernetes DaemonSet vulcand needs to know requests from the local node can match Host("localhost") rules. This --aliases flag allows an author of a vulcand DaemonSet to tell vulcand the name of the node it's currently running on, such that vulcand correctly routes requests for Host("localhost"). The --aliases flag allows the user to pass in multiple aliases separated by commas.

Example

$ vulcand --aliases 'Host("localhost")=Host("192.168.1.1")'

vulcand-docs's Issues

vulcand error reported: failed to add middleware: Max connections should be >= 0

Copying all the etdctl setup statements from the manual (http://www.vulcanproxy.com/proxy.html#etcd), then starting vulcand, I get the following error. Vulcand still runs (no panic), but perhaps a max connections setting needs to be added to the example in the manual?

$ etcdctl set /vulcand/hosts/localhost/locations/loc1/middlewares/ratelimit/rl1 '{"Type": "ratelimit", "Middleware":{"Requests":1, "PeriodSeconds":1, "Burst":3, "Variable": "client.ip"}}'
{"Type": "ratelimit", "Middleware":{"Requests":1, "PeriodSeconds":1, "Burst":3, "Variable": "client.ip"}}
$ etcdctl set /vulcand/hosts/localhost/locations/loc1/middlewares/connlimit/rl1 '{"Type": "connlimit", "Middleware":{"Requests":1, "PeriodSeconds":1, "Burst":3, "Variable": "client.ip"}}'
{"Type": "connlimit", "Middleware":{"Requests":1, "PeriodSeconds":1, "Burst":3, "Variable": "client.ip"}}
$ vulcand
ERROR Oct  4 21:26:22.217: PID:4504 [mux.go:451] failed to add middleware: Max connections should be >= 0

Examples / Advanced

Hi guys,

Is it possible to publish some configuration examples to show the full spectrum of features of vulcand ?

• Create an upstream using least connections
• Create a hierarchical distribution of a query to some frontends/backends
• Create a timeout system to provide an answer to a request but keeping the request cascading to some backends or frontends

I mean some distributed queries examples and more advanced examples.

It would be amazing to have an UI to browse and organize the mappings, like https://github.com/bmorton/vulcan-salute/tree/dockerfile. I could not make it work with the current version but I wanted to test vulcand with 2k combinations of frontends and backends.

Any comments, examples or feedbacks would be appreciated about upper ideas :-)

Cheers,
Luc