simult

README

simult

simult is a smart load-balancer project.

Installing

Install to linux instance:

wget -q -O- https://raw.githubusercontent.com/simult/simult/master/install.sh | bash

Install from source code to $GOPATH/bin:

go get -u github.com/simult/simult/...

Configuration

The following table lists the configurable parameters of the simult-server and their default values.

Parameter	Description	Default
global.promresetonreload	reset prometheus metrics next reload	false
global.rlimitnofile	number of allowed open files by system	system_default or 1024
default.tlsparams	default tls parameters when using tls	{}
default.keepalivetimeout	default frontend http keep-alive timeout. zero or negative means unlimited	65s
default.connecttimeout	default backend connect timeout. zero or negative means unlimited	2s
frontends	all frontends	{}
frontends.name	a frontend	{}
frontends.name.maxconn	maximum number of frontend network connections. zero or negative means unlimited	0
frontends.name.timeout	frontend timeout. zero or negative means unlimited	0
frontends.name.keepalivetimeout	http keep-alive timeout. zero or negative means unlimited	default.keepalivetimeout
frontends.name.defaultbackend	sets backend when no route matched	""
frontends.name.routes	all routes	[]
frontends.name.routes.index	a route	{}
frontends.name.routes.index.host	wildcarded host, eg "*.example.com"	"*"
frontends.name.routes.index.path	wildcarded path, eg "/example/*"	"*"
frontends.name.routes.index.backend	backend name route to	{}
frontends.name.routes.index.restrictions	all restrictions	[]
frontends.name.routes.index.restrictions.network	network CIDR IP, eg "127.0.0.0/8"	""
frontends.name.routes.index.restrictions.path	wildcarded path, eg "/example/*"	""
frontends.name.routes.index.restrictions.invert	invert restriction condition	false
frontends.name.routes.index.restrictions.andafter	AND operation with next restriction instead of OR	false
frontends.name.listeners	all listeners	[]
frontends.name.listeners.index	a listener	{}
frontends.name.listeners.index.address	listener bind address	""
frontends.name.listeners.index.tls	use tls	false
frontends.name.listeners.index.tlsparams	tls parameters	{}
frontends.name.listeners.index.tlsparams.certpath	tls certificate directory or file	"."
frontends.name.listeners.index.tlsparams.keypath	tls key directory or file	"."
backends	all backends	{}
backends.name	a backend	{}
backends.name.maxconn	maximum number of total backend connections. zero or negative means unlimited	0
backends.name.servermaxconn	maximum number of active connections per backend server. zero or negative means unlimited	0
backends.name.timeout	backend timeout. zero or negative means unlimited	0
backends.name.connecttimeout	connect timeout. zero or negative means unlimited	default.connecttimeout
backends.name.reqheaders	override request headers	{}
backends.name.healthcheck	healthcheck name	""
backends.name.mode	backend mode: roundrobin, leastconn, affinitykey	"roundrobin"
backends.name.affinitykey.source	"kind: key". kind: remoteip, realip, httpheader, httpcookie. key is, header for httpheader, cookie for httpcookie	"remoteip"
backends.name.affinitykey.maxservers	sets maximum number of servers to distribute traffic. zero value: one server, negative values: unlimited	1
backends.name.affinitykey.threshold	sets threshold to distribute traffic to next server. zero or negative means no threshold	0
backends.name.servers	backend servers	[]
backends.name.servers.index	backend server at this format: "url weight", eg "http://10.5.2.2 125". elements other than url are optional. weight is 1 by default, and must be in [0, 255]	""
healthchecks	all healthchecks	{}
healthchecks.name	a healthcheck	{}
healthchecks.name.http	http healthcheck	{}
healthchecks.name.http.path	check path	"/"
healthchecks.name.http.host	check request http host	""
healthchecks.name.http.interval	check interval	10
healthchecks.name.http.timeout	fail timeout	5
healthchecks.name.http.fall	fall threshold	3
healthchecks.name.http.rise	rise threshold	2
healthchecks.name.http.resp	expected response body	""

Prometheus

simult-server has builtin prometheus exporter. Prometheus can access metrics using management address (defined with command-line arguments) and /metrics path.

Prometheus namespace can be defined with command-line argument -prom-namespace. Prometheus namespace is "simult" by default.

Labels

All labels of all metrics define same thing if nothing else is specified.

Name	Description
frontend	frontend name
host	matched frontend route host
path	matched frontend route path
method	request method
backend	backend name
server	backend server
code	response status code
listener	listener address
error	error message

Metrics

Prometheus metrics are form of namespace_subsystem_name. The following table lists prometheus metrics of the simult-server.

Subsystem	Name	Type	Labels	Description
http_frontend	read_bytes	Counter	frontend, host, path, method, backend, server, code, listener	number of bytes read from remote client
http_frontend	write_bytes	Counter	frontend, host, path, method, backend, server, code, listener	number of bytes written to remote client
http_frontend	requests_total	Counter	frontend, host, path, method, backend, server, code, listener, error	number of requests processed
http_frontend	request_duration_seconds	Histogram	frontend, host, path, method, backend, server, code, listener	observer of request duration. it doesn't include errored requests
http_frontend	connections_total	Counter	frontend, listener	number of connections received
http_frontend	dropped_connections_total	Counter	frontend, listener	number of connections dropped after received them. this happens when maximum connection count exceeds
http_frontend	active_connections	Gauge	frontend, listener	active connection count
http_frontend	idle_connections	Gauge	frontend, listener	idle connection count
http_backend	read_bytes	Counter	backend, server, code, frontend, host, path, method, listener	number of bytes read from backend server
http_backend	write_bytes	Counter	backend, server, code, frontend, host, path, method, listener	number of bytes written to backend server
http_backend	time_to_first_byte_seconds	Histogram	backend, server, code, frontend, host, path, method, listener	observer of the time to first byte of backend server
http_backend	active_connections	Gauge	backend, server	active connection count of backend server
http_backend	idle_connections	Gauge	backend, server	idle connection count of backend server
http_backend	server_health	Gauge	backend, server	health status(0 or 1) of backend server