Gopnik configuration

Config format

Gopnik uses JSON format for config files with strict-json parsing library. This library disallows unexpected fields inside config sections; fileds starting with # are treated as comments:

{
	"Normal section": {
		"some": "values"
	},
	"#Ignored section": {
		"some": "values"
	}
}

One config can be used for all daemons and utilities, or separate configs can be specified. General config structure is:

{
	"#Daemons configuration": null,
	"Dispatcher": {
		"..."
	},
	"Render": {
		"..."
	},
	"Prerender": {
		"..."
	},

	"#Common configuration": null,
	"MetaSize": 8,
	"TileSize": 256,
	"CachePlugin": {
		"Plugin": "CacheProxyPlugin",
		"PluginConfig": {
			"..."
		}
	},
	"RenderPools": [
		"..."
	]
}

Common options

MetaSize - tiles per metatile. See also nice article about metatiles from MapBox.
TileSize - “base” size of tiles. Commonly is 256.
CachePlugin - pluggable tile storage. See below how to use the plugin system.
RenderPools - configuration of render pools. See details below.
MonitoringPlugins - metric exporters. See details below.

Dispatcher

Dispatcher parameters:

Name	Type	Default value	Description
Addr	string	“:8080”	Main address
DebugAddr	string	“:9080”	Address for monitoring
HTTPReadTimeout	string	“60s”	HTTP client read timeout
HTTPWriteTimeout	string	“60s”	HTTP client write timeout
RequestTimeout	string	“600s”	Timeout for dynamic rendering request
PingPeriod	string	“30s”	Ping gopniks every PingPeriod
Threads	int	NumCPU	set GOMAXPROCS to Threads. -1 for NumCPU
Logging	json.RawMessage	nil	see logging section below
ClusterPlugin	app.PluginConfig	nil	dynamic rendering cluster plugin
FilterPlugin	app.PluginConfig	nil	filter plugin for tags

Render

Name	Type	Default value	Description
Addr	string	“:8090”	Main address
DebugAddr	string	“:9090”	Address for monitoring
Threads	int	1	set GOMAXPROCS to Threads. -1 for NumCPU
HotCacheDelay	string	“0s”	Time period after cache set is done and before hot cache drop
Logging	json.RawMessage	nil	see logging section below
PerfLog	string	””	Performance log file

Prerender

Name	Type	Default value	Description
DebugAddr	string	“:8097”	Address for monitoring
UIAddr	string	“:8088”	WebUI address
Threads	int	1	set GOMAXPROCS to Threads. -1 for NumCPU
Logging	json.RawMessage	nil	see logging section below
PerfLog	string	””	Performance log file
Slaves	app.PluginConfig	nil	Cluster of slaves
RequestTimeout	string	“1h”	Timeout for request to gopnik
NodeQueueSize	int	100	Number of parallel requests per node

Plugins

//There are some kind of plugins: cache, cluster, tag filter and monitoring. //Options requires plugin look like this:

Different kinds of plugins are: cache, cluster, tag filter and monitoring. Some options require plugins to be used. They have the following fields:

{
	"Plugin": "...",
	"PluginConfig": {
		"..."
	}
}

See default plugins description for details.

Render pools

RenderPools section is a list of different renders configuration. Gopnik will use first relevant render from top. Each render pool is discribed by the following parameters:

Name	Type	Default value	Description
Cmd	[]string	nil	Slave render command line. See details below
MinZoom	uint	0	Minimum allowed zoom
MaxZoom	uint	0	Maximum allowed zoom
Tags	[]string	nil	Render to be used only when request have all tags from list
PoolSize	uint	0	Number of render instances
HPQueueSize	uint	0	Size of high priority task queue
LPQueueSize	uint	0	Size of task low priority queue
RenderTTL	uint	0	Restart render after RenderTTL completed tasks
ExecutionTimeout	string	””	Timeout for one request

Slave options

Command line options for default render slave:

Argument	Type	Default value	Description
-stylesheet	string	””	Path to mapnik xml stylesheet
-tileSize	uint	256	Tile size in pixels
-bufferSize	int	-1	Size of metatile buffer
-fontsPath	[]string	nil	List of font paths
-pluginsPath	string	nil	Mapnik plugins path
-scaleFactor	float64	1.0	Scale factor. Commonly equals (slave tile size) / (gopnik’s tile size)
-imageFormat	string	“png8”	Mapnik image format (e.g. “png8” or “png24”)

Logging

Each daemon has logging section with followig options:

Name	Type	Default value	Description
Backend	string	””	Backend for loggin (“Console”, “Syslog” or empty)
Level	string	””	Log level (“Critical”, “Error”, “Warning”, “Notice”, “Info”, “Debug”)
Format	string	”[%{level}] %{message}”	Log format. See go-logging page for details
Options	json.RawMessage	nil	Backend options

Console backend

Console backend writes log direct to stderr.

Name	Type	Default value	Description
Color	bool	false	Use color output

Syslog backend

Syslog logger backend connects to the syslog daemon using UNIX sockets with given prefix. If prefix is not specified, it will be derived from the launched command.

Name	Type	Default value	Description
Prefix	string	””	Syslog prefix

Monitoring exporters

In common section of config you can set list of metric exporters.

{
	"MonitoringPlugins": [
		{
			"..."
		},
		{
			"..."
		}
	]
}

Only graphite exporter are available by default. Check default plugins description page for details.