config

Documentation

Overview

Package config provides parser for cloudprober configs.

Example Usage:

c, err := config.ParseTemplate(config, sysvars.SysVars())

ParseTemplate processes a config file as a Go text template using the provided variable map (usually GCP metadata variables) and some predefined macros.

Macros

Cloudprober configs support Go text templates with sprig functions (https://masterminds.github.io/sprig/) and the following macros to make configs construction easier:

	gceCustomMetadata
	 	Get value of a GCE custom metadata key. It first looks for the given key in
		the instance's custom metadata and if it is not found there, it looks for it
		in the project's custom metaata.

		# Get load balancer IP from metadata.
		probe {
		  name: "http_lb"
		  type: HTTP
		  targets {
		    host_names: "{{gceCustomMetadata "lb_ip"}}"
		  }
		}

	extractSubstring
		Extract substring from a string using regex. Example use in config:

		# Sharded VM-to-VM connectivity checks over internal IP
		# Instance name format: ig-<zone>-<shard>-<random-characters>, e.g. ig-asia-east1-a-00-ftx1
		{{$shard := .instance | extractSubstring "[^-]+-[^-]+-[^-]+-[^-]+-([^-]+)-.*" 1}}
		probe {
		  name: "vm-to-vm-{{$shard}}"
		  type: PING
		  targets {
		    gce_targets {
		      instances {}
		    }
		    regex: "{{$targets}}"
		  }
		  run_on: "{{$run_on}}"
		}

	mkMap or dict
		Same as dict: https://masterminds.github.io/sprig/dicts.html. Returns a
		map built from the arguments. It's useful as Go templates take only one
		argument. With this function, we can create a map of multiple values and
		pass it to a template. Example use in config:

		{{define "probeTmpl"}}
		probe {
		  type: {{.typ}}
		  name: "{{.name}}"
		  targets {
		    host_names: "www.google.com"
		  }
		}
		{{end}}

		{{template "probeTmpl" dict "typ" "PING" "name" "ping_google"}}
		{{template "probeTmpl" dict "typ" "HTTP" "name" "http_google"}}

	mkSlice or list
		Same as list: https://masterminds.github.io/sprig/lists.html. It can be
		used with the built-in'range' function to replicate text.

		{{with $regions := list "us=central1" "us-east1"}}
		{{range $_, $region := $regions}}

		probe {
		  name: "service-a-{{$region}}"
		  type: HTTP
		  targets {
		    host_names: "service-a.{{$region}}.corp.xx.com"
		  }
		}

		{{end}}
		{{end}}

    configDir
		configDir expands to the config file's directory. This is useful to
		specify files relative to the config file.

    	probe {
		  name: "test_x"
		  type: EXTERNAL
		  probe_external {
		    # test_x.sh is in the same directory as the config file.
		    command: "{{configDir}}/test_x.sh"
    	  }
    	}

Index

• Variables
• func ConfigTest(cs ConfigSource) error
• func DefaultConfig() string
• func DumpConfig(outFormat string, cs ConfigSource) ([]byte, error)
• type ConfigSource
  • func ConfigSourceWithFile(fileName string, opts ...Option) ConfigSource
  • func DefaultConfigSource(opts ...Option) ConfigSource
• type Option
  • func WithBaseVars(vars map[string]any) Option
  • func WithSurfacerConfig(sconfig string) Option

Variables

var EnvRegex = regexp.MustCompile(`\*\*\$([^*\s]+)\*\*`)

EnvRegex is the regex used to find environment variable placeholders in the config file. The placeholders are of the form **$<env_var_name>**, and are added during Go template processing for envSecret functions.

Functions

func ConfigTest

func ConfigTest(cs ConfigSource) error

func DefaultConfig

func DefaultConfig() string

DefaultConfig returns the default config string.

func DumpConfig

func DumpConfig(outFormat string, cs ConfigSource) ([]byte, error)

Types

type ConfigSource

type ConfigSource interface {
	GetConfig() (*configpb.ProberConfig, error)
	RawConfig() string
	ParsedConfig() string
}

func ConfigSourceWithFile

func ConfigSourceWithFile(fileName string, opts ...Option) ConfigSource

func DefaultConfigSource

func DefaultConfigSource(opts ...Option) ConfigSource

type Option

type Option func(ConfigSource) ConfigSource

func WithBaseVars

func WithBaseVars(vars map[string]any) Option

func WithSurfacerConfig

func WithSurfacerConfig(sconfig string) Option