config

Documentation

Overview

Package config provides parser for cloudprober configs.

Example Usage:

c, err := config.Parse(*configFile, sysvars.SysVars())

Parse processes a config file as a Go text template and parses it into a ProberConfig proto. Config file is processed using the provided variable map (usually GCP metadata variables) and some predefined macros.

Macros

Cloudprober configs support some macros to make configs construction easier:

*) env: get the value of an environment variable. A common use-case for this is using it inside a kubernetes cluster. Example:

# Use an environment variable in probe config
probe {
  name: "dns_google_jp"
  type: DNS
  targets {
    host_names: "1.1.1.1"
  }
  dns_probe {
    resolved_domain: "{{env "TEST_DOM"}}"
  }
  interval_msec: 5000  # 5s
  timeout_msec: 1000   # 1s
}

# Then run cloudprober as:
TEST_DOM=google.co.jp ./cloudprober --config_file=cloudprober.cfg

*) 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 - mkMap 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" mkMap "typ" "PING" "name" "ping_google"}}

{{template "probeTmpl" mkMap "typ" "HTTP" "name" "http_google"}}

*) mkSlice - mkSlice returns a slice consisting of the arguments. 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

{{with $shards := mkSlice "00" "01" "02" "03"}}
{{range $_, $shard := $shards}}
{{$targets := printf "^ig-([^-]+-[^-]+-[^-]+)-%s-[^-]+$" $shard}}
{{$run_on := printf "^ig-([^-]+-[^-]+-[^-]+)-%s-[^-.]+(|[.].*)$" $shard}}

probe {
  name: "vm-to-vm-{{$shard}}"
  type: PING
  targets {
    gce_targets {
      instances {}
    }
    regex: "{{$targets}}"
  }
  run_on: "{{$run_on}}"
}

{{end}}
{{end}}

Index

• func DefaultConfig() string
• func Parse(config string, sysVars map[string]string) (*configpb.ProberConfig, error)
• func ParseTemplate(config string, sysVars map[string]string) (string, error)
• func ReadFromGCEMetadata(metadataKeyName string) (string, error)

Functions

func DefaultConfig

func DefaultConfig() string

DefaultConfig returns the default config string.

func Parse

func Parse(config string, sysVars map[string]string) (*configpb.ProberConfig, error)

Parse processes a config file as a Go text template and parses it into a ProberConfig proto.

func ParseTemplate

func ParseTemplate(config string, sysVars map[string]string) (string, error)

ParseTemplate processes a config file as a Go text template.

func ReadFromGCEMetadata

func ReadFromGCEMetadata(metadataKeyName string) (string, error)

ReadFromGCEMetadata reads the config from the GCE metadata. To allow for instance level as well as project-wide config, we look for the config in metadata in the following manner:

	a. If cloudprober_config is set in the instance's custom metadata, its
        value is returned.
	b. If (and only if), the key is not found in the step above, we look for
	   the same key in the project's custom metadata.