connectivity

Documentation

Overview

Package connectivity implements a single, simple stream of booleans to answer the question "are we connected?".

It can potentially fire two falses in a row, if a disconnected state is followed by a dbus watch error. Other than that, it's edge triggered.

webchecker checks whether we're actually connected by doing an http GET to the Ubuntu connectivity check URL, http://start.ubuntu.com/connectivity-check.html

We could make it be https to make extra doubly sure, but it's expensive overkill for the majority of cases.

Index

• type ConnectedState
  • func New(endp bus.Endpoint, config ConnectivityConfig, log logger.Logger) *ConnectedState
  • func (cs *ConnectedState) Cancel()
  • func (cs *ConnectedState) Track(out chan<- bool)
• type ConnectivityConfig
• type Webchecker
  • func NewWebchecker(url string, target string, timeout time.Duration, log logger.Logger) Webchecker

Types

type ConnectedState

type ConnectedState struct {
	// contains filtered or unexported fields
}

ConnectedState helps tracking connectivity.

func New

func New(endp bus.Endpoint, config ConnectivityConfig, log logger.Logger) *ConnectedState

New makes a ConnectedState for connectivity tracking.

The endpoint need not be dialed; Track() will Dial() and Close() it as it sees fit.

func (*ConnectedState) Cancel

func (cs *ConnectedState) Cancel()

Cancel stops the ConnectedState machinary.

func (*ConnectedState) Track

func (cs *ConnectedState) Track(out chan<- bool)

Track sends the initial NetworkManager state and changes to it over the "out" channel. Sends "false" as soon as it detects trouble, "true" after checking actual connectivity.

type ConnectivityConfig

type ConnectivityConfig struct {
	// how long to wait after a state change to make sure it's "stable"
	// before acting on it
	StabilizingTimeout config.ConfigTimeDuration `json:"stabilizing_timeout"`
	// How long to wait between online connectivity checks.
	RecheckTimeout config.ConfigTimeDuration `json:"recheck_timeout"`
	// The URL against which to do the connectivity check.
	ConnectivityCheckURL string `json:"connectivity_check_url"`
	// The expected MD5 of the content at the ConnectivityCheckURL
	ConnectivityCheckMD5 string `json:"connectivity_check_md5"`
}

The configuration for ConnectedState, intended to be populated from a config file.

type Webchecker

type Webchecker interface {
	// Webcheck checks whether retrieving the URL works, and if its
	// contents match the target. If so, then it sends true; if anything
	// fails, it sends false.
	Webcheck(chan<- bool)
	// Close idle connections.
	Close()
}

func NewWebchecker

func NewWebchecker(url string, target string, timeout time.Duration, log logger.Logger) Webchecker

Build a webchecker for the given URL, that should match the target MD5.