126 lines
2.5 KiB
Go
126 lines
2.5 KiB
Go
package main
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import (
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"encoding/json"
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"fmt"
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"io/ioutil"
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"net/http"
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"strconv"
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"time"
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)
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// SiteAlertConfig is an instance of a site to be monitored
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// in the config file
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type SiteAlertConfig struct {
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URL string `json:"url"`
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}
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// Config is the config that we're running with
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type Config struct {
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RefreshInterval int `json:"refresh"`
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Alerts []SiteAlertConfig `json:"alerts"`
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}
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var config *Config
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var allAlerts []Alert
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func main() {
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loadConfig()
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for {
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fmt.Println("Kicking off refresh.")
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for i := range allAlerts {
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fmt.Println("Checking URL: " + allAlerts[i].url + "...")
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if allAlerts[i].Refresh() {
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for j := 0; j < 25; j++ {
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fmt.Println(" CHANGE DETECTED!")
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}
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}
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}
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fmt.Println("Refresh Completed.")
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time.Sleep(time.Minute)
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}
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}
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func loadConfig() {
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fmt.Print("Loading Config...")
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jsonInp, err := ioutil.ReadFile("config.json")
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assertError(err)
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assertError(json.Unmarshal(jsonInp, &config))
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t, e := json.Marshal(config)
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if e != nil {
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fmt.Println(e)
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} else {
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fmt.Println(string(t))
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}
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for i := range config.Alerts {
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allAlerts = append(allAlerts, *CreateNewAlert(config.Alerts[i].URL))
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}
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fmt.Println("Found " + strconv.Itoa(len(allAlerts)) + " alerts")
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}
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// Alert is for monitoring a page
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type Alert struct {
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url string
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contents string
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response *http.Response
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err error
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updateTime time.Time
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lastChangeContents string
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lastChangeResponse *http.Response
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lastChangeError error
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lastChangeTime time.Time
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}
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// CreateNewAlert returns an alert object for url 'u'
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func CreateNewAlert(u string) *Alert {
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a := Alert{url: u}
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a.response, a.err = http.Get(u)
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return &a
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}
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// Refresh refetches the url for the alert and returns
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// true if it changed.
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func (a *Alert) Refresh() bool {
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var changed bool
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r, e := http.Get(a.url)
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if e != a.err {
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a.Update(r, "", e)
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return true
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}
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if body, err := ioutil.ReadAll(r.Body); err == nil {
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b := string(body)
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if b != a.contents {
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changed = true
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a.Update(r, b, e)
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}
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} else {
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e = err
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}
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r.Body.Close()
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if e != a.err {
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a.Update(r, "", e)
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return true
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}
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return changed
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}
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// Update updates the contents of the alert with the new changes
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func (a *Alert) Update(r *http.Response, body string, e error) {
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a.lastChangeContents = a.contents
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a.lastChangeResponse = a.response
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a.lastChangeError = a.err
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a.lastChangeTime = a.updateTime
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a.contents = body
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a.response = r
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a.err = e
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a.updateTime = time.Now()
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}
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func assertError(err error) {
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if err != nil {
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panic(err)
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}
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}
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