feat: alerting for disk used

cmd/main.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"context"
+	"encoding/json"
 	"flag"
 	"fmt"
 	"go/slack-bot/pkg/check"
@@ -19,6 +21,7 @@ type SlackConf struct {
 	BotID         string `hcl:"bot_id"`
 	DestChannelID string `hcl:"dest_channel_id"`
 	WebhookID     string `hcl:"webhook_id"`
+	DryRun        *bool  `hcl:"dry_run"`
 }
 
 func main() {
@@ -29,10 +32,40 @@ func main() {
 	conf := ParseConfiguration(configFile)
 	slackNotifier := notify.NewSlackNotifier(conf.BotID, conf.DestChannelID, conf.WebhookID)
 
-	msg := check.NewCliChecker().
-		Check()
+	dfChecker := check.NewDfChecker("disk is full", "bash", "-c", "df | grep -v 'auto_home'")
 
-	slackNotifier.Notify(msg)
+	msg := dfChecker.Check(func(stdout string) notify.Message {
+		parsedDf, err := dfChecker.Parse(stdout)
+		if err != nil {
+			return notify.Message{
+				Content:      fmt.Sprint("disk is full : ", err),
+				ShouldNotify: true,
+			}
+		} else {
+			casted := parsedDf.(check.DfOut)
+			shouldNotify := check.FileSystemChecker("devfs", 70, casted)
+			if shouldNotify {
+				j, err := json.MarshalIndent(casted, "", "    ")
+				if err != nil {
+					return notify.Message{
+						Content:      fmt.Sprint("disk is full : ", err),
+						ShouldNotify: true,
+					}
+				}
+				return notify.Message{
+					Content:      fmt.Sprintf("disk is full : ```%s```\n", j),
+					ShouldNotify: true,
+				}
+			} else {
+				return notify.Message{
+					ShouldNotify: false,
+				}
+			}
+		}
+	})
+
+	dryRunCtx := context.WithValue(context.Background(), notify.DryRunContextKey, conf.DryRun)
+	slackNotifier.Notify(dryRunCtx, msg)
 }
 
 //ParseConfiguration take filename path and parse it to Config.SlackConf

pkg/check/command.go

@@ -1,24 +1,51 @@
 package check
 
-import "go/slack-bot/pkg/notify"
+import (
+	"fmt"
+	"go/slack-bot/pkg/notify"
+	"os/exec"
+)
 
+//Checker representation of check set
 type Checker interface {
-	Check() notify.Message
+	Check(f func(stdout string) notify.Message) notify.Message
+}
+
+//AdvancedChecker like Checker except contain Parsing step
+type AdvancedChecker interface {
+	Checker
+	Parse(stdout string) (interface{}, error)
 }
 
 //CliChecker implement checker with cli command
 type CliChecker struct {
+	alertingMessage string
+	command         []string
 }
 
-//NewCliChecker buld new cli checker
-func NewCliChecker() *CliChecker {
-	return &CliChecker{}
+//NewCliChecker build new cli checker
+func NewCliChecker(alertingMessage string, command ...string) Checker {
+	return &CliChecker{
+		alertingMessage: alertingMessage,
+		command:         command,
+	}
 }
 
 //Check function use to run cli call to check some parameter
-func (cc *CliChecker) Check() notify.Message {
-	return notify.Message{
-		Content:      "full disk",
-		ShouldNotify: true,
+func (cc *CliChecker) Check(f func(stdout string) notify.Message) notify.Message {
+	message := notify.Message{ShouldNotify: false}
+
+	out, err := exec.Command(cc.command[0], cc.command[1:]...).CombinedOutput()
+	if err != nil {
+		// command fail notify with error
+		message = notify.Message{
+			Content:      fmt.Sprint(cc.alertingMessage, " : ", string(out), err),
+			ShouldNotify: true,
+		}
+	} else {
+		// command success check if condition required notify
+		message = f(string(out))
 	}
+
+	return message
 }

pkg/check/df.go

@@ -0,0 +1,80 @@
+package check
+
+import (
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+//DfChecker df command implementation of AdvancedChecker
+type DfChecker struct {
+	CliChecker
+	pourcentRegexMatcher *regexp.Regexp
+}
+
+type DfOut []DfOutLine
+type DfOutLine struct {
+	Filesystem,
+	Size,
+	Used,
+	Available string
+	PourcentUsed int
+	Mounted      string
+}
+
+//NewDfChecker build new checker for df command
+func NewDfChecker(alertingMessage string, command ...string) AdvancedChecker {
+
+	return &DfChecker{
+		CliChecker: CliChecker{
+			alertingMessage: alertingMessage,
+			command:         command,
+		},
+		pourcentRegexMatcher: regexp.MustCompile(`(?P<value>.*)%`),
+	}
+}
+
+//DfParser parse df stdout
+func (dc *DfChecker) Parse(stdout string) (interface{}, error) {
+	var dfOut DfOut
+
+	for _, line := range strings.Split(stdout, "\n")[1:] {
+		if strings.TrimSpace(line) == "" {
+			continue
+		}
+
+		var cleanedColumns []string
+		for _, col := range strings.Split(line, " ") {
+			if v := strings.TrimSpace(col); v != "" {
+				cleanedColumns = append(cleanedColumns, v)
+			}
+		}
+
+		valueIndex := dc.pourcentRegexMatcher.SubexpIndex("value")
+		v, err := strconv.Atoi(dc.pourcentRegexMatcher.FindStringSubmatch(cleanedColumns[4])[valueIndex])
+		if err != nil {
+			return dfOut, err
+		}
+		// extract pourcent used from columns
+		dfOut = append(dfOut, DfOutLine{
+			Filesystem:   cleanedColumns[0],
+			Size:         cleanedColumns[1],
+			Used:         cleanedColumns[2],
+			Available:    cleanedColumns[3],
+			PourcentUsed: v,
+			Mounted:      cleanedColumns[len(cleanedColumns)-1],
+		})
+	}
+	return dfOut, nil
+}
+
+func FileSystemChecker(fileSystemName string, criticalPourcent int, dfOut DfOut) bool {
+	for _, line := range dfOut {
+		if line.Filesystem == fileSystemName {
+			if line.PourcentUsed > criticalPourcent {
+				return true
+			}
+		}
+	}
+	return false
+}

pkg/notify/slack.go

@@ -1,13 +1,19 @@
 package notify
 
 import (
+	"context"
 	"fmt"
 	"log"
 
 	"github.com/slack-go/slack"
 )
 
-const slackHookBaseURL = "hooks.slack.com/services"
+type SlackContextKey string
+
+const (
+	slackHookBaseURL                 = "hooks.slack.com/services"
+	DryRunContextKey SlackContextKey = "dryRun"
+)
 
 //Notifier interface represent mean to send notification
 type Notifier interface {
@@ -36,16 +42,21 @@ func NewSlackNotifier(BotID, DestChannelID, WebhookID string) *SlackNotifier {
 }
 
 //Notify send notification to channel
-func (sn *SlackNotifier) Notify(message Message) {
+func (sn *SlackNotifier) Notify(ctx context.Context, message Message) {
 	if message.ShouldNotify {
 		msg := &slack.WebhookMessage{
 			Text: message.Content,
 		}
 
 		url := fmt.Sprintf("https://%s/%s/%s/%s", slackHookBaseURL, sn.BotID, sn.DestChannelID, sn.WebhookID)
-		err := slack.PostWebhook(url, msg)
-		if err != nil {
-			log.Printf("Send message error %+v", err)
+		if v := ctx.Value(DryRunContextKey); v != nil && v == true {
+			log.Printf("dryrun mode : slack notify to %s\n", url)
+			log.Printf("dryrun mode : %+v\n", msg)
+		} else {
+			err := slack.PostWebhook(url, msg)
+			if err != nil {
+				log.Printf("Send message error %+v", err)
+			}
 		}
 	}
 }