Initial commit

.env.example

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+IMAP_SERVER=
+IMAP_USERNAME=
+IMAP_PASSWORD=

.gitignore

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+/.vscode
+/.idea
+
+.env
+imap-mailbox-exporter

LICENCE

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+MIT License
+
+Copyright (c) 2022 jop-software Inh. Johannes Przymusinski
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

Makefile

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+BINARY=imap-mailbox-exporter
+
+build:
+	go build -o $(BINARY) ./...
+
+run: build
+	./$(BINARY)
+
+test:
+	go test ./...
+
+test-coverage:
+	go test ./... -cover
+
+test-coverage-html:
+	go test ./... -coverprofile=coverage.out && go tool cover -html=coverage.out

README.md

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+# Imap Mailbox Exporter
+
+> Export the amount of mails in a mailbox for use in prometheus.
+
+## Usage
+
+### Configuration
+
+```dotenv
+IMAP_SERVER=""
+IMAP_USERNAME=""
+IMAP_PASSWORD=""
+```
+
+### Probe
+
+```txt
+http://127.0.0.1:9101/probe?mailbox=INBOX
+```
+
+### Provided metrics
+
+```txt
+# HELP probe_mailbox_count Displays the count of mails found in the mailbox
+# TYPE probe_mailbox_count gauge
+probe_mailbox_count 0
+```
+
+## License
+
+This project is licensed under the [MIT License](./LICENCE)
+
+<div align="center">
+    <span>&copy; 2022, jop-software Inh. Johannes Przymusinski</span>
+</div>

go.mod

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+module github.com/jop-software/imap-mailbox-exporter
+
+go 1.18
+
+require (
+	github.com/emersion/go-imap v1.2.1
+	github.com/joho/godotenv v1.4.0
+	github.com/prometheus/client_golang v1.12.2
+)
+
+require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.1.2 // indirect
+	github.com/emersion/go-sasl v0.0.0-20200509203442-7bfe0ed36a21 // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
+	github.com/prometheus/client_model v0.2.0 // indirect
+	github.com/prometheus/common v0.32.1 // indirect
+	github.com/prometheus/procfs v0.7.3 // indirect
+	golang.org/x/sys v0.0.0-20220114195835-da31bd327af9 // indirect
+	golang.org/x/text v0.3.7 // indirect
+	google.golang.org/protobuf v1.26.0 // indirect
+)

main.go

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+package main
+
+import (
+	"errors"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+
+	"github.com/emersion/go-imap/client"
+	"github.com/joho/godotenv"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+// Config holds the base IMAP credentialsf
+type Config struct {
+	ImapUsername string
+	ImapPassword string
+	ImapServer   string
+}
+
+func (c *Config) validate() bool {
+	return c.ImapUsername != "" && c.ImapServer != "" && c.ImapPassword != ""
+}
+
+// NewConfig creates and validated a new Config struct from environment variables
+func NewConfig() (*Config, error) {
+	config := &Config{
+		ImapServer:   os.Getenv("IMAP_SERVER"),
+		ImapUsername: os.Getenv("IMAP_USERNAME"),
+		ImapPassword: os.Getenv("IMAP_PASSWORD"),
+	}
+
+	if !config.validate() {
+		return nil, errors.New("not all needed configuration flags could be found")
+	}
+
+	return config, nil
+}
+
+var config *Config
+
+func countMailsInMailbox(mailbox string) (uint32, error) {
+	c, err := client.DialTLS(config.ImapServer, nil)
+	if err != nil {
+		return 0, err
+	}
+
+	defer c.Logout()
+
+	// Login
+	if err := c.Login(config.ImapUsername, config.ImapPassword); err != nil {
+		return 0, err
+	}
+
+	// Select INBOX
+	mbox, err := c.Select(mailbox, true)
+	if err != nil {
+		return 0, err
+	}
+
+	return mbox.Messages, nil
+}
+
+func main() {
+	// We can ignore errors here, because the config might be set from environment variables
+	_ = godotenv.Load()
+
+	// Intialize Config
+	conf, err := NewConfig()
+	if err != nil {
+		log.Fatalf("Could not load configuration: %v", err)
+	}
+
+	config = conf
+
+	http.HandleFunc("/-/health", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte("Healthy"))
+	})
+
+	http.HandleFunc("/probe", func(w http.ResponseWriter, r *http.Request) {
+		mailbox := r.URL.Query().Get("mailbox")
+		if mailbox == "" {
+			http.Error(w, "Mailbox parameter is missing", http.StatusBadRequest)
+			return
+		}
+
+		probeCountGauge := prometheus.NewGauge(prometheus.GaugeOpts{
+			Name: "probe_mailbox_count",
+			Help: "Displays the count of mails found in the mailbox",
+		})
+
+		registry := prometheus.NewRegistry()
+		registry.MustRegister(probeCountGauge)
+
+		// TODO: Proper error handling
+		count, err := countMailsInMailbox(mailbox)
+		if err != nil {
+			http.Error(w, fmt.Sprintf("Cound not load mailbox data: %v", err), http.StatusInternalServerError)
+			return
+		}
+
+		probeCountGauge.Set(float64(count))
+
+		h := promhttp.HandlerFor(registry, promhttp.HandlerOpts{})
+		h.ServeHTTP(w, r)
+	})
+
+	http.Handle("/metrics", promhttp.Handler())
+
+	log.Fatal(http.ListenAndServe(":9101", nil))
+}