add support for pi-hole running behind https

This adds support for a new environment variable `PIHOLE_PROTOCOL`,
which defaults to `http`.

README.md

@@ -61,6 +61,21 @@ $ docker run \
   ekofr/pihole-exporter:latest
 ```
 
+If you are running pi-hole behind https, you must both set the `PIHOLE_PROTOCOL` environment variable
+as well as include your ssl certificates to the docker image as it does not have any baked in:
+
+```
+$ docker run \
+  -e 'PIHOLE_PROTOCOL=https' \
+  -e 'PIHOLE_HOSTNAME=192.168.1.2' \
+  -e 'PIHOLE_PASSWORD=mypassword' \
+  -e 'INTERVAL=30s' \
+  -e 'PORT=9617' \
+  -v '/etc/ssl/certs:/etc/ssl/certs:ro' \
+  -p 9617:9617 \
+  ekofr/pihole-exporter:latest
+```
+
 ### From sources
 
 Optionally, you can download and build it from the sources. You have to retrieve the project sources by using one of the following way:

config/configuration.go

@@ -15,6 +15,7 @@ import (
 
 // Config is the exporter CLI configuration.
 type Config struct {
+	PIHoleProtocol string        `config:"pihole_protocol"`
 	PIHoleHostname string        `config:"pihole_hostname"`
 	PIHolePassword string        `config:"pihole_password"`
 	PIHoleApiToken string        `config:"pihole_api_token"`
@@ -24,6 +25,7 @@ type Config struct {
 
 func getDefaultConfig() *Config {
 	return &Config{
+		PIHoleProtocol: "http",
 		PIHoleHostname: "127.0.0.1",
 		PIHolePassword: "",
 		PIHoleApiToken: "",

internal/pihole/client.go

@@ -7,6 +7,7 @@ import (
 	"log"
 	"net/http"
 	"net/url"
+	"os"
 	"strconv"
 	"strings"
 	"time"
@@ -15,14 +16,15 @@ import (
 )
 
 var (
-	loginURLPattern = "http://%s/admin/index.php?login"
-	statsURLPattern = "http://%s/admin/api.php?summaryRaw&overTimeData&topItems&recentItems&getQueryTypes&getForwardDestinations&getQuerySources&jsonForceObject"
+	loginURLPattern = "%s://%s/admin/index.php?login"
+	statsURLPattern = "%s://%s/admin/api.php?summaryRaw&overTimeData&topItems&recentItems&getQueryTypes&getForwardDestinations&getQuerySources&jsonForceObject"
 )
 
 // Client struct is a PI-Hole client to request an instance of a PI-Hole ad blocker.
 type Client struct {
 	httpClient http.Client
 	interval   time.Duration
+	protocol   string
 	hostname   string
 	password   string
 	sessionID  string
@@ -30,8 +32,14 @@ type Client struct {
 }
 
 // NewClient method initializes a new PI-Hole client.
-func NewClient(hostname, password, apiToken string, interval time.Duration) *Client {
+func NewClient(protocol, hostname, password, apiToken string, interval time.Duration) *Client {
+	if protocol != "http" && protocol != "https" {
+		log.Printf("protocol %s is invalid. Must be http or https.", protocol)
+		os.Exit(1)
+	}
+
 	return &Client{
+		protocol: protocol,
 		hostname: hostname,
 		password: password,
 		apiToken: apiToken,
@@ -101,7 +109,7 @@ func (c *Client) setMetrics(stats *Stats) {
 }
 
 func (c *Client) getPHPSessionID() (sessionID string) {
-	loginURL := fmt.Sprintf(loginURLPattern, c.hostname)
+	loginURL := fmt.Sprintf(loginURLPattern, c.protocol, c.hostname)
 	values := url.Values{"pw": []string{c.password}}
 
 	req, err := http.NewRequest("POST", loginURL, strings.NewReader(values.Encode()))
@@ -130,7 +138,7 @@ func (c *Client) getPHPSessionID() (sessionID string) {
 func (c *Client) getStatistics() *Stats {
 	var stats Stats
 
-	statsURL := fmt.Sprintf(statsURLPattern, c.hostname)
+	statsURL := fmt.Sprintf(statsURLPattern, c.protocol, c.hostname)
 
 	if c.isUsingApiToken() {
 		statsURL = fmt.Sprintf("%s&auth=%s", statsURL, c.apiToken)

main.go

@@ -26,14 +26,14 @@ func main() {
 
 	metrics.Init()
 
-	initPiHoleClient(conf.PIHoleHostname, conf.PIHolePassword, conf.PIHoleApiToken, conf.Interval)
+	initPiHoleClient(conf.PIHoleProtocol, conf.PIHoleHostname, conf.PIHolePassword, conf.PIHoleApiToken, conf.Interval)
 	initHttpServer(conf.Port)
 
 	handleExitSignal()
 }
 
-func initPiHoleClient(hostname, password, apiToken string, interval time.Duration) {
-	client := pihole.NewClient(hostname, password, apiToken, interval)
+func initPiHoleClient(protocol, hostname, password, apiToken string, interval time.Duration) {
+	client := pihole.NewClient(protocol, hostname, password, apiToken, interval)
 	go client.Scrape()
 }