Merge pull request #7 from nchlswhttkr/config-file

Load environment variables from a config file

Closes #1

Author: hugomd

README.md

@@ -25,12 +25,28 @@ docker run -d --restart always \
   hugomd/cloudflare-ddns -duration 2h
 ```
 
+You can load environment variables through a config file of key/value pairs.
+
+```sh
+echo "PROVIDER=YOUR_PROVIDER" > config.env
+docker run \
+  -v $PWD/config.env:/tmp/config.env \
+  hugomd/cloudflare-ddns -config /tmp/config.env
+```
+
 # Supported Providers
 
 | Provider                             | Reference (used for `PROVIDER` environment variable) |
 |--------------------------------------|------------------------------------------------------|
 | [Cloudflare](https://cloudflare.com) | `cloudflare`                                         |
 
+# CLI
+
+| Parameter             | Description                                                                                                                                                                | Example           | Required |
+|-----------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------|----------|
+| `-duration`           | Runs program perpetually and recheck after specified interval; parses time strings such as `5m`, `15m`, `2h30m5s`. If not specified, or if equal to 0s, run once and exit. | 2h                | `false`  |
+| `-config`             | Loads environment variables from a given file. Variables should be specified as lines of `key=value` pairs. No variables will be loaded if a file is not specified.        | `/tmp/config.env` | `false`  |
+
 # Environment Variables
 
 All providers require the following environment variable:
@@ -48,10 +64,6 @@ All providers require the following environment variable:
 | `CLOUDFLARE_HOST`               | The record you want to update                                                                                           | `subdomain.example.com` | `true`   |
 | `CLOUDFLARE_EMAIL`              | Email associated with your Cloudflare account                                                                           | `[email protected]`  | `true`   |
 
-| Parameter             | Description                                                                                                                                                                | Example       | Required |
-|-----------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|----------|
-| `-duration`           | Runs program perpetually and recheck after specified interval; parses time strings such as `5m`, `15m`, `2h30m5s`. If not specified, or if equal to 0s, run once and exit. | 2h            | `false`  |
-
 # Contributing
 
 ## Adding a new provider

main.go

@@ -9,6 +9,7 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"strings"
 	"time"
 )
 
@@ -27,11 +28,29 @@ func checkIP() (string, error) {
 	return string(bytes.TrimSpace(buf)), nil
 }
 
+func setEnvVarsFromConfig(filename *string) error {
+	contents, err := ioutil.ReadFile(*filename)
+	if err != nil {
+		return err
+	}
+
+	lines := strings.Split(string(contents), "\n")
+	for _, line := range lines {
+		if strings.Contains(line, "=") {
+			values := strings.SplitN(line, "=", 2)
+			os.Setenv(values[0], values[1])
+		}
+	}
+
+	return nil
+}
+
 func main() {
 	var runonce bool
 	var ticker *time.Ticker
 
 	CheckDuration := flag.Duration("duration", 0, "update interval (ex. 15s, 1m, 6h); if not specified or set to 0s, run only once and exit")
+	ConfigFile := flag.String("config", "", "location of an (optional) config file to load environment variables from")
 	flag.Parse()
 
 	if *CheckDuration == time.Duration(0) {
@@ -40,6 +59,13 @@ func main() {
 		ticker = time.NewTicker(*CheckDuration)
 	}
 
+	if *ConfigFile != "" {
+		err := setEnvVarsFromConfig(ConfigFile)
+		if err != nil {
+			panic(err)
+		}
+	}
+
 	runddns()
 
 	if runonce {