feat(backends): support reading API keys from external key files

README.md

@@ -64,6 +64,8 @@ The config file is resolved in the following order:
 
 ### Backends
 
+For backends requiring an API key, you can specify the key directly with `*-api-key` or provide a path to a key file using `*-api-key-file` (e.g. `owm-api-key-file=/path/to/key.txt`). When both are specified, `*-api-key` takes precedence.
+
 __[Open-Meteo](https://open-meteo.com/)__ — free, no API key required:
 ```
 backend=openmeteo

backends/apikey.go

@@ -0,0 +1,26 @@
+package backends
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+// ResolveAPIKey determines the API key to use based on key and keyFile.
+// If key is non-empty, it takes precedence and is returned directly.
+// If key is empty and keyFile is non-empty, the contents of keyFile are read
+// with any trailing whitespace and newlines trimmed.
+// If both key and keyFile are empty, an empty string and nil error are returned.
+func ResolveAPIKey(key, keyFile string) (string, error) {
+	if key != "" {
+		return key, nil
+	}
+	if keyFile == "" {
+		return "", nil
+	}
+	data, err := os.ReadFile(keyFile)
+	if err != nil {
+		return "", fmt.Errorf("unable to read api key file %s: %w", keyFile, err)
+	}
+	return strings.TrimRight(string(data), "\r\n \t"), nil
+}

backends/apikey_test.go

@@ -0,0 +1,177 @@
+package backends
+
+import (
+	"flag"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestResolveAPIKey_InlineKey(t *testing.T) {
+	key, err := ResolveAPIKey("inline-secret", "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if key != "inline-secret" {
+		t.Fatalf("expected 'inline-secret', got '%s'", key)
+	}
+}
+
+func TestResolveAPIKey_KeyFromFile(t *testing.T) {
+	tmpDir := t.TempDir()
+	keyPath := filepath.Join(tmpDir, "key.txt")
+	expectedKey := "test-secret-key-12345"
+
+	if err := os.WriteFile(keyPath, []byte(expectedKey), 0600); err != nil {
+		t.Fatalf("failed to create temp key file: %v", err)
+	}
+
+	key, err := ResolveAPIKey("", keyPath)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if key != expectedKey {
+		t.Fatalf("expected '%s', got '%s'", expectedKey, key)
+	}
+}
+
+func TestResolveAPIKey_TrailingWhitespaceAndNewlines(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	testCases := []struct {
+		name     string
+		content  string
+		expected string
+	}{
+		{
+			name:     "trailing newline",
+			content:  "my-secret-key\n",
+			expected: "my-secret-key",
+		},
+		{
+			name:     "trailing CRLF",
+			content:  "my-secret-key\r\n",
+			expected: "my-secret-key",
+		},
+		{
+			name:     "trailing spaces and tabs",
+			content:  "my-secret-key \t  ",
+			expected: "my-secret-key",
+		},
+		{
+			name:     "multiple trailing newlines and spaces",
+			content:  "my-secret-key \r\n\n\t  \n",
+			expected: "my-secret-key",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			filePath := filepath.Join(tmpDir, tc.name+".txt")
+			if err := os.WriteFile(filePath, []byte(tc.content), 0600); err != nil {
+				t.Fatalf("failed to write test key file: %v", err)
+			}
+
+			key, err := ResolveAPIKey("", filePath)
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if key != tc.expected {
+				t.Fatalf("expected '%s', got '%s'", tc.expected, key)
+			}
+		})
+	}
+}
+
+func TestResolveAPIKey_Precedence(t *testing.T) {
+	tmpDir := t.TempDir()
+	keyPath := filepath.Join(tmpDir, "file_key.txt")
+
+	if err := os.WriteFile(keyPath, []byte("file-key-value"), 0600); err != nil {
+		t.Fatalf("failed to write temp key file: %v", err)
+	}
+
+	// When both inline key and key file are present, inline key must take precedence
+	key, err := ResolveAPIKey("inline-key-value", keyPath)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if key != "inline-key-value" {
+		t.Fatalf("expected 'inline-key-value', got '%s'", key)
+	}
+
+	// Even if keyFile points to a non-existent file, inline key must still succeed without error
+	nonExistentPath := filepath.Join(tmpDir, "non_existent.txt")
+	key, err = ResolveAPIKey("inline-key-value", nonExistentPath)
+	if err != nil {
+		t.Fatalf("unexpected error when inline key takes precedence over missing file: %v", err)
+	}
+	if key != "inline-key-value" {
+		t.Fatalf("expected 'inline-key-value', got '%s'", key)
+	}
+}
+
+func TestResolveAPIKey_MissingFile(t *testing.T) {
+	nonExistentPath := filepath.Join(t.TempDir(), "does_not_exist.txt")
+
+	key, err := ResolveAPIKey("", nonExistentPath)
+	if err == nil {
+		t.Fatalf("expected error for missing key file, got nil with key '%s'", key)
+	}
+	if key != "" {
+		t.Fatalf("expected empty key on error, got '%s'", key)
+	}
+}
+
+func TestResolveAPIKey_BothEmpty(t *testing.T) {
+	key, err := ResolveAPIKey("", "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if key != "" {
+		t.Fatalf("expected empty key, got '%s'", key)
+	}
+}
+
+func TestBackendFlagsRegistered(t *testing.T) {
+	// Call Setup on all backend configurations to ensure flags are registered
+	owm := &openWeatherConfig{}
+	owm.Setup()
+
+	caiyun := &CaiyunConfig{}
+	caiyun.Setup()
+
+	openmeteo := &openmeteoConfig{}
+	openmeteo.Setup()
+
+	pirate := &pirateweatherConfig{}
+	pirate.Setup()
+
+	weather := &weatherApiConfig{}
+	weather.Setup()
+
+	wwo := &wwoConfig{}
+	wwo.Setup()
+
+	expectedFlags := []string{
+		"owm-api-key",
+		"owm-api-key-file",
+		"caiyun-api-key",
+		"caiyun-api-key-file",
+		"openmeteo-api-key",
+		"openmeteo-api-key-file",
+		"pirateweather-api-key",
+		"pirateweather-api-key-file",
+		"weather-api-key",
+		"weather-api-key-file",
+		"wwo-api-key",
+		"wwo-api-key-file",
+	}
+
+	for _, flagName := range expectedFlags {
+		f := flag.Lookup(flagName)
+		if f == nil {
+			t.Errorf("expected flag %s to be registered, but was nil", flagName)
+		}
+	}
+}

backends/caiyun.go

@@ -20,13 +20,15 @@ const (
 )
 
 type CaiyunConfig struct {
-	apiKey string
-	lang   string
-	debug  bool
+	apiKey     string
+	apiKeyFile string
+	lang       string
+	debug      bool
 }
 
 func (c *CaiyunConfig) Setup() {
 	flag.StringVar(&c.apiKey, "caiyun-api-key", "", "caiyun backend: the api `KEY` to use")
+	flag.StringVar(&c.apiKeyFile, "caiyun-api-key-file", "", "caiyun backend: the path to a `FILE` containing the api key")
 	flag.StringVar(&c.lang, "caiyun-lang", "en", "caiyun backend: the `LANGUAGE` to request from caiyunapp.com/")
 	flag.BoolVar(&c.debug, "caiyun-debug", true, "caiyun backend: print raw requests and responses")
 }
@@ -143,6 +145,12 @@ func (c *CaiyunConfig) GetWeatherDataFromLocalBegin(lng float64, lat float64, nu
 }
 
 func (c *CaiyunConfig) Fetch(location string, numdays int) iface.Data {
+	apiKey, err := ResolveAPIKey(c.apiKey, c.apiKeyFile)
+	if err != nil {
+		log.Fatalf("Failed to read caiyun API key file: %v\n", err)
+	}
+	c.apiKey = apiKey
+
 	if c.debug {
 		log.Printf("caiyun location %v", location)
 	}

backends/open-meteo.com.go

@@ -15,8 +15,9 @@ import (
 )
 
 type openmeteoConfig struct {
-	apiKey string
-	debug  bool
+	apiKey     string
+	apiKeyFile string
+	debug      bool
 }
 
 type curCond struct {
@@ -108,6 +109,7 @@ var (
 
 func (opmeteo *openmeteoConfig) Setup() {
 	flag.StringVar(&opmeteo.apiKey, "openmeteo-api-key", "", "openmeteo backend: the api `KEY` to use if commercial usage")
+	flag.StringVar(&opmeteo.apiKeyFile, "openmeteo-api-key-file", "", "openmeteo backend: the path to a `FILE` containing the api key if commercial usage")
 	flag.BoolVar(&opmeteo.debug, "openmeteo-debug", false, "openmeteo backend: print raw requests and responses")
 }
 
@@ -165,6 +167,12 @@ func (opmeteo *openmeteoConfig) Fetch(location string, numdays int) iface.Data {
 	var params []string
 	var loc string
 
+	apiKey, err := ResolveAPIKey(opmeteo.apiKey, opmeteo.apiKeyFile)
+	if err != nil {
+		log.Fatalf("Failed to read openmeteo API key file: %v\n", err)
+	}
+	opmeteo.apiKey = apiKey
+
 	if numdays <= 0 {
 		log.Fatal("Number of days less than 1 ")
 	}

backends/openweathermap.org.go

@@ -16,9 +16,10 @@ import (
 )
 
 type openWeatherConfig struct {
-	apiKey string
-	lang   string
-	debug  bool
+	apiKey     string
+	apiKeyFile string
+	lang       string
+	debug      bool
 }
 
 type openWeatherResponse struct {
@@ -72,6 +73,7 @@ const (
 
 func (c *openWeatherConfig) Setup() {
 	flag.StringVar(&c.apiKey, "owm-api-key", "", "openweathermap backend: the api `KEY` to use")
+	flag.StringVar(&c.apiKeyFile, "owm-api-key-file", "", "openweathermap backend: the path to a `FILE` containing the api key")
 	flag.StringVar(&c.lang, "owm-lang", "en", "openweathermap backend: the `LANGUAGE` to request from openweathermap")
 	flag.BoolVar(&c.debug, "owm-debug", false, "openweathermap backend: print raw requests and responses")
 }
@@ -280,9 +282,14 @@ func (c *openWeatherConfig) Fetch(location string, numdays int) iface.Data {
 	var ret iface.Data
 	loc := ""
 
-	if len(c.apiKey) == 0 {
+	apiKey, err := ResolveAPIKey(c.apiKey, c.apiKeyFile)
+	if err != nil {
+		log.Fatalf("Failed to read openweathermap.org API key file: %v\n", err)
+	}
+	if len(apiKey) == 0 {
 		log.Fatal("No openweathermap.org API key specified.\nYou have to register for one at https://home.openweathermap.org/users/sign_up")
 	}
+	c.apiKey = apiKey
 	if matched, err := regexp.MatchString(`^-?[0-9]*(\.[0-9]+)?,-?[0-9]*(\.[0-9]+)?$`, location); matched && err == nil {
 		s := strings.Split(location, ",")
 		loc = fmt.Sprintf("lat=%s&lon=%s", s[0], s[1])

backends/pirateweather.net.go

@@ -19,19 +19,26 @@ const (
 )
 
 type pirateweatherConfig struct {
-	apiKey string
-	debug  bool
+	apiKey     string
+	apiKeyFile string
+	debug      bool
 }
 
 func (c *pirateweatherConfig) Setup() {
 	flag.StringVar(&c.apiKey, "pirateweather-api-key", "", "pirateweather backend: the api `KEY` to use")
+	flag.StringVar(&c.apiKeyFile, "pirateweather-api-key-file", "", "pirateweather backend: the path to a `FILE` containing the api key")
 	flag.BoolVar(&c.debug, "pirateweather-debug", false, "pirateweather backend: print raw req and res")
 }
 
 func (c *pirateweatherConfig) Fetch(location string, numdays int) iface.Data {
-	if c.apiKey == "" {
+	apiKey, err := ResolveAPIKey(c.apiKey, c.apiKeyFile)
+	if err != nil {
+		log.Fatalf("Failed to read pirateweather.net API key file: %v\n", err)
+	}
+	if apiKey == "" {
 		log.Fatal("No pirateweather.net API key specified.\nYou have to register for one at https://pirateweather.net/")
 	}
+	c.apiKey = apiKey
 
 	if c.debug {
 		log.Printf("pirateweather location %v", location)

backends/weatherapi.com.go

@@ -57,9 +57,10 @@ type hourlyWeather struct {
 }
 
 type weatherApiConfig struct {
-	apiKey string
-	debug  bool
-	lang   string
+	apiKey     string
+	apiKeyFile string
+	debug      bool
+	lang       string
 }
 
 const (
@@ -122,6 +123,7 @@ var (
 
 func (c *weatherApiConfig) Setup() {
 	flag.StringVar(&c.apiKey, "weather-api-key", "", "weatherapi backend: the api `Key` to use")
+	flag.StringVar(&c.apiKeyFile, "weather-api-key-file", "", "weatherapi backend: the path to a `FILE` containing the api key")
 	flag.StringVar(&c.lang, "weather-api-lang", "en", "weatherapi backend: the `LANGUAGE` to request from weatherapi")
 	flag.BoolVar(&c.debug, "weather-api-debug", false, "weatherapi backend: print raw requests and responses")
 }
@@ -218,9 +220,14 @@ func (c *weatherApiConfig) parseCurCond(forecastInfo currentCond) (iface.Cond, e
 func (c *weatherApiConfig) Fetch(location string, numdays int) iface.Data {
 	var ret iface.Data
 
-	if len(c.apiKey) == 0 {
+	apiKey, err := ResolveAPIKey(c.apiKey, c.apiKeyFile)
+	if err != nil {
+		log.Fatalf("Failed to read weatherapi.com API key file: %v\n", err)
+	}
+	if len(apiKey) == 0 {
 		log.Fatal("No weatherapi.com API key specified.\nYou have to register for one at https://weatherapi.com/signup.aspx")
 	}
+	c.apiKey = apiKey
 
 	resp, err := c.fetch(
 		fmt.Sprintf(weatherApiURI, c.apiKey, location, strconv.Itoa(numdays), c.lang),