merge: PR #8 from feature/env-interpolation

feature/env-interpolation

Author: quyxishi

README.md

@@ -178,6 +178,7 @@ You can configure periodic probes using a simple `curl` command in a cron job or
 - [x] Whitebox YAML configuration w/ auto-reload by SIGHUP ([#7](https://github.com/quyxishi/whitebox/pull/7)).
 - [x] Response status/body validation.
 - [x] Custom HTTP-headers qualify support.
+- [x] Configuration environment variables interpolation support.
 - [ ] Authorization/OAuth 2.0 support.
 - [ ] Configuration for TLS protocol of HTTP probe support.
 - [ ] More advanced metrics.

VERSION

@@ -1 +1 @@
-1.0.1
+1.1.0

cmd/api/cli.go

@@ -1,11 +1,7 @@
 package main
 
 import (
-	"log/slog"
-	"os"
-
 	"github.com/alecthomas/kong"
-	"github.com/goccy/go-yaml"
 	"github.com/quyxishi/whitebox/internal/config"
 )
 
@@ -22,20 +18,5 @@ func (h *CLI) LoadConfig() (*config.WhiteboxConfig, error) {
 	}
 
 	// if path provided, load from file
-	file, err := os.Open(h.ConfigPath)
-	if err != nil {
-		return nil, err
-	}
-	defer func() {
-		if err := file.Close(); err != nil {
-			slog.Error("failed to close file instance", "err", err)
-		}
-	}()
-
-	var config config.WhiteboxConfig
-	if err := yaml.NewDecoder(file).Decode(&config); err != nil {
-		return nil, err
-	}
-
-	return &config, nil
+	return config.Load(h.ConfigPath)
 }

cmd/api/main.go

@@ -74,12 +74,12 @@ func main() {
 
 	_, err := parser.Parse(os.Args[1:])
 	if err != nil {
-		parser.FatalIfErrorf(fmt.Errorf("unable to parse cli args due: %w", err))
+		parser.FatalIfErrorf(fmt.Errorf("unable to parse cli args due: %v", err))
 	}
 
 	cfg, err := cli.LoadConfig()
 	if err != nil {
-		parser.FatalIfErrorf(fmt.Errorf("unable to load config file due: %w", err))
+		parser.FatalIfErrorf(fmt.Errorf("unable to load config file due: %v", err))
 	}
 
 	wrapper := config.NewConfigWrapper(cfg)

go.mod

@@ -44,7 +44,7 @@ require (
 	github.com/dgryski/go-metro v0.0.0-20250106013310-edb8663e5e33 // indirect
 	github.com/fsnotify/fsnotify v1.9.0 // indirect
 	github.com/gabriel-vasile/mimetype v1.4.12 // indirect
-	github.com/ghodss/yaml v1.0.1-0.20220118164431-d8423dcdf344
+	github.com/ghodss/yaml v1.0.1-0.20220118164431-d8423dcdf344 // indirect
 	github.com/gin-contrib/sse v1.1.0 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect
 	github.com/go-playground/universal-translator v0.18.1 // indirect

internal/api/v1/probe/handler.go

@@ -43,7 +43,7 @@ import (
 func matchRegularExpression(body []byte, predicate string) (bool, error) {
 	regex, err := regexp.Compile(predicate)
 	if err != nil {
-		return false, fmt.Errorf("failed to compile regex:%s due: %w", predicate, err)
+		return false, fmt.Errorf("failed to compile regex:%s due: %v", predicate, err)
 	}
 
 	return regex.Match(body), nil
@@ -54,17 +54,17 @@ func newCELExpression(predicate string) (*cel.Program, error) {
 		cel.Variable("body", cel.DynType),
 	)
 	if err != nil {
-		return nil, fmt.Errorf("failed to construct CEL environment due: %w", err)
+		return nil, fmt.Errorf("failed to construct CEL environment due: %v", err)
 	}
 
 	ast, issues := env.Compile(predicate)
 	if issues != nil && issues.Err() != nil {
-		return nil, fmt.Errorf("failed to compile CEL:%s due: %w", predicate, issues.Err())
+		return nil, fmt.Errorf("failed to compile CEL:%s due: %v", predicate, issues.Err())
 	}
 
 	celExpr, err := env.Program(ast, cel.InterruptCheckFrequency(100))
 	if err != nil {
-		return nil, fmt.Errorf("failed to construct CEL:%s due: %w", predicate, err)
+		return nil, fmt.Errorf("failed to construct CEL:%s due: %v", predicate, err)
 	}
 
 	return &celExpr, nil
@@ -73,7 +73,7 @@ func newCELExpression(predicate string) (*cel.Program, error) {
 func matchCELExpression(ctx context.Context, body []byte, predicate string) (bool, error) {
 	var bodyJSON any
 	if err := json.Unmarshal(body, &bodyJSON); err != nil {
-		return false, fmt.Errorf("failed to unmarshall http body to json due: %w", err)
+		return false, fmt.Errorf("failed to unmarshall http body to json due: %v", err)
 	}
 
 	evalPayload := map[string]any{
@@ -82,12 +82,12 @@ func matchCELExpression(ctx context.Context, body []byte, predicate string) (boo
 
 	celExpr, err := newCELExpression(predicate)
 	if err != nil {
-		return false, fmt.Errorf("unable to perform CEL validation due: %w", err)
+		return false, fmt.Errorf("unable to perform CEL validation due: %v", err)
 	}
 
 	result, details, err := (*celExpr).ContextEval(ctx, evalPayload)
 	if err != nil {
-		return false, fmt.Errorf("failed to evaluate CEL:%s due: %w", predicate, err)
+		return false, fmt.Errorf("failed to evaluate CEL:%s due: %v", predicate, err)
 	}
 	if result.Type() != cel.BoolType {
 		return false, fmt.Errorf("on CEL:%s evaluation result is not a boolean, details: %v", predicate, details)
@@ -105,7 +105,7 @@ func matchRegularExpressionsOnHeaders(headers http.Header, key string, predicate
 
 	regex, err := regexp.Compile(predicate)
 	if err != nil {
-		return false, fmt.Errorf("failed to compile regex:%s due: %w", predicate, err)
+		return false, fmt.Errorf("failed to compile regex:%s due: %v", predicate, err)
 	}
 
 	for _, v := range values {

internal/config/config.go

@@ -6,7 +6,7 @@ import (
 	"os"
 	"time"
 
-	"github.com/ghodss/yaml"
+	"github.com/goccy/go-yaml"
 )
 
 const DefaultScopeName string = "default"
@@ -45,21 +45,21 @@ func Load(path string) (*WhiteboxConfig, error) {
 		return nil, err
 	}
 
+	expandedData := ExpandEnvironment(data)
+
 	var config WhiteboxConfig
-	if err := yaml.Unmarshal(data, &config); err != nil {
+	if err := yaml.Unmarshal(expandedData, &config); err != nil {
 		slog.Error("unable to parse whitebox config file", "err", err)
 		return nil, err
 	}
 
 	for name, scope := range config.Scopes {
-		if err := scope.Validate(); err != nil {
+		if err := scope.Http.Validate(); err != nil {
 			slog.Error("whitebox scope configuration is invalid", "name", name, "err", err)
-			return nil, fmt.Errorf("invalid scope configuration: %w", err)
+			return nil, fmt.Errorf("invalid scope configuration: %v", err)
 		}
 	}
 
-	// todo! cover case when scope doesn't have http declared
-
 	if _, ok := config.Scopes[DefaultScopeName]; !ok {
 		config.Scopes[DefaultScopeName] = NewScopeRecord()
 	}
@@ -80,25 +80,6 @@ func NewScopeRecord() ScopeRecord {
 	}
 }
 
-// Validate ensures the scope configuration semantic correctness
-func (h *ScopeRecord) Validate() error {
-	for i, rule := range h.Http.FailIf {
-		switch rule.Mod {
-		case FailIf_BodyMatchesRegexp, FailIf_BodyJsonMatchesCEL:
-			// Valid
-		case "":
-			return fmt.Errorf("http.fail_if[%d]: mod is required", i)
-		default:
-			return fmt.Errorf("http.fail_if[%d]: unknown module '%s'", i, rule.Mod)
-		}
-
-		if rule.Val == "" {
-			return fmt.Errorf("http.fail_if[%d]: val (pattern/expression) cannot be empty", i)
-		}
-	}
-	return nil
-}
-
 type HttpRecord struct {
 	// Fallbacks to 5 by default
 	MaxRedirects int `yaml:"max_redirects,omitempty"`
@@ -121,6 +102,25 @@ func NewHttpRecord() HttpRecord {
 	}
 }
 
+// Validate ensures the http configuration semantic correctness
+func (h *HttpRecord) Validate() error {
+	for i, rule := range h.FailIf {
+		switch rule.Mod {
+		case FailIf_SSL, FailIf_BodyMatchesRegexp, FailIf_BodyJsonMatchesCEL, FailIf_HeaderMatchesRegexp, FailIf_StatusCodeMatches:
+			// Valid
+		case "":
+			return fmt.Errorf("http.fail_if[%d]: mod is required", i)
+		default:
+			return fmt.Errorf("http.fail_if[%d]: unknown module '%s'", i, rule.Mod)
+		}
+
+		if rule.Val == "" && rule.Mod != FailIf_SSL {
+			return fmt.Errorf("http.fail_if[%d]: val (pattern/expression) cannot be empty", i)
+		}
+	}
+	return nil
+}
+
 type FailIfRecord struct {
 	// Predicate, see FailIf_* constants modules
 	Mod FailIfModule `yaml:"mod,omitempty"`

internal/config/env.go

@@ -0,0 +1,35 @@
+package config
+
+import (
+	"os"
+	"regexp"
+)
+
+// ${VAR} or ${VAR:-default}
+var envVarRegex = regexp.MustCompile(`\${([A-Za-z_][A-Za-z0-9_]*)(?::-([^}]*))?}`)
+
+// Replaces ${VAR} and ${VAR:-default} with actual environment values.
+func ExpandEnvironment(data []byte) []byte {
+	return envVarRegex.ReplaceAllFunc(data, func(match []byte) []byte {
+		s := string(match)
+
+		// ReplaceAllFunc gives the whole match, not subgroups directly
+		submatches := envVarRegex.FindStringSubmatch(s)
+		if len(submatches) < 2 {
+			return match
+		}
+
+		var defaultValue string
+		if len(submatches) > 2 {
+			defaultValue = submatches[2]
+		}
+
+		// Lookup environment variable
+		val, exists := os.LookupEnv(submatches[1])
+		if !exists {
+			return []byte(defaultValue)
+		}
+
+		return []byte(val)
+	})
+}

internal/serial/parse.go

@@ -96,7 +96,7 @@ func ParseSubscriptionURI(json_sub_uri string, params *ParseSubParams) (out stri
 
 		for _, s := range debugFields {
 			if err := j.Set(s.key, s.val); err != nil {
-				return "", fmt.Errorf("failed to patch config with key '%s': %w", s.key, err)
+				return "", fmt.Errorf("failed to patch config with key '%s': %v", s.key, err)
 			}
 		}
 

whitebox.yml

@@ -33,7 +33,8 @@ scopes:
       method: POST
 
       headers:
-        Authorization: "Bearer dXNlcjpwYXNz"
+        # Environment variables interpolation
+        Authorization: "Bearer ${BEARER_AUTH:-dXNlcjpwYXNz}"
         Content-Type: "application/json"
 
       body: '{"ping": true}'