feat(config): add body_size_limit to TOML config (#42)

* feat(config): add body_size_limit to toml config

* docs: document body_size_limit in readme and example config

Author: pgagnidze

README.md

@@ -289,6 +289,7 @@ headers = ["Authorization: Bearer token"]
 **Global settings** (apply to all targets unless overridden):
 
 - `refresh_interval`, `timeout`, `follow_redirects`, `accept_redirects`, `receive_alert`, `count`
+- `body_size_limit`: Response body cap in bytes (default `1048576` = 1 MiB; `0` means no limit)
 - `webhook_url`, `webhook_headers`: Default webhook settings
 - `only`, `skip`: Target filtering arrays
 - `regions`: AWS regions for remote executors
@@ -299,9 +300,12 @@ headers = ["Authorization: Bearer token"]
 - `method`, `headers`, `body`: HTTP request options
 - `assert_text`, `should_fail`: Response validation
 - `skip_ssl`, `follow_redirects`, `accept_redirects`: Connection options
+- `body_size_limit`: Per-target response body cap (set to `0` to disable capping for this target)
 - `webhook_url`, `webhook_headers`: Per-target notifications
 - `regions`: Target-specific AWS regions
 
+> **Note:** Response bodies are capped at `body_size_limit` bytes when evaluating `assert_text`. If your asserted text appears beyond the cap, the assertion fails and the probe logs a warning (visible in the Recent Logs widget in TUI mode, or on stderr in simple mode). Raise `body_size_limit` or set it to `0` for targets returning large payloads.
+
 ## Multi-Region Monitoring
 
 Deploy remote executors as AWS Lambda functions across 13 global regions for distributed monitoring from multiple geographic locations.

aws/invocation.go

@@ -26,6 +26,7 @@ type LambdaRequest struct {
 	SkipSSL         bool     `json:"skip_ssl"`
 	AssertText      string   `json:"assert_text"`
 	ShouldFail      bool     `json:"should_fail"`
+	BodySizeLimit   int64    `json:"body_size_limit,omitempty"`
 }
 
 type LambdaResponse struct {
@@ -111,6 +112,7 @@ func invokeLambdaInRegion(url string, config net.NetworkConfig, region string, p
 		SkipSSL:         config.SkipSSL,
 		AssertText:      config.AssertText,
 		ShouldFail:      config.ShouldFail,
+		BodySizeLimit:   config.BodySizeLimit,
 	}
 
 	payload, err := json.Marshal(request)

config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"time"
 
+	"github.com/Owloops/updo/net"
 	"github.com/spf13/viper"
 )
 
@@ -29,6 +30,7 @@ type Target struct {
 	WebhookURL      string   `mapstructure:"webhook_url"`
 	WebhookHeaders  []string `mapstructure:"webhook_headers"`
 	Regions         []string `mapstructure:"regions"`
+	BodySizeLimit   *int64   `mapstructure:"body_size_limit"`
 }
 
 // BoolVal returns the value of a *bool, or the fallback if nil.
@@ -39,6 +41,14 @@ func BoolVal(p *bool, fallback bool) bool {
 	return fallback
 }
 
+// Int64Val returns the value of an *int64, or the fallback if nil.
+func Int64Val(p *int64, fallback int64) int64 {
+	if p != nil {
+		return *p
+	}
+	return fallback
+}
+
 type Global struct {
 	RefreshInterval int      `mapstructure:"refresh_interval"`
 	Timeout         int      `mapstructure:"timeout"`
@@ -55,6 +65,7 @@ type Global struct {
 	WebhookURL      string   `mapstructure:"webhook_url"`
 	WebhookHeaders  []string `mapstructure:"webhook_headers"`
 	Regions         []string `mapstructure:"regions"`
+	BodySizeLimit   int64    `mapstructure:"body_size_limit"`
 }
 
 type Config struct {
@@ -72,6 +83,7 @@ func LoadConfig(configFile string) (*Config, error) {
 	viper.SetDefault("global.receive_alert", true)
 	viper.SetDefault("global.count", 0)
 	viper.SetDefault("global.method", _defaultMethod)
+	viper.SetDefault("global.body_size_limit", net.DefaultBodySizeLimit)
 
 	if err := viper.ReadInConfig(); err != nil {
 		return nil, err
@@ -110,6 +122,10 @@ func LoadConfig(configFile string) (*Config, error) {
 			v := config.Global.SkipSSL
 			target.SkipSSL = &v
 		}
+		if target.BodySizeLimit == nil {
+			v := config.Global.BodySizeLimit
+			target.BodySizeLimit = &v
+		}
 		if target.WebhookURL == "" && config.Global.WebhookURL != "" {
 			target.WebhookURL = config.Global.WebhookURL
 		}

config/config_test.go

@@ -4,6 +4,8 @@ import (
 	"os"
 	"testing"
 	"time"
+
+	"github.com/Owloops/updo/net"
 )
 
 func TestLoadConfig(t *testing.T) {
@@ -151,6 +153,104 @@ name = "Inherit"
 	}
 }
 
+// TestBodySizeLimitInheritance verifies that a target inherits
+// global.body_size_limit when unset, overrides when explicitly set,
+// and supports 0 as "unlimited".
+func TestBodySizeLimitInheritance(t *testing.T) {
+	configContent := `
+[global]
+body_size_limit = 2097152
+
+[[targets]]
+url = "https://inherit.example.com"
+name = "Inherit"
+
+[[targets]]
+url = "https://override.example.com"
+name = "Override"
+body_size_limit = 524288
+
+[[targets]]
+url = "https://unlimited.example.com"
+name = "Unlimited"
+body_size_limit = 0
+`
+
+	tmpFile, err := os.CreateTemp("", "test-config-bodysize-*.toml")
+	if err != nil {
+		t.Fatalf("Failed to create temp file: %v", err)
+	}
+	defer func() {
+		if err := os.Remove(tmpFile.Name()); err != nil {
+			t.Logf("Failed to remove temp file: %v", err)
+		}
+	}()
+
+	if _, err := tmpFile.WriteString(configContent); err != nil {
+		t.Fatalf("Failed to write config: %v", err)
+	}
+	if err := tmpFile.Close(); err != nil {
+		t.Fatalf("Failed to close temp file: %v", err)
+	}
+
+	cfg, err := LoadConfig(tmpFile.Name())
+	if err != nil {
+		t.Fatalf("LoadConfig failed: %v", err)
+	}
+
+	if cfg.Global.BodySizeLimit != 2097152 {
+		t.Errorf("Global.BodySizeLimit = %d, want 2097152", cfg.Global.BodySizeLimit)
+	}
+
+	if got := Int64Val(cfg.Targets[0].BodySizeLimit, -1); got != 2097152 {
+		t.Errorf("Inherit target: BodySizeLimit = %d, want 2097152 (inherited)", got)
+	}
+	if got := Int64Val(cfg.Targets[1].BodySizeLimit, -1); got != 524288 {
+		t.Errorf("Override target: BodySizeLimit = %d, want 524288", got)
+	}
+	if got := Int64Val(cfg.Targets[2].BodySizeLimit, -1); got != 0 {
+		t.Errorf("Unlimited target: BodySizeLimit = %d, want 0 (explicit unlimited)", got)
+	}
+}
+
+// TestBodySizeLimitDefault verifies that when neither global nor target
+// set body_size_limit, the viper default of net.DefaultBodySizeLimit applies.
+func TestBodySizeLimitDefault(t *testing.T) {
+	configContent := `
+[[targets]]
+url = "https://example.com"
+`
+
+	tmpFile, err := os.CreateTemp("", "test-config-bodysize-default-*.toml")
+	if err != nil {
+		t.Fatalf("Failed to create temp file: %v", err)
+	}
+	defer func() {
+		if err := os.Remove(tmpFile.Name()); err != nil {
+			t.Logf("Failed to remove temp file: %v", err)
+		}
+	}()
+
+	if _, err := tmpFile.WriteString(configContent); err != nil {
+		t.Fatalf("Failed to write config: %v", err)
+	}
+	if err := tmpFile.Close(); err != nil {
+		t.Fatalf("Failed to close temp file: %v", err)
+	}
+
+	cfg, err := LoadConfig(tmpFile.Name())
+	if err != nil {
+		t.Fatalf("LoadConfig failed: %v", err)
+	}
+
+	if cfg.Global.BodySizeLimit != net.DefaultBodySizeLimit {
+		t.Errorf("Global.BodySizeLimit = %d, want %d (default)", cfg.Global.BodySizeLimit, net.DefaultBodySizeLimit)
+	}
+	if got := Int64Val(cfg.Targets[0].BodySizeLimit, -1); got != net.DefaultBodySizeLimit {
+		t.Errorf("Target BodySizeLimit = %d, want %d (default inherited)", got, net.DefaultBodySizeLimit)
+	}
+}
+
 func TestLoadConfigDefaults(t *testing.T) {
 	configContent := `
 [[targets]]

example-config.toml

@@ -6,6 +6,7 @@ accept_redirects = false
 receive_alert = false
 count = 0
 skip = ["GitHub-API"]
+# body_size_limit = 1048576  # Cap response body reads at 1 MiB (default); 0 = no limit
 # regions = ["us-east-1", "eu-central-1", "ap-southeast-1"]
 
 [[targets]]

lambda/lambda.go

@@ -48,6 +48,7 @@ type CheckRequest struct {
 	SkipSSL         bool     `json:"skip_ssl"`
 	AssertText      string   `json:"assert_text"`
 	ShouldFail      bool     `json:"should_fail"`
+	BodySizeLimit   int64    `json:"body_size_limit,omitempty"`
 }
 
 type CheckResponse struct {
@@ -110,7 +111,7 @@ func handleRequest(ctx context.Context, req CheckRequest) (CheckResponse, error)
 		Headers:         req.Headers,
 		Method:          req.Method,
 		Body:            req.Body,
-		BodySizeLimit:   net.DefaultBodySizeLimit,
+		BodySizeLimit:   req.BodySizeLimit,
 	}
 
 	result := net.CheckWebsite(req.URL, netConfig)

simple/monitoring.go

@@ -214,7 +214,7 @@ func monitorTargetSimple(ctx context.Context, target config.Target, targetIndex
 			Headers:         target.Headers,
 			Method:          target.Method,
 			Body:            target.Body,
-			BodySizeLimit:   net.DefaultBodySizeLimit,
+			BodySizeLimit:   config.Int64Val(target.BodySizeLimit, net.DefaultBodySizeLimit),
 		}
 
 		regions := target.Regions

tui/monitoring.go

@@ -279,7 +279,7 @@ func monitorTargetTUI(ctx context.Context, target config.Target, targetIndex int
 			Headers:         target.Headers,
 			Method:          target.Method,
 			Body:            target.Body,
-			BodySizeLimit:   net.DefaultBodySizeLimit,
+			BodySizeLimit:   config.Int64Val(target.BodySizeLimit, net.DefaultBodySizeLimit),
 		}
 
 		regions := target.Regions