fix: rewrite download URL host to match HARNESS_BASE_URL for TLS compatibility

Fixes download_execution_logs TLS certificate errors when HARNESS_BASE_URL
is set to a custom/vanity domain (e.g., mycompany.harness.io).

The /blob/download API returns pre-signed URLs hardcoded to app.harness.io.
This rewrites the host to match the configured base URL and uses the
configured HTTP client with its TLS/proxy settings instead of bare http.Get().

Fixes #39

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mehulparmariitr

common/client/client.go

@@ -567,6 +567,13 @@ func (c *Client) RequestRaw(
 	return nil
 }
 
+// HTTPClient returns the underlying *http.Client used by this Client.
+// This is useful when you need to make HTTP requests that don't require
+// auth header injection but should share the same transport/TLS configuration.
+func (c *Client) HTTPClient() *http.Client {
+	return c.client
+}
+
 // Do is a wrapper of http.Client.Do that injects the auth header in the request.
 func (c *Client) Do(r *http.Request) (*http.Response, error) {
 	slog.DebugContext(r.Context(), "Request", "method", r.Method, "url", r.URL.String())

common/client/logs.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"log/slog"
+	"net/url"
 	"time"
 
 	"github.com/harness/mcp-server/common/client/dto"
@@ -99,5 +100,42 @@ func (l *LogService) GetDownloadLogsURL(ctx context.Context, scope dto.Scope, pl
 		return "", lastErr
 	}
 
-	return response.Link, nil
+	// Rewrite the download URL host to match the configured base URL.
+	// The API may return a pre-signed URL with a hardcoded host (e.g., app.harness.io)
+	// that differs from HARNESS_BASE_URL, causing TLS failures in environments with
+	// custom domains or corporate proxies.
+	rewrittenLink, err := rewriteDownloadURLHost(response.Link, l.LogServiceClient.BaseURL)
+	if err != nil {
+		slog.WarnContext(ctx, "Failed to rewrite download URL host, using original URL", "error", err)
+		return response.Link, nil
+	}
+
+	return rewrittenLink, nil
+}
+
+// rewriteDownloadURLHost replaces the host of a download URL with the host from the
+// configured base URL, so that the download request routes through the same trusted
+// endpoint as all other API calls.
+func rewriteDownloadURLHost(downloadLink string, baseURL *url.URL) (string, error) {
+	if baseURL == nil {
+		return downloadLink, nil
+	}
+
+	parsed, err := url.Parse(downloadLink)
+	if err != nil {
+		return "", fmt.Errorf("failed to parse download URL: %w", err)
+	}
+
+	// Only rewrite if the hosts actually differ
+	if parsed.Host == baseURL.Host {
+		return downloadLink, nil
+	}
+
+	slog.Info("Rewriting download URL host to match configured base URL",
+		"original_host", parsed.Host,
+		"new_host", baseURL.Host)
+
+	parsed.Scheme = baseURL.Scheme
+	parsed.Host = baseURL.Host
+	return parsed.String(), nil
 }

common/client/logs_test.go

@@ -0,0 +1,69 @@
+package client
+
+import (
+	"net/url"
+	"testing"
+)
+
+func TestRewriteDownloadURLHost(t *testing.T) {
+	tests := []struct {
+		name         string
+		downloadLink string
+		baseURL      string
+		wantURL      string
+		wantErr      bool
+	}{
+		{
+			name:         "rewrites app.harness.io to custom domain",
+			downloadLink: "https://app.harness.io/storage/harness-download/logs/abc123?token=xyz",
+			baseURL:      "https://mycompany.harness.io",
+			wantURL:      "https://mycompany.harness.io/storage/harness-download/logs/abc123?token=xyz",
+		},
+		{
+			name:         "no rewrite when hosts match",
+			downloadLink: "https://app.harness.io/storage/logs/abc123",
+			baseURL:      "https://app.harness.io",
+			wantURL:      "https://app.harness.io/storage/logs/abc123",
+		},
+		{
+			name:         "nil base URL returns original link",
+			downloadLink: "https://app.harness.io/storage/logs/abc123",
+			baseURL:      "",
+			wantURL:      "https://app.harness.io/storage/logs/abc123",
+		},
+		{
+			name:         "preserves query parameters",
+			downloadLink: "https://app.harness.io/storage/logs?accountID=abc&prefix=key&X-Amz-Signature=sig123",
+			baseURL:      "https://mycompany.harness.io",
+			wantURL:      "https://mycompany.harness.io/storage/logs?accountID=abc&prefix=key&X-Amz-Signature=sig123",
+		},
+		{
+			name:         "preserves path structure",
+			downloadLink: "https://app.harness.io/storage/harness-download/comp-log-service/deep/nested/path.zip",
+			baseURL:      "https://custom.example.com",
+			wantURL:      "https://custom.example.com/storage/harness-download/comp-log-service/deep/nested/path.zip",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var baseURL *url.URL
+			if tt.baseURL != "" {
+				var err error
+				baseURL, err = url.Parse(tt.baseURL)
+				if err != nil {
+					t.Fatalf("failed to parse base URL: %v", err)
+				}
+			}
+
+			got, err := rewriteDownloadURLHost(tt.downloadLink, baseURL)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("rewriteDownloadURLHost() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.wantURL {
+				t.Errorf("rewriteDownloadURLHost() = %v, want %v", got, tt.wantURL)
+			}
+		})
+	}
+}

common/pkg/tools/logs.go

@@ -56,6 +56,7 @@ func NewExtendedLogService(logService *client.LogService) *ExtendedLogService {
 type DownloadLogsConfig struct {
 	MaxLogLines    int                                                                                               // Enforce max lines (0 = use request parameter)
 	GetDownloadURL func(ctx context.Context, scope dto.Scope, planExecutionID string, logKey string) (string, error) // Custom URL fetching logic
+	HTTPClient     *http.Client                                                                                      // HTTP client for downloading logs (inherits TLS/proxy config)
 }
 
 // DefaultDownloadLogsConfig returns the default configuration for downloading logs
@@ -67,6 +68,7 @@ func (l *ExtendedLogService) DefaultDownloadLogsConfig() *DownloadLogsConfig {
 			headers := map[string]string{}
 			return l.GetDownloadLogsURL(ctx, scope, planExecutionID, logKey, headers)
 		},
+		HTTPClient: l.LogService.LogServiceClient.HTTPClient(),
 	}
 }
 
@@ -451,8 +453,13 @@ func DownloadExecutionLogsTool(config *config.McpServerConfig, client LogService
 				return mcp.NewToolResultError(fmt.Sprintf("failed to fetch log download URL: %v", err)), nil
 			}
 
-			// Download the logs into outputPath
-			resp, err := http.Get(logDownloadURL)
+			// Download the logs using the configured HTTP client (inherits TLS/proxy settings)
+			// instead of http.Get which uses the default client with no TLS customization.
+			httpClient := downloadLogsConfig.HTTPClient
+			if httpClient == nil {
+				httpClient = http.DefaultClient
+			}
+			resp, err := httpClient.Get(logDownloadURL)
 			if err != nil {
 				return mcp.NewToolResultError(fmt.Sprintf("failed to download logs: %v", err)), nil
 			}