Fix PDF rendering (#252)

* Fix pdf rendering issues

* Fix pdf rendering issues

* Update README.md

README.md

@@ -404,24 +404,7 @@ Options:
       --workers int             The number of workers to scan (default 5)
 ```
 
-The listed options can be passed to GoTestWAF as follows:
-
-* If running the GoTestWAF Docker container, pass the configuration options in the `docker run` command after the Docker image name.
-
-    For example, to run GoTestWAF with WebSocket check, you can specify the WebSocket URL via the `wsURL` option:
-
-    ```sh
-    docker run --rm --network="host" -it -v ${PWD}/reports:/app/reports \
-        wallarm/gotestwaf --url=http://127.0.0.1:8080/ --wsURL=ws://127.0.0.1:8080/api/ws
-    ```
-
-* If running GoTestWAF with `go run`, pass the configuration options and its values as the parameters for the main script.
-
-    For example, to run GoTestWAF with WebSocket check, you can specify the WebSocket URL via the `wsURL` option:
-
-    ```sh
-    go run ./cmd --url=http://127.0.0.1:8080/ --wsURL=ws://127.0.0.1:8080/api/ws
-    ```
+GoTestWAF supports two HTTP clients for performing requests, selectable via the `--httpClient` option. The default client is the standard Golang HTTP client. The second option is Chrome, which can be used with the `--httpClient=chrome` CLI argument. Note that on Linux systems, you must add the `--cap-add=SYS_ADMIN` argument to the Docker arguments to run GoTestWAF with Chrome as the request performer.
 
 ### Report name
 

internal/report/render.go

@@ -9,9 +9,31 @@ import (
 	"github.com/pkg/errors"
 )
 
+// chromium-browser \
+// --headless \
+// --no-zygote \
+// --single-process \
+// --no-sandbox \
+// --disable-gpu \
+// --run-all-compositor-stages-before-draw \
+// --no-pdf-header-footer \
+// --print-to-pdf=test.pdf \
+// report.html
+
+var chromeDPExecAllocatorOptions = append(
+	chromedp.DefaultExecAllocatorOptions[:],
+	chromedp.Flag("no-zygote", true),
+	chromedp.Flag("no-sandbox", true),
+	chromedp.Flag("disable-gpu", true),
+	chromedp.Flag("run-all-compositor-stages-before-draw", true),
+)
+
 func renderToPDF(ctx context.Context, fileToRenderURL string, pathToResultPDF string) error {
-	chromeCtx, cancel := chromedp.NewContext(ctx)
-	defer cancel()
+	allocCtx, allocCtxCancel := chromedp.NewExecAllocator(ctx, chromeDPExecAllocatorOptions...)
+	defer allocCtxCancel()
+
+	chromeCtx, chromeCtxCancel := chromedp.NewContext(allocCtx)
+	defer chromeCtxCancel()
 
 	var buf []byte