Add PreReq option to the sr API

Signed-off-by: Mihai Todor <[email protected]>

pkg/sr/client.go

@@ -64,6 +64,7 @@ type Client struct {
 		pass string
 	}
 	bearerToken string
+	preReq      PreReqFunc
 }
 
 // NewClient returns a new schema registry client.
@@ -144,6 +145,12 @@ start:
 	}
 	cl.applyParams(ctx, req)
 
+	if cl.preReq != nil {
+		if err := cl.preReq(req); err != nil {
+			return fmt.Errorf("pre-request hook failed for %s %q: %w", method, reqURL, err)
+		}
+	}
+
 	resp, err := cl.httpcl.Do(req)
 	if err != nil {
 		if len(urls) == 0 {

pkg/sr/clientopt.go

@@ -85,6 +85,16 @@ func BearerToken(token string) ClientOpt {
 	}}
 }
 
+// PreReqFunc is a hook func which mutates a request.
+type PreReqFunc func(req *http.Request) error
+
+// PreReq sets a hook func to call before every request is sent.
+func PreReq(preReq PreReqFunc) ClientOpt {
+	return clientOpt{func(cl *Client) {
+		cl.preReq = preReq
+	}}
+}
+
 // DefaultParams sets default parameters to apply to every request.
 func DefaultParams(ps ...Param) ClientOpt {
 	return clientOpt{func(cl *Client) {