feat: make write request public

We have a use case where manipulating the information we have to shape
them as influxdb.Metric is very expensive. We already have the line
protocol for them.

This change allow us to pass the line protocol directly to the Write
function without having to do any extra manipulation.

Signed-off-by: Gianluca Arbezzano <[email protected]>
Co-Authored-by: Chris Goller  <[email protected]>

write.go

@@ -41,7 +41,13 @@ func (c *Client) Write(ctx context.Context, bucket, org string, m ...Metric) (n
 		}
 	}
 
-	req, err := c.makeWriteRequest(bucket, org, buf)
+	var req *http.Request
+
+	if c.contentEncoding == "gzip" {
+		req, err = NewWriteGzipRequest(c.url, c.userAgent, c.authorization, bucket, org, c.compressionLevel, buf)
+	} else {
+		req, err = NewWriteRequest(c.url, c.userAgent, c.authorization, bucket, org, buf)
+	}
 	if err != nil {
 		return 0, err
 	}
@@ -78,16 +84,13 @@ func parseInt32(v string) (int32, error) {
 	return int32(retry), nil
 }
 
-func (c *Client) makeWriteRequest(bucket, org string, body io.Reader) (*http.Request, error) {
-	var err error
-	if c.contentEncoding == "gzip" {
-		body, err = gzip.CompressWithGzip(body, c.compressionLevel)
-		if err != nil {
-			return nil, err
-		}
+func NewWriteGzipRequest(url *url.URL, userAgent, token, bucket, org string, compressionLevel int, body io.Reader) (*http.Request, error) {
+	body, err := gzip.CompressWithGzip(body, compressionLevel)
+	if err != nil {
+		return nil, err
 	}
 
-	u, err := makeWriteURL(c.url, bucket, org)
+	u, err := makeWriteURL(url, bucket, org)
 	if err != nil {
 		return nil, err
 	}
@@ -98,14 +101,26 @@ func (c *Client) makeWriteRequest(bucket, org string, body io.Reader) (*http.Req
 	}
 
 	req.Header.Set("Content-Type", "text/plain; charset=utf-8")
+	req.Header.Set("Content-Encoding", "gzip")
+	req.Header.Set("User-Agent", userAgent)
+	req.Header.Set("Authorization", token)
+	return req, nil
+}
 
-	if c.contentEncoding == "gzip" {
-		req.Header.Set("Content-Encoding", "gzip")
+func NewWriteRequest(url *url.URL, userAgent, token, bucket, org string, body io.Reader) (*http.Request, error) {
+	u, err := makeWriteURL(url, bucket, org)
+	if err != nil {
+		return nil, err
 	}
 
-	req.Header.Set("User-Agent", c.userAgent)
-	req.Header.Set("Authorization", c.authorization)
+	req, err := http.NewRequest(http.MethodPost, u, body)
+	if err != nil {
+		return nil, err
+	}
 
+	req.Header.Set("Content-Type", "text/plain; charset=utf-8")
+	req.Header.Set("User-Agent", userAgent)
+	req.Header.Set("Authorization", token)
 	return req, nil
 }