SSE are cool.

This an example using the Echo framework in Golang. It sets up the connection, consumes a channel and sends that data to the user. It also exits the loop if the connection is broken, this is communicated via the request context.

func BuildingSSE(c echo.Context) error {
	c.Response().Header().Set(echo.HeaderCacheControl, "no-cache")
	c.Response().Header().Set(echo.HeaderConnection, "keep-alive")
	c.Response().Header().Set(echo.HeaderContentType, "text/event-stream")

	queue := queue.GetBuildQueue()

	ctx := c.Request().Context()
	for {
		select {
		case result := <-queue.BuildLogsChannel:
			fmt.Fprint(c.Response(), buildSSE("message", result))
			c.Response().Flush()
		case <-ctx.Done():
			return nil
		}
	}
}

func buildSSE(event, context string) string {
	var result string
	if len(event) != 0 {
		result = result + "event: " + event + "\n"
	}
	if len(context) != 0 {
		result = result + "data: " + context + "\n"
	}
	result = result + "\n"
	return result
}