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How to get response body in Zuul post filter?

How it is possible to read a response body while using Zuul as a proxy in post filter?

I am trying to call the code like this:

@Component
public class PostFilter extends ZuulFilter {

    private static final Logger log = LoggerFactory.getLogger(PostFilter.class);

    @Override
    public String filterType() {
        return "post";
    }

    @Override
    public int filterOrder() {
        return 2000;
    }

    @Override
    public boolean shouldFilter() {
        return true;
    }

    @Override
    public Object run() {
        RequestContext ctx = RequestContext.getCurrentContext();
        ctx.getResponseBody(); // null

        // cant't do this, cause input stream is used later in other filters and I got InputStream Closed exception
        // GZIPInputStream gzipInputStream = new GZIPInputStream(stream);
        return null;
    }

}

Answer

I’ve managed to overcome this. The solution consists of 4 steps:

  1. Read ctx.getResponseDataStream() into a ByteArrayOutputStream
  2. Copy OutputStream to 2 InputStreams.
  3. Use one of it for your custom purposes.
  4. Use the second to reassign to context: context.setResponseBody(inputStream)
    • reading stream from point 1 would cause that the stream cannot be read again, so this way you’re passing a new fresh stream that wasn’t read yet