topic Re: x-dynatrace header max length in Open Q&A

x-dynatrace header max length

Romanenkov_Al3x — Mon, 28 Nov 2022 14:07:56 GMT

Hello. Can anybody tell me - max length of x-dynatrace header. Customer setting up firewall rules, so they need max length all request headers to allow application work, otherwise requests are blocked.

Thanks.

Alex

Re: x-dynatrace header max length

HannahM — Mon, 28 Nov 2022 13:59:18 GMT

I don't believe there is a size limit from a Dynatrace perspective. Typically, the HTTP header size limit is dependent on the server. (Apache, Nginx, IIS, Tomcat)

Re: x-dynatrace header max length

Romanenkov_Al3x — Mon, 28 Nov 2022 14:19:35 GMT

I need value from Dynatrace. Expected answer - for example 200 symbols.

Look like this:

FW4;-712055999;35;-1057699572;862004;0;1310537445;1367;c15c;2h01;3hc0f4c90c;4h0d2734;6h6765016c4c42ea4085044906606ef4e6;7hc487f83ef5f244e3

This header added by Dynatrace. Only Dynatrace can know it. The question is not about web server settings.

Thanks,

Alex

Re: x-dynatrace header max length

harald_berger — Tue, 29 Nov 2022 06:46:11 GMT

Hi,

Unfortunately the header length is not fixed. Depending on the situation encoded binary info will be added to header.

Harry

Re: x-dynatrace header max length

Romanenkov_Al3x — Wed, 30 Nov 2022 09:58:37 GMT

Thanks for fast response.

Re: x-dynatrace header max length

Rene — Thu, 03 Apr 2025 08:15:30 GMT

@harald_berger

Hello Harald,

We use Dynatrace for mainframe Cobol under CICS and have used a TAG buffer length of 100 bytes for the stubs based on the examples in your documentation.

assets.dynatrace.com/global/doc/appmon/integrations-and-extensions/development-kits/agent-development-kit-adk/cics-and-ims-adk/adkcobol.txt

Now it has turned out that the length can also be greater than 100 bytes and we are having problems processing it correctly.

We know that the length is not fixed. In our tests, with different applications, we see lengths of 74 bytes, 85 bytes, 142 bytes.

What length would you recommend so that we can most likely cover all possible cases in the future?

Thanks
BR; Rene

Re: x-dynatrace header max length

harald_berger — Thu, 03 Apr 2025 08:53:44 GMT

Hi Rene,

170 characters should be sufficient, if no custom tags are propagated.

Harry

Re: x-dynatrace header max length

Patrick_H — Thu, 03 Apr 2025 09:26:44 GMT

The x-dynatrace header can contain different content as it is used for e.g. web RUM and mobile RUM - see https://docs.dynatrace.com/docs/shortlink/rum-firewall
For mobile RUM the header content can vary in length, but is just calculated it and a max size of 150 chars for the header value (excluding x-dynatrace: name) should be save.
I can't speak for web RUM here where this header is set on OneAgent - so you probably will need a solution using biggest possible value for all scenarios.