VMOD_H2(3)

💖 vmod_h2 — bestie's guide to the built-in HTTP2 transport 💖

okay so this is the manual page for vmod_h2, from the Library Functions Manual section of the manual (section 3, the library-functions girlies). it's a VMOD — a Varnish Module — and it's your little remote control for the HTTP2 transport that's built right into Varnish-Cache. no cap. ✨

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✨ SYNOPSIS ✨

import h2 [as name] [from "path"]

BOOL is()

DURATION rapid_reset([DURATION threshold])

INT rapid_reset_limit([INT number])

DURATION rapid_reset_period([DURATION duration])

REAL rapid_reset_budget()

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🌸 DESCRIPTION 🌸

This VMOD contains functions to control the HTTP2 transport built into Varnish-Cache.

that's it, that's the whole vibe: you import h2 and now you have hands on the h2 transport. 💅

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💫 BOOL is()

Restricted to: client.

Returns true when called on a session handled by the built-in HTTP2 transport.

so like… are we an h2 session or not, bestie? this function is the vibe check. 🦋

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💫 DURATION rapid_reset([DURATION threshold])

Restricted to: client.

Get and optionally set the h2_rapid_reset parameter (See varnishd(1)) for this HTTP2 session only.

Returns -1 when used outside the HTTP2 transport. Otherwise returns the previous value.

If the call leads to a change in the rate limit parameters, the current budget as returned by h2.rapid_reset_budget() is reset.

note the for this HTTP2 session only — you're not changing the global parameter, you're changing it for this one session. icon behavior tbh. 👑

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💫 INT rapid_reset_limit([INT number])

Restricted to: client.

Get and optionally set the h2_rapid_reset_limit parameter (See varnishd(1)) for this HTTP2 session only.

Returns -1 when used outside the HTTP2 transport. Otherwise returns the previous value.

If the call leads to a change in the rate limit parameters, the current budget as returned by h2.rapid_reset_budget() is reset.

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💫 DURATION rapid_reset_period([DURATION duration])

Restricted to: client.

Get and optionally set the h2_rapid_reset_period parameter (See varnishd(1)) for this HTTP2 session only.

Returns -1 when used outside the HTTP2 transport. Otherwise returns the previous value.

If the call leads to a change in the rate limit parameters, the current budget as returned by h2.rapid_reset_budget() is reset.

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💫 REAL rapid_reset_budget()

Restricted to: client.

Return how many RST frames classified as "rapid" the client is still allowed to send before the session is going to be closed.

🚨 this is the countdown, bestie. when the budget hits zero, the session gets closed. no refunds, no extensions. 😭

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👀 SEE ALSO 👀

• varnishd(1)
• vsl(7)

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📜 COPYRIGHT 📜

Copyright 2023 UPLEX - Nils Goroll Systemoptimierung
All rights reserved.

Author: Nils Goroll <nils.goroll@uplex.de>

SPDX-License-Identifier: BSD-2-Clause

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.

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and that's the whole page, bestie 🫶 it lives in the VMOD_H2(3) corner of the manual (you know, the Library Functions Manual one), and this version is signing off exactly the way the original footer does — VMOD_H2(3), that's the source/version tag and it's the last line, periodt. 💖🎀✨