draft-ietf-httpapi-ratelimit-headers-09.unpg.txt   draft-ietf-httpapi-ratelimit-headers-latest.txt 
HTTPAPI Working Group R. Polli HTTPAPI Working Group R. Polli
Internet-Draft Team Digitale, Italian Government Internet-Draft Team Digitale, Italian Government
Intended status: Standards Track A. Martinez Intended status: Standards Track A. Martinez
Expires: September 19, 2025 Red Hat Expires: November 22, 2025 Red Hat
D. Miller D. Miller
Microsoft Microsoft
March 18, 2025 May 21, 2025
RateLimit header fields for HTTP RateLimit header fields for HTTP
draft-ietf-httpapi-ratelimit-headers-09 draft-ietf-httpapi-ratelimit-headers-latest
Abstract Abstract
This document defines the RateLimit-Policy and RateLimit HTTP header This document defines the RateLimit-Policy and RateLimit HTTP header
fields for servers to advertise their quota policies and the current fields for servers to advertise their quota policies and the current
service limits, thereby allowing clients to avoid being throttled. service limits, thereby allowing clients to avoid being throttled.
About This Document About This Document
This note is to be removed before publishing as an RFC. This note is to be removed before publishing as an RFC.
skipping to change at line 52 skipping to change at page 2, line 7
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Table of Contents Table of Contents
1. Introduction 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Goals 1.1. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Notational Conventions 1.2. Notational Conventions . . . . . . . . . . . . . . . . . 5
2. Terminology 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. RateLimit-Policy Field 3. RateLimit-Policy Field . . . . . . . . . . . . . . . . . . . 6
3.1. Quota Policy Item 3.1. Quota Policy Item . . . . . . . . . . . . . . . . . . . . 6
3.1.1. Quota Parameter 3.1.1. Quota Parameter . . . . . . . . . . . . . . . . . . . 6
3.1.2. Quota Unit Parameter 3.1.2. Quota Unit Parameter . . . . . . . . . . . . . . . . 6
3.1.3. Window Parameter 3.1.3. Window Parameter . . . . . . . . . . . . . . . . . . 7
3.1.4. Partition Key Parameter 3.1.4. Partition Key Parameter . . . . . . . . . . . . . . . 7
3.2. RateLimit Policy Field Examples 3.2. RateLimit Policy Field Examples . . . . . . . . . . . . . 7
4. RateLimit Field 4. RateLimit Field . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Service Limit Item 4.1. Service Limit Item . . . . . . . . . . . . . . . . . . . 8
4.1.1. Remaining Parameter 4.1.1. Remaining Parameter . . . . . . . . . . . . . . . . . 8
4.1.2. Reset Parameter 4.1.2. Reset Parameter . . . . . . . . . . . . . . . . . . . 9
4.1.3. Partition Key Parameter 4.1.3. Partition Key Parameter . . . . . . . . . . . . . . . 9
4.2. RateLimit Field Examples 4.2. RateLimit Field Examples . . . . . . . . . . . . . . . . 9
5. Server Behavior 5. Server Behavior . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. Generating Partition Keys 5.1. Generating Partition Keys . . . . . . . . . . . . . . . . 10
5.2. Performance Considerations 5.2. Performance Considerations . . . . . . . . . . . . . . . 11
6. Client Behavior 6. Client Behavior . . . . . . . . . . . . . . . . . . . . . . . 11
6.1. Consuming Partition Keys 6.1. Consuming Partition Keys . . . . . . . . . . . . . . . . 12
6.2. Intermediaries 6.2. Intermediaries . . . . . . . . . . . . . . . . . . . . . 12
6.3. Caching 6.3. Caching . . . . . . . . . . . . . . . . . . . . . . . . . 13
7. Security Considerations 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13
7.1. Throttling does not prevent clients from issuing requests 7.1. Throttling does not prevent clients from issuing requests 13
7.2. Information disclosure 7.2. Information disclosure . . . . . . . . . . . . . . . . . 13
7.3. Remaining quota units are not granted requests 7.3. Remaining quota units are not granted requests . . . . . 14
7.4. Reliability of the reset parameter 7.4. Reliability of the reset parameter . . . . . . . . . . . 14
7.5. Resource exhaustion 7.5. Resource exhaustion . . . . . . . . . . . . . . . . . . . 14
7.5.1. Denial of Service 7.5.1. Denial of Service . . . . . . . . . . . . . . . . . . 15
8. Privacy Considerations 8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 16
9. IANA Considerations 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
9.1. RateLimit quota unit registry 9.1. RateLimit quota unit registry . . . . . . . . . . . . . . 16
9.1.1. Registration Template 9.1.1. Registration Template . . . . . . . . . . . . . . . . 17
10. References 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
10.1. Normative References 10.1. Normative References . . . . . . . . . . . . . . . . . . 17
10.2. Informative References 10.2. Informative References . . . . . . . . . . . . . . . . . 18
Appendix A. Rate-limiting and quotas Appendix A. Rate-limiting and quotas . . . . . . . . . . . . . . 18
A.1. Interoperability issues A.1. Interoperability issues . . . . . . . . . . . . . . . . . 19
Appendix B. Examples Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 20
B.1. Responses without defining policies B.1. Responses without defining policies . . . . . . . . . . . 20
B.1.1. Throttling information in responses B.1.1. Throttling information in responses . . . . . . . . . 20
B.1.2. Multiple policies in response B.1.2. Multiple policies in response . . . . . . . . . . . . 21
B.1.3. Use for limiting concurrency B.1.3. Use for limiting concurrency . . . . . . . . . . . . 22
B.1.4. Use in throttled responses B.1.4. Use in throttled responses . . . . . . . . . . . . . 23
B.2. Responses with defined policies B.2. Responses with defined policies . . . . . . . . . . . . . 23
B.2.1. Throttling window specified via parameter B.2.1. Throttling window specified via parameter . . . . . . 23
B.2.2. Dynamic limits with parameterized windows B.2.2. Dynamic limits with parameterized windows . . . . . . 24
B.2.3. Dynamic limits for pushing back and slowing down B.2.3. Dynamic limits for pushing back and slowing down . . 24
B.3. Dynamic limits for pushing back with Retry-After and slow B.3. Dynamic limits for pushing back with Retry-After and slow
down down . . . . . . . . . . . . . . . . . . . . . . . . . . 25
B.3.1. Missing Remaining information B.3.1. Missing Remaining information . . . . . . . . . . . . 26
B.3.2. Use with multiple windows B.3.2. Use with multiple windows . . . . . . . . . . . . . . 27
FAQ FAQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
RateLimit header fields currently used on the web RateLimit header fields currently used on the web . . . . . . . . 30
Acknowledgements Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 31
Changes Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
F.1. Since draft-ietf-httpapi-ratelimit-headers-07 F.1. Since draft-ietf-httpapi-ratelimit-headers-07 . . . . . . 32
F.2. Since draft-ietf-httpapi-ratelimit-headers-03 F.2. Since draft-ietf-httpapi-ratelimit-headers-03 . . . . . . 32
F.3. Since draft-ietf-httpapi-ratelimit-headers-02 F.3. Since draft-ietf-httpapi-ratelimit-headers-02 . . . . . . 32
F.4. Since draft-ietf-httpapi-ratelimit-headers-01 F.4. Since draft-ietf-httpapi-ratelimit-headers-01 . . . . . . 32
F.5. Since draft-ietf-httpapi-ratelimit-headers-00 F.5. Since draft-ietf-httpapi-ratelimit-headers-00 . . . . . . 32
Authors' Addresses Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33
1. Introduction 1. Introduction
Rate limiting of HTTP clients has become a widespread practice, Rate limiting of HTTP clients has become a widespread practice,
especially for HTTP APIs. Typically, servers who do so limit the especially for HTTP APIs. Typically, servers who do so limit the
number of acceptable requests in a given time window (e.g. 10 number of acceptable requests in a given time window (e.g. 10
requests per second). See Appendix A for further information on the requests per second). See Appendix A for further information on the
current usage of rate limiting in HTTP. current usage of rate limiting in HTTP.
Currently, there is no standard way for servers to communicate quotas Currently, there is no standard way for servers to communicate quotas
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