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forceHttp11Action Action

Pin the connection between Fluxzy and the upstream server to HTTP/1.1 via ALPN, even when both sides support HTTP/2.

HTTP/2 is the default for almost every modern endpoint, which means HTTP/1.1 behaviour is sometimes hard to observe. forceHttp11Action is the simplest way to pin the upstream leg back to 1.1 so you can read the framing, compare implementations, or reproduce a protocol specific bug.

When to use this action

Reach for forceHttp11Action when you want to observe how a client or server behaves over HTTP/1.1, regardless of what they would normally negotiate. Fluxzy sets the ALPN list during the TLS handshake to advertise only http/1.1, so the upstream picks 1.1 by protocol.

Typical situations include:

  • Comparing request and response framing between HTTP/1.1 and HTTP/2 on the same endpoint.
  • Debugging a client library bug that only reproduces on HTTP/1.1.
  • Working around an upstream HTTP/2 implementation that drops connections under specific load patterns.
  • Capturing exchanges in a more human readable format for documentation or training.

The action runs on the onAuthorityReceived scope, so the protocol is pinned before the TLS handshake starts. It only affects the Fluxzy to remote leg of the connection.

Real world examples

Force HTTP/1.1 for a single API host

Lets you compare 1.1 and 2 behaviour by toggling this rule on or off.

rules:
- filter:
    typeKind: HostFilter
    pattern: api.internal.example.com
  actions:
  - typeKind: ForceHttp11Action

Downgrade everything except one allow listed CDN

Useful for a temporary debugging session where most traffic should remain on HTTP/2 but one host needs investigation.

rules:
- filter:
    typeKind: FilterCollection
    operation: And
    children:
    - typeKind: AnyFilter
    - typeKind: HostFilter
      pattern: cdn.example.com
      inverted: true
  actions:
  - typeKind: ForceHttp11Action

Force HTTP/1.1 only for a specific path family

Targets a subset of endpoints, leaving the rest of the host on the default ALPN result.

rules:
- filter:
    typeKind: FilterCollection
    operation: And
    children:
    - typeKind: HostFilter
      pattern: payments.example.com
    - typeKind: PathFilter
      pattern: /legacy/
  actions:
  - typeKind: ForceHttp11Action

Reference

forceHttp11Action

Description

Force the connection between fluxzy and remote to be HTTP/1.1. This value is enforced by ALPN settings set during the SSL/Handshake handshake.

Evaluation scope

Evaluation scope defines the timing where this filter will be applied.

onAuthorityReceived This scope denotes the moment fluxzy is aware the destination authority. In a regular proxy connection, it will occur the moment where fluxzy parsed the CONNECT request.

YAML configuration name

forceHttp11Action

Settings

This action has no specific characteristic

Example of usage

The following examples apply this action to any exchanges

Force the connection between fluxzy and remote to be HTTP/1.1. This value is enforced by ALPN settings set during the SSL/Handshake handshake.

rules:
- filter:
    typeKind: AnyFilter
  actions:
  - typeKind: ForceHttp11Action

.NET reference

View definition of ForceHttp11Action for .NET integration.

See also

The following actions are related to this action:

Frequently asked questions

Does it also affect the client side of the connection?

No. It only changes the protocol Fluxzy uses to talk to the upstream. The client to Fluxzy connection is negotiated separately.

Will the action fail if the server does not support HTTP/1.1?

Practically every public HTTPS server supports HTTP/1.1, so failures are rare. If a server truly only speaks HTTP/2, the TLS handshake will close because ALPN cannot agree on a protocol.

Can I combine it with forceTlsVersionAction?

Yes. They are independent. Pin TLS 1.2 plus HTTP/1.1 together to closely match an older client baseline.

What is the difference with serveHttp11Action?

serveHttp11Action affects the connection between the client and Fluxzy. forceHttp11Action affects the connection between Fluxzy and the upstream server.

Learn more about Fluxzy rules