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I'm getting a "request header too large" error on my application after installing Istio. Can the additional headers added by Istio be too large?

RMNull
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1 Answers1

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Requests coming to your Pod are handled by Envoy (with a sidecar). You could try to modify it's configuration to support bigger headers.

There is a Github issue that could be your starting point:

Hi all, in case it helps, with Istio 1.5, this works:

$ cat envoyfilter3.yaml

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: hcm-tweaks
  namespace: istio-system
spec:
  configPatches:
  - applyTo: NETWORK_FILTER # http connection manager is a filter in Envoy
    match:
      context: GATEWAY
      listener:
        filterChain:
          filter:
            name: "envoy.http_connection_manager"
    patch:
      operation: MERGE
      value:
        typed_config:
          "@type": "type.googleapis.com/envoy.config.filter.network.http_connection_manager.v2.HttpConnectionManager"
          xff_num_trusted_hops: 5
          max_request_headers_kb: 90

Main difference versus the doc: removed WorkloadSelector, removed sni, added type_config."@type"

Please remember that this is a working example on Istio version 1.5. You'll need to modify in accordance with the Istio release notes.

Additional resources:

Dawid Kruk
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  • Thanks for the solution @Dawid Kruk . Could it possible that the headers added by Istio were so big that it caused this issue? – RMNull Feb 10 '21 at 10:55
  • Without more information about your infrastructure/your application/your `Istio` configuration it could be hard to pinpoint the actual issue. I would rather go a way that your application is sending too big headers. – Dawid Kruk Feb 11 '21 at 12:58