package envoy.config.common.mutation_rules.v3

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The HeaderMutation structure specifies an action that may be taken on HTTP headers.

Used in: extensions.filters.http.header_mutation.v3.Mutations, extensions.http.early_header_mutation.header_mutation.v3.HeaderMutation

• oneof action

  • string remove = 1

    Remove the specified header if it exists.

  • core.v3.HeaderValueOption append = 2

    Append new header by the specified HeaderValueOption.

The HeaderMutationRules structure specifies what headers may be manipulated by a processing filter. This set of rules makes it possible to control which modifications a filter may make. By default, an external processing server may add, modify, or remove any header except for an "Envoy internal" header (which is typically denoted by an x-envoy prefix) or specific headers that may affect further filter processing: * ``host`` * ``:authority`` * ``:scheme`` * ``:method`` Every attempt to add, change, append, or remove a header will be tested against the rules here. Disallowed header mutations will be ignored unless ``disallow_is_error`` is set to true. Attempts to remove headers are further constrained -- regardless of the settings, system-defined headers (that start with ``:``) and the ``host`` header may never be removed. In addition, a counter will be incremented whenever a mutation is rejected. In the ext_proc filter, that counter is named ``rejected_header_mutations``. [#next-free-field: 8]

Used in: extensions.filters.http.ext_authz.v3.ExtAuthz, extensions.filters.http.ext_proc.v3.ExternalProcessor

• optional google.protobuf.BoolValue allow_all_routing = 1

  By default, certain headers that could affect processing of subsequent filters or request routing cannot be modified. These headers are ``host``, ``:authority``, ``:scheme``, and ``:method``. Setting this parameter to true allows these headers to be modified as well.

• optional google.protobuf.BoolValue allow_envoy = 2

  If true, allow modification of envoy internal headers. By default, these start with ``x-envoy`` but this may be overridden in the ``Bootstrap`` configuration using the :ref:`header_prefix <envoy_v3_api_field_config.bootstrap.v3.Bootstrap.header_prefix>` field. Default is false.

• optional google.protobuf.BoolValue disallow_system = 3

  If true, prevent modification of any system header, defined as a header that starts with a ``:`` character, regardless of any other settings. A processing server may still override the ``:status`` of an HTTP response using an ``ImmediateResponse`` message. Default is false.

• optional google.protobuf.BoolValue disallow_all = 4

  If true, prevent modifications of all header values, regardless of any other settings. A processing server may still override the ``:status`` of an HTTP response using an ``ImmediateResponse`` message. Default is false.

• optional type.matcher.v3.RegexMatcher allow_expression = 5

  If set, specifically allow any header that matches this regular expression. This overrides all other settings except for ``disallow_expression``.

• optional type.matcher.v3.RegexMatcher disallow_expression = 6

  If set, specifically disallow any header that matches this regular expression regardless of any other settings.

• optional google.protobuf.BoolValue disallow_is_error = 7

  If true, and if the rules in this list cause a header mutation to be disallowed, then the filter using this configuration will terminate the request with a 500 error. In addition, regardless of the setting of this parameter, any attempt to set, add, or modify a disallowed header will cause the ``rejected_header_mutations`` counter to be incremented. Default is false.