.. _config_http_filters_local_rate_limit: Local rate limit ================ * Local rate limiting :ref:`architecture overview ` * :ref:`v3 API reference ` * This filter should be configured with the name *envoy.filters.http.local_ratelimit*. The HTTP local rate limit filter applies a :ref:`token bucket ` rate limit when the request's route or virtual host has a per filter :ref:`local rate limit configuration `. If the local rate limit token bucket is checked, and there are no tokens available, a 429 response is returned (the response is configurable). The local rate limit filter then sets the :ref:`x-envoy-ratelimited` response header. :ref:`Additional response headers ` can be configured to be returned. :ref:`Request headers ` can be configured to be added to forwarded requests to the upstream when the local rate limit filter is enabled but not enforced. Depending on the value of the config :ref:`local_rate_limit_per_downstream_connection `, the token bucket is either shared across all workers or on a per connection basis. This results in the local rate limits being applied either per Envoy process or per downstream connection. By default the rate limits are applied per Envoy process. Example configuration --------------------- Example filter configuration for a globally set rate limiter (e.g.: all vhosts/routes share the same token bucket): .. code-block:: yaml name: envoy.filters.http.local_ratelimit typed_config: "@type": type.googleapis.com/envoy.extensions.filters.http.local_ratelimit.v3.LocalRateLimit stat_prefix: http_local_rate_limiter token_bucket: max_tokens: 10000 tokens_per_fill: 1000 fill_interval: 1s filter_enabled: runtime_key: local_rate_limit_enabled default_value: numerator: 100 denominator: HUNDRED filter_enforced: runtime_key: local_rate_limit_enforced default_value: numerator: 100 denominator: HUNDRED response_headers_to_add: - append: false header: key: x-local-rate-limit value: 'true' local_rate_limit_per_downstream_connection: false Example filter configuration for a globally disabled rate limiter but enabled for a specific route: .. code-block:: yaml name: envoy.filters.http.local_ratelimit typed_config: "@type": type.googleapis.com/envoy.extensions.filters.http.local_ratelimit.v3.LocalRateLimit stat_prefix: http_local_rate_limiter The route specific configuration: .. code-block:: yaml route_config: name: local_route virtual_hosts: - name: local_service domains: ["*"] routes: - match: { prefix: "/path/with/rate/limit" } route: { cluster: service_protected_by_rate_limit } typed_per_filter_config: envoy.filters.http.local_ratelimit: "@type": type.googleapis.com/envoy.extensions.filters.http.local_ratelimit.v3.LocalRateLimit token_bucket: max_tokens: 10000 tokens_per_fill: 1000 fill_interval: 1s filter_enabled: runtime_key: local_rate_limit_enabled default_value: numerator: 100 denominator: HUNDRED filter_enforced: runtime_key: local_rate_limit_enforced default_value: numerator: 100 denominator: HUNDRED response_headers_to_add: - append: false header: key: x-local-rate-limit value: 'true' - match: { prefix: "/" } route: { cluster: default_service } Note that if this filter is configured as globally disabled and there are no virtual host or route level token buckets, no rate limiting will be applied. .. _config_http_filters_local_rate_limit_descriptors: Using rate limit descriptors for local rate limiting ---------------------------------------------------- Rate limit descriptors can be used to override local per-route rate limiting. A route's :ref:`rate limit action ` is used to match up a :ref:`local descriptor ` in the filter config descriptor list. The local descriptor's token bucket settings are then used to decide if the request should be rate limited or not depending on whether the local descriptor's entries match the route's rate limit actions descriptor entries. If there is no matching descriptor entries, the default token bucket is used. Example filter configuration using descriptors: .. literalinclude:: _include/local-rate-limit-with-descriptors.yaml :language: yaml :lines: 15-75 :caption: :download:`local-rate-limit-with-descriptors.yaml <_include/local-rate-limit-with-descriptors.yaml>` In this example, requests are rate-limited for routes prefixed with "/foo" as follow. If requests come from a downstream service cluster "foo" for "/foo/bar" path, then 10 req/min are allowed. But if they come from a downstream service cluster "foo" for "/foo/bar2" path, then 100 req/min are allowed. Otherwise, 1000 req/min are allowed. Statistics ---------- The local rate limit filter outputs statistics in the *.http_local_rate_limit.* namespace. 429 responses -- or the configured status code -- are emitted to the normal cluster :ref:`dynamic HTTP statistics `. .. csv-table:: :header: Name, Type, Description :widths: 1, 1, 2 enabled, Counter, Total number of requests for which the rate limiter was consulted ok, Counter, Total under limit responses from the token bucket rate_limited, Counter, Total responses without an available token (but not necessarily enforced) enforced, Counter, Total number of requests for which rate limiting was applied (e.g.: 429 returned) .. _config_http_filters_local_rate_limit_runtime: Runtime ------- The HTTP rate limit filter supports the following runtime fractional settings: http_filter_enabled % of requests that will check the local rate limit decision, but not enforce, for a given *route_key* specified in the :ref:`local rate limit configuration `. Defaults to 0. http_filter_enforcing % of requests that will enforce the local rate limit decision for a given *route_key* specified in the :ref:`local rate limit configuration `. Defaults to 0. This can be used to test what would happen before fully enforcing the outcome.