mirror of https://github.com/hashicorp/consul
48 lines
3.3 KiB
Markdown
48 lines
3.3 KiB
Markdown
---
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layout: docs
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page_title: Envoy Extensions
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description: >-
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Learn how Envoy extensions enables you to add support for additional Envoy features without modifying the Consul codebase.
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---
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# Envoy extensions overview
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This topic provides an overview of Envoy extensions in Consul service mesh deployments. You can modify Consul-generated Envoy resources to add additional functionality without modifying the Consul codebase.
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## Introduction
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Consul supports two methods for modifying Envoy behavior. You can either modify the Envoy resources Consul generates through [escape hatches](/consul/docs/connect/proxies/envoy#escape-hatch-overrides) or configure your services to use Envoy extensions using the `EnvoyExtension` parameter. Implementing escape hatches requires rewriting the Envoy resources so that they are compatible with Consul, a task that also requires understanding how Consul names Envoy resources and enforces intentions.
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Instead of modifying Consul code, you can configure your services to use Envoy extensions through the `EnvoyExtensions` field. This field is definable in [`proxy-defaults`](/consul/docs/connect/config-entries/proxy-defaults#envoyextensions) and [`service-defaults`](/consul/docs/connect/config-entries/service-defaults#envoyextensions) configuration entries.
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## Supported extensions
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Envoy extensions enable additional service mesh functionality in Consul by changing how the sidecar proxies behave. Extensions dynamically modify the configuration of Envoy proxies based on Consul configuration entries, enabling a wider set of use cases for the service mesh traffic that passes through an Envoy proxy. Consul supports the following extensions:
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- External authorization
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- Lua
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- Lambda
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- Property override
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- WebAssembly (Wasm)
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### External authorization
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The `ext-authz` extension lets you configure external authorization filters for Envoy proxy so that you can route requests to external authorization systems. Refer to the [external authorization documentation](/consul/docs/connect/proxies/envoy-extensions/usage/ext-authz) for more information.
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### Lambda
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The `lambda` Envoy extension enables services to make requests to AWS Lambda functions through the mesh as if they are a normal part of the Consul catalog. Refer to the [Lambda extension documentation](/consul/docs/connect/proxies/envoy-extensions/usage/lambda) for more information.
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### Lua
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The `lua` Envoy extension enables HTTP Lua filters in your Consul Envoy proxies. It allows you to run Lua scripts during Envoy requests and responses from Consul-generated Envoy resources. Refer to the [Lua extension documentation](/consul/docs/connect/proxies/envoy-extensions/usage/lua) for more information.
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### Property override
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The `property-override` extension lets you set and unset individual properties on the Envoy resources that Consul generates. Use the extension instead of [escape-hatch overrides](/consul/docs/connect/proxies/envoy#escape-hatch-overrides) to enable advanced Envoy configuration. Refer to the [property override documentation](/consul/docs/connect/proxies/envoy-extensions/usage/property-override) for more information.
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### WebAssembly
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The `wasm` extension enables you to configure TCP and HTTP filters that invoke custom WebAssembly (Wasm) plugins. Refer to the [WebAssembly extenstion documentation](/consul/docs/connect/proxies/envoy-extensions/usage/wasm) for more information.
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