186 lines
6.7 KiB
Plaintext
186 lines
6.7 KiB
Plaintext
---
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layout: docs
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page_title: Lua Envoy Extension
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description: >-
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Learn how the `lua` Envoy extension enables Consul to run Lua scripts during Envoy requests and responses from Consul-generated Envoy resources.
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---
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# Run Lua scripts in Envoy proxy
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The Lua Envoy extension enables the [HTTP Lua filter](https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_filters/lua_filter) in your Consul Envoy proxies, letting you run Lua scripts when requests and responses pass through Consul-generated Envoy resources.
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Envoy filters support setting and getting dynamic metadata, allowing a filter to share state information with subsequent filters. To set dynamic metadata, configure the HTTP Lua filter. Users can call `streamInfo:dynamicMetadata()` from Lua scripts to get the request's dynamic metadata.
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## Configuration specifications
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To use the Lua Envoy extension, configure the following arguments in the `EnvoyExtensions` block:
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| Arguments | Description |
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| -------------- | ------------------------------------------------------------------------------------------------ |
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| `ProxyType` | Determines the proxy type the extension applies to. The only supported value is `connect-proxy`. |
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| `ListenerType` | Specifies if the extension is applied to the `inbound` or `outbound` listener. |
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| `Script` | The Lua script that is configured to run by the HTTP Lua filter. |
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## Workflow
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There are two steps to configure the Lua Envoy extension:
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1. Configure EnvoyExtensions through `service-defaults` or `proxy-defaults`.
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1. Apply the configuration entry.
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### Configure `EnvoyExtensions`
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To use Envoy extensions, you must configure and apply a `proxy-defaults` or `service-defaults` configuration entry with the Envoy extension.
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- When you configure Envoy extensions on `proxy-defaults`, they apply to every service.
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- When you configure Envoy extensions on `service-defaults`, they apply to a specific service.
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Consul applies Envoy extensions configured in `proxy-defaults` before it applies extensions in `service-defaults`. As a result, the Envoy extension configuration in `service-defaults` may override configurations in `proxy-defaults`.
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The following example configures the Lua Envoy extension on every service by using the `proxy-defaults`.
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<Tabs>
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<Tab heading="HCL" group="hcl">
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<CodeBlockConfig filename="lua-envoy-extension-proxy-defaults.hcl">
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```hcl
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Kind = "proxy-defaults"
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Name = "global"
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Protocol = "http"
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EnvoyExtensions {
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Name = "builtin/lua"
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Arguments = {
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ProxyType = "connect-proxy"
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Listener = "inbound"
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Script = <<-EOS
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function envoy_on_request(request_handle)
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meta = request_handle:streamInfo():dynamicMetadata()
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m = meta:get("consul")
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request_handle:headers():add("x-consul-service", m["service"])
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request_handle:headers():add("x-consul-namespace", m["namespace"])
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request_handle:headers():add("x-consul-datacenter", m["datacenter"])
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request_handle:headers():add("x-consul-trust-domain", m["trust-domain"])
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end
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EOS
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}
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}
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```
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</CodeBlockConfig>
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</Tab>
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<Tab heading="JSON" group="json">
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<CodeBlockConfig filename="lua-envoy-extension-proxy-defaults.json">
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```hcl
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{
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"kind": "proxy-defaults",
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"name": "global",
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"protocol": "http",
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"envoy_extensions": [{
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"name": "builtin/lua",
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"arguments": {
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"proxy_type": "connect-proxy",
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"listener": "inbound",
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"script": "function envoy_on_request(request_handle)\nmeta = request_handle:streamInfo():dynamicMetadata()\nm = \nmeta:get("consul")\nrequest_handle:headers():add("x-consul-service", m["service"])\nrequest_handle:headers():add("x-consul-namespace", m["namespace"])\nrequest_handle:headers():add("x-consul-datacenter", m["datacenter"])\nrequest_handle:headers():add("x-consul-trust-domain", m["trust-domain"])\nend"
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}
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}]
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}
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```
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</CodeBlockConfig>
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</Tab>
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<Tab heading="Kubernetes" group="kubernetes">
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<CodeBlockConfig filename="lua-envoy-extension-proxy-defaults.yaml">
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```yaml
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apiVersion: consul.hashicorp.com/v1alpha1
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kind: ProxyDefaults
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metadata:
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name: global
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spec:
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protocol: http
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envoyExtensions:
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name = "builtin/lua"
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arguments:
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proxyType: "connect-proxy"
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listener: "inbound"
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script: |-
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function envoy_on_request(request_handle)
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meta = request_handle:streamInfo():dynamicMetadata()
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m = meta:get("consul")
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request_handle:headers():add("x-consul-service", m["service"])
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request_handle:headers():add("x-consul-namespace", m["namespace"])
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request_handle:headers():add("x-consul-datacenter", m["datacenter"])
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request_handle:headers():add("x-consul-trust-domain", m["trust-domain"])
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end
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```
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</CodeBlockConfig>
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</Tab>
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</Tabs>
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For a full list of parameters for `EnvoyExtensions`, refer to the [`service-defaults`](/consul/docs/connect/config-entries/service-defaults#envoyextensions) and [`proxy-defaults`](/consul/docs/connect/config-entries/proxy-defaults#envoyextensions) configuration entries reference documentation.
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!> **Warning:** Applying `EnvoyExtensions` to `ProxyDefaults` may produce unintended consequences. We recommend enabling `EnvoyExtensions` with `ServiceDefaults` in most cases.
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Refer to [Configuration specification](#configuration-specification) section to find a full list of arguments for the Lua Envoy extension.
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### Apply the configuration entry
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Apply the `proxy-defaults` or `service-defaults` configuration entry.
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<Tabs>
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<Tab heading="HCL" group="hcl">
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```shell-session
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$ consul config write lua-envoy-extension-proxy-defaults.hcl
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```
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</Tab>
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<Tab heading="JSON" group="json">
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```shell-session
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$ consul config write lua-envoy-extension-proxy-defaults.json
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```
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</Tab>
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<Tab heading="Kubernetes" group="kubernetes">
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```shell-session
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$ kubectl apply lua-envoy-extension-proxy-defaults.yaml
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```
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</Tab>
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</Tabs>
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## Examples
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In the following example, the `service-defaults` configure the Lua Envoy extension to insert the HTTP Lua filter for service `myservice` and add the Consul service name to the`x-consul-service` header for all inbound requests. The `ListenerType` makes it so that the extension applies only on the inbound listener of the service's connect proxy.
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<CodeBlockConfig filename="lua-envoy-extension.json">
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```hcl
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Kind = "service-defaults"
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Name = "myservice"
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EnvoyExtensions {
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Name = "builtin/lua"
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Arguments = {
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ProxyType = "connect-proxy"
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Listener = "inbound"
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Script = <<EOF
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function envoy_on_request(request_handle)
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local service = request_handle:streamInfo():dynamicMetadata():get("consul")["service"]
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request_handle:headers():add("x-consul-service", service)
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end
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EOF
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}
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}
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```
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</CodeBlockConfig>
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Alternatively, you can apply the same extension configuration to [`proxy-defaults`](/consul/docs/connect/config-entries/proxy-defaults#envoyextensions) configuration entries.
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