Istio provider: add/update READMEs

README.md

@@ -16,6 +16,10 @@ translated to [Gateway API](https://gateway-api.sigs.k8s.io/) directly.
 
 Note: Ingress2gateway is not intended to copy annotations from Ingress to Gateway API.
 
+### Istio
+
+With the introduction of the new [Istio](pkg/i2gw/providers/istio/README.md) provider, you can convert Istio API entities like Gateway and VirtualService to corresponding resources of the Gateway API, such as Gateway, HTTP/TLS/TCPRoutes, and ReferenceGrants.
+
 ## Installation
 
 If you have a Go development environment locally, you can install ingress2gateway with `go install github.com/kubernetes-sigs/[email protected]`
@@ -106,6 +110,7 @@ Ingress2gateway also supports translating provider-specific resources and ingres
 
 - [ingress-nginx](pkg/i2gw/providers/ingressnginx/README.md)
 - [kong](pkg/i2gw/providers/kong/README.md)
+- [istio](pkg/i2gw/providers/istio/README.md)
 
 If your provider, or a specific feature, is not currently supported, please open an issue and describe your use case.
 

pkg/i2gw/providers/istio/README.md

@@ -1,5 +1,82 @@
 # Istio Provider
 
-## WIP
+The provider translates Istio API entities: [Gateway](https://istio.io/latest/docs/reference/config/networking/gateway/) and [VirtualService](https://istio.io/latest/docs/reference/config/networking/virtual-service) to the K8S Gateway API: Gateway, HTTPRoute, TLSRoute, TCPRoute and ReferenceGrants.
 
-Follow #100 for updates on the progress
+If certain field of the Istio API entity lacks a direct equivalent in K8S Gateway API, this field is logged and ignored during the translation.
+
+## Examples
+
+You can find the examples demonstrating how the resources are translated within the [fixtures](./fixtures/) directory.
+
+There are examples for:
+
+* Istio Gateway -> K8S API Gateway
+* VirtualService -> HTTPRoute
+* VirtualService -> TLSRoute
+* VirtualService -> TCPRoute
+* Creation of the K8S API ReferenceGrants for cross namespace references
+
+## Conversion of Ingress resources to Gateway API
+
+### Generated ReferenceGrants and xRoute.parentRefs
+
+Translator verifies if the xRoute can be connected to the Gateway and if parentRefs to it should be generated.
+
+It considers the following fields:
+
+`parentRefs` would be generated if:
+
+1. VirtualService can be exported to the Gateway's namespaces, values from `virtualService.Spec.ExportTo`
+2. There's an overlap between Gateway's `Server.Hosts` and `virtualService.Spec.Hosts`
+
+If Gateway and VirtualService are in the different namespaces, then a `ReferenceGrant` would be created to allow translated xRoute to reference translated Gateway.
+
+### Istio Gateway
+
+K8S API Gateway Listener is generated for each host of each server of istio gateway.Spec.Server.
+
+Listener names are generated in the following format: `$PROTOCOL_NAME-protocol-$NAMESPACE-ns-$HOSTNAME"`. The format is chosen to ensure API compliance where all listener names MUST be unique within the Gateway.
+
+#### Protocols
+
+Istio supported protocols -> K8S Gateway Listener protocols
+
+* HTTP|HTTPS|TCP|TLS - converted as is
+* HTTP2|GRPC -> if `tls` is set then HTTPS else HTTP
+* MONGO -> TCP
+
+#### TLS
+
+Modes translation:
+
+* PASSTHROUGH and AUTO_PASSTHROUGH -> gw.TLSModePassthrough
+* SIMPLE and MUTUAL -> gw.TLSModeTerminate
+* other istio tls modes are not translated
+
+### Istio VirtualService
+
+#### HTTP
+
+The list of fields showing how istio.VirtualService.Http fields are converted to the HTTPRoute equivalents
+
+* match []HTTPMatchRequest -> []gw.HTTPRouteMatch
+* route []HTTPRouteDestination -> []gw.HTTPBackendRef
+* redirect HTTPRedirect -> gw.HTTPRequestRedirectFilter
+* rewrite HTTPRewrite -> gw.HTTPURLRewriteFilter
+* timeout Duration -> gw.HTTPRouteTimeouts.Request
+* mirror and mirrors -> []gw.HTTPRequestMirrorFilters
+* headers.request -> requestHeaderModifier gw.HTTPHeaderFilter
+* headers.response -> responseHeaderModifier gw.HTTPHeaderFilter
+
+#### TLS
+
+The list of fields showing how istio.VirtualService.Tls fields are converted to the TLSRoute equivalents
+
+* match.sniHosts -> TLSRouteSpec.Hostnames
+* route []RouteDestination ->  []gw.BackendRef
+
+#### TCP
+
+The list of fields showing how istio.VirtualService.Tlc fields are converted to the TCPRoute equivalents
+
+* route []RouteDestination ->  []gw.BackendRef