AWS managed argo cd doc (#3064)

* Added docs page for AWS managed argo cd

* Fixed linting

* Apply suggestion from @steve-fenton-octopus

* Sentence case for headings

Co-authored-by: Steve Fenton <99181436+steve-fenton-octopus@users.noreply.github.com>

---------

Co-authored-by: Steve Fenton <99181436+steve-fenton-octopus@users.noreply.github.com>

Author: tleed5

src/pages/docs/argo-cd/instances/aws-managed-argo-cd.md

@@ -0,0 +1,55 @@
+---
+layout: src/layouts/Default.astro
+pubDate: 2026-03-13
+modDate: 2026-03-13
+title: AWS Managed Argo CD
+description: Install Argo CD Gateway on EKS with Argo CD Capability
+navOrder: 10
+hideInThisSectionHeader: true
+---
+
+The Argo CD Gateway can be installed into an AWS EKS cluster and connect to an Argo CD instance managed by the Argo CD Capability.
+
+## Differences from a standard Argo CD instance
+
+AWS managed Argo CD instances differ from standard self-hosted installations in the following ways:
+
+### External URL
+
+Standard installations connect to Argo CD using the in-cluster Kubernetes service DNS name (e.g. `argocd-server.argocd.svc.cluster.local`). AWS managed Argo CD instances are not accessible via in-cluster DNS, so the publicly accessible EKS capabilities URL must be used instead.
+
+### Valid TLS certificate
+
+AWS managed Argo CD instances are served with a publicly trusted TLS certificate. Unlike self-hosted installations that may use self-signed certificates, the **Argo CD instance uses self-signed certificates** option should remain unchecked to keep certificate verification enabled.
+
+### gRPC-Web
+
+AWS EKS Argo CD instances are exposed through a load balancer that does not support native gRPC (HTTP/2). The gateway must be configured to use gRPC-Web, which encapsulates gRPC communication over HTTP/1.1, by setting `gateway.argocd.grpcWeb="true"` or `gateway.argocd.grpcWebRootPath="/argo/api"`.
+
+## Installation
+
+The installation process follows the [standard process](/docs/argo-cd/instances#installing-the-octopus-argo-cd-gateway), with a few adjustments required for AWS managed Argo CD instances.
+
+1. Replace the default value for the Argo CD service DNS name with the publicly accessible URL for the Argo CD instance, without the protocol prefix. For example: `xxxxxxxx.eks-capabilities.ap-southeast-2.amazonaws.com`
+2. Uncheck the **Argo CD instance uses self-signed certificates** option
+3. Copy the generated Helm command and append the following value: `--set gateway.argocd.grpcWeb="true"`, if your Argo CD instance's API is not hosted at the root path you can set the following value instead: `--set gateway.argocd.grpcWebRootPath="/argo/api"`
+
+The resulting Helm command will look similar to the following:
+
+```bash
+helm install --atomic \
+--create-namespace --namespace octo-argo-gateway-<instance-name> \
+--version "*.*" \
+--set registration.octopus.name="<instance-name>" \
+--set registration.octopus.serverApiUrl="https://your-instance.octopus.app/" \
+--set registration.octopus.serverAccessToken="API-XXXXXXXXXXXXXXXX" \
+--set registration.octopus.spaceId="Spaces-1" \
+--set gateway.octopus.serverGrpcUrl="grpc://your-instance.octopus.app:8443" \
+--set gateway.argocd.serverGrpcUrl="grpc://xxxxxxxx.eks-capabilities.<region>.amazonaws.com" \
+--set gateway.argocd.insecure="false" \
+--set gateway.argocd.plaintext="false" \
+--set gateway.argocd.authenticationToken="<Argo API Token>" \
+--set gateway.argocd.grpcWeb="true" \
+<instance-name> \
+oci://registry-1.docker.io/octopusdeploy/octopus-argocd-gateway-chart
+```