docs: document application proxy

docs/docs-content/clusters/cluster-management/cluster-proxy.md

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+---
+sidebar_label: "Configure Applications to Use Proxy Server"
+title: "Configure Applications to Use Proxy Server"
+description: "Guide to configure configurations in a cluster to use a proxy server."
+hide_table_of_contents: false
+sidebar_position: 201
+tags: ["clusters", "cluster management", "proxy"]
+---
+
+You can configure applications that operate in your Palette clusters to use a proxy server to access the internet
+instead of accessing the internet directly.
+
+Before you are able to configure applications in a cluster to use the proxy server, you must first ensure that the
+cluster itself is configured to use the proxy server. This means that the host Operating System (OS) and the Palette
+agent inside the cluster will use the proxy server for its outbound communications. The steps to do this vary depending
+on your environment.
+
+After the cluster is configured to use the proxy server, you can proceed to configure the applications inside the
+cluster to use the proxy server. You can do this by applying the `spectrocloud.com/connection: proxy` label to the
+specific job, deployment, or daemon set to instruct an application to use the proxy settings of the cluster.
+
+:::tip
+
+We recommend you review the [gRPC and Proxies](../../architecture/grps-proxy.md) article to be aware of network proxies
+that Palette supports. Palette uses gRPC to communicate with clusters, and depending on the proxy server you use, you
+may need to configure the proxy server to support gRPC.
+
+:::
+
+## Prerequisites
+
+- An active proxy server reachable by your cluster.
+
+<Tabs groupId="scenario">
+
+<TabItem value="Palette SaaS Non-Edge">
+
+- A PCG is deployed into an active and healthy Kubernetes cluster. Refer to
+  [Deploy a PCG to an Existing Kubernetes Cluster](../pcg/deploy-pcg-k8s.md) for or
+  [Deploy a PCG with Palette CLI](../pcg/deploy-pcg/deploy-pcg.md) additional guidance.
+
+- The PCG is configured to use the proxy server that you intend for your applications to use for outbound
+  communications. For more information, refer to
+  [Enabled and Manage Proxy Configurations](../pcg/manage-pcg/configure-proxy.md).
+
+  - If you deployed a [PCG through the Palette CLI](../pcg/pcg.md#supported-environments), refer to the respective
+    platform installation guide for instructions on how to configure proxy settings during the installation process
+    through the CLI.
+
+</TabItem>
+
+<TabItem value="Self-Hosted Palette Non-Edge">
+
+- A self-hosted Palette instance is deployed into an active and healthy Kubernetes cluster. Refer to
+  [Self-Hosted Palette Installation](../../enterprise-version/install-palette/install-palette.md) for additional
+  guidance.
+
+- The self-hosted Palette instance is configured to use the proxy server that you intend for your applications to use
+  for outbound communications.
+
+</TabItem>
+
+<TabItem value="Edge">
+
+- Your Edge host is configured to use the proxy server that you intend for your applications to use for outbound
+  communications. Refer to [Edge Host Installation](../edge/site-deployment/stage.md) for more information.
+
+</TabItem>
+
+</Tabs>
+
+## Configure Applications to Use Proxy Server
+
+<Tabs groupId="scenario">
+
+<TabItem value="Palette SaaS Non-Edge">
+
+1.  If you are using Palette SaaS, you must deploy a Private Cloud Gateway (PCG) and configure it to use a proxy server
+    before you can configure cluster applications to use the proxy server. For more information about PCGs, refer to
+    [Private Cloud Gateway](../pcg/pcg.md). You must configure proxy settings for the PCG, and then clusters created by
+    cloud accounts configured to use the PCG will inherit its proxy settings.
+
+    If you are provisioning the PCG using the Palette CLI, you can configure the proxy settings during the PCG
+    installation through the Palette CLI's interactive prompts. If you are using Helm to provision a PCG or have an
+    existing PCG that is not yet configured to use proxy, refer to
+    [Enable and Manage Proxy Configurations for PCG](../pcg/manage-pcg/configure-proxy.md) to learn how to install Reach
+    on a PCG cluster and use it to configure proxy settings.
+
+2.  If you deployed the PCG using the Palette CLI, the cloud account is created automatically. You can skip this step.
+
+    Once you have deployed the PCG, you must create a new cloud account associated with the PCG. Refer to the following
+    resources to learn how to create a cloud account:
+
+    - [Add an AWS Account to Palette](../public-cloud/aws/add-aws-accounts.md)
+    - [Register and Manage Azure Cloud Account](../public-cloud/azure/azure-cloud.md)
+    - [Register and Manage GCP Accounts](../public-cloud/gcp/add-gcp-accounts.md)
+
+3.  Create a cluster profile that contains your application. Refer to
+    [Create a Cluster Profile](../../profiles/cluster-profiles/cluster-profiles.md) for additional guidance.
+
+    In your cluster profile, apply the `spectrocloud.com/connection: proxy` label to the deployment, job, or daemon set
+    in the pack that contains your application.
+
+    You must apply the label to every specific job, deployment, or daemon set that needs to use the proxy servers. For
+    example, if you have a Kafka deployment that requires access to the internet through your proxy, you need to apply
+    the label to the Kafka deployment.
+
+    ```yaml {10}
+    apiVersion: apps/v1
+    kind: Deployment
+    metadata:
+      name: kafka
+    spec:
+      template:
+        metadata:
+          labels:
+            app: kafka
+            spectrocloud.com/connection: proxy
+    ```
+
+4.  Start creating your cluster using the cloud account associated with the PCG. The cluster will inherit proxy settings
+    from the PCG automatically. Refer to the following resources on cluster creation.
+
+    - [Create and Manage AWS Cluster](../public-cloud/aws/create-cluster.md)
+    - [Create and Manage Azure IaaS Cluster](../public-cloud/azure/create-azure-cluster.md)
+    - [Create and Manage GCP IaaS Cluster](../public-cloud/gcp/create-gcp-iaas-cluster.md)
+
+</TabItem>
+
+<TabItem value="Self-Hosted Palette Non-Edge">
+
+1.  If you are using a self-hosted Palette instance, you have the opportunity to configure proxy settings during
+    installation. If you are using the Palette CLI for installation, refer to
+    [Self Hosted Palette - Installation](../../enterprise-version/install-palette/install-on-kubernetes/install.md) to
+    learn how to specify proxy settings during installation. If you used Helm charts for installation, refer to
+    [Enable and Manage Proxy Configurations](../pcg/manage-pcg/configure-proxy.md) to learn how to install reach and use
+    it to configure proxy settings. The process to install Reach on an existing self-hosted Palette instance is the same
+    as the process to install Reach on an existing PCG cluster.
+
+2.  Create a cluster profile that contains your application. Refer to
+    [Create a Cluster Profile](../../profiles/cluster-profiles/cluster-profiles.md) for additional guidance.
+
+    In your cluster profile, apply the `spectrocloud.com/connection: proxy` label to the deployment, job, or daemon set
+    in the pack that contains your application.
+
+    You must apply the label to every specific job, deployment, or daemon set that needs to use the proxy servers. For
+    example, if you have a Kafka deployment that requires access to the internet through your proxy, you need to apply
+    the label to the Kafka deployment.
+
+    ```yaml {10}
+    apiVersion: apps/v1
+    kind: Deployment
+    metadata:
+      name: kafka
+    spec:
+      template:
+        metadata:
+          labels:
+            app: kafka
+            spectrocloud.com/connection: proxy
+    ```
+
+3.  Start creating your cluster using the cluster profile. The cluster will inherit proxy settings from the PCG
+    automatically. Refer to the following resources on cluster creation.
+
+    - [Create and Manage AWS Cluster](../public-cloud/aws/create-cluster.md)
+    - [Create and Manage Azure IaaS Cluster](../public-cloud/azure/create-azure-cluster.md)
+    - [Create and Manage GCP IaaS Cluster](../public-cloud/gcp/create-gcp-iaas-cluster.md)
+
+</TabItem>
+
+<TabItem value="Edge">
+
+1.  For Edge clusters, you specify the proxy settings for your Edge host during installation in your Edge installer
+    **user-data**. For more information, refer to [Installation](../edge/site-deployment/stage.md). If your Edge host is
+    deployed in airgap mode, you may also specify the proxy settings in Local UI. For more information, refer to
+    [Configure HTTP-Proxy in Local UI](../edge/local-ui/host-management/configure-proxy.md).
+
+2.  Create a cluster profile that contains your application. Refer to
+    [Create a Cluster Profile](../../profiles/cluster-profiles/cluster-profiles.md) for additional guidance.
+
+    In your cluster profile, apply the `spectrocloud.com/connection: proxy` label to the deployment, job, or daemon set
+    in the pack that contains your application.
+
+    You must apply the label to every specific job, deployment, or daemon set that needs to use the proxy servers. For
+    example, if you have a Kafka deployment that requires access to the internet through your proxy, you need to apply
+    the label to the Kafka deployment.
+
+    ```yaml {10}
+    apiVersion: apps/v1
+    kind: Deployment
+    metadata:
+      name: kafka
+    spec:
+      template:
+        metadata:
+          labels:
+            app: kafka
+            spectrocloud.com/connection: proxy
+    ```
+
+3.  Create a cluster using the cluster profile. For more information, refer to
+    [Create Cluster Definition](../edge/site-deployment/cluster-deployment.md).
+
+</TabItem>
+
+</Tabs>
+
+## Validate
+
+1. Access your cluster with kubectl. For more information, refer to [Access Cluster with kubectl](./palette-webctl.md).
+
+2. Issue the following command. Replace `pod-name` with the name of the pod for your application and replace
+   `your-namespace` with the namespace where the pod resides.
+
+   ```
+   kubectl get pod pod-name --output jsonpath='{.spec.containers[*].env}' --namespace your-namespace | jq .
+   ```
+
+   The command will yield output similar to the following. If the output includes the proxy settings you configured, you
+   can validate that the application is configured to use the proxy server.
+
+   ```json
+   [
+     {
+       "name": "http_proxy",
+       "value": "http://10.10.180.0:3128"
+     },
+     {
+       "name": "https_proxy",
+       "value": "http://10.10.180.0:3128"
+     },
+     {
+       "name": "NO_PROXY",
+       "value": ""
+     },
+     {
+       "name": "USER_NO_PROXY",
+       "value": ""
+     }
+   ]
+   ```