pipelines: Added proxy documentation (#4073)

* pipelines: Added proxy documentation

Signed-off-by: Helber Belmiro <[email protected]>

* Update content/en/docs/components/pipelines/operator-guides/server-config.md

Co-authored-by: Matt Prahl <[email protected]>
Signed-off-by: Helber Belmiro <[email protected]>

* pipelines: Removed unneeded sections

Signed-off-by: Helber Belmiro <[email protected]>

---------

Signed-off-by: Helber Belmiro <[email protected]>
Co-authored-by: Matt Prahl <[email protected]>

Author: hbelmiro

content/en/docs/components/pipelines/operator-guides/server-config.md

@@ -39,4 +39,49 @@ For full fledged Kubeflow, each namespace corresponds to a project with the same
 To configure the `ALLOWED_ARTIFACT_DOMAIN_REGEX` value for user namespace, add an entry in `ml-pipeline-ui-artifact`
 just like this example in [sync.py](https://github.com/kubeflow/pipelines/blob/b630d5c8ae7559be0011e67f01e3aec1946ef765/manifests/kustomize/base/installs/multi-user/pipelines-profile-controller/sync.py#L304-L310) for `ALLOWED_ARTIFACT_DOMAIN_REGEX` environment variable,
 the entry is identical to the environment variable instruction in Standalone Kubeflow Pipelines
-deployment.
+deployment.
+
+## Proxy
+
+Since KFP 2.5, you can set a server-scoped proxy configuration for the backend by setting any of the following environment variables (in uppercase) in the 
+API Server deployment. All variables are optional.
+
+- `HTTP_PROXY`
+- `HTTPS_PROXY`
+- `NO_PROXY`
+
+If `HTTP_PROXY` or `HTTPS_PROXY` is set and `NO_PROXY` is not set, `NO_PROXY` will automatically be set to `localhost,127.0.0.1,.svc.cluster.local,kubernetes.default.svc,metadata-grpc-service,0,1,2,3,4,5,6,7,8,9`.
+
+### Example of an API Server deployment with `HTTP_PROXY`, `HTTPS_PROXY`, and `NO_PROXY` set
+
+```yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  labels:
+    app: ml-pipeline
+    application-crd-id: kubeflow-pipelines
+  name: ml-pipeline
+  namespace: kubeflow
+spec:
+  selector:
+    matchLabels:
+      app: ml-pipeline
+      application-crd-id: kubeflow-pipelines
+  template:
+    metadata:
+      annotations:
+        cluster-autoscaler.kubernetes.io/safe-to-evict: "true"
+      labels:
+        app: ml-pipeline
+        application-crd-id: kubeflow-pipelines
+    spec:
+      containers:
+      - env:
+        - name: HTTP_PROXY
+          value: http://squid.squid.svc.cluster.local:3128
+        - name: HTTPS_PROXY
+          value: http://squid.squid.svc.cluster.local:3128
+        - name: NO_PROXY
+          value: localhost,127.0.0.1,.svc.cluster.local,kubernetes.default.svc,metadata-grpc-service,0,1,2,3,4,5,6,7,8,9
+```