Update http_proxy.md

docs/http_proxy.md

@@ -20,7 +20,8 @@ export HTTP_PROXY=http://<proxy hostname:port>
 export HTTPS_PROXY=https://<proxy hostname:port>
 export NO_PROXY=localhost,127.0.0.1,10.96.0.0/12,192.168.0.0/16
 
-minikube start --docker-env=HTTP_PROXY=$HTTP_PROXY --docker-env HTTPS_PROXY=$HTTPS_PROXY
+minikube start --docker-env=HTTP_PROXY=$HTTP_PROXY --docker-env HTTPS_PROXY=$HTTPS_PROXY \
+  --docker-env NO_PROXY=$NO_PROXY
 ```
 
 To make the exported variables permanent, consider adding the declarations to ~/.bashrc or wherever your user-set environment variables are stored.
@@ -32,11 +33,39 @@ set HTTP_PROXY=http://<proxy hostname:port>
 set HTTPS_PROXY=https://<proxy hostname:port>
 set NO_PROXY=localhost,127.0.0.1,10.96.0.0/12,192.168.0.0/16
 
-minikube start --docker-env=HTTP_PROXY=$HTTP_PROXY --docker-env HTTPS_PROXY=$HTTPS_PROXY --docker-env NO_PROXY=$NO_PROXY
+minikube start --docker-env=HTTP_PROXY=$HTTP_PROXY --docker-env HTTPS_PROXY=$HTTPS_PROXY \
+  --docker-env NO_PROXY=$NO_PROXY
 ```
 
 To set these environment variables permanently, consider adding these to your [system settings](https://support.microsoft.com/en-au/help/310519/how-to-manage-environment-variables-in-windows-xp) or using [setx](https://stackoverflow.com/questions/5898131/set-a-persistent-environment-variable-from-cmd-exe)
 
+## Debugging
+
+### unable to cache ISO... connection refused
+
+```
+Unable to start VM: unable to cache ISO: https://storage.googleapis.com/minikube/iso/minikube.iso:
+failed to download: failed to download to temp file: download failed: 5 error(s) occurred:
+
+* Temporary download error: Get https://storage.googleapis.com/minikube/iso/minikube.iso:
+proxyconnect tcp: dial tcp <host>:<port>: connect: connection refused
+```
+
+This error indicates that the host:port combination defined by HTTPS_PROXY is incorrect, or that the proxy is unavailable.
+
+## Unable to pull images..Client.Timeout exceeded while awaiting headers
+
+```
+Unable to pull images, which may be OK: 
+
+failed to pull image "k8s.gcr.io/kube-apiserver:v1.13.3": output: Error response from daemon:
+Get https://k8s.gcr.io/v2/: net/http: request canceled while waiting for connection
+(Client.Timeout exceeded while awaiting headers)
+```
+
+This error indicates that the container runtime running within the VM does not have access to the internet. Verify that you are passing the appropriate value to `--docker-env HTTPS_PROXY`.
+
+
 ## Additional Information
 
 - [Configure Docker to use a proxy server](https://docs.docker.com/network/proxy/)