Show how to access internal services with kubectl proxy

slides/kube-fullday.yml

@@ -33,6 +33,7 @@ chapters:
   - kube/kubectlrun.md
 - - kube/kubectlexpose.md
   - kube/ourapponkube.md
+  - kube/kubectlproxy.md
   - kube/dashboard.md
 - - kube/kubectlscale.md
   - kube/daemonset.md

slides/kube-halfday.yml

@@ -35,6 +35,7 @@ chapters:
 - - kube/kubectlrun.md
   - kube/kubectlexpose.md
   - kube/ourapponkube.md
+  #- kube/kubectlproxy.md
 - - kube/dashboard.md
   - kube/kubectlscale.md
   - kube/daemonset.md

slides/kube-selfpaced.yml

@@ -32,6 +32,7 @@ chapters:
   - kube/kubectlrun.md
 - - kube/kubectlexpose.md
   - kube/ourapponkube.md
+  - kube/kubectlproxy.md
   - kube/dashboard.md
 - - kube/kubectlscale.md
   - kube/daemonset.md

slides/kube/kubectlproxy.md

@@ -0,0 +1,117 @@
+# Accessing internal services with `kubectl proxy`
+
+- `kubectl proxy` runs a proxy in the foreground
+
+- This proxy lets us access the Kubernetes API without authentication
+
+  (`kubectl proxy` adds our credentials on the fly to the requests)
+
+- This proxy lets us access the Kubernetes API over plain HTTP
+
+- This is a great tool to learn and experiment with the Kubernetes API
+
+- The Kubernetes API also gives us a proxy to HTTP and HTTPS services
+
+- Therefore, we can use `kubectl proxy` to access internal services
+
+  (Without using a `NodePort` or similar service)
+
+---
+
+## Secure by default
+
+- By default, the proxy listens on port 8001
+
+  (But this can be changed, or we can tell `kubectl proxy` to pick a port)
+
+- By default, the proxy binds to `127.0.0.1`
+
+  (Making it unreachable from other machines, for security reasons)
+
+- By default, the proxy only accepts connections from:
+
+  `^localhost$,^127\.0\.0\.1$,^\[::1\]$`
+
+- This is great when running `kubectl proxy` locally
+
+- Not-so-great when running it on a remote machine
+
+---
+
+## Running `kubectl proxy` on a remote machine
+
+- We are going to bind to `INADDR_ANY` instead of `127.0.0.1`
+
+- We are going to accept connections from any address
+
+.exercise[
+
+- Run an open proxy to the Kubernetes API:
+  ```bash
+  kubectl proxy --port=8888 --address=0.0.0.0 --accept-hosts=.*
+  ```
+
+]
+
+.warning[Anyone can now do whatever they want with our Kubernetes cluster!
+<br/>
+(Don't do this on a real cluster!)]
+
+---
+
+## Viewing available API routes
+
+- The default route (i.e. `/`) shows a list of available API endpoints
+
+.exercise[
+
+- Point your browser to the IP address of the node running `kubectl proxy`, port 8888
+
+]
+
+The result should look like this:
+```json
+{
+  "paths": [
+    "/api",
+    "/api/v1",
+    "/apis",
+    "/apis/",
+    "/apis/admissionregistration.k8s.io",
+    …
+```
+
+---
+
+## Connecting to a service through the proxy
+
+- The API can proxy HTTP and HTTPS requests by accessing a special route:
+  ```
+  /api/v1/namespaces/`name_of_namespace`/services/`name_of_service`/proxy
+  ```
+
+- Since we now have access to the API, we can use this special route
+
+.exercise[
+
+- Access the `hasher` service through the special proxy route:
+  ```open
+  http://`X.X.X.X`:8888/api/v1/namespaces/default/services/hasher/proxy
+  ```
+
+]
+
+You should see the banner of the hasher service: `HASHER running on ...`
+
+---
+
+## Stopping the proxy
+
+- Remember: as it is running right now, `kubectl proxy` gives open access to our cluster
+
+.exercise[
+
+- Stop the `kubectl proxy`
+
+]
+