From f73fb9283248f5e9fe9a66a8869be80e56884a69 Mon Sep 17 00:00:00 2001
From: Jerome Petazzoni <jerome.petazzoni@gmail.com>
Date: Mon, 18 Nov 2019 12:57:26 -0600
Subject: [PATCH] Put pods before services

The flow is better this way, since we can introduce pods
just after seeing them in kubectl describe node.

Also, add some extra info when we curl the Kubernetes API.
---
 slides/k8s/kubectlget.md | 149 ++++++++++++++++++++++++++-------------
 1 file changed, 101 insertions(+), 48 deletions(-)

diff --git a/slides/k8s/kubectlget.md b/slides/k8s/kubectlget.md
index 44566b26..2107a0c0 100644
--- a/slides/k8s/kubectlget.md
+++ b/slides/k8s/kubectlget.md
@@ -71,7 +71,7 @@
 
 - Show the capacity of all our nodes as a stream of JSON objects:
   ```bash
-    kubectl get nodes -o json | 
+    kubectl get nodes -o json |
             jq ".items[] | {name:.metadata.name} + .status.capacity"
   ```
 
@@ -182,53 +182,6 @@ class: extra-details
 
 ---
 
-## Services
-
-- A *service* is a stable endpoint to connect to "something"
-
-  (In the initial proposal, they were called "portals")
-
-.exercise[
-
-- List the services on our cluster with one of these commands:
-  ```bash
-  kubectl get services
-  kubectl get svc
-  ```
-
-]
-
---
-
-There is already one service on our cluster: the Kubernetes API itself.
-
----
-
-## ClusterIP services
-
-- A `ClusterIP` service is internal, available from the cluster only
-
-- This is useful for introspection from within containers
-
-.exercise[
-
-- Try to connect to the API:
-  ```bash
-  curl -k https://`10.96.0.1`
-  ```
-  
-  - `-k` is used to skip certificate verification
-
-  - Make sure to replace 10.96.0.1 with the CLUSTER-IP shown by `kubectl get svc`
-
-]
-
---
-
-The error that we see is expected: the Kubernetes API requires authentication.
-
----
-
 ## Listing running containers
 
 - Containers are manipulated through *pods*
@@ -467,3 +420,103 @@ class: extra-details
 
 [KEP-0009]: https://github.com/kubernetes/enhancements/blob/master/keps/sig-node/0009-node-heartbeat.md
 [node controller documentation]: https://kubernetes.io/docs/concepts/architecture/nodes/#node-controller
+
+---
+
+## Services
+
+- A *service* is a stable endpoint to connect to "something"
+
+  (In the initial proposal, they were called "portals")
+
+.exercise[
+
+- List the services on our cluster with one of these commands:
+  ```bash
+  kubectl get services
+  kubectl get svc
+  ```
+
+]
+
+--
+
+There is already one service on our cluster: the Kubernetes API itself.
+
+---
+
+## ClusterIP services
+
+- A `ClusterIP` service is internal, available from the cluster only
+
+- This is useful for introspection from within containers
+
+.exercise[
+
+- Try to connect to the API:
+  ```bash
+  curl -k https://`10.96.0.1`
+  ```
+
+  - `-k` is used to skip certificate verification
+
+  - Make sure to replace 10.96.0.1 with the CLUSTER-IP shown by `kubectl get svc`
+
+]
+
+The command above should either time out, or show an authentication error. Why?
+
+---
+
+## Time out
+
+- Connections to ClusterIP services only work *from within the cluster*
+
+- If we are outside the cluster, the `curl` command will probably time out
+
+  (Because the IP address, e.g. 10.96.0.1, isn't routed properly outside the cluster)
+
+- This is the case with most "real" Kubernetes clusters
+
+- To try the connection from within the cluster, we can use [shpod](https://github.com/jpetazzo/shpod)
+
+---
+
+## Authentication error
+
+This is what we should see when connecting from within the cluster:
+```json
+$ curl -k https://10.96.0.1
+{
+  "kind": "Status",
+  "apiVersion": "v1",
+  "metadata": {
+
+  },
+  "status": "Failure",
+  "message": "forbidden: User \"system:anonymous\" cannot get path \"/\"",
+  "reason": "Forbidden",
+  "details": {
+
+  },
+  "code": 403
+}
+```
+
+---
+
+## Explanations
+
+- We can see `kind`, `apiVersion`, `metadata`
+
+- These are typical of a Kubernetes API reply
+
+- Because we *are* talking to the Kubernetes API
+
+- The Kubernetes API tells us "Forbidden"
+
+  (because it requires authentication)
+
+- The Kubernetes API is reachable from within the cluster
+
+  (many apps integrating with Kubernetes will use this)