Added diagram

Author: odrodrig

workshop/Lab3/README.md

@@ -8,15 +8,29 @@ When looking at what kind of storage class you would like to use in Kubernetes,
 
 In this lab we will deploy a Mongo database on top of block storage on Kubernetes.
 
+![archDiagram](./images/archDiagram.png)
+
+The basic architecture is as follows
+
+1. When we install MongoDB with the helm chart, a `Persistent Volume Claim` (PVC) is created on the cluster. This PVC is a request for storage to be used by the application.
+
+2. In IBM Cloud, the request goes to the IBM Cloud storage provider which then provisions a physical storage device within IBM Cloud.
+
+3. A `Persistent Volume` (PV) is then created which acts as a reference to the physical storage device created earlier. This PV is then mounted as a directory in a container's file system.
+
+4. The guestbook application receives requests to store guestbook entries from the user which the guestbook pod then sends to the MongoDB pod to store.
+
+5. The MongoDB pod receives the request to store information and persists the data to the mounted directory from the Persistent Volume.
+
 ## Setup
 
 Before we get into the lab we first need to do some setup to ensure that the lab will flow smoothly.
 
-1. Replace `<docker username>` with your DockerHub username and run the following command (be sure to replace the `< >` too!).
+<!-- 1. Replace `<docker username>` with your DockerHub username and run the following command (be sure to replace the `< >` too!).
 
 ```bash
-DOCKER_USERNAME=<docker username>
-```
+DOCKERUSER=<docker username>
+``` -->
 
 1. In your terminal, navigate to where you would like to store the files used in this lab and run the following.
 
@@ -41,6 +55,39 @@ By default IBM Kubernetes Service Clusters don't have the option to deploy block
 
 1. Follow the steps outlined [here](https://cloud.ibm.com/docs/containers?topic=containers-block_storage#install_block) to install the block storage `storageClass`.
 
+1. First you need to add the `iks-charts` helm repo to your local helm repos. This will allow you to utilize a variety of charts to install software on the IBM Kubernetes Service.
+
+    ```bash
+    helm repo add iks-charts https://icr.io/helm/iks-charts
+    ```
+
+1. Then, we need to update the repo to ensure that we have the latest charts:
+
+    ```bash
+    helm repo update
+    ```
+
+1. Install the block storage plugin from the `iks-charts` repo:
+
+    ```bash
+    helm install block-storage-plugin iks-charts/ibmcloud-block-storage-plugin
+    ```
+
+1. Lastly, verify that the plugin installation was successful by retrieving the list of storage classes in the cluster:
+
+    ```bash
+    kubectl get storageclasses
+    ```
+
+    You should notice a few options that start with `ibmc-block` as seen below.
+
+    ```bash
+    NAME                       PROVISIONER         RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
+    ibmc-block-bronze          ibm.io/ibmc-block   Delete          Immediate           true                   62s
+    ibmc-block-custom          ibm.io/ibmc-block   Delete          Immediate           true                   62s
+    ibmc-block-gold            ibm.io/ibmc-block   Delete          Immediate           true                   62s
+    ```
+
 ## Helm Repo setup
 
 The lab uses Bitnami's Mongodb [Helm chart](https://github.com/bitnami/charts/tree/master/bitnami/mongodb) to show case the use of block storage. Set the Bitnami helm repo prior to installing mongodb.
@@ -83,7 +130,9 @@ Dryrun:
 helm install mongo bitnami/mongodb --set global.storageClass=ibmc-block-gold,auth.password=testing,auth.username=guestbookAdmin,auth.database=guestbook -n mongo --dry-run > mongdb-install-dryrun.yaml
 ```
 
-This command will test out our helm install command and save the output manifests in a file called `mongodb-install-dryrun.yaml`
+>There is a detailed breakdown of this command in the next section titled `Installing MongoDB` if you would like to understand what this helm command is doing.
+
+This command will test out our helm install command and save the output manifests in a file called `mongodb-install-dryrun.yaml`. You can then examine this manifest file so that you know exactly what will be installed on your cluster.
 
 Check out the file in your code editor and take a look at the `PersistentVolumeClaim` object. There should be a property named `storageClassName` in the spec and the value should be `ibmc-block-gold` to signify that we will be using block storage for our database.
 
@@ -264,9 +313,9 @@ In this file we are telling the application which datasource we should use; in-m
 
 ```bash
 cd $WORK_DIR/guestbook-nodejs/src
-IMAGE_NAME=$DOCKER_USERNAME/guestbook-nodejs:mongo
+IMAGE_NAME=$DOCKERUSER/guestbook-nodejs:mongo
 docker build -t $IMAGE_NAME .
-docker login -u $DOCKER_USERNAME
+docker login -u $DOCKERUSER
 docker push $IMAGE_NAME
 ```