Type in the Sample Code

Labs are designed for learning. I learn by doing. While I can read, as they say in the local vernacular in my propinquity “Wicked Fast,” I don’t process read information to the depth that I need in order to retain it. I need to type in the code in order to learn. Here’s a technique I use to do that.

In my current lab we have a bunch of Kubernetes resources to create. These are specified as YAML files. The lab creator has made it easy for the student by making the heredocs, like this

cat << EOF | oc apply -f -
apiVersion: hostpathprovisioner.kubevirt.io/v1alpha1  
kind: HostPathProvisioner                             
  name: hostpath-provisioner                          
  imagePullPolicy: IfNotPresent                       
    path: "/var/hpvolumes"                            
    useNamingPrefix: "false"  

In order to learn this code, I type it in by hand, removing the first line (starts with ‘cat’) and the final EOF. However, as I found during this lab, it is very easy to add a typo in even a short file like this. Thus, you might be tempted to just run the heredocs. But that removes one of the key benefits of the lab: mentally processing the text that affects change in the system.

What I’ve been doing is typing in the sample code, and, before running it, creating a second file with an exact copy from the instructions. For example, the last one I did was for Node Network Configuration policy, stored in a file called nmstate.yaml. I copied the original code in nmstate.yaml.check and ran

$ diff nmstate.yaml.check nmstate.yaml            
< kind: NodeNetworkConfigurationPolicy                
> kind: NodeNetworkConfitguraiotnPolicy               

As you can see, my typo was pretty easy to identify. Once I corrected it:

$ oc apply -f nmstate.yaml                        

I was able to successfully execute the sample code, and move on with the lesson.

This may seem like a lot of extra work, but it makes the lab so much more valuable. It also enforces the rule that I have learned and relearned in my time as a programmer: let the computer check your work.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.