Red Hat OpenShift Development I: Introduction to Containers with Podman
In this course, the main computer system for hands-on learning activities is workstation.
The system called bastion must always be running.
These two systems are in the lab.example.com DNS domain.
All student computer systems have a standard user account, student, which has student as the password.
The root password on all student systems is redhat.
Table 1. Classroom Machines
| Machine name | IP addresses | Role |
|---|---|---|
| workstation.lab.example.com | 172.25.250.9 | Graphical workstation that the student uses |
| bastion.lab.example.com | 172.25.250.254 | Router to link VMs to central course servers |
| classroom.lab.example.com | 172.25.252.254 | Server to host the required classroom materials for the course |
| utility.lab.example.com | 172.25.250.253 | Server to provide supporting services that the RHOCP cluster requires, including DHCP and NFS and routing to the RHOCP servers |
| master01.ocp4.example.com | 192.168.50.10 | An OpenShift control plane and compute node |
| registry.ocp4.example.com | 192.168.50.50 | Server to provide an image registry service |
The bastion system acts as a router between the network that connects the student machines and the classroom network.
If bastion is down, then other student machines might not function properly, or might even hang during boot.
The utility system acts as a router between the network that connects the OpenShift cluster machines and the student network.
If utility is down, then the OpenShift cluster does not function properly, or might even hang during boot.
Students use the workstation machine to access a dedicated OpenShift cluster, for which they have cluster administrator privileges.
Table 2. OpenShift Access Methods
| Access method | Endpoint |
|---|---|
| Web console | https://console-openshift-console.apps.ocp4.example.com |
| API | https://api.ocp4.example.com:6443 |
The OpenShift cluster has a standard user account, developer, which has developer as the password.
The administrative account, admin, has redhatocp as the password.
- Cannot log in to RHOCP
Red Hat OpenShift Container Platform (RHOCP) can take a long time to start. Consequently, you might encounter authentication errors when executing lab scripts, for example:
[student@workstation ~]$
lab start openshift-multipodStarting lab. SUCCESS Copying container files SUCCESS Copy exercise files FAIL Verifying your OpenShift API URL - API could not be reached: https://api.ocp4.example.com:6443 - Cannot continue starting labYou might also encounter errors when executing the
oc logincommand, for example:[student@workstation ~]$
oc login -u developer -p developer \ https://api.ocp4.example.com:6443error: EOFIn that case, wait for RHOCP to come online, and try again. This can take up to 20 minutes, depending on the classroom load.
You are assigned remote computers in a Red Hat Online Learning (ROLE) classroom. Self-paced courses are accessed through a web application that is hosted at . Log in to this site with your Red Hat Customer Portal user credentials.
The virtual machines in your classroom environment are controlled through web page interface controls. The state of each classroom virtual machine is displayed on the tab.
Table 3. Machine States
| Virtual Machine State | Description |
|---|---|
| building | The virtual machine is being created. |
| active | The virtual machine is running and available. If it just started, it still might be starting services. |
| stopped | The virtual machine is completely shut down. On starting, the virtual machine boots into the same state that it was in before shutdown. The disk state is preserved. |
Table 4. Classroom Actions
| Button or Action | Description |
|---|---|
| Create the ROLE classroom. Creates and starts all the virtual machines that are needed for this classroom. Creation can take several minutes to complete. | |
| The ROLE classroom virtual machines are being created. Creates and starts all the virtual machines that are needed for this classroom. Creation can take several minutes to complete. | |
| Delete the ROLE classroom. Destroys all virtual machines in the classroom. All saved work on those systems' disks is lost. | |
| Start all virtual machines in the classroom. | |
| All virtual machines in the classroom are starting. | |
| Stop all virtual machines in the classroom. |
Table 5. Machine Actions
| Button or Action | Description |
|---|---|
Connect to the system console of the virtual machine in a new browser tab.
You can log in directly to the virtual machine and run commands, when required.
Normally, log in to the workstation virtual machine only, and from there, use ssh to connect to the other virtual machines. | |
| → | Start (power on) the virtual machine. |
| → | Gracefully shut down the virtual machine, preserving disk contents. |
| → | Forcefully shut down the virtual machine, while still preserving disk contents. This action is equivalent to removing the power from a physical machine. |
| → | Forcefully shut down the virtual machine and reset associated storage to its initial state. All saved work on that system's disks is lost. |
At the start of an exercise, if instructed to reset a single virtual machine node, click → for only that specific virtual machine.
If you are instructed to reset all virtual machines, click → on each virtual machine in the list.
If you want to return the classroom environment to its original state at the start of the course, then click to remove the entire classroom environment. After the lab is deleted, then click to provision a new set of classroom systems.
Warning
The operation cannot be undone. All completed work in the classroom environment is lost.
The Red Hat Online Learning enrollment entitles you to a set allotment of computer time. To help to conserve your allotted time, the ROLE classroom uses timers, which shut down or delete the classroom environment when the appropriate timer expires.
To adjust the timers, locate the two buttons at the bottom of the course management page. Click the auto-stop button to add another hour to the auto-stop timer. Click the auto-destroy button to add another day to the auto-destroy timer. Auto-stop has a maximum of 11 hours, and auto-destroy has a maximum of 14 days. Be careful to keep the timers set while you are working, so that your environment is not unexpectedly shut down. Be careful not to set the timers unnecessarily high, which could waste your subscription time allotment.
