6 CloudLab for Classes
CloudLab can be a good environment for classes: it provides students with separate, isolated environments in which to do their work, and those environments can easily be brought to a known clean state so that all students get a consistent environment. Students get root access on their nodes, making CloudLab ideal for classes that require configuration or code changes to the operating system, or low-level access to the hardware. Because CloudLab is a network testbed, it is also idea for class projects that make use of multiple nodes.
There are some limitations that you should be aware of before deciding to use CloudLab for a class:
CloudLab has limited resources: in large classes, if students leave work to the last minute, or all students try to work on a deadline at the same time, they may run into problems getting the nodes they need in time.
CloudLab has a policy that resources can only be held while they are actively being used. Make sure that students are aware that individual resource allocations are not meant to last all quarter/semester: students should start experiments when they are ready to begin work, and terminate them when they are done.
You will want to make sure that students understand that storage on nodes in CloudLab is ephemeral and will be cleared out when experiments terminate. Addtionally, while CloudLab makes every effort to provide a reliable service, hardware failures, etc. can cause data loss. Students need to be sure to regularly copy off important work to avoid loss due to experiment termination or equipment failures.
Resource reservations can be useful for classes: they ensure that a certain number of resources are available for use by a project during a specified time period. It’s important to note that the resource pool is shared by all members of the project: for example, if you reserve 10 nodes, they can be used by up to 10 different experiments. Students do not need to do anything special to use these reservations: simply starting an experiment during the reservation period will automatically make use of the reservation.
If you have any questions about using CloudLab for classes, see the getting help chapter of this manual. We ask that instructors and TAs be the primary point of contact for students in requesting help with CloudLab: CloudLab has a small support staff that cannot handle a large volume of student support.
6.1 Creating Your Project on CloudLab
Students should not apply for their own projects on CloudLab: the instructor or an assistant (such as a TA) should apply for a project. Be sure to check the box indicating that the project is for a class, and include enough information in the application for us to have a look at the class, such as a link to the syllabus if available.
We ask that you create a new project for each class that you teach; eg. each quarter/semester of a course should apply for a new project on CloudLab. If course staff (instructors, TAs, etc.) already have an account on CloudLab, they can re-use their existing accounts: simply log in before applying for the new project.
Once the project has been approved, students will apply to join it as described below. Course staff can approve these accounts, without CloudLab staff having to get involved. One way to smooth the process of approving accounts for large classes is to allow TAs to approve them; when approving a new account, you may give it "manager" permissions, which allows the account to approve others. You may also give users this status via the "Members" tab of the project page at any time.
6.2 Having Students Join Your Project
When a CloudLab project is approved, the project leader will receive an email with a link to join the project. This link can be distributed to students in the course, who will use it to apply for an account. Once a student applies, the project leader will receive email with the application, and can approve or deny it. Alternately, students can join the project by following the standard CloudLab "join an existing project" instructions, and enter the name of the class’s project.
Students who apply to start their own project will have their project requests denied, and be asked to join the main project for the class.
Students who already have an account on CloudLab can join the project without making a new account; simply log in before applying to join the new project.
6.3 Project-Based Classes
Classes that are based around students working independently or in groups are an ideal use case for CloudLab; all members of the project are given logins on all experiments started under the project, which enables easy collaboration.
6.4 Assignment-Based Classes
For classes in which all students are working on the same task, it can be useful to either use an existing profile or create a new one. This way, all students will have the same environment, simplifying instructions and making debugging easier. The page for each profile has a "share" button that can be used to get a link to include with the assignment.
For large classes, we recommend considering whether virtual machines can meet students’ needs, as this reduces the resource load on CloudLab. Virtual machines should use shared mode so that they run on shared, not exclusive, hosts.
All members of a project are given shells on all experiments in the project: thus, TAs can log into nodes being used by students to help examine or debug code.