Giorgio's Dumpster

Okay, let’s face it: the world is finally figuring out that cloud is for everyone, and not just for large-scale enterprises. This is a big step ahead, but when it comes to new adopters there are still many misconceptions and wrong expectations.

Wrong expectations are probably the most common reason for failure, because they usually lead to disasters that leave moving back to a legacy infrastructure design as the only option left.

(Image Source: XKCD)

But, turns out, it’s easier than you would expect. There is a basic set of rules and guidelines, and if you follow them you can easily be successful.

Let’s begin in this article with the 8 don’ts:

1. Never, ever trust a single instance of a given service. Don’t rely on redundant database platforms, replicated block devices, and so forth. They can still fail: accounting for this kind of failure at the application layer is the way to go.
2. Don’t put all your eggs in a bucket: cloud platforms are available in different geographical locations by nature, so you should really leverage this. True geographical redundancy can be hard to achieve at the beginning, but try at least to have read replicas spread over the world, so that in case of downtime in the main region you’re using your service would just be degraded and not completely unreachable.
3. Never think small. Some design patterns could seem overkills at first sight, but believe me, they are not. If you focus on designing your service so that it is ready for scaling up when needed, you won’t have to worry about later.
4. Don’t design complex software platforms: micro services are the way to go. Keep them simple and easy to maintain. It will be easier to scale them, and not only from a technical point of view: imagine how easy could be handing over not a part of a complex software, but a micro service to a new dedicated development team.
5. Never forget that performance is the key: a killer SQL query could still be affordable if you have a small number of users, but is going to be an issue when your platform grows. Make your application as efficient as possible, even when it doesn’t seem needed.
6. Don’t forget that everything could break, at any time. Keep your instances as simple as possible, so that they are easy to operate. If one fails or starts misbehaving, just respawn it, don’t waste your time trying to fix or debug it. In an ideal world, they should all be stateless.
7. Vertical scaling is a no go. Choose the size of your instances based on the performance you want a single request to have, but always spread multiple requests horizontally. This pattern will help a lot with availability as well.
8. Don’t be ‘legacy’: the world around you is moving very fast, and just looking at it makes no sense. New releases of software packages usually improve their performance and efficienty, and new versions of the services your cloud provider is offering you usually improve a number of items, cost being usually the main one. Running a legacy instance type just because your platform is too hard to upgrade to a newer operating system makes no sense and will kill your business in the long term.

Here we are. Now go and build!

The term “Cloud Computing” has been openly used for almost ten years now, but there are still some misconceptions around the concept itself and around some more specific words like “IaaS” (Infrastructure as a Service).

Sometimes I have to face pointless discussions with people that have completely wrong ideas and expectations: this can be annoying from my point of view, but can be catastrophic for realities deciding to make “the big move” without having completely understood what the cloud is all about.

If you have come across this post as you’re still trying to figure out what “Cloud Computing” and “IaaS” mean, then let me save your life and probably your job with some clarifications.

The market offering isn’t helping us, as service providers are confused as well and they use to define “IaaS” completely unrelated products. The US NIST has released a document containing a list of 5 “Essential Characteristics” of cloud services, but they are not so specific and won’t help you make any choice.

When words are being used in such a confused way, you have to decide which of the many interpretations is the “authoritative” one: my authorities for this article are Amazon Web Services (and not because I work for them, but because ten years ago they have been the first at offering an IaaS platform) and OpenStack (that is, AWS concepts and terms reviewed by the biggest open source community in the cloud computing world).

So, what you should expect or not expect from an IaaS offering?

• You should expect to be billed based on a Pay as you go model. Let’s be serious, if you have to pay an one time or monthly fee for your account and/or services you are using then this is not really cloud. Offering pay as you go services is a real technical challenge for the service provider, and if they aren’t giving you this option then you should have some doubts about them being up to date with the technology. Some providers will offer you discounts on long term commitments and this is fine, but always look for the PayG option, please.
• You should expect to have full access to API and CLI tools and not just to a GUI. This is critical also if you are not planning to use them from the beginning. Cloud is all about automation, and if you stick with a service that only offers a GUI, then you will be forever bound to your mouse (and hands): if you come from an on premise physical server environment you could not see my point right now, but in the cloud you will start using automation soon, at least in its basic form. Because it’s easy and useful.
• You should not expect your instances (virtual machines) to be always available. This is something I’ve already blogged about a few years ago (in italian, I’m sorry) but it’s still one of the biggest, most spread and more dangerous misconceptions. Cloud services are based on commodity hardware, and thus the instances on top of that should be considered in the same way, as a commodity. The single instance could be there or couldn’t be, and your customers don’t have to notice: you have to plan for high availability at application level, taking into account the various kinds of failure. Some additional services like Block Storage, Object Storage and Load Balancing as a Service will help you achieving the high levels of availability you need. If your service provider is offering you an extreme level of HA, then you’re probably paying for something you don’t need (if you’re using 5 web nodes, then what’s the matter if one of them goes down for a while?).
• You should expect instant provisioning: seriously, provisioning has to happen in seconds. Be careful not to underestimate this: you could be happy with a 24 hours delivery time for your first bunch of servers, but believe me you won’t be when you will need to rapidly scale because of a traffic peak. Maybe I’m being too picky here but I expect the provisioning of my account to happen in real time as well: I’m not happy with providers asking me to send a physical signed contract or my IDs before using their service.
• You should expect the service you choose not to have limits that could (and will) impact you. Okay, not all of us need the scale of AWS, but make sure your provider won’t go out of capacity when you will need it: planning for infrastructure is their job, and from your point of view you must always be able to use the resources you need, when you need them, with no previous commitment.
• You should (probably) expect to have access to multiple autonomous regions: being it for active-active HA or just for backup and disaster recovery purposes, doesn’t make so much sense to choose a provider that is hosting its entire platform in a single datacenter. Yes, you could choose to use 2 different services providers hosting services in different locations, but this is not going to be easy to deal with.
• You should (probably) expect not to be locked in by small-scale service providers: always look for open standards, expecially if the company you’re buying resources from is still at a scale where going out of business from one day to another is a (remote) possibility.
• You should not expect to be able to easily scale vertically (increase instance size, or a single resource inside the instance): cloud computing is based on horizontal scalability (that means adding building blocks, not making the existing ones bigger), and this is why service provider don’t focus so much on hot resize of instances or on the ability to add RAM if you need RAM without modifying anything else. This is related to availability as well: if you can’t afford a planned downtime on a single instance in your infrastructure, then you’re doing something wrong.

That’s it, at least for now. I’m sure moving to the cloud is the right choice almost for every company in the world, but please make sure you fully understand it before making any choice. Really.

Giorgio