Why is Multi-Cloud a Hard Problem?

I was one of the individuals who helped put this together and hopefully can answer your question. Specifically about complexity and the productivity of going multi-cloud.

Here is what we found, previously when people talked about going to the cloud the state of the art was everything is done targeting a specific cloud provider, you put your software in immutable AMI's and you use ASG, and ELB, along with S3 and EBS to have really robust systems. You instrument everything with CloudWatch and make sure everything is locked down with IAM and security groups.

What we have seen lately is that because of Kubernetes that has all changed. Most systems being designed today are being done very much provider agnostic, and the only time you want to be locked into a specific technology is when the vendor provided solution doesn't really have an alternative in a truly vendor agnostic stack. Part of what this service is doing is taking the last true bit of Gravity for a cloud provider and removing it, you can now run in both clouds just as easily as if you were all in on one of them. There are some additional costs if you are transferring all your data across the wire, but that is where the power of Vitess's sharding comes in. You can run your service across two clouds, while minimizing the amount of cross talk, until you want to migrate off.

Also while this post makes a big deal about being multi-cloud, this also gives you true multi-region databases. Thats something that was really only available with Spanner or CosmosDB previously, both of which require you to target them explicitly. PlanetScaleDB lets you use your existing MySQL compatible software.

If you wouldn't buy the license key from Oracle, don't rent the network API from Amazon.

Proprietary software can be good in contexts where the integration surface is small. The denominator you want to code against in such a way that you become deeply intertwined with it & would have a hard time backing out is open source.

The "lowest common denominator" being Linux, Postgres, Kubernetes, etc. is not such a terrible thing.

Multi-cloud deployments often happen organically in large organizations, e.g. because there are always legacy systems, possibly different procurement processes in sub-companies, different legal requirements in national branches leading to the use of different vendors or acquisitions of companies with different tech stacks. And while consolidating all IT on a single platform sounds really tempting it can quickly become a disaster and spectacularly fail as well, so multi-cloud deployments are probably here to stay.

We in the DoD are very intent on ensuring that we don't have single point of failures or the ability for an adversary to cut access to our capabilities. That especially includes compute/store.

So Global high availability (Hybrid multi cloud) and no vendor lock are pretty important.

There is a reason : quit a cew saas provider are on only one cloud... Sooo if you want or need to use a service and want a good connection, you need to go with a few things to the other cloud provider...

Agree with the sentiment.

Many enterprises got really excited about multi-cloud really fast but then gave up once they faced the harsh reality of increased complexity (and, as a consequence, cost and time).

People tend to grossly overestimate the actual size of the ‘common denominator’. On the face of it services look almost identical (every cloud has compute, blob storage, block storage, etc.), in reality, there are so many subtle differences between analogous services (API, pricing model, failure modes, performance, security models) that the support and operation cost easily more than doubles. So even in large enterprises where there is a top-down edict to ‘be multi-cloud’ actual BU/team silos tend to stick to one or the other provider.

The other often overlooked aspect is that clouds offer bulk discounts (I’ve seen up to 40%) for customers that spend many tens or hundreds of millions of dollars, but one can only get this if they stick to one provider. In other words, the economics of multi-cloud doesn’t scale well.

Kubernetes strives to be the common layer, but cross-cloud deployments tend to be very convoluted and non-trivial. They require a lot of manual work, tons of expertise in different domains (networking, security), greatly increase management overhead, and introduce funny new failure modes. In addition, Kubernetes is just one piece of the puzzle. After one is done with Kubernetes, they still need to figure out their user-facing services for launching containers, provisioning and managing databases, message queues, analytics, and machine learning pipelines. Now compare that entire ordeal with clicking a few buttons (or writing several pages of Terraform) and having everything setup and ready to go in an instant and on-demand. Yes, you do have to tie yourself to a single cloud, give up some degrees of freedom, and use extremely high-margin proprietary services (like Kinesis instead of Kafka) but it’s so so much easier, faster and cheaper (at least in the short to medium term).

To answer the original question (and sorry for going off on a tangent), I haven’t seen any company actually succeed with multi-cloud (my sample is 100+ SMBs and large enterprises). Even extremely tech-savvy and sophisticated companies like Twitter (with their shift to GCP) tend to think of all this as something that doesn’t necessarily need to be built anymore and should be bought instead.

What I do see all the time, is companies trying to figure out a way to marry their existing on-prem and (single) cloud provider setups. It is still a struggle though, and will probably always be to a certain extent.

Edit: typos

Not everyone rips you off on egress fees the way Amazon/MS/Google do. Quite a few of the 2nd tier providers (eg. Vultr, Linode, Digital Ocean, Upcloud, etc) offer $0.01/GB for public outbound bandwidth with a free allowance each month (usually anywhere from 1-10+TB/month/instance depending on what you deployed). Some companies even waive fees for companies they're partnered with (eg. if you use Wasabi or Backblaze B2 instead of S3 you won't be charged transfer fees to a number of cloud providers or Cloudflare thanks to the bandwidth alliance).

Multi-person arguing is pretty easy.

Yes there is a requirement for a full mesh, and generally it has to be in all regions. GCP will route for you at the Network level so we could get away with not all GCP regions being peered to all AWS and Azure regions, but all AWS and Azure regions need to be peered to each other.

For the HA of VPN links for most providers its handled automatically, AWS <-> Azure and AWS <-> GCP both are HA links offered by the provider. Azure <-> GCP is a Classic VPN so we need two of them and we need to manage the routes to make sure they would fail over in the event of a loss of one system.

Throughput is another story, we are very much limited by the throughput of the various VPN's. We haven't pushed GCP or Azure to the max to see what they can do, but according to the documentation we should be expecting around 300Mbps across each link in the mesh before we start to see throttling. At that point it makes sense for us to move to a co-located exchange and peer with dedicated connections.

Finally for other providers, when we start to get them inbound we will be looking at using the transit gateway's of the various providers to reduce the total number off links needed, or standing up virtual routers to act as exchanges.

Hopefully we will be doing another post with more technical details and some benchmarks!