Shulou(Shulou.com)06/03 Report--

In the field of cloud computing, container and serverless computing have occupied the forefront of development.

Author | Emra Samdan

Translation | bocloudresearch

A little history.

Not long ago, application development, deployment, and maintenance were much more complex and time-consuming than they are today. Initially, maintenance requires fixing not only the application's code, but also support for physical machines. Keeping the server, hardware, and software up to date is also a critical task.

At the beginning of this century, a new model called Infrastructure as a Service (IaaS) quickly became popular. IaaS offers the possibility of renting remote servers and virtual machines from third-party providers who are fully responsible for managing hardware, networking, and booking.

With the advent of IaaS, the idea of simplifying the work of developers by eliminating all non-coding responsibilities of developers has driven innovation in new methods, models, and services.

What is the container?

Docker's official website provides the following short but elegant definition: "A container is a standard software unit that packages code and all its dependencies to allow applications to run quickly and reliably between different computing environments. In other words, by using containers, developers can ensure that their applications can run on any cloud platform or local server. In some ways, containers are similar to virtual machines, for example, both are isolated resources. However, the virtual machine simulates the physical device, while the container creates the abstraction of the application layer.

What is serverless computing?

In serverless computing, the entire application or part of the application is decoupled into multiple functions, each triggered by time such as HTTP requests, new messages arriving in the message queue, or saving or modifying new objects in storage. The platform can run these functions at specific times or cycles, which is very helpful for cron jobs (scheduled tasks).

To make this system work, the developer simply writes functional code, packages it and its dependencies into a zip file, and then sends the zip file to the serverless endpoint, where the provider is responsible for provisioning and extending.

One of the key features of serverless is the pay-on-demand model, in which companies pay only according to the actual execution time of the function. Today, AWS Lambda should be the most popular serverless provider.

What do containers and serverless have in common?

Right. Nowadays, serverless and containers are very popular, which allow developers to focus on their own code rather than infrastructure, which greatly increases the speed of development. Both containers and serverless are well suited for micro-services and component-based architectures. When using them, deployment and scaling are usually faster and more cost-effective than using traditional monolithic architectures, because you are working on a small part of the application, not the entire application. While containers and serverless share these commonalities, each technology has its own advantages, disadvantages, and use cases.

Advantages of containerization

The first advantage of containers is portability. Because the container already contains everything it needs to run, you only need to place a machine with the container engine installed to run it. Containers are platform independent, so they can run on Linux, Windows, macOS, Mesos, Docker, Swarm, or Kubernetes. They can even run in another container.

Containers are also more efficient than virtual machines in the use of computing resources. Although both containers and virtual machines are virtualized, the virtual machine uses its own operating system to simulate the entire computer, thus consuming more resources. On the other hand, containers can share the same operating system, making the operating system smaller and faster to boot and shut down.

Another benefit of the container is that it allows the developer to take complete control of the application. While this means that system settings must be configured manually, it also means real flexibility. This is not possible on serverless because all content without a server is managed by a cloud provider.

Use case for the container

Containers are really helpful when we want to ReFactor some large monolithic applications into smaller independent parts in order to migrate to the microservice architecture and achieve better performance, testability, and scalability. For example, split the previous large application into several separate services: one responsible for user management, the other responsible for converting media files, and so on. Each service can be easily extended to provide better performance as the load on its scope of responsibility increases. But this is not possible for single applications, where new instances need to be added to the entire system, which is both expensive and time-consuming.

Therefore, the container is suitable for long-running applications, as well as applications with specific system requirements, which are difficult to set up without full control of the system.

Advantages of Serverless

Because of the pay-on-demand model mentioned above, hosting serverless applications can be much cheaper than using any other method. There is no need to pay for the free time of the feature, and if there is no traffic, there will be no charge on the monthly bill. Almost all serverless providers have a free layer, which includes a fixed number of requests and execution time per month. Usually, the number provided is enough for small websites or startups to run for free.

For containers, distributing applications to parts or micro-services is a key step. In serverless, it distributes the application or its parts to a single function, each responsible for a specific logical segment. It is easier for engineers to understand and develop the logic of individual functions, which greatly increases the speed of development and deployment. It is less risky to deploy a small number of features than to deploy the entire application.

Another big advantage of being serverless is automatic scaling. Serverless functions run in small, stateless temporary containers under the control of the provider. The provider takes full responsibility for extensions that respond to peak loads and can launch hundreds of instances in a matter of seconds. Moreover, you still only have to pay for the total execution time of all functions.

When is a good time to use serverless?

Serverless's event-driven nature makes it useful for applications (or parts thereof) that don't always need to run.

Suppose you are developing media processing capabilities for an existing application. Although the new module will not be used often, it still needs enough computing power to complete its tasks. Putting it in an application may require switching to a more powerful instance-- this is a risky move, because running some heavy tasks at the same time may cause delays for all other users. In this case, more costs need to be paid, and some of the problems caused by the above bottlenecks are still faced.

Conversely, if serverless is selected, the media handling functionality will be isolated from the rest of the application. When it is not used, you do not have to pay for it, and you can always ensure that it does not affect the rest of the application.

The disadvantages of containers

Even if no one is using the application, at least one virtual machine instance that hosts the container is always running. As a result, containers are more expensive than no servers.

Even if the container can expand quickly in a shared computer, other extensions are not very fast because of the need to extend the computer itself. However, using containers with business process systems such as Kubernetes or AWS ECS can make the extension smarter.

The disadvantages of having no server

For most developers, the scariest part of serverless is vendor locking. When you submit to serverless, you are actually stacking on a single cloud provider. The serverless applications and api architectures used in these functions vary from provider to provider, so the cost of changing the provider or switching to an internal solution can be high. However, some experts do not agree with this view, claiming that vendor locking is not actually a problem.

Using a serverless approach is not easy to achieve observability, monitoring, and debugging. Because applications can be dispersed into multiple parts, each with its own bug and errors, it is important to control and view the global situation.

Can containers and serverless operate together?

Containers and no servers can be operated together, and the answer is yes. It can be very effective to run the main application function as a containerized microservice, while using serverless for some background operations or functions that are rarely used (but taking up CPU).

Another interesting combination is provided by AWS Fargate. This service combines the advantages of serverless and containers, allowing you to have more control over your application without having to worry about scaling problems.

Conclusion

Container and serverless are generally considered to be competing technologies. But if you look closely, you will see that they are just different technologies, and when used in the same project, they can actually make up for each other's shortcomings. It is important to remember that "old" does not mean "outdated" and "new" does not mean "better". The effectiveness of the solution depends on specific use cases, project requirements, team experience, and team preferences.

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