Glossary
Add-On
A recurring/ongoing service that isn’t a hosting service; for example, the database disk space add-on or persistent storage.
Application
Within the context of Sevalla’s Application Hosting, an application is a set of instructions executed by a server to perform one or more tasks. Our current infrastructure is designed to serve and support the deployment of applications with a server behind the application.
Application Hosting
One of Sevalla’s Hosting Services. It is a Platform as a Service (PaaS) that provides you with the tools you need to deploy applications from a Git repository.
Artifact registry
The location where built images are stored. Each application has a single image that can be turned into a container.
Automatic deployment
When Automatic deployment on commit is enabled and a new commit is made to the default branch of your Git repository, a new version of the application will be deployed from Sevalla.
Background worker
A process that runs in the background, separate from the main application, and is inaccessible from the internet. Used to keep long-running processes separate from the main application to help maintain a good user experience. Not meant to be run as a one-time job that finishes after a certain amount of time. If a background process finishes after it completes its job, the pod will shut down, restart itself, and repeat the process. For a process that finishes after completing its job, use a cron job process.
Build time
The time it takes for an image to be built from an application’s source code. Builds are performed on machines specifically designated for building images. Multiple build machine sizes exist, and you can choose between these machines depending on the resources required to build the application. Build time is billed at different rates, separate from your application’s hosting pods.
Buildpack
Buildpacks are scripts that run when an application is deployed. They are used to install dependencies for your application and configure your environment.
Commit
A commit records changes to one or more files in a Git branch and assigns a unique ID (called an SHA or hash) that identifies the specific changes and when those changes are made.
Concurrent builds
With free unlimited concurrent builds in Sevalla’s Application Hosting, you can start as many builds as you want, in as many different applications as you want, all at the same time. You are not limited to a set number of builds per application or account, and there’s no additional charge for concurrent builds.
That means you can simultaneously start a build in one application, switch to and start a build in another application, or add a completely new application, all without waiting for other builds to finish.
Concurrent connections/users
Concurrent connections are connections that are happening simultaneously (i.e. at the same time). While there is a relationship between concurrent connections and users, it is not always a direct 1:1 relationship. One user can spawn multiple connections, depending on their actions and depending on the application’s code.
An application’s maximum concurrent connections depends on a number of factors, including its code, usage patterns of users, etc. To calculate this number, you need to know your application’s resource consumption. There are a number of load testing tools you can use to send concurrent connections to the application and see the resource usage during that time:
Connection
Connections are how applications communicate.
An External connection allows your database to communicate with an external application. This would be used in a situation where you are hosting only your database with us but not the frontend of your application. Because an external connection makes an internet round-trip, it is much slower than an internal connection.
An Internal connection stays within our network and is thus much faster and more secure. We recommend this method if you host both your frontend and your database with Sevalla.
Cron job
A process you can schedule at a specific interval once a day, once a month, every 10 minutes, etc) so you can automate repetitive tasks for your application. The process only launches based on the configured timing and shuts down after finishing the required operation.
Database
A collection of data that is stored in an organized manner so it can be retrieved or updated efficiently. You can choose from a number of database types with Sevalla’s Database Hosting service.
Deployment
A deployment is a rebuild of your application in a new container, usually done after updating your application’s code, but can be configured to happen automatically (see automatic deployment above). The deployment invokes any buildpacks and applies any environment variables each time the application is deployed.
Environment variables
Variables such as API keys, database connection details, or other configuration values or secrets. By using environment variables, you can avoid putting this information in your code as cleartext (unencrypted text).
Ephemeral
Services, pods, applications, containers, etc., that do not exist indefinitely and cannot be used to store data like uploaded images, videos, etc. Data that is part of the application itself (a favicon or logo, etc.) can be stored in ephemeral locations because when the application is rebuilt, its data is put back in place when the application is deployed.
Ephemeral containers provide resilience. Multiple versions of a pod can be launched, and if needed, new pods can be launched without the application suffering downtime.
Git repository
A Git repository is where your application’s code and historical versions of that code are saved.
Hosting services
Sevalla’s services that allow you to host specific types of content:
Other services include add-ons like the database disk space add-on or persistent storage.
Image
An image is the result of the building process from the application code. Pods are created based on Images.
Instance
See Pod below.
Logs
Runtime logs from the application build process.
Monorepo
A software development strategy where code for several projects is stored in the same repository. To use a monorepo with Application Hosting, you must specify the Build path when you add the application or in Settings > Edit details.
Sevalla company
A company is an organizational unit within Sevalla. Each company can have multiple users of various roles associated with it but can only have one owner. A company can have multiple applications, databases, or static sites.
Node
A node is a virtual machine that houses pods.
Overages
If you use more than the included resources, you incur overages. Our Application Hosting and Database Hosting do not incur overages because they are usage-based, and you only pay for the resources your application or database uses.
Persistent storage
Persistent storage (aka persistent volume) retains data after an application is shut down or restarted. It’s used for data that needs to be preserved across multiple sessions or devices, such as session data, user preferences, and cached content.
Stateful applications use persistent storage to request storage volume from an underlying storage system. The storage volume is mounted as a file system which allows the application to read or write to the storage device as if it were a local disk.
Pod
A Pod is a container that runs a Process. Each Pod has a Pod Size that defines the resources available to the Pod in terms of processor cores (CPU) and memory (RAM). Depending on the Process in the Pod, you may want to increase or decrease the resources to run applications more efficiently.
Pod scaling
The ability to increase the resources available to a pod (vertical scaling) or increase the number of pods (horizontal scaling) that run the same Process to ensure high availability and load balancing.
Pod size
Pod size determines the number of processor cores (CPU) and memory (RAM) available to the pod. Depending on the process the pod is running, you may want to increase or decrease the resources to run the application efficiently.
Postpaid
Postpaid services are paid for after the service is received. Utility bills are a common example where normally you pay after services have been rendered, receiving the amount used and the price in an invoice. Sevalla’s Application Hosting and Database Hosting services are postpaid. You pay only for the resources used at the end of each monthly billing cycle. These services are prorated to the second and postpaid.
Process
The smallest unit you can deploy in our Application Hosting. While this is usually a well-defined item, like a frontend for a web application, it could also serve as the backend for a mobile application. While it is usually well-defined, it’s up to you to decide what you want to run within a Pod or what constitutes a process. It’s possible to run multiple processes within a pod, but the Pod’s resources will be split up among those processes.
Start command
The command required to start your application is called the start command for applications built with a buildpack. If you use a Dockerfile to create your container image, you must specify the ENTRYPOINT or CMD in your Dockerfile.
Static Site Hosting
Static Site Hosting is a service that allows you to host static websites for free. Static websites are websites that are built using HTML, CSS, and JavaScript and do not require a server-side language like PHP or a database like MySQL.
Usage-based pricing
Usage-based pricing means that you only pay for the resources used. For Application Hosting and Database Hosting, we bill monthly at the end of your billing cycle or when your use of the services reaches a preset billing threshold, whichever occurs first.
Virtual Machines
Virtual Machines (VMs) emulate completely separate servers and can hold multiple containers and multiple databases. At Sevalla, our infrastructure, which includes VMs, is built on Google Cloud Platform’s top-tier infrastructure.