Glossary
The terms below show up across the Atlas docs and console. Some are Atlas-specific, others are general cloud vocabulary that means the same here as anywhere else; where Atlas does something particular, the entry says so.
A
- Account: Owns your resources, the instances, networks, and volumes, and carries a role (Atlas Admin, Atlas User, or Atlas ReadOnly) that scopes what it can do. Every account belongs to a domain.
- Availability Zone (AZ): Across cloud providers, an isolated data center location inside a Region. Atlas runs a single zone,
is1, so in practice you’ll only ever see the one.
C
- Cluster: Several Host nodes (physical servers) pooled together and managed as one set of resources.
- Compute Offering: The CPU and RAM bundle an instance gets, named like Atlas.a4, Atlas.a5, or Atlas.a6.
- Core: One virtual CPU, or vCPU, handed to an instance.
D
- Disk Offering: Describes a Data Volume’s size and its performance, meaning IOPS.
- Data Volume: Extra storage you attach to an instance, kept separate from the OS root disk.
- Domain: A container for accounts and, optionally, sub-domains. The natural place to separate environments such as prod and dev, or to keep tenants apart. A domain is the billable unit.
E
- Elastic IP (EIP): A static public IP you can move from one instance to another.
- Egress Rule: A firewall rule that governs traffic leaving a network.
G
- Guest Network: A virtual network (VLAN or VXLAN) isolated to a single account.
- Gateway: The router interface that gives a network its connectivity.
H
- Host: The physical server running the KVM hypervisor that your instances actually run on.
- Hypervisor: KVM, the software layer that creates and runs the virtual machines.
I
- Image / Template: A ready-made OS image, Ubuntu or CentOS for instance, that you launch instances from.
- Instance: A Virtual Machine. The two words are interchangeable here.
- Ingress Rule: A firewall rule that governs traffic coming into a network.
K
- Key Pair: The SSH public and private keys you use to log into an instance instead of a password.
N
- Network: The L2/L3 connectivity layer that ties instances together. See Guest Networks.
- Network ACL: Stateless firewall rules applied at the subnet level inside a VPC.
P
- Port Forwarding: Sends an external public port through to a private IP and port inside the network.
- Public IP: An IPv4 address that’s routable from anywhere on the internet.
- Project: A way to group resources and users together so a team can manage them as a unit.
R
- Region: In general cloud terms, a geographic area holding one or more Availability Zones. Atlas runs a single zone,
is1. - Role: What an account is allowed to do. Atlas Admin has full control over its domain and any sub-domains; Atlas User can view and edit resources but not delete them; Atlas ReadOnly can view but not change them.
- Root Volume: An instance’s primary disk, the one its operating system lives on.
- Router (Virtual Router): A system VM that handles a Guest Network’s plumbing, DHCP, DNS, NAT, VPN, and the firewall.
S
- Security Group: Stateful firewall rules applied directly to an instance’s network interface.
- Snapshot: A point-in-time backup of a Volume.
- Source NAT: The primary public IP used for outbound traffic from a private network.
- Static NAT: 1-to-1 mapping of a Public IP to a Private IP.
T
- Template: System image used to create new VMs.
- Tier: A logical subnet within a VPC (e.g., Web Tier, App Tier).
U
- User: A login, its credentials and two-factor (2FA) settings, that belongs to an account. One person can hold more than one account when they need different scopes.
- User Data: Scripts or cloud-init configuration passed to an instance at launch.
V
- VLAN: Virtual Local Area Network; L2 isolation mechanism.
- VM: Virtual Machine; see Instance.
- Volume: A virtual hard disk (standard or SSD).
- VPC (Virtual Private Cloud): An isolated network environment with user-defined subnets, routes, and gateways.
- VPN: Virtual Private Network; secure connection logic.