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docs: ensure definitions have anchors

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Move the words being defined in the /docs/internal/architecture page to be
small headers so that they can be linked to with anchors from Learn guides and
other documentation location.
This commit is contained in:
Tim Gross
2021-05-18 14:13:49 -04:00
committed by Tim Gross
parent b32da80e78
commit e6c4a75bcf
1 changed files with 68 additions and 42 deletions
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website/content/docs/internals/architecture.mdx
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@@ -20,58 +20,84 @@ spelunking through the source code.
Before describing the architecture, we provide a glossary of terms to help
clarify what is being discussed:
- **Job** - A Job is a specification provided by users that declares a workload for
Nomad. A Job is a form of _desired state_; the user is expressing that the job should
be running, but not where it should be run. The responsibility of Nomad is to make sure
the _actual state_ matches the user desired state. A Job is composed of one or more
task groups.
#### Job
- **Task Group** - A Task Group is a set of tasks that must be run together. For example, a
web server may require that a log shipping co-process is always running as well. A task
group is the unit of scheduling, meaning the entire group must run on the same client node and
cannot be split.
A Job is a specification provided by users that declares a workload for
Nomad. A Job is a form of _desired state_; the user is expressing that the
job should be running, but not where it should be run. The responsibility of
Nomad is to make sure the _actual state_ matches the user desired state. A
Job is composed of one or more task groups.
- **Driver** – A Driver represents the basic means of executing your **Tasks**.
Example Drivers include Docker, QEMU, Java, and static binaries.
#### Task Group
- **Task** - A Task is the smallest unit of work in Nomad. Tasks are executed by drivers,
which allow Nomad to be flexible in the types of tasks it supports. Tasks
specify their driver, configuration for the driver, constraints, and resources required.
A Task Group is a set of tasks that must be run together. For example, a web
server may require that a log shipping co-process is always running as well. A
task group is the unit of scheduling, meaning the entire group must run on the
same client node and cannot be split.
- **Client** - A Nomad client is an agent configured to run and manage tasks
using available compute resources on a machine. The agent is responsible for
registering with the servers, watching for any work to be assigned and executing
tasks. The Nomad agent is a long lived process which interfaces with the servers.
#### Driver
- **Allocation** - An Allocation is a mapping between a task group in a job and a client
node. A single job may have hundreds or thousands of task groups, meaning an equivalent
number of allocations must exist to map the work to client machines. Allocations are created
by the Nomad servers as part of scheduling decisions made during an evaluation.
A Driver represents the basic means of executing your **Tasks**. Example
Drivers include Docker, QEMU, Java, and static binaries.
- **Evaluation** - Evaluations are the mechanism by which Nomad makes scheduling decisions.
When either the _desired state_ (jobs) or _actual state_ (clients) changes, Nomad creates
a new evaluation to determine if any actions must be taken. An evaluation may result
in changes to allocations if necessary.
#### Task
- **Server** - Nomad servers are the brains of the cluster. There is a cluster of servers
per region and they manage all jobs and clients, run evaluations, and create task allocations.
The servers replicate data between each other and perform leader election to ensure high
availability. More information about latency requirements for servers can be found
in [Network Topology](/docs/install/production/requirements#network-topology).
A Task is the smallest unit of work in Nomad. Tasks are executed by drivers,
which allow Nomad to be flexible in the types of tasks it supports. Tasks
specify their driver, configuration for the driver, constraints, and resources
required.
- **Regions** - Nomad models infrastructure as regions and datacenters. A region will contain
one or more datacenters. A set of servers joined together will represent a single
region. Servers federate across regions to make Nomad globally aware.
#### Client
- **Datacenters** - Nomad models a datacenter as an abstract grouping of clients within
a region. Nomad clients are not required to be in the same datacenter as the servers
they are joined with, but do need to be in the same region. Datacenters provide
a way to express fault tolerance among jobs as well as isolation of infrastructure.
A Nomad client is an agent configured to run and manage tasks using available
compute resources on a machine. The agent is responsible for registering with
the servers, watching for any work to be assigned and executing tasks. The
Nomad agent is a long lived process which interfaces with the servers.
- **Bin Packing** - Bin Packing is the process of filling bins with items in a way that
maximizes the utilization of bins. This extends to Nomad, where the clients are "bins"
and the items are task groups. Nomad optimizes resources by efficiently bin packing
tasks onto client machines.
#### Allocation
An Allocation is a mapping between a task group in a job and a client node. A
single job may have hundreds or thousands of task groups, meaning an
equivalent number of allocations must exist to map the work to client
machines. Allocations are created by the Nomad servers as part of scheduling
decisions made during an evaluation.
#### Evaluation
Evaluations are the mechanism by which Nomad makes scheduling decisions. When
either the _desired state_ (jobs) or _actual state_ (clients) changes, Nomad
creates a new evaluation to determine if any actions must be taken. An
evaluation may result in changes to allocations if necessary.
#### Server
Nomad servers are the brains of the cluster. There is a cluster of servers per
region and they manage all jobs and clients, run evaluations, and create task
allocations. The servers replicate data between each other and perform leader
election to ensure high availability. More information about latency
requirements for servers can be found in [Network
Topology](/docs/install/production/requirements#network-topology).
#### Regions
Nomad models infrastructure as regions and datacenters. A region will contain
one or more datacenters. A set of servers joined together will represent a
single region. Servers federate across regions to make Nomad globally aware.
#### Datacenters
Nomad models a datacenter as an abstract grouping of clients within a
region. Nomad clients are not required to be in the same datacenter as the
servers they are joined with, but do need to be in the same
region. Datacenters provide a way to express fault tolerance among jobs as
well as isolation of infrastructure.
#### Bin Packing
Bin Packing is the process of filling bins with items in a way that maximizes
the utilization of bins. This extends to Nomad, where the clients are "bins"
and the items are task groups. Nomad optimizes resources by efficiently bin
packing tasks onto client machines.
# High-Level Overview