DCS 3: Stack Definition Language Source

AuthorAdam Bozanich
StatusFinal
TypeStandards Track
CategoryInterface
Created2020-03-09

Summary

Stack Definition Language

Specification

Deployment services, datacenters, pricing, etc.. are described by a YAML configuration file. Configuration files may end in .yml or .yaml.

A complete deployment has the following sections:

A full example deployment configuration can be found here.

version

Indicates version of Akash configuration file. Currently only "1.0" is accepted.

services

The top-level services entry contains a map of workloads to be ran on the Akash deployment. Each key is a service name; values are a map containing the following keys:

Name Required Meaning
image Yes Docker image of the container
depends-on No List of services which must be brought up before the current service
args No Arguments to use when executing the container
env No Environment variables to set in running container
expose No Entities allowed to connec to to the services. See services.expose.

services.expose

expose is a list describing what can connect to the service. Each entry is a map containing one or more of the following fields:

Name Required Meaning
port Yes Container port to expose
as No Port number to expose the container port as
accept No List of hosts to accept connections for
proto No Protocol type (tcp,http, or https)
to No List of entities allowed to connect. See services.expose.to

The port value governs the default proto value as follows:

port proto default
80 http
443 https
all others tcp

services.expose.to

expose.to is a list of clients to accept connections from. Each item is a map with one or more of the following entries:

Name Value Default Description
service A service in this deployment   Allow the given service to connect
global true or false false If true, allow connections from outside of the datacenter

If no service is given and global is true, any client can connect from anywhere (web servers typically want this).

If a service name is given and global is false, only the services in the current datacenter can connect. If a service name is given and global is true, services in other datacenters for this deployment can connect.

If global is false then a service name must be given.

profiles

The profiles section contains named compute and placement profiles to be used in the deployment.

profiles.compute

profiles.compute is map of named compute profiles. Each profile specifies compute resources to be leased for each service instance uses uses the profile.

Example:

This defines a profile named web having resource requirements of 2 vCPUs, 2 gigabytes of memory, and 5 gigabytes of storage space available.

web:
  cpu: 2
  memory: "2Gi"
  storage: "5Gi"

cpu units represent a vCPU share and can be fractional. When no suffix is present the value represents a fraction of a whole CPU share. With a m suffix, the value represnts the number of milli-CPU shares (1/1000 of a CPU share).

Example:

Value CPU-Share
1 1
0.5 1/2
"100m" 1/10
"50m" 1/20

memory, storage units are described in bytes. The following suffixes are allowed for simplification:

Suffix Value
k 1000
Ki 1024
M 1000^2
Mi 1024^2
G 1000^3
Gi 1024^3
T 1000^4
Ti 1024^4
P 1000^5
Pi 1024^5
E 1000^6
Ei 1024^6

profiles.placement

profiles.placement is map of named datacenter profiles. Each profile specifies required datacenter attributes and pricing configuration for each compute profile that will be used within the datacenter.

Example:

westcoast:
  attributes:
    region: us-west
  pricing:
    web: 8u
    db: 100u

This defines a profile named westcoast having required attributes {region="us-west"}, and with a max price for the web and db compute profiles of 8 and 15 micro (10^-6) tokens per block, respectively.

Pricing may be expressed in decimal or scientific notation for Akash units, or may be suffixed with mu,µ, or u to represent micro Akash.

Examples:

Value Micro Akash Tokens
1 1000000
1e-4 100
20u 20

deployment

The deployment section defines how to deploy the services. It is a mapping of service name to deployment configuration.

Each service to be deployed has an entry in the deployment. This entry is maps datacenter profiles to compute profiles to create a final desired configuration for the resources required for the service.

Example:

web:
  westcoast:
    profile: web
    count: 20

This says that the 20 instances of the web service should be deployed to a datacenter matching the westcoast datacenter profile. Each instance will have the resources defined in the web compute profile available to it.

Bibliography

All content herein is licensed under Apache 2.0.