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Stack Definition Language (SDL)

Customers / tenants define the deployment services, datacenters, requirements, and pricing parameters, in a "manifest" file (deploy.yaml). The file is written in a declarative language called Software Definition Language (SDL). SDL is a human friendly data standard for declaring deployment attributes. The SDL file is a "form" to request resources from the Network. SDL is compatible with the YAML standard and similar to Docker Compose files.

Configuration files may end in .yml or .yaml.

A complete deployment has the following sections:

An example deployment configuration can be found here.

Networking

Networking - allowing connectivity to and between workloads - can be configured via the Stack Definition Language (SDL) file for a deployment. By default, workloads in a deployment group are isolated - nothing else is allowed to connect to them. This restriction can be relaxed.

version

Indicates version of Akash configuration file. Currently only "2.0" 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

Best practices:

  • avoid using :latest image tags as Akash Providers heavily cache images
depends-on No NOTE - field is marked for future use and currently has no impact on deployments.
command No Custom command use when executing container
args No Arguments to custom command use when executing the container
env No Environment variables to set in running container. See services.env
expose No Entities allowed to connect to the services. See services.expose

services.env

A list of environment variables to expose to the running container.

env:
  - API_KEY=0xcafebabe
  - CLIENT_ID=0xdeadbeef

services.expose

Notes Regarding Port Use in the Expose Stanza

  • HTTPS is possible in Akash deployments but only self signed certs are generated.
  • To implement signed certs the deployment must be front ended via a solution such as Cloudflare. If interested in this path, we have created docs for Cloudflare with Akash.
  • You can expose any other port besides 80 as the ingress port (HTTP, HTTPS) port using as: 80 directive if the app understands HTTP / HTTPS. Example of exposing a React web app using this method:
      - port: 3000
        as: 80
        to:
          - global: true
        accept:
          - www.mysite.com
  • In the SDL it is only necessary to expose port 80 for web apps. With this specification both ports 80 and 443 are exposed.

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, udp, or http)
to No List of entities allowed to connect. See services.expose.to

The as value governs the default proto value as follows:

NOTE - when as is not set, it will default to the value set by the port mandatory directive.

NOTE - when one exposes as: 80 (HTTP), the Kubernetes ingress controler makes the application available over HTTPS as well, though with the default self-signed ingress certs.

port proto default
80 http, 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. It also specifies optional list of signatures of which tenants expects audit of datacenter attributes.

Example:

westcoast:
  attributes:
    region: us-west
  signedBy:
    allOf:
      - "akash1vz375dkt0c60annyp6mkzeejfq0qpyevhseu05"
    anyOf:
      - "akash1vl3gun7p8y4ttzajrtyevdy5sa2tjz3a29zuah"
  pricing:
    web:
      denom: uakt
      amount: 8
    db:
      denom: uakt
      amount: 100

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 uakt per block, respectively. It also requires that the provider's attributes have been signed by the accounts akash1vz375dkt0c60annyp6mkzeejfq0qpyevhseu05 and akash1vl3gun7p8y4ttzajrtyevdy5sa2tjz3a29zuah.

profiles.placement.signedBy

Optional

The signedBy section allows you to state attributes that must be signed by one or more accounts of your choosing. This allows for requiring a third-party certification of any provider that you deploy to.

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.