Preparing your application

KuberLogic provides a simple way to deploy your application as SaaS by supporting docker-compose.yml structure.

caution

KuberLogic only supports a single application type configured via docker-compose.yml. Any change to this file will be propagated to all KuberLogic managed applications.

You will be asked to enter path to the docker-compose.yml during the installation process, otherwise KuberLogic will be provisioned with demo application.

Limitations

There are few limitations about supported docker-compose.yml:

Only one service can have its ports published

Will work:

version: "3"
services:
  - name: my-service
    image: my-image
    command:
      - "./run.sh"
- name: my-service-2
  image: my-image
  ports:
    - "8080:8080"
  command:
    - "./run.sh"

Will not work:

version: "3"
services:
  - name: my-service
    image: my-image
    ports:
      - "8080:8080"
    command:
      - "./run.sh"
- name: my-service-2
  image: my-image
  ports:
    - "8080:8080"
  command:
    - "./run.sh"

Only a single port can be published.

Will work:

version: "3"
services:
  - name: my-service
    image: my-image
    command:
      - "./run.sh"
- name: my-service-2
  image: my-image
  ports:
    - "8080:8080"
  command:
    - "./run.sh"

Will not work:

version: "3"
services:
  - name: my-service
    image: my-image
    command:
      - "./run.sh"
- name: my-service-2
  image: my-image
  ports:
    - "8080:8080"
    - "8081:8081"
  command:
    - "./run.sh"

Local volume mounts are not supported

Will work:

version: "3"
volumes:
  data:

services:
  - name: my-service
    image: my-image
    command:
      - "./run.sh"
    volumes:
      - data:/data

Will not work:

version: "3"
services:
  - name: my-service
    image: my-image
    command:
      - "./run.sh"
    volumes:
      - ./data:/data

Templating docker-compose.yml

KuberLogic also supports templating certain service fields in docker-compose.yml by using Go templates.

Fields that can be templated are:

• image
• command
• environment variables' values
• x-kuberlogic-file-configs extension
• x-kuberlogic-secrets extension

Service parameters that can be accessed in the template are:

• Name: The name of the service
• Namespace: The namespace of the service
• Host: The host of the service
• Replicas: The number of replicas of the service
• VolumeSize: The size of the volume of the service
• Version: The version of the service
• TLSEnabled: Whether the service is TLS enabled
• Parameters: The advanced parameters of the service

There are also a few functions that can be used for environment variables:

• Endpoint: Returns the endpoint of the service
• Base64: Encodes string using Base64 algorithm
• GenerateKey <len: int,optional>: Generate a random key of the specified length
• GenerateRSAKey <bits: int,optional>: Generate a random RSA key of the specified length
• Secret <name: string>: Retrieves a secret from an application secret storage.

caution

Generate... functions will generate different values each time the template is rendered. This will result in constant service restarts.

You should use x-kuberlogic-secrets configuration parameter to have a consistent value. See this page for more information.

Examples

Specify the image version

Provisioned services will use version as the image tag or "latest" if not specified.

version: "3"
services:
  - name: my-service
    image: my-image:{{ default .Version "latest" }}
    command:
      - "./run.sh"
    ports:
      - "8080:8080"

Configure service URL parameter

version: "3"
services:
  - name: my-service
    image: my-image
    command:
      - "./run.sh"
    ports:
      - "8080:8080"
    environment:
      - BASE_URL={{ Endpoint "localhost.com" }}

Generate a random key and save it to the persistent secret

version: "3"
services:
  - name: my-service
    image: my-image
    command:
      - "./run.sh"
    ports:
      - "8080:8080"
    environment:
      - SECRET_KEY={{ GenerateKey 30 | PersistentSecret }}

Generate a random RSA key, encode it with Base64, persist in secret and share it between different services

RSA key will be generated and saved in a persistent secret under the "PRIVATE_RSA_KEY" key.

version: "3"
services:
  - name: my-service
    image: my-image
    command:
      - "./run.sh"
    ports:
      - "8080:8080"
    environment:
      - SECRET_KEY={{ GenerateRSAKey 2048 | Base64 | PersistentSecret "PRIVATE_RSA_KEY" }}
  - name: my-service-2
    image: my-image
    command:
      - "./run.sh"
    ports:
      - "8080:8080"
    environment:
      - SECRET_KEY={{ GenerateRSAKey 2048 | Base64 | PersistentSecret "PRIVATE_RSA_KEY" }}