Docker Init (with templates!)

Sample implementation of generic templates for the Docker Init command.

Usage

Download the binary compiled for your architecture (Linux, Windows or Mac OS) from Releases.

You may rename the binary to fake-docker, all the following samples are using this command name by default.

Using -h flag provides detail on the use of the different commands available.

Init

Init command produces Docker assets using a selected template.

$ ./fake-docker init -h
Init Command

Usage:
  docker init [flags]
  docker init [command]

Available Commands:
  catalog     Catalog Command

Flags:
  -d, --directory string     Local Directory containing templates to be used
  -h, --help                 help for init
  -o, --output string        Local Directory to write produced files
  -p, --prompt stringArray   Property=Value list containing prompt values
  -t, --template string      Name of the template to be used

Use "docker init [command] --help" for more information about a command.

Init Catalog

Init Catalog provides information relative to existing templates, reading from default inner templates folder or available in external directory

$ ./fake-docker init catalog -h
Catalog Command

Usage:
  docker init catalog [flags]

Flags:
  -d, --directory string  Local Directory containing templates to be used
  -h, --help              help for catalog
  -t, --template string   Name of the template to get details

Testing default templates

Default templates are provided in project's templates folder.

Use included alfresco template by using the -t flag:

$ ./fake-docker init -t alfresco
✔ 7.4
✔ postgres
✔ Yes
✔ Yes
✔ None
What is the name of your server?: localhost

Docker assets will be produced by default in output folder:

$ tree output
output
├── README.md
├── compose.yaml
├── db
│   └── compose.yaml
├── legacy-ui
│   └── compose.yaml
├── messaging
│   └── compose.yaml
├── proxy
│   └── compose.yaml
├── repo
│   └── compose.yaml
├── search
│   └── compose.yaml
├── transform
│   └── compose.yaml
└── ui
    └── compose.yaml

Alfresco can be tested using a regular Docker command:

$ cd output
$ docker compose up

Testing external templates

The project includes a sample for external templates definition in folder _samples.

Use included nginx-golang-db template from external directory by using following flags:

$ ./fake-docker init -d _samples -t nginx-golang-db
✔ postgres

Docker assets will be produced by default in output folder:

$ tree output
output
├── README.md
├── backend
│   ├── Dockerfile
│   ├── go.mod
│   ├── go.sum
│   └── main.go
├── compose.yaml
├── db
│   └── password.txt
└── proxy
    └── nginx.conf

It can be tested using a regular Docker command:

$ cd output
$ docker compose up --build

Review generated README.md file in output folder for additional testing instructions.

Creating your own template

A Docker Init template is composed by a root folder that contains a set of .tpl files. The name of the template is given by this root folder name.

Templates, with .tpl extension, can be created using text/template format.

In addition to Docker assets, a file named prompts.yaml must be located in template root folder. This file includes options to be gathered from user interaction or retrieved as command line parameters.

Every option must be specified as select or prompt according following syntax.

Select

<id>
    label: <label>
    multiple: true | false
    options:
      - <option1>
      - ...
      - <optionN>

For instance:

Volumes:
  label: Which container volume method do you want to use?
  options:
    - None
    - Native
    - Bind

By default, multiple is set to false. If more than one option is allowed to be chosen, add the multiple: true node. Selected values will be stored as a single string, separated with commas.

Prompt

<id>
    label: <label>
    default: <value>
    password: true | false

For instance:

Server:
  label: What is the name of your server?
  default: localhost

By default, password is set to false. If user typing should be screened as an asterisk string, add the password: true node.

Conditional

The prompt is enabled only when a boolean condition is met. The condition can include any of the previous prompts as identifier and the expression is evaluated following goval rules.

<id>
    label: <label>
    [options | default]: ...
    condition: <value>

For instance:

MessagingUser:
   label: Choose the user name for your ActiveMQ user
   condition: Messaging=="Yes" && MessagingCredentials=="Yes"
   default: admin

Template Folder structure

As a sample, following folder hierarchy would be defining the template service:

service
├── README.md.tpl
├── compose.yaml.tpl
├── prompts.yaml
└── proxy
    └── nginx.conf.tpl

Note that prompts.yaml is the only file that doesn't include the template extension .tpl