⏳ Sablier

Sablier is an API that start containers for a given duration.

It provides an integrations with multiple reverse proxies and different loading strategies.

Which allows you to start your containers on demand and shut them down automatically as soon as there's no activity.

• ⏳ Sablier
  • ⚡️ Quick start
  • ⚙️ Configuration
  • Loading with a waiting page
    • Dynamic Strategy Configuration
    • Creating your own loading theme
  • Blocking the loading until the session is ready
  • Reverse proxies integration plugins
  • Credits

⚡️ Quick start

# Create and stop nginx container
docker run -d --name nginx nginx
docker stop nginx

# Create and stop whoami container
docker run -d --name whoami containous/whoami:v1.5.0
docker stop whoami

# Start Sablier with the docker provider
docker run -v /var/run/docker.sock:/var/run/docker.sock -p 10000:10000 ghcr.io/acouvreur/sablier:latest --provider.name=docker

# Start the containers, the request will hang until both containers are up and running
curl 'http://localhost:10000/api/strategies/blocking?names=nginx&names=whoami&session_duration=1m'
{
  "session": {
    "instances": [
  {
        "instance": {
          "name": "nginx",
          "currentReplicas": 1,
          "status": "ready"
    },
        "error": null
  },
  {
        "instance": {
          "name": "nginx",
          "currentReplicas": 1,
          "status": "ready"
    },
        "error": null
  }
    ],
    "status":"ready"
  }
}

⚙️ Configuration

Cli	Yaml file	Environment variable	Default	Description
--provider.name	provider.name	PROVIDER_NAME	docker	Provider to use to manage containers [docker swarm kubernetes]
--server.base-path	server.base-path	SERVER_BASE_PATH	/	The base path for the API
--server.port	server.port	SERVER_PORT	10000	The server port to use
--sessions.default-duration	sessions.default-duration	SESSIONS_DEFAULT_DURATION	5m	The default session duration
--sessions.expiration-interval	sessions.expiration-interval	SESSIONS_EXPIRATION_INTERVAL	20s	The expiration checking interval. Higher duration gives less stress on CPU. If you only use sessions of 1h, setting this to 5m is a good trade-off.
--storage.file	storage.file	STORAGE_FILE		File path to save the state
--strategy.blocking.default-timeout	strategy.blocking.default-timeout	STRATEGY_BLOCKING_DEFAULT_TIMEOUT	1m	Default timeout used for blocking strategy
--strategy.dynamic.custom-themes-path	strategy.dynamic.custom-themes-path	STRATEGY_DYNAMIC_CUSTOM_THEMES_PATH		Custom themes folder, will load all .html files recursively
--strategy.dynamic.default-refresh-frequency	strategy.dynamic.default-refresh-frequency	STRATEGY_DYNAMIC_DEFAULT_REFRESH_FREQUENCY	5s	Default refresh frequency in the HTML page for dynamic strategy
--strategy.dynamic.default-theme	strategy.dynamic.default-theme	STRATEGY_DYNAMIC_DEFAULT_THEME	hacker-terminal	Default theme used for dynamic strategy

Loading with a waiting page

The Dynamic Strategy provides a waiting UI with multiple themes. This is best suited when this interaction is made through a browser.

Name	Preview
ghost
shuffle
hacker-terminal
matrix

Dynamic Strategy Configuration

Cli	Yaml file	Environment variable	Default	Description
strategy
--strategy.dynamic.custom-themes-path	strategy.dynamic.custom-themes-path	STRATEGY_DYNAMIC_CUSTOM_THEMES_PATH		Custom themes folder, will load all .html files recursively
--strategy.dynamic.default-refresh-frequency	strategy.dynamic.default-refresh-frequency	STRATEGY_DYNAMIC_DEFAULT_REFRESH_FREQUENCY	5s	Default refresh frequency in the HTML page for dynamic strategy
--strategy.dynamic.default-theme	strategy.dynamic.default-theme	STRATEGY_DYNAMIC_DEFAULT_THEME	hacker-terminal	Default theme used for dynamic strategy

Creating your own loading theme

Use --strategy.dynamic.custom-themes-path to specify the folder containing your themes.

Your theme will be rendered using a Go Template structure such as :

type TemplateValues struct {
	DisplayName      string
	InstanceStates   []RenderOptionsInstanceState
	SessionDuration  string
	RefreshFrequency string
	Version          string
}

type RenderOptionsInstanceState struct {
	Name            string
	CurrentReplicas int
	DesiredReplicas int
	Status          string
	Error           error
}

• ⚠️ IMPORTANT ⚠️ You should always use RefreshFrequency like this:

  <head>
    ...
    <meta http-equiv="refresh" content="{{ .RefreshFrequency }}" />
    ...
  </head>
  

  This will refresh the loaded page automatically every RefreshFrequency.
• You cannot load new themes added in the folder without restarting
• You can modify the existing themes files
• Why? Because we build a theme whitelist in order to prevent malicious payload crafting by using theme=../../very_secret.txt
• Custom themes must end with .html
• You can load themes by specifying their name and their relative path from the --strategy.dynamic.custom-themes-path value.

  /my/custom/themes/
  ├── custom1.html      # custom1
  ├── custom2.html      # custom2
  └── special
      └── secret.html   # special/secret
  

You can see the available themes from the API:

> curl 'http://localhost:10000/api/strategies/dynamic/themes'

{
  "custom": [
    "custom"
  ],
  "embedded": [
    "ghost",
    "hacker-terminal",
    "matrix",
    "shuffle"
  ]
}

Blocking the loading until the session is ready

The Blocking Strategy waits for the instances to load before serving the request This is best suited when this interaction from an API.

Reverse proxies integration plugins

• Traefik

Credits

• Hourglass icons created by Vectors Market - Flaticon
• tarampampam/error-pages for the themes