docker-documentation/general/fleet.md

description
Fleet is a web-based image management tool for organisations who ship a large list of Docker images.

Fleet

How Fleet works

Fleet stores a snapshot of Docker Images in its own database, consisting of metadata deemed most pertinent to both the users of the images, and the repository owner. It will synchronise with Docker Hub over a set interval in order to update its stored data.

It then displays this snapshot data on its own status page as a useful list, containing links to each repository and image owned by the repository owner. Each image also contains a status which is managed by the repository owner, who can define images as either Stable or Unstable. This is designed to quickly help users know when an image is undergoing a state of instability which is known by the owner.

Why a snapshot?

In short, Docker Hub's API is very slow. It would not be a good long-term solution to just proxy the responses from Docker Hub and translate the data into something considered useful by downstream clients. By caching the image information in its own database, Fleet is able to more efficiently return the status data for each image and repository. In doing so, it is also able to provide more concise data, such as image versions, as part of the primary response, rather than requiring users to make a separate call.

As an example comparison between obtaining all image name, pull and version information for all LinuxServer images from Docker Hub, and then obtaining that same data via Fleet's API:

API	Time ms
Docker Hub multiple calls	52000ms
Fleet	50ms

API

Fleet exposes a single API endpoint which can be used to obtain image list and pull count information for all relevant images maintained by the repository

{% api-method method="get" host="https://fleet.base.url" path="/api/v1/images" %} {% api-method-summary %} Get All Repositories and Images {% endapi-method-summary %}

{% api-method-description %} Returns all synchronised images. {% endapi-method-description %}

{% api-method-spec %} {% api-method-request %}

{% api-method-response %} {% api-method-response-example httpCode=200 %} {% api-method-response-example-description %} All synchronised repositories and images returned. {% endapi-method-response-example-description %}

{
    "status": "OK",
    "data" {
        "totalPullCount": 1862494227,
        "repositories": {
            "lsiobase": [
                {
                    "name": "alpine",
                    "pullCount": 4275970,
                    "version": "3.6",
                    "stable": true
                },
                {
                    "name": "alpine.arm64",
                    "pullCount": 66234,
                    "version": "edge",
                    "stable": true
                },
                ...
            ],
            "linuxserver": [
                {
                    "name": "airsonic",
                    "pullCount": 4608329,
                    "version": "v10.2.1",
                    "stable": true
                },
                {
                    "name": "apache",
                    "pullCount": 3011699,
                    "version": "latest",
                    "stable": true
                },
                ...
            ]
            ...
        }
    }
}

{% endapi-method-response-example %} {% endapi-method-response %} {% endapi-method-spec %} {% endapi-method %}

{% hint style="info" %} Any repositories not synchronised with Docker Hub e.g. staging or metadata repositories will not be returned as part of the API. This also applies to images which the repository owner does not wish to be part of the primary image list. {% endhint %}

Running Fleet

{% hint style="warning" %} Fleet is a Java application, so requires at least JRE 1.8. {% endhint %}

Grab the latest Fleet release from GitHub.

SQL

Fleet stores its data in a MariaDB database which you need to provide. In order for the application to manage its tables and procedures, the user you provide it needs to have the relevant GRANT permissions to the fleet database. The following script should be sufficient to get the initial database set up.

{% hint style="info" %} The schema must be called fleet. {% endhint %}

CREATE SCHEMA `fleet`;
CREATE USER 'fleet_user' IDENTIFIED BY 'supersecretpassword';
GRANT ALL ON `fleet`.* TO 'fleet_user';

The username and password that you define must then be provided as part of Fleet's configuration.

Configuration File

All primary configuration for Fleet at runtime is loaded in via a fleet.properties file. This can be located anywhere on the file system, and is loaded in via a Runtime argument:

# Runtime
fleet.app.port=8080
fleet.refresh.interval=60

# User for management of images and repositories
fleet.admin.username=
fleet.admin.password=

# Database Connectivity
fleet.database.driver=org.mariadb.jdbc.Driver
fleet.database.url=jdbc:mariadb://<IP_OR_URL>:3306/fleet
fleet.database.username=
fleet.database.password=

# Docker Hub
fleet.dockerhub.username=
fleet.dockerhub.password=

All configuration can be loaded either via the config file, via JVM arguments, or via the system environment. Fleet will first look in the configuration file, then JVM runtime, and finally in the system environment. It will load the first value it finds, which can be useful when needing to override specific properties.

{% hint style="info" %} If you place a property in the system environment, ensure that the property uses underscores rather than periods. This is due to a limitation in BASH environments where exported variables must not contain this character. E.g. fleet.app.port=8080 becomes export fleet_app_port=8080 {% endhint %}

Property Name	Purpose
fleet.app.port	The port which the application will be running under.
fleet.refresh.interval	How often the application should synchronise with Docker Hub to update its list of known images. This is in minutes.
fleet.admin.username	The username of the administrator who will be managing the application.
fleet.admin.password	A plain-text password for the administrator user.
fleet.database.driver	The driver to use for connections to Fleet's database. This should be org.mariadb.jdbc.Driver
fleet.database.url	The full JDBC connection string to the database.
fleet.database.username	The username of the SQL user which will be managing the data in the Fleet database. This should have full GRANT access to the fleet database as it also manages any database migrations.
fleet.database.password	The password for the SQL user
fleet.dockerhub.username	The username for the Docker Hub repository owner.
fleet.dockerhub.password	The password for the Docker Hub repository owner.

Runtime Configuration

As well as the base configuration file, Fleet also supports some runtime arguments by means of the -D flag. These can be used to direct Fleet to behave in a specific way at runtime.

Runtime Argument	Purpose
fleet.config.base	The absolute path of the configuration file.
fleet.show.passwords	Tells fleet to show passwords in plain text in its logs. Not recommended.
fleet.nuke.database	Be very careful. This will tell Fleet to completely wipe and rebuild its database. This can be useful if the owner deems the database to be too far out of synchronisation with Docker Hub, or if images have since been removed but are still showing in Fleet.
fleet.skip.sync.on.startup	By default, Fleet will run a synchronisation process when it first starts up. Setting this flag will tell it to skip the first run. The next synchronisation will be at the set interval.