Quickstart: Cat Videos Example

This example describes a video sharing service. The individual videos are organized in directories. Every directory has an owner and every video has the same owner as it's parent directory. The owner has elevated privileges about the video files that aren't modeled individually in Ory Keto. The only other privilege modeled in this example is "view access." Every owner has view access to their objects, and this privilege can be granted to other users as well. The video sharing application interprets the special * user ID as any user, including anonymous users. Note that Ory Keto doesn't interpret this subject any differently from other subjects. It also doesn't know anything about directory structures or induced ownership.

Terminology

The "Keto client" is the application interacting with Keto. In this case we refer to the video sharing service backend as the Keto client.

Starting the Example

First, install Keto.

Now you can start the example using either docker-compose or a bash script. The bash script requires you to have the keto binary in your $PATH.

Alternatively, use Docker to automatically get the required images.

# clone the repository if you don't have it yet
git clone git@github.com:ory/keto.git && cd keto

docker-compose -f contrib/cat-videos-example/docker-compose.yml up
# or
./contrib/cat-videos-example/up.sh

# output: all initially created relation tuples

# NAMESPACE       OBJECT          RELATION NAME   SUBJECT
# videos          /cats/1.mp4     owner           videos:/cats#owner
# videos          /cats/1.mp4     view            videos:/cats/1.mp4#owner
# videos          /cats/1.mp4     view            *
# videos          /cats/2.mp4     owner           videos:/cats#owner
# videos          /cats/2.mp4     view            videos:/cats/2.mp4#owner
# videos          /cats           owner           cat lady
# videos          /cats           view            videos:/cats#owner

State of the System

At the current state only one user with the username cat lady has added videos. Both videos are in the /cats directory owned by cat lady. The file /cats/1.mp4 can be viewed by anyone (*), while /cats/2.mp4 has no extra sharing options, and can therefore only be viewed by its owner, cat lady. The relation tuple definitions are located in the contrib/cat-videos-example/relation-tuples directory.

Simulating the Video Sharing Application

Now you can open a second terminal to run the queries against, just like the video service client would do. In this example we will use the Keto CLI client.

If you want to run the Keto CLI within Docker, set the alias

alias keto="docker run -it --network cat-videos-example_default -e KETO_READ_REMOTE=\"keto:4466\" oryd/keto:v0.7.0-alpha.1"

in your terminal session. Alternatively, you need to set the remote endpoint so that the Keto CLI knows where to connect to (not necessary if using Docker):

export KETO_READ_REMOTE="127.0.0.1:4466"

Check Incoming Requests

First off, we get a request by an anonymous user that would like to view /cats/2.mp4. The client now has to ask Keto if that operation should be allowed or denied.

# Is "*" allowed to "view" the object "videos":"/cats/2.mp4"?
keto check "*" view videos /cats/2.mp4
# output:

# Denied

We already discussed that this request should be denied, but it's always good to see this in action.

Now cat lady wants to change some view permissions of /cats/1.mp4. For this, the video service application has to show all users that are allowed to view the video. It uses Keto's expand-API to get these data:

# Who is allowed to "view" the object "videos":"/cats/2.mp4"?
keto expand view videos /cats/1.mp4
# output:

# ∪ videos:/cats/1.mp4#view
# ├─ ∪ videos:/cats/1.mp4#owner
# │  ├─ ∪ videos:/cats#owner
# │  │  ├─ ☘ cat lady️
# ├─ ☘ *️

Here we can see the full subject set expansion. The first branch

videos:/cats/1.mp4#view

indicates that every owner of the object is allowed to view

videos:/cats/1.mp4#owner

In the next step we see that the object's owners are the owners of /cats

videos:/cats#owner

We see that cat lady is the owner of /cats.

Note that there is no direct relation tuple that would grant cat lady view access on /cats/1.mp4 as this is indirectly defined via the ownership relation.

The special user * on the other hand was directly granted view access on the object, as it's a first-level leaf of the expansion tree. The following CLI command proves that this is the case:

# Is "*" allowed to "view" the object "videos":"/cats/1.mp4"?
keto check "*" view videos /cats/1.mp4
# output:

# Allowed

Updating the view permissions will be added here at a later stage.