tinytodo

TinyTodo

TinyTodo is a simple application for managing task lists. It uses Cedar to control who has access to what.

TinyTodo allows individuals, called Users to organize, track, and share their todo lists. Users create Lists which they can populate with tasks. As tasks are completed, they can be checked off the list. A list's creater, called its owner, can share a list with either Users or Teams, either as a reader or an editor. A reader can only view the contents of a list, while an editor can modify it (e.g., add tasks, or check them off the list).

Usage

The code is structured as a server, written in Rust, that processes HTTP commands. A client tinytodo.py, written in Python3, can be used to interact with the server. This is just a demo app, so there is no permanent storage of todo lists -- they last only as long as the server is running.

Build

You need Python3 and Rust. Rust can be installed via rustup. Python3 can be installed here or using your system's package manager.

This example expects that the cedar repository is cloned into the toplevel (../cedar-examples) directory. You can instruct Cargo to use your local version of cedar-policy by adding path = "../cedar/cedar-policy" to Cargo.toml.

Install the needed python packages in a virtual environment, and build the server as follows.

python3 -m venv ./venv
source ./venv/bin/activate
pip3 install -r requirements.txt
cargo build --release

The Rust executable is stored in target/release/tiny-todo-server.

Run

To start the client within Python interactive mode, enter

python3 -i ./tinytodo.py

To start the server, from the Python primary prompt >>> enter

start_server()

When it starts up, the server reads in the Cedar policies in policies.cedar, and the Cedar entities, which define the TinyTodo Users and Teams, from entities.json. It validates the policies are consistent with tinytodo.cedarschema, and will abort if they are not.

Client code tinytodo.py defines the functions you can call, which serve as the list of commands. See also TUTORIAL.md for a detailed description of how to use these commands, and how TinyTodo works. Here is a brief description of the commands:

• start_server() -- starts the TinyTodo server on port 8080. To use port XXX instead, provide port=XXX as the argument instead. Fails if server is already running.
• stop_server() -- shuts down the TinyTodo server, if running. Called automatically on exit.
• set_user(user) -- sets the user to use for the commands that follow. Parameter user can be any of emina, aaron, andrew, or kesha. In the following commands, you can override this user by providing an additional parameter at the start that names the user.
• get_lists() -- gives the lists owned by the current user
• create_list(name) -- creates the list named name (a string) owned by the current user; prints the numeric ID of the created list on success
• get_list(list) -- gets information about list list, indicated by its numeric ID.
• create_task(list,name) -- creates a new (uncompleted) task for list list named name (a string); prints the task's numeric ID on success, which is its position in the list
• toggle_task(list,task) -- toggles the completion status of the task task (a numeric ID) for list list
• change_task_description(list,task,name) -- changes the name of task task in list list to name (a string)
• delete_task(list,task) -- deletes task task from list list. Reorders remaining tasks
• delete_list(list) -- deletes the given list
• share_list(list,target,readonly) -- shares the given list with target; if readonly (a boolean) is True then the target has reader status for the list, else editor status. readonly is an optional parameter, defaulting to readonly. target can be a user or a team, where legal teams are temp, interns, and admin
• unshare_list(list,target) -- revokes access to list for target, which can be a user or a team