Lacus

A capturing system using playwright, as a web service.

Install guide

System dependencies

You need poetry installed, see the install guide.

Prerequisites

Lacus supports valkey or redis, but valkey is prefered now due to the change of license. So we will use valkey below, but as of now, redis also works.

Installing valkey

System dependencies:

sudo apt-get update
sudo apt install build-essential
# To run the tests
sudo apt install tcl

You need to have valkey cloned and installed in the same directory you clone the lacus repository in: lacus and valkey must be in the same directory, and not valkey cloned in the lacus directory.

git clone https://github.com/valkey-io/valkey.git

Compile valkey:

cd valkey
git checkout 7.2
make
# Optionally, you can run the tests:
make test
cd ..

Installation

Clone this repository if you haven't done it already:

git clone https://github.com/ail-project/lacus.git

The directory tree must look like that:

.
├── valkey  => cloned valkey
└── lacus => cloned lacus

From the lacus directory, run:

poetry install

Install the system dependencies required by playwright (will call sudo):

poetry shell
playwright install-deps

Initialize the .env file:

echo LACUS_HOME="`pwd`" >> .env

Initialize the config and install playwright browsers:

poetry run update --init

It will launch the instance if you answer yes to the "restart" question.

Configuration

Edit the config file config/generic.json, and configure it accordingly to your needs.

Usage

Start the tool (as usual, from the directory):

poetry run start

You can stop it with

poetry run stop

With the default configuration, you can access the web interface on http://0.0.0.0:7100, where you will find the API and can start playing with it.

Maintenance

If you have recurring messages like the ones below you can remove the uuid from the queue as follows.

2023-11-17 08:00:59,936 LacusCore WARNING:[ef7f653d-4cfd-4e7b-9b91-58c9c2658868] Attempted to clear capture that is still being processed.
2023-11-17 08:01:00,939 LacusCore WARNING:[ef7f653d-4cfd-4e7b-9b91-58c9c2658868] Attempted to clear capture that is still being processed.
2023-11-17 08:01:01,941 LacusCore WARNING:[ef7f653d-4cfd-4e7b-9b91-58c9c2658868] Attempted to clear capture that is still being processed.
2023-11-17 08:01:02,944 LacusCore WARNING:[ef7f653d-4cfd-4e7b-9b91-58c9c2658868] Attempted to clear capture that is still being processed.
2023-11-17 08:01:03,947 LacusCore WARNING:[ef7f653d-4cfd-4e7b-9b91-58c9c2658868] Attempted to clear capture that is still being processed.
...

While valkey is running connect to it via its socket and zrem then entry.

ail@ail-tokyo:~$ cd lacus/
ail@ail-tokyo:~/lacus$ ../valkey/src/valkey-cli -s cache/cache.sock
valkey cache/cache.sock> zrem lacus:ongoing ef7f653d-4cfd-4e7b-9b91-58c9c2658868
(integer) 1
valkey cache/cache.sock>

Useful environment variables

There are env varibles you can pass to help making better captures, or avoir captures to fail when they shouldn't:

• PW_TEST_SCREENSHOT_NO_FONTS_READY avoids captures to get stuck on screenshot when the fonts don't load (https://github.com/microsoft/playwright/issues/28995)
• PLAYWRIGHT_CHROMIUM_USE_HEADLESS_NEW improves stealth for chromium by using the new headless mode (a little bit slower): https://github.com/Lookyloo/PlaywrightCapture/issues/55

To use them, you can run the capture manager this way:

PLAYWRIGHT_CHROMIUM_USE_HEADLESS_NEW=1 PW_TEST_SCREENSHOT_NO_FONTS_READY=1 capture_manager