This is a command-line tool for the capture and management of Dagster UI screenshots. It is intended to be used to automate the production of screenshots for the Dagster docs site.

This package depends on the Python selenium for browser automation, which in turn depends on a system package chromedriver. On macOS, this should install dagster-ui-screenshot:

$ brew install chromedriver
$ xattr -d com.apple.quarantine /opt/homebrew/bin/chromedriver  # May not need to run this
$ pip install -e dagster-ui-screenshot

The core function of dagster-ui-screenshot is to generate Dagster UI screenshot image files from "screenshot spec" records. A screenshot spec is a JSON/YAML object with fields specifying parameters that can be used to quasi-automatically generate a screenshot. Specs live in a "screenshot database", which is just a directory containing a hierarchy of YAML files, each containing multiple screenshot specs.

Specs have the following fields. Only the id field requires explicit specification for all specs:

• id: E.g. a/b/c.png, for a screenshot with id "c.png" in docs/screenshots/a/b.yaml. The full ID of the spec is formed by joining the (extensionless) path to the defining YAML file with the relative ID. For the special name index.yaml, the index part is dropped. For example, a spec with id field "baz.png" stored in either screenshots/foo/bar.yaml or screenshots/foo/bar/index.yaml has the full ID foo/bar/baz.png. The full ID can be treated as a relative path that, when further qualified with an output root directory, specifies the path to an image file. The default output root is next/public/images, so by default the spec with ID foo/bar/baz.png corresponds to an image in next/public/images/foo/bar/baz.png.
• route (optional) Dagster UI route (i.e. path part of the URL) that will be loaded before taking a screenshot. Defaults to /.
• workspace (optional): path (relative to the repo root) to a python or workspace YAML file that defines the workspace that should be loaded before attempting screenshot capture. The script will pass the path to dagster-webserver --python-file or dagster-webserver --workspace (depending on file type) to load a set of Dagster definitions. This is required for screenshots generated from a local webserver instance, can should be omitted for screenshots generated from a remote webserver.
• base_url (optional): Base url (protocol and host) of a Dagster webserver instance to be targeted for a screenshot. Can point to a local or remote host. Defaults to https://localhost:3000.
• vetted (optional): boolean indicating whether the current screenshot in the repo was generated using the spec.
• steps (optional): manual steps that the person generating the screenshot should carry out before the screenshot is taken.
• width (optional): width in pixels of the browser window in which the screenshot will be taken.
• height (optional): height in pixels of the browser window in which the screenshot will be taken.

The command line application dagster-ui-screenshot is used to manage the specs. Install dagster-ui-screenshot into your environment with pip install -e dagster-ui-screenshot-- this will make the dagster-ui-screenshot executable available on your path.

To generate the screenshot for a spec, run

dagster-ui-screenshot capture <id>`

This will attempt to render the specified Dagster UI view using the browser automation tool Selenium. If no steps are specified in the target spec, the screenshot will be automatically captured. If steps were specified, after the initial Dagster UI view has rendered, the user will be prompted to execute the steps and then press a key to trigger screenshot capture. Screenshots are written by default to the output path next/public/images/<id>. Note that successfully executing dagster-ui-screenshot capture will overwrite any existing image at the output path.

In addition to the core functionality of capturing screenshots, there are also dagster-ui-screenshot audit and dagster-ui-screenshot show. You can learn more about these commands by running dagster-ui-screenshot --help.