Add management command to manage crawls in the database

README.md

@@ -25,15 +25,15 @@ or a local
 
 To build the Docker image:
 
-```
+```sh
 docker build -t website-indexer:main .
 ```
 
 #### Viewing a sample crawl using Docker
 
 To then run the viewer application using sample data:
 
-```
+```sh
 docker run -it \
     -p 8000:8000 \
     website-indexer:main
@@ -44,18 +44,30 @@ The web application using sample data will be accessible at http://localhost:800
 #### Crawling a website and viewing the crawl results using Docker
 
 To crawl a website using the Docker image,
-storing the result in a local SQLite database named `crawl.sqlite3`:
+storing the result in a local SQLite database named `crawl.sqlite3`,
+first create the database file:
 
+```sh
+docker run -it \
+    -v `pwd`:/data \
+    -e DATABASE_URL=sqlite:////data/crawl.sqlite3 \
+    website-indexer:main \
+    python manage.py migrate
 ```
+
+and then run the crawl, storing results into that database file:
+
+```sh
 docker run -it \
     -v `pwd`:/data \
+    -e DATABASE_URL=sqlite:////data/crawl.sqlite3 \
     website-indexer:main \
-    python manage.py crawl https://www.consumerfinance.gov /data/crawl.sqlite3
+    python manage.py crawl https://www.consumerfinance.gov
 ```
 
 To then run the viewer web application to view that crawler database:
 
-```
+```sh
 docker run -it \
     -p 8000:8000 \
     -v `pwd`:/data \
@@ -69,15 +81,15 @@ The web application with the crawl results will be accessible at http://localhos
 
 Create a Python virtual environment and install required packages:
 
-```
+```sh
 python3.12 -m venv venv
 source venv/bin/activate
 pip install -r requirements/base.txt
 ```
 
 From the repo's root, compile frontend assets:
 
-```
+```sh
 yarn
 yarn build
 ```
@@ -93,7 +105,7 @@ yarn watch
 
 Run the viewer application using sample data:
 
-```
+```sh
 ./manage.py runserver
 ```
 
@@ -104,17 +116,61 @@ The web application using sample data will be accessible at http://localhost:800
 To crawl a website and store the result in a local SQLite database named `crawl.sqlite3`:
 
 ```sh
-./manage.py crawl https://www.consumerfinance.gov crawl.sqlite3
+DATABASE_URL=sqlite:///crawl.sqlite3 /manage.py crawl https://www.consumerfinance.gov
 ```
 
 To then run the viewer web application to view that crawler database:
 
-```
+```sh
 DATABASE_URL=sqlite:///crawl.sqlite3 ./manage.py runserver
 ```
 
 The web application with the crawl results will be accessible at http://localhost:8000/
 
+### Managing crawls in the database
+
+The `./manage.py manage_crawls` command can be used to list, delete, and cleanup old crawls (assuming `DATABASE_URL` is set appropriately).
+
+Crawls in the database have a `status` field which can be one of `Started`, `Finished`, or `Failed`.
+
+#### Listing crawls
+
+To list crawls in the database:
+
+```sh
+./manage.py manage_crawls list
+```
+
+This will list crawls in the database, including each crawl's unique ID.
+
+#### Deleting crawls
+
+To delete an existing crawl, for example one with ID `123`:
+
+```sh
+./manage.py manage_crawls delete 123
+```
+
+`--dry-run` can be added to the `delete` command to preview its output
+without modifying the database.
+
+#### Cleaning crawls
+
+To clean old crawls, leaving behind one crawl of each status:
+
+```sh
+./manage.py manage_crawls clean
+```
+
+To modify the number of crawls left behind, for example leaving behind two of each status:
+
+```sh
+./manage.py manage_crawls clean --keep=2
+```
+
+`--dry-run` can also be added to the `clean` command to preview its output
+without modifying the database.
+
 ## Configuration
 
 ### Database configuration
@@ -127,7 +183,7 @@ project to convert that variable into a Django database specification.
 
 For example, to use a SQLite file at `/path/to/db.sqlite`:
 
-```
+```sh
 export DATABASE_URL=sqlite:////path/to/db.sqlite
 ```
 
@@ -136,7 +192,7 @@ only three are needed when referring to a relative path.)
 
 To point to a PostgreSQL database instead:
 
-```
+```sh
 export DATABASE_URL=postgres://username:password@localhost/dbname
 ```
 
@@ -162,27 +218,27 @@ under the `sample/src` subdirectory.
 
 To regenerate the same database file, first delete it:
 
-```
+```sh
 rm ./sample/sample.sqlite3
 ```
 
 Then, start a Python webserver to serve the sample website locally:
 
-```
+```sh
 cd ./sample/src && python -m http.server
 ```
 
 This starts the sample website running at http://localhost:8000.
 
 Then, in another terminal, recreate the database file:
 
-```
+```sh
 ./manage.py migrate
 ```
 
 Finally, perform the crawl against the locally running site:
 
-```
+```sh
 ./manage.py crawl http://localhost:8000/
 ```
 
@@ -204,13 +260,13 @@ should be updated at the same time as the sample database.
 
 To run Python unit tests, first install the test dependencies in your virtual environment:
 
-```
+```sh
 pip install -r requirements/test.txt
 ```
 
 To run the tests:
 
-```
+```sh
 pytest
 ```
 
@@ -219,7 +275,7 @@ The Python tests make use of a test fixture generated from
 
 To recreate this test fixture:
 
-```
+```sh
 ./manage.py dumpdata --indent=4 crawler > crawler/fixtures/sample.json
 ```
 
@@ -229,13 +285,13 @@ This project uses [Black](https://github.com/psf/black) as a Python code formatt
 
 To check if your changes to project code match the desired coding style:
 
-```
+```sh
 black . --check
 ```
 
 You can fix any problems by running:
 
-```
+```sh
 black .
 ```
 
@@ -244,13 +300,13 @@ for JavaScript, CSS, and HTML templates.
 
 To check if your changes to project code match the desired coding style:
 
-```
+```sh
 yarn prettier
 ```
 
 You can fix any problems by running:
 
-```
+```sh
 yarn prettier:fix
 ```
 
@@ -267,7 +323,7 @@ and to deploy both the crawler and the viewer application to that server.
 
 To install Fabric in your virtual environment:
 
-```
+```sh
 pip install -r requirements/deploy.txt
 ```
 
@@ -276,7 +332,7 @@ pip install -r requirements/deploy.txt
 To configure a remote RHEL8 server with the appropriate system requirements,
 you'll need to use some variation of this command:
 
-```
+```sh
 fab configure
 ```
 
@@ -286,7 +342,7 @@ See [the Fabric documentation](https://docs.fabfile.org/en/latest/cli.html)
 for possible options; for example, to connect using a host configuration
 defined as `crawler` in your `~/.ssh/config`, you might run:
 
-```
+```sh
 fab configure -H crawler
 ```
 
@@ -299,7 +355,7 @@ The `configure` command:
 
 To run the deployment, you'll need to use some variation of this command:
 
-```
+```sh
 fab deploy
 ```
 

crawler/management/commands/manage_crawls.py

@@ -0,0 +1,53 @@
+from django.db.models import OuterRef, Subquery
+
+import djclick as click
+
+from crawler.models import Crawl
+
+
+@click.group()
+def cli():
+    pass
+
+
+@cli.command()
+def list():
+    for crawl in Crawl.objects.all():
+        click.secho(crawl)
+
+
+@cli.command()
+@click.argument("crawl_id", type=int)
+@click.option("--dry-run", is_flag=True)
+def delete(crawl_id, dry_run):
+    crawl = Crawl.objects.get(pk=crawl_id)
+    click.secho(f"Deleting {crawl}")
+
+    if not dry_run:
+        crawl.delete()
+    else:
+        click.secho("Dry run, skipping deletion")
+
+
+@cli.command()
+@click.option(
+    "--keep", type=int, help="Keep this many crawls of each status", default=1
+)
+@click.option("--dry-run", is_flag=True)
+def clean(keep, dry_run):
+    crawls_to_keep = (
+        Crawl.objects.filter(status=OuterRef("status"))
+        .order_by("-started")
+        .values("pk")[:keep]
+    )
+
+    crawls_to_delete = Crawl.objects.exclude(pk__in=Subquery(crawls_to_keep))
+
+    click.secho(f"Deleting {crawls_to_delete.count()} crawls")
+    for crawl in crawls_to_delete:
+        click.secho(crawl)
+
+    if not dry_run:
+        crawls_to_delete.delete()
+    else:
+        click.secho("Dry run, skipping deletion")

crawler/models.py

@@ -30,7 +30,15 @@ class Status(models.TextChoices):
     failure_message = models.TextField(null=True, blank=True)
 
     class Meta:
-        ordering = ["started"]
+        ordering = ["-started"]
+
+    def __str__(self):
+        s = f"Crawl {self.pk} ({self.status}) started {self.started}, config {self.config}"
+
+        if self.failure_message:
+            s += f", failure message: {self.failure_message}"
+
+        return s
 
     @classmethod
     def start(cls, config: CrawlConfig):