diff --git a/README.md b/README.md
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+++ b/README.md
@@ -1,66 +1,98 @@
 # QuickCategories
 
 [This tool](https://tools.wmflabs.org/quickcategories/) allows users to add and remove categories from pages in batches.
 It is currently work-in-progress, and not usable yet.
 
 For more information,
 please see the tool’s [on-wiki documentation page](https://meta.wikimedia.org/wiki/User:Lucas_Werkmeister/QuickCategories).
 
 ## Toolforge setup
 
 On Wikimedia Toolforge, this tool runs under the `quickcategories` tool name.
-Source code resides in `~/www/python/src/`,
-a virtual environment is set up in `~/www/python/venv/`,
-logs end up in `~/uwsgi.log`.
+Source code resides in `~/www/python/src/`.
+
+### Webservice
+
+The web frontend of the tool runs as a standard Python web service,
+with a virtual environment in `~/www/python/venv/`
+and logs ending up in `~/uwsgi.log`.
 
 If the web service is not running for some reason, run the following command:
 ```
 webservice --backend=kubernetes python start
 ```
 If it’s acting up, try the same command with `restart` instead of `start`.
 
-To update the service, run the following commands after becoming the tool account:
+### Background runner
+
+The background runner for batches runs as a [Kubernetes continuous job](https://wikitech.wikimedia.org/wiki/Help:Toolforge/Kubernetes#Kubernetes_continuous_jobs),
+with a deployment described by the `deployment.yaml` file in the source code repository.
+To inspect the current status, get the currently running pod via `kubectl get pods`;
+you can then, for example, view its logs with `kubectl logs NAME`
+or enter a debugging shell with `kubectl exec -it NAME bash`.
+
+To stop the runner, use `kubectl delete deployment quickcategories.background-runner`.
+You can start a new one with `kubectl create -f deployment.yaml`
+(or `~/www/python/src/deployment.yaml` if you’re not in the source code directory).
+It sets up its own virtual environment, so it should be ready after a minute or so.
+
+### Update
+
+The following commands should work to update the tool after becoming the tool account:
+
 ```
-webservice --backend=kubernetes python shell
-source ~/www/python/venv/bin/activate
+# stop current processes
+webservice --backend=kubernetes python stop
+kubectl delete deployment quickcategories.background-runner
+
+# update source code
 cd ~/www/python/src
 git fetch
 git diff @ @{u} # inspect changes
 git merge --ff-only @{u}
-pip3 install -r requirements.txt
-webservice --backend=kubernetes python restart
+
+# update webservice venv
+webservice --backend=kubernetes python shell
+source ~/www/python/venv/bin/activate
+pip3 install --upgrade pip
+pip3 install -r ~/www/python/src/requirements.txt
+exit
+
+# start new processes
+webservice --backend=kubernetes python start
+kubectl create -f deployment.yaml
 ```
 
 ## Local development setup
 
 You can also run the tool locally, which is much more convenient for development
 (for example, Flask will automatically reload the application any time you save a file).
 
 ```
 git clone https://phabricator.wikimedia.org/source/tool-quickcategories.git
 cd tool-quickcategories
 pip3 install -r requirements.txt
 FLASK_APP=app.py FLASK_ENV=development flask run
 ```
 
 If you want, you can do this inside some virtualenv too.
 
 ## Contributing
 
 To send a patch, you can use any of the following methods:
 
 * [Submit a pull request on GitHub.](https://github.com/lucaswerkmeister/tool-quickcategories)
 * Use `git send-email`.
   (Send the patch(es) to the email address from the Git commit history.)
 * Upload the changes to a repository of your own and use `git request-pull` (same email address).
 * Upload a diff on [GitHub Gist](https://gist.github.com/)
   and send the link to the tool’s maintainer(s) via email, Twitter, on-wiki message, or whatever.
 * [Create a Diff on Phabricator.](https://phabricator.wikimedia.org/differential/diff/create/)
   Make sure to add @LucasWerkmeister as subscriber.
 
 They’re listed in the maintainer(s)’ order of preference, from most to least preferred,
 but feel free to use any of these methods as it best suits you.
 
 ## License
 
 The code in this repository is released under the AGPL v3, as provided in the `LICENSE` file.
diff --git a/deployment.yaml b/deployment.yaml
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+apiVersion: extensions/v1beta1
+kind: Deployment
+metadata:
+  name: quickcategories.background-runner
+  namespace: quickcategories
+spec:
+  replicas: 1
+  template:
+    metadata:
+      labels:
+        name: quickcategories.background-runner
+    spec:
+      containers:
+        - name: background-runner
+          image: docker-registry.tools.wmflabs.org/toollabs-python35-base:latest
+          command: [ '/bin/bash', '-c' ]
+          args:
+            # venvs are not position-independent, so we build our own instead of
+            # mounting /data/project/quickcategories/www/python/venv somewhere
+            # (this also lets us use different Python versions for runner and webservice)
+            - python3 -m venv /tmp/venv &&
+              source /tmp/venv/bin/activate &&
+              pip install --upgrade pip &&
+              pip install -r /srv/quickcategories/requirements.txt &&
+              exec python3 /srv/quickcategories/background_runner.py
+          env:
+            # config.yaml specifies ~/replica.my.cnf as config path, we place it in /etc
+            - name: HOME
+              value: '/etc/'
+          volumeMounts:
+            # we mount the config file and source code in non-standard locations (i. e.
+            # not under /data/project/quickcategories) so that anything that’s confused about
+            # where it’s running will just crash instead of possibly doing the wrong thing
+            - name: replica-my-cnf
+              mountPath: '/etc/replica.my.cnf'
+              readOnly: true
+            - name: src
+              mountPath: '/srv/quickcategories/'
+              readOnly: true
+      volumes:
+        - name: replica-my-cnf
+          hostPath:
+            path: '/data/project/quickcategories/replica.my.cnf'
+        - name: src
+          hostPath:
+            path: '/data/project/quickcategories/www/python/src/'