Add a Tips, tricks, and shortcuts for Porch developers (Lazy Dog) to Porch documentation (#955)

* Add Lazy Dog to Porch documentation

Signed-off-by: liamfallon <liam.fallon@est.tech>

* Fix typo in reference

Signed-off-by: liamfallon <liam.fallon@est.tech>

* Deleted irrelevant comment at bottom

Signed-off-by: liamfallon <liam.fallon@est.tech>

* Fix typo

Signed-off-by: liamfallon <liam.fallon@est.tech>

* Fix typo

Signed-off-by: liamfallon <liam.fallon@est.tech>

* Fix copilot comments

Signed-off-by: liamfallon <liam.fallon@est.tech>

* Fix copilot comments

Signed-off-by: liamfallon <liam.fallon@est.tech>

* Fix copilot comments

Signed-off-by: liamfallon <liam.fallon@est.tech>

---------

Signed-off-by: liamfallon <liam.fallon@est.tech>

Author: liamfallon

docs/content/en/docs/9_troubleshooting_and_faq/_index.md

@@ -37,6 +37,11 @@ Recovering from data loss scenarios:
 - DB cache loss with and without backups
 - Backup strategies for Porch components
 
+### [Porch Lazy Dog (Lathund)]({{% relref "lazy-dog" %}})
+
+A quick reference of tips, tricks, workarounds, and shortcuts for developers working with Porch. Please raise a PR to
+add your Porch magic spells to the Lazy Dog.
+
 ## Getting Help
 
 If you encounter issues not covered in this guide:

docs/content/en/docs/9_troubleshooting_and_faq/lazy-dog/_index.md

@@ -0,0 +1,54 @@
+---
+title: "Porch Lazy Dog (Lathund)"
+type: docs
+weight: 9
+description: Tips, tricks, and shortcuts for Porch developers
+---
+
+![Lazy Dog](/images/porch/LazyDog.svg)
+
+A quick reference [Lazy Dog/Lathund](https://watchingtheswedes.com/2021/09/05/swedish-expression-lazy-dog/) of tips,
+tricks, workarounds, and shortcuts for developers working with Porch. Please raise a PR to add your Porch magic spells to the Lazy Dog.
+
+## Debugging Starlark scripts
+
+Debugging Starlark scripts can be difficult, especially when running mutation pipelines in Porch. One technique is to put `print` statements in the code to print the value of variables. For example:
+
+```python
+def set_package_name(resources, root_kptfile_path, root_package_name):
+  for r in resources:
+    resource_path = r["metadata"]["annotations"]["internal.config.kubernetes.io/package-path"]
+    resource_name = r["metadata"]["annotations"]["config.kubernetes.io/path"]
+    print("Resource Path: " + resource_path)
+    print("Resource Name: " + resource_name)
+```
+
+But that's not enough in Porch.
+
+To force output of the result of partial rendering of failing pipelines in kpt, you must set [the following annotation](https://kpt.dev/book/04-using-functions/#debugging-render-failures) on the `Kptfile`:
+
+```yaml
+apiVersion: kpt.dev/v1
+kind: Kptfile
+metadata:
+  name: wordpress
+  annotations:
+    kpt.dev/save-on-render-failure: "true"
+```
+
+You also must set an annotation on the Package Revision so that Porch will [push draft package revisions even when they
+fail](https://docs.porch.nephio.org/docs/4_tutorials_and_how-tos/working_with_package_revisions/#troubleshooting).
+
+```bash
+kubectl annotate packagerevision <name> porch.kpt.dev/push-on-render-failure=true
+```
+
+If the mutation pipeline is passing, you won't get any output from your `print()` statement because Porch assumes
+everything is OK and does not print any output. The easiest way to work around this is to put a deliberate runtime error
+into your Starlark script, which will cause an error and trigger the output:
+
+```python
+  set_package_name(ctx.resource_list["items"], root_kptfile_path, root_package_name)
+
+  i = 10/0 # Deliberate division by zero error
+```