Chore: troubleshooting document

Related: #171 #165 #143

README.md

@@ -104,6 +104,10 @@ Combining molecule and travis CI allows us to test how new PRs will behave when
 
 See [contributor guideline](CONTRIBUTING.md).
 
+## Troubleshooting
+
+See [troubleshooting](TROUBLESHOOTING.md).
+
 ## License
 
 This project is licensed under MIT License. See [LICENSE](/LICENSE) for more details.

TROUBLESHOOTING.md

+# Troubleshooting
+
+## Bad requests (HTTP 400)
+
+This role downloads checksums from the Github project to verify the integrity of artifacts installed on your servers. When downloading the checksums, a "bad request" error might occur.
+
+This happens in environments which (knowningly or unknowling) use the [netrc mechanism](https://www.gnu.org/software/inetutils/manual/html_node/The-_002enetrc-file.html) to auto-login into servers.
+
+Unless netrc is needed by your playbook and ansible roles, please unset the var like so:
+
+```
+$ NETRC= ansible-playbook ...
+```
+
+Or:
+
+```
+$ export NETRC=
+$ ansible-playbook ...
+```