Documentation: Add guidelines about debugging connectivity problems

Python may have skipped installing its SSL root certificate bundle on
macOS. Educate the user about how to improve the situation.

Author: amotl

README.rst

@@ -80,6 +80,13 @@ Now, run it::
 If you would like to run ``crash`` from any directory, and without the leading
 ``./``, the file has to be in a directory that is on your `PATH`_.
 
+Troubleshooting
+===============
+
+The documentation section about `troubleshooting connection errors`_ provides
+support and guidelines how to debug and resolve problems when connecting to
+`CrateDB`_ or `CrateDB Cloud`_.
+
 Contributing
 ============
 
@@ -97,8 +104,11 @@ Looking for more help? Check out our `support channels`_.
 .. _command-line interface: https://en.wikipedia.org/wiki/Command-line_interface
 .. _contribution docs: CONTRIBUTING.rst
 .. _Crate.io: https://crate.io/
+.. _CrateDB: https://github.com/crate/crate
+.. _CrateDB Cloud: https://console.cratedb.cloud
 .. _developer docs: DEVELOP.rst
 .. _PATH: https://en.wikipedia.org/wiki/PATH_(variable)
 .. _pip: https://pypi.python.org/pypi/pip
 .. _CrateDB shell documentation: https://crate.io/docs/crate/crash/
 .. _support channels: https://crate.io/support/
+.. _troubleshooting connection errors: https://cratedb.com/docs/crate/crash/en/latest/troubleshooting.html

docs/index.rst

@@ -30,6 +30,7 @@ The CrateDB Shell (aka *Crash*) is an interactive `command-line interface`_
    getting-started
    run
    commands
+   troubleshooting
    appendices/index
 
 .. _command-line interface: https://en.wikipedia.org/wiki/Command-line_interface

docs/troubleshooting.rst

@@ -0,0 +1,49 @@
+===============
+Troubleshooting
+===============
+
+This sections enumerates potential connection problems with ``crash``,
+and how to investigate and resolve them.
+
+
+Debugging connection errors
+===========================
+
+If you are connecting to `CrateDB`_, for example like this::
+
+    crash --hosts 'http://localhost:4200' -U 'admin' -W
+
+... and ``crash`` responds with a connection error message like this::
+
+    CONNECT ERROR
+
+you may want to add the ``--verbose`` command line option, in order to find out
+about the reason why the connection fails. It could be a DNS / name resolution
+error, or it could be a problem related to SSL termination.
+
+
+SSL connection errors
+=====================
+
+`A recent problem`_ outlined SSL connectivity problems when connecting to
+`CrateDB Cloud`_::
+
+    crash --hosts 'https://MY-CLUSTER-NAME.eks1.eu-west-1.aws.cratedb.net:4200' -U 'admin' -W -v
+
+The verbose output using ``crash -v`` signaled a certificate verification error
+like that::
+
+    Server not available, exception: HTTPSConnectionPool(host='MY-CLUSTER-NAME.eks1.eu-west-1.aws.cratedb.net', port=4200):
+    Max retries exceeded with url: / (Caused by SSLError(SSLCertVerificationError(1, '
+    [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1006)')))
+
+If you are on macOS, the Python Installer offers an easy option to install the
+required SSL root certificates. Because ``crash`` uses Python, this is the
+right choice to resolve the problem durably.
+
+.. figure:: https://github.com/crate/crash/assets/453543/c4e49d7e-86d8-40f6-b0d8-f64889f9d972
+
+
+.. _a recent problem: https://community.cratedb.com/t/issue-connecting-to-cratedb-cloud-cluster-from-local-machine/1707
+.. _CrateDB: https://github.com/crate/crate
+.. _CrateDB Cloud: https://console.cratedb.cloud