pydnstest 0.2.2

Tool to test DNS changes on a staging server and verify in production

pydnstest

Python tool for testing DNS changes (add, remove, rename, change records) against a staging DNS server, verifying the same changes against production, or confirming that a record returns the same result in both environments.

pydnstest is licensed under the GNU Affero General Public License version 3.

Note - while the code is 100% covered by tests, this is a young project, and I’m not sure that every code path has been executed in a live environment. As such, until I can confirm that, I’d recommend repeating the same tests manually for critical applications (like… say… everything in DNS…) I expect this to change quite soon, and am happy to receive both bug reports and confirmations that everything works.

Requirements

• Python 2.6+ (currently tested with 2.6, 2.7, 3.2, 3.3)

• Python VirtualEnv and pip (recommended installation method; your OS/distribution should have packages for these)

• or the following packages:

  • pydns (python2) or py3dns (python3)

  • pyparsing

Installation

It’s recommended that you install into a virtual environment (virtualenv / venv). See the virtualenv usage documentation for information on how to create a venv. If you really want to install system-wide, you can (using sudo).

pip install pydnstest

Configuration

Create a configuration file at ~/.dnstest.ini (or another location, which you can tell dnstest about with the -f /path/to/dnstest.ini option) and open it in a text editor. Using the example below, change the values to the correct ones for your environment (this is an ini-style file, parsed with Python’s ConfigParser module):

[servers]
# set your production/live DNS server address
prod: 1.2.3.4

# set your test/staging DNS server address
test: 1.2.3.5

[defaults]
# whether or not we should have reverse DNS for valid A records, True or False
have_reverse_dns: True

# set this to your default domain, to be appended to input names that are only a hostname, not a FQDN
domain: .example.com

# set to 'True' to ignore the TTL value when comparing DNS responses
ignore_ttl: False

# set to the (float) number of seconds to sleep between DNS tests
sleep: 0.0

• in the [servers] section:

  • prod: the IP address of your production/live DNS server

  • test: the IP address of your test/staging DNS server

• in the [defaults] section:

  • have_reverse_dns: True if you want to check for reverse DNS by default, False otherwise

  • domain: the default domain (i.e. “.example.com”) to append to any input which appears to be a hostname (i.e. not a FQDN or an IP address)

  • ignore_ttl: True if you want to ignore the ‘ttl’ attribute when comparing responses from prod and test servers

Usage

pydnstest takes one or more specifications for DNS changes to be made, in a natural-language-like grammar, and tests a staging DNS server (and optionally verifies against a production/live server once the changes are live). For each specification, it prints out a simple one-line OK/NG summary, and optionally some helpful secondary messages and/or warnings. At the moment, it takes input either on STDIN or read from a file.

The following usage examples all assume that you’ve installed pydnstest in a virtualenv located at ~/venv_dir. If you installed system-wide, simply omit the first two lines (cd ~/venv_dir and source bin/activate).

Grammar

add [record|name|entry] <hostname_or_fqdn> [with ][value|address|target] <hostname_fqdn_or_ip>
remove [record|name|entry] <hostname_or_fqdn>
rename [record|name|entry] <hostname_or_fqdn> [with] [value|address|target] <value> to <hostname_or_fqdn>
change [record|name|entry] <hostname_or_fqdn> to <hostname_fqdn_or_ip>
confirm <hostname_or_fqdn> (checks that TEST and PROD return identical results)

Sample input file

add foo.example.com with address 1.2.3.4
remove bar.example.com
rename baz.example.com with value 1.2.3.5 to blam.example.com
change quux.example.com to 1.2.3.6
confirm blam.example.com

Usage with input file

Write a test file with the following content, at ~/inputfile.txt:

add record newhost.example.com with address 10.188.8.90
add record newhost-console.example.com with address 10.188.15.90

And then run the tests on it:

jantman@palantir$ cd ~/venv_dir
jantman@palantir$ source bin/activate
(venv_dir)jantman@palantir$ pydnstest -f ~/inputfile.txt
OK: newhost.example.com => 10.188.8.90 (TEST)
        PROD server returns NXDOMAIN for newhost.example.com (PROD)
        REVERSE OK: 10.188.8.90 => newhost.example.com (TEST)
OK: newhost-console.example.com => 10.188.15.90 (TEST)
        PROD server returns NXDOMAIN for newhost-console.example.com (PROD)
        REVERSE OK: 10.188.15.90 => newhost-console.example.com (TEST)
++++ All 2 tests passed. (pydnstest 0.1.0)

Verify once in prod

After making the above changes live, verify them in production:

jantman@palantir$ cd ~/venv_dir
jantman@palantir$ source bin/activate
(venv_dir)jantman@palantir$ pydnstest -f ~/inputfile.txt -V
OK: newhost.example.com => 10.188.8.90 (PROD)
        REVERSE OK: 10.188.8.90 => newhost.example.com (PROD)
OK: newhost-console.example.com => 10.188.15.90 (PROD)
        REVERSE OK: 10.188.15.90 => newhost-console.example.com (PROD)
++++ All 2 tests passed. (pydnstest 0.1.0)

Run one quick test

Do a quick one-off test passed in on stdin, to confirm that prod and test return the same result for a given name:

jantman@palantir$ cd ~/venv_dir
jantman@palantir$ source bin/activate
(venv_dir)jantman@palantir$ echo "confirm foo.example.com" | pydnstest
OK: prod and test servers return same response for 'foo.example.com'
    response: {'name': 'foo.example.com', 'data': '10.10.8.2', 'typename': 'A', 'classstr': 'IN', 'ttl': 360, 'type': 1, 'class': 1, 'rdlength': 4}
++++ All 1 tests passed. (pydnstest 0.1.0)

Bugs and Feature Requests

Bug reports and feature requests are happily accepted via the GitHub Issue Tracker. Pull requests are welcome. Issues that don’t have an accompanying pull request will be worked on as my time and priority allows.

License

pydnstest is licensed under the GNU Affero General Public License version 3, with the additional term that the Copyright and Authors attributions may not be removed or otherwise altered, except to add the Author attribution of a contributor to the work. (Additional Terms pursuant to Section 7b of the AGPL v3).

I chose AGPL mostly because I want this software to continue to evolve and benefit from community involvement and improvement.

Development

To install for development:

1. Fork the pydnstest repository on GitHub

2. Create a new branch off of master in your fork.

$ virtualenv pydnstest
$ cd pydnstest && source bin/activate
$ pip install -e [e-mail]:YOURNAME/pydnstest.git@BRANCHNAME#egg=pydnstest
$ cd src/pydnstest

The git clone you’re now in will probably be checked out to a specific commit, so you may want to git checkout BRANCHNAME.

Guidelines

• pep8 compliant with some exceptions (see pytest.ini)

• 100% test coverage with pytest (with valid tests)

Testing

Testing is done via pytest, driven by tox and currently encompasses testing for both the input language parsing, and the DNS testing logic (via stubbing the DNS lookup methods and returning known results).

Be aware that the tests also run a few live DNS queries (dnstest_dns_test.py / TestDNS class) against domains that I control, mostly as a sanity check for changes in the underlying pydns library. These may occasionally timeout or fail, as is the case with any live network tests.

• testing is as simple as:

  • pip install tox

  • tox

• If you want to see code coverage: tox -e cov

  • this produces two coverage reports - a summary on STDOUT and a full report in the htmlcov/ directory

Release Checklist

1. Start a release_ branch.

2. Confirm that there are CHANGES.txt entries for all major changes.

3. Ensure that Travis tests passing in all environments.

4. Ensure that test coverage is no less than the last release (ideally, 100%).

5. Increment the version number in pydnstest/version.py and add version and release date to CHANGES.txt, then push to GitHub.

6. Confirm that README.rst renders correctly on GitHub.

7. Upload package to testpypi, confirm that README.rst renders correctly.

   • Make sure your ~/.pypirc file is correct

   • python setup.py register -r https://testpypi.python.org/pypi

   • python setup.py sdist upload -r https://testpypi.python.org/pypi

   • Check that the README renders at https://testpypi.python.org/pypi/pydnstest

8. Squash merge the release_ branch to master, push to GitHub.

9. Tag the release in Git, push tag to GitHub:

   • tag the release. for now the message is quite simple: git tag -a vX.Y.Z -m 'X.Y.Z released YYYY-MM-DD'

   • push the tag to GitHub: git push origin vX.Y.Z

11. Upload package to live pypi:

    • python setup.py upload

10. make sure any GH issues fixed in the release are closed