Contributing¶

Get Source Code¶

Clone the repo from github:

$ git clone git@github.com:tomcatmanager/tomcatmanager.git

Create Python Environments¶

tomcatmanager uses tox to run the test suite against multiple python versions. tox expects that when it runs python3.7 it will actually get a python from the 3.7.x series.

I recommend using pyenv with the pyenv-virtualenv plugin to manage these various python versions. If you are a Windows user, pyenv won’t work for you, you’ll probably have to use conda.

This distribution includes a shell script build-pyenvs.sh which automates the creation of these environments.

If you prefer to create these virtual envs by hand, do the following:

$ cd tomcatmanager
$ pyenv install 3.9.1
$ pyenv virtualenv -p python3.9 3.9.1 tomcatmanager-3.9
$ pyenv install 3.8.7
$ pyenv virtualenv -p python3.8 3.8.7 tomcatmanager-3.8
$ pyenv install 3.7.10
$ pyenv virtualenv -p python3.7 3.7.10 tomcatmanager-3.7
$ pyenv install 3.6.13
$ pyenv virtualenv -p python3.6 3.6.13 tomcatmanager-3.6

Now set pyenv to make all four of those available at the same time:

$ pyenv local tomcatmanager-3.8 tomcatmanager-3.7 tomcatmanager-3.6 tomcatmanager-3.5

Whether you ran the script, or did it by hand, you now have isolated virtualenvs for each of the minor python versions. This table shows various python commands, the version of python which will be executed, and the virtualenv it will utilize.

Command	python	virtualenv
`python`	3.9.1	tomcatmanager-3.9
`python3`	3.9.1	tomcatmanager-3.9
`python3.9`	3.9.1	tomcatmanager-3.9
`python3.8`	3.8.7	tomcatmanager-3.5
`python3.7`	3.7.10	tomcatmanager-3.7
`python3.6`	3.6.13	tomcatmanager-3.6
`pip`	3.9.1	tomcatmanager-3.9
`pip3`	3.9.1	tomcatmanager-3.9
`pip3.9`	3.9.1	tomcatmanager-3.9
`pip3.8`	3.8.7	tomcatmanager-3.8
`pip3.7`	3.7.10	tomcatmanager-3.7
`pip3.6`	3.6.13	tomcatmanager-3.6

Install Dependencies¶

Now install all the development dependencies:

$ pip install -e .[dev]

This installs the tomcatmanager package “in-place”, so the package points to the source code instead of copying files to the python site-packages folder.

All the dependencies now have been installed in the tomcatmanager-3.9 virtualenv. If you want to work in other virtualenvs, you’ll need to manually select it, and install again:

$ pyenv shell tomcatmanager-3.8
$ pip install -e .[dev]

Branches, Tags, and Versions¶

This project uses a simplified version of the git flow branching strategy. We don’t use release branches, and we generally don’t do hotfixes, so we don’t have any of those branches either. The master branch always contains the latest release of the code uploaded to PyPI, with a tag for the version number of that release.

The develop branch is where all the action occurs. Feature branches are welcome. When it’s time for a release, we merge develop into master.

This project uses semantic versioning.

Invoking Common Development Tasks¶

This project uses many other python modules for various development tasks, including testing, rendering documentation, and building and distributing releases. These modules can be configured many different ways, which can make it difficult to learn the specific incantations required for each project you are familiar with.

This project uses invoke to provide a clean, high level interface for these development tasks. To see the full list of functions available:

$ invoke -l

You can run multiple tasks in a single invocation, for example:

$ invoke clean docs sdist wheel

That one command will remove all superflous cache, testing, and build files, render the documentation, and build a source distribution and a wheel distribution.

Testing¶

Unit testing provides reliability and consistency in released software. This project strives for 100% unit test coverage. We aren’t quite there on the interactive program, but the API has 100% coverage.

This repository has Github Actions configured to run tests when you push or merge a pull request. Any push triggers a test run against all supported versions of python in a linux environment. Any pull request triggers a test run against all supported versions of python on all supported operating systems.

To ensure the tests can run without an external dependencies, tests/mock_server80.py contains a HTTP server which emulates the behavior of Tomcat Manager 8.0. There is a test fixture to start this server, and all the tests run against this fixture. I created this fixture to speed up testing time. It doesn’t do everything a real Tomcat server does, but it’s close enough for the tests to run, and it allows you to parallelize the test suite using python-xdist.

You can run the tests against all the supported versions of python using tox:

$ tox

tox expects that when it runs python3.7 it will actually get a python from the 3.7.x series. That’s why we set up the various python environments earlier.

If you just want to run the tests in your current python environment, use pytest:

$ pytest

This runs all the test in tests/ and also runs doctests in tomcatmanager/ and docs/.

You can speed up the test suite by using pytest-xdist to parallelize the tests across the number of cores you have:

$ pip install pytest-xdist
$ pytest -n8

In many of the doctests you’ll see something like:

>>> tomcat = getfixture('tomcat')

This getfixture() helper imports fixtures defined in conftest.py, which has several benefits:

reduces the amount of redundant code in doctests which shows connecting to a tomcat server and handling exceptions
allows doctests to execute against a mock tomcat server

Testing Against A Real Server¶

If you wish, you can run the test suite against a real Tomcat Server instead of against the mock server included in this distribution. Running the test suite will deploy and undeploy an app hundreds of times, and will definitely trigger garbage collection, so you might not want to run it against a production server.

It’s also slow (which is why the tests normally run against a mock server). When I run the test suite against a stock Tomcat on a Linode with 2 cores and 4GB of memory it takes approximately 3 minutes to complete. I don’t think throwing more CPU at this would make it any faster: during the run of the test suite the Tomcat Server never consumes more than a few percent of the CPU capacity.

You must prepare some files on the server in order for the test suite to run successfully. Some of the tests instruct the Tomcat Server to deploy an application from a warfile stored on the server. I suggest you use the minimal application included in this distribution at tomcatmanager/tests/war/sample.war, but you can use any valid war file. Put this file in some directory on the server; I typically put it in /tmp/sample.war.

You must also construct a minimal context file on the server. You can see an example of such a context file in tomcatmanager/tests/war/context.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!-- Context configuration file for my web application -->
<Context path='/ignored' docBase='/tmp/sample.war'>
</Context>

The docBase attribute must point to a valid war file or the tests will fail. It can be the same minimal war file you already put on the server. The path attribute is ignored for context files that are not visible to Tomcat when it starts up, so it doesn’t matter what you have there. I typically put this context file at /tmp/context.xml.

You will also need:

the url where the manager app of your Tomcat Server is available
a user with the manager-script role
the password for the aforementioned user

With all these prerequisites ready, you can feed them to pytest as shown:

$ pytest --url=http://localhost:8080/manager --user=ace \
--password=newenglandclamchowder --warfile=/tmp/sample.war \
--contextfile=/tmp/context.xml

Warning

If you test against a real Tomcat server, you should not use the pytest-xdist plugin to parallelize testing across multiple CPUs or many platforms. Many of the tests depend on deploying and undeploying an app at a specific path, and that path is shared across the entire test suite. It wouldn’t help much anyway because the testing is constrained by the speed of the Tomcat server.

If you kill the test suite in the middle of a run, you may leave the test application deployed in your tomcat server. If this happens, you must undeploy it before rerunning the test suite or you will get lots of errors.

When the test suite deploys applications, it will be at the path returned by the safe_path fixture in conftest.py. You can modify that fixture if for some reason you need to deploy at a different path.

Code Quality¶

Use pylint to check code quality. There is a pylint config file for the tests and for the main module:

$ pylint --rcfile=tests/pylintrc tests
$ pylint --rcfile=tomcatmanager/pylintrc src

You are welcome to use the pylint comment directives to disable certain messages in the code, but pull requests containing these directives will be carefully scrutinized.

Code Formatting¶

Use black to format your code. We use the default configuration, including a line length of 88 characters.

To format all the code in the project using black, do:

$ invoke black

You can check whether black would make any changes to the source code by:

$ invoke black-check

Black integrates with many common editors and IDE’s, that’s the easiest way to ensure that your code is always formatted.

Please format the code in your PR using black before submitting it, this project is configured to not allow merges if black would change anything.

Documentation¶

Documentation is not an afterthought for this project. All PR’s must include relevant documentation or they will be rejected.

The documentation is written in reStructured Test, and is assembled from both the docs/ directory and from the docstrings in the code. We use Sphinx formatted docstrings. We encourage references to other methods and classes in docstrings, and choose to optimize docstrings for clarity and usefulness in the rendered output rather than ease of reading in the source code.

The code includes type hints as a convenience, but does not provide stub files nor do we use mypy to check for proper static typing. Our philosophy is that the dynamic nature of Python is a benefit and we shouldn’t impose static type checking, but annotations of expected types can be helpful for documentation purposes.

Sphinx transforms the documentation source files into html:

$ cd docs
$ make html

The output will be in docs/build/html. We treat warnings as errors, and the documentation has none. Pull requests which generate errors when the documentation is build will be rejected.

If you are doing a lot of documentation work, the sphinx-autobuild module has been integrated. Type:

$ cd docs
$ make livehtml

Then point your browser at http://localhost:8000 to see the documentation automatically rebuilt as you save your changes.

Use doc8 to check documentation quality:

$ invoke doc8

This project is configured to prevent merges to the main or develop branch if doc8 returns any errors.

When code is pushed to the main branch, which only happens when we cut a new release, the documentation is automatically built and deployed to https://tomcatmanager.readthedocs.io/en/stable/. When code is pushed to the develop branch, the documentation is automatically built and deployed to https://tomcatmanager.readthedocs.io/en/develop/.

Make a Release¶

To make a release and deploy it to PyPI, do the following:

Merge everything to be included in the release into the develop branch.
Run tox to make sure the tests pass in all the supported python versions.
Review and update CHANGELOG.rst.
Update and close the milestone corresponding to the release at https://github.com/tomcatmanager/tomcatmanager/milestones
Push the develop branch to github.
Create a pull request on github to merge the develop branch into master. Wait for the checks to pass.
Merge the develop branch into the master branch and close the pull request.
Tag the master branch with the new version number, and push the tag.
Create a new release on Github.
Build source distribution, wheel distribution, and upload them to pypi staging:
```
$ invoke pypi-test
```
Build source distribution, wheel distribution, and upload them to pypi:
```
$ invoke pypi
```
Docs are automatically deployed to http://tomcatmanager.readthedocs.io/en/stable/. Make sure they look good. Add a “Version” in readthedocs which points to the tag you just created. Prune old versions as necessary.
Switch back to the develop branch. Merge changes in from master.
Add an Unreleased section to the top of CHANGELOG.rst. Push the change to github.