- Saying hello: How to make the plugin actually do something
- Growing up: How to make it distributable
- Frontend fun: How to add functionality to OctoPrint's web interface
- Settings Galore: How to make parts of your plugin user adjustable
- Style matters: Injecting custom CSS into the page
- Where do we go from here?
Over the course of this little tutorial we'll build a full fledged, installable OctoPrint plugin that displays "Hello World!" at some locations throughout OctoPrint and also offers some other basic functionality to give you an idea of what you can achieve with OctoPrint's plugin system.
First of all let use make sure that you have OctoPrint checked out and set up for development on your local development environment:
$ cd ~/devel $ git clone https://github.com/foosel/OctoPrint [...] $ cd OctoPrint $ virtualenv venv [...] $ source venv/bin/activate (venv) $ pip install -e[develop] [...] (venv) $ octoprint --help Usage: octoprint [OPTIONS] COMMAND [ARGS]... [...]
You can also develop your plugin directly on your Raspberry Pi running OctoPi of course. In that
case please ignore the above instructions, you'll only need to activate the
$ source ~/oprint/bin/activate (oprint) $ octoprint --help Usage: octoprint [OPTIONS] COMMAND [ARGS]... [...]
We'll start at the most basic form a plugin can take - just a couple of simple lines of Python code:
Saving this as
~/.octoprint/plugins yields you something resembling these log entries upon server startup:
(venv) $ octoprint serve 2015-01-27 11:14:35,124 - octoprint.server - INFO - Starting OctoPrint 1.2.0-dev-448-gd96e56e (devel branch) [...] 2015-01-27 11:14:35,124 - octoprint.plugin.core - INFO - Loading plugins from /home/pi/.octoprint/plugins, /home/pi/OctoPrint/src/octoprint/plugins and installed plugin packages... [...] 2015-01-27 11:14:36,135 - octoprint.plugin.core - INFO - 3 plugin(s) registered with the system: [...] | Hello World (1.0.0) = /home/pi/.octoprint/plugins/helloworld.py [...]
OctoPrint found that plugin in the folder and took a look into it. The name and the version it displays in that log
entry it got from the
__plugin_version__ lines. It also read the description from
__plugin_description__ and stored it in an internal data structure, but we'll just ignore this for now.
Apart from being discovered by OctoPrint, our plugin does nothing yet. We want to change that. Let's make it print
"Hello World!" to the log upon server startup. Modify our
helloworld.py like this:
and restart OctoPrint. You now get this output in the log:
2015-01-27 11:17:10,792 - octoprint.plugins.helloworld - INFO - Hello World!
Neat, isn't it? We added a custom class that subclasses one of OctoPrint's :ref:`plugin mixins <sec-plugins-mixins>`
with :class:`~octoprint.plugin.StartupPlugin` and another control property,
__plugin_implementation__, that instantiates
our plugin class and tells OctoPrint about it. Taking a look at the documentation of :class:`~octoprint.plugin.StartupPlugin` we see that
this mixin offers two methods that get called by OctoPrint during startup of the server, :func:`~octoprint.plugin.StartupPlugin.on_startup` and
:func:`~octoprint.plugin.StartupPlugin.on_after_startup`. We decided to add our logging output by overriding :func:`~octoprint.plugin.StartupPlugin.on_after_startup`, but we could also have
used :func:`~octoprint.plugin.StartupPlugin.on_startup` instead, in which case our logging statement would be executed before the server was done starting
up and ready to serve requests.
You'll also note that we are using
self._logger for logging. Where did that one come from? OctoPrint's plugin system
injects :ref:`a couple of useful objects <sec-plugins-mixins-injectedproperties>` into our plugin implementation classes,
one of those being a fully instantiated python logger ready to be
used by your plugin. As you can see in the log output above, that logger uses the namespace
for our little plugin here, or more generally
If you now want to distribute this plugin to other OctoPrint users (since it is so awesome to be greeted upon server startup), let's take a look at how you'd go about that now before our plugin gets more complicated.
You basically have two options to distribute your plugin. One would be about the exact same way we are using it now,
as a simple python file following the naming convention
<plugin identifier>.py that your users add to their
~/.octoprint/plugins folder. You already know how that works. But let's say you have more than just a simple plugin
that can be done in one file. Distributing multiple files and getting your users to install them in the right way
so that OctoPrint will be able to actually find and load them is certainly not impossible, but we want to do it in the
best way possible, meaning we want to make our plugin a fully installable python module that your users will be able to
install directly via OctoPrint's built-in Plugin Manager
or alternatively manually utilizing Python's standard package manager
So let's begin. We'll use the cookiecutter template for OctoPrint plugins here, so we'll first need to install that:
(venv) $ pip install cookiecutter
Then we can use the
octoprint dev plugin:new command  to generate a new OctoPrint plugin skeleton for us:
(venv) $ cd ~/devel (venv) $ octoprint dev plugin:new helloworld Cloning into 'cookiecutter-octoprint-plugin'... remote: Counting objects: 101, done. remote: Total 101 (delta 0), reused 0 (delta 0), pack-reused 101 Receiving objects: 100% (101/101), 53.69 KiB, done. Resolving deltas: 100% (35/35), done. plugin_package [octoprint_helloworld]: plugin_name [OctoPrint-Helloworld]: repo_name [OctoPrint-Helloworld]: full_name [You]: Your Name email [firstname.lastname@example.org]: email@example.com github_username [you]: yourGithubName plugin_version [0.1.0]: 1.0.0 plugin_description [TODO]: A quick "Hello World" example plugin for OCtoPrint plugin_license [AGPLv3]: plugin_homepage [https://github.com/yourGithubName/OctoPrint-Helloworld]: plugin_source [https://github.com/yourGithubName/OctoPrint-Helloworld]: plugin_installurl [https://github.com/yourGithubName/OctoPrint-Helloworld/archive/master.zip]: (venv) $ cd OctoPrint-HelloWorld
octoprint dev plugin:new isn't recognized as a command (and also doesn't show up in the output of
octoprint --help, make sure you installed cookiecutter into the same python environment as OctoPrint.
This will create a project structure in the
OctoPrint-HelloWorld folder we just changed to that looks like this:
extras/ README.txt helloworld.md octoprint_helloworld/ static/ css/ README.txt js/ README.txt less/ README.txt templates/ README.txt __init__.py translations/ README.txt .editorconfig .gitignore babel.cfg MANIFEST.in README.md requirements.txt setup.py
While we'll need some of those folders later on, we'll now delete everything that we don't need right now first, that will make it easier to understand what folder does what later on. Delete the following folders and anything in them:
The final project structure should look like this for now:
octoprint_helloworld/ __init__.py .editorconfig .gitignore babel.cfg MANIFEST.in README.md requirements.txt setup.py
Out of curiosity, take a look into the
setup.py file. The cookiecutter template should have prefilled all the
configuration parameters for you:
plugin_identifier = "helloworld" plugin_package = "octoprint_helloworld" plugin_name = "OctoPrint-Helloworld" plugin_version = "1.0.0" plugin_description = """A quick "Hello World" example plugin for OctoPrint""" plugin_author = "Your Name" plugin_author_email = "firstname.lastname@example.org" plugin_url = "https://github.com/yourGithubName/OctoPrint-Helloworld" plugin_license = "AGPLv3"
Now all that's left to do is to move our
helloworld.py into the
octoprint_helloworld folder and renaming it to
__init__.py. Make sure to delete the copy under
~/.octoprint/plugins in the process, including the
The plugin is now ready to be installed via
python setup.py install. However, since we are still
working on our plugin, it makes more sense to use
python setup.py develop for now -- this way the plugin becomes
discoverable by OctoPrint, however we don't have to reinstall it after any changes we will still do. We can have the
octoprint dev plugin:install command do everything for us here, it will ensure to use the python binary belonging
to your OctoPrint installation:
(venv) $ octoprint dev plugin:install running develop running egg_info creating OctoPrint_HelloWorld.egg-info [...] Finished processing dependencies for OctoPrint-HelloWorld==1.0.0
Restart OctoPrint. Your plugin should still be properly discovered and the log line should be printed:
2015-01-27 13:43:34,134 - octoprint.server - INFO - Starting OctoPrint 1.2.0-dev-448-gd96e56e (devel branch) [...] 2015-01-27 13:43:34,134 - octoprint.plugin.core - INFO - Loading plugins from /home/pi/.octoprint/plugins, /home/pi/OctoPrint/src/octoprint/plugins and installed plugin packages... [...] 2015-01-27 13:43:34,818 - octoprint.plugin.core - INFO - 3 plugin(s) registered with the system: [...] | Hello World (1.0.0) = /home/pi/devel/OctoPrint-HelloWorld/octoprint_helloworld [...] 2015-01-27 13:43:38,997 - octoprint.plugins.helloworld - INFO - Hello World!
Looks like it still works!
Something is still a bit ugly though. Take a look into
setup.py. It seems like we have a bunch
of information now defined twice:
The nice thing about our plugin now being a proper python package is that OctoPrint can and will access the metadata defined
setup.py! So, we don't really need to define all this data twice. Remove
and restart OctoPrint:
2015-01-27 13:46:33,786 - octoprint.plugin.core - INFO - 3 plugin(s) registered with the system: [...] | OctoPrint-HelloWorld (1.0.0) = /home/pi/devel/OctoPrint-HelloWorld/octoprint_helloworld [...]
Our "Hello World" Plugin still gets detected fine, but it's now listed under the same name it's installed under,
"OctoPrint-HelloWorld". That's a bit redundant and squashed, so we'll override that bit via
Restart OctoPrint again:
2015-01-27 13:48:54,122 - octoprint.plugin.core - INFO - 3 plugin(s) registered with the system: [...] | Hello World (1.0.0) = /home/pi/OctoPrint-HelloWorld/octoprint_helloworld [...]
Much better! You can override pretty much all of the metadata defined within
setup.py from within your Plugin itself --
take a look at :ref:`the available control properties <sec-plugins-controlproperties>` for all available
Following the README of the Plugin Skeleton you could now already publish your plugin on Github and it would be directly installable by others using pip:
(venv) $ pip install https://github.com/yourGithubName/OctoPrint-HelloWorld/archive/master.zip
But let's add some more features instead.
Outputting a log line upon server startup is all nice and well, but we want to greet not only the administrator of our OctoPrint instance but actually everyone that opens OctoPrint in their browser. Therefore, we need to modify OctoPrint's web interface itself.
We can do this using the :class:`TemplatePlugin` mixin. For now, let's start with a little "Hello World!" in OctoPrint's
navigation bar right at the top that links to the Wikipedia node about "Hello World" programs. For this we'll first
add the :class:`TemplatePlugin` to our
Next, we'll create a sub folder
templates underneath our
octoprint_helloworld folder, and within that a file
helloworld_navbar.jinja2 like so:
Our plugin's directory structure should now look like this:
octoprint_helloworld/ templates/ helloworld_navbar.jinja2 __init__.py .editorconfig .gitignore babel.cfg MANIFEST.in README.md requirements.txt setup.py
Restart OctoPrint and open the web interface in your browser (make sure to clear your browser's cache!).
Now look at that!
Remember that Wikipedia link we added to our little link in the navigation bar? It links to the english Wikipedia. But what if we want to allow our users to adjust that according to their wishes, e.g. to link to the german language node about "Hello World" programs instead?
To allow your users to customized the behaviour of your plugin you'll need to implement the :class:`~octoprint.plugin.SettingsPlugin`
mixin and override it's :func:`~octoprint.plugin.SettingsPlugin.get_settings_defaults` method. We'll save the URL to
inject into the link under the key
url in our plugin's settings and set it to the old value by default. We'll therefore
return just a single key in our default settings dictionary. To be able to quickly see if we've done that right we'll
extend our little startup message to also log the current setting to the console. We can access that via
which is a little settings manager OctoPrint conveniently injects into our Plugin when we include the :class:`~octoprint.plugin.SettingsPlugin`
Let's take a look at how all that would look in our plugin's
Restart OctoPrint. You should see something like this:
2015-01-30 11:41:06,058 - octoprint.plugins.helloworld - INFO - Hello World! (more: https://en.wikipedia.org/wiki/Hello_world)
So far so good. But how do we now get that value into our template? We have two options, the static one using so called template variables and a dynamic one which retrieves that data from the backend and binds it into the template using Knockout data bindings. First let's take a look at the static version using template variables. We already have the :class:`~octoprint.plugin.TemplatePlugin` mixin included in our plugin, we just need to override its method :func:`~octoprint.plugin.TemplatePlugin.get_template_vars` to add our URL as a template variable.
Adjust your plugin's
__init__.py like this:
Also adjust your plugin's
templates/helloworld_navbar.jinja2 like this:
OctoPrint injects the template variables that your plugin defines prefixed with
plugin_<plugin identifier>_ into
the template renderer, so your
url got turned into
plugin_helloworld_url which you can now use as a simple
Jinja2 Variable in your plugin's template.
Restart OctoPrint and shift-reload the page in your browser (to make sure you really get a fresh copy). The link should still work and point to the URL we defined as default.
Let's change the URL! Open up your OctoPrint instance's
config.yaml file and add the following to it (if a
section doesn't yet exist in the file, create it):
Restart OctoPrint. Not only should the URL displayed in the log file have changed, but also the link should now (after a proper shift-reload) point to the german Wikipedia node about "Hello World" programs:
2015-01-30 11:47:18,634 - octoprint.plugins.helloworld - INFO - Hello World! (more: https://de.wikipedia.org/wiki/Hallo-Welt-Programm)
Nice! But not very user friendly. We don't have any way yet to edit the URL from within OctoPrint and have to restart the server and reload the page every time we want a value change to take effect. Let's try adding a little settings dialog for our plugin in which we can edit the URL and take any changes take immediate effect.
First of all, we'll create the settings dialog. You might already have guessed that we'll need another template for that.
So in your plugin's
templates folder create a new file
helloworld_settings.jinja2 and put the following content
Note how we access our plugin's property via
settings observable is made
available in the
SettingsViewModel and holds the exact data structure returned from the server for all of
OctoPrint's settings. Accessing plugin settings hence works by following the path under which they are stored in
OctoPrint's internal settings data model (made public via the
plugins.<plugin identifier>.<configuration key>.
We'll bind our own settings dialog to the existing
SettingsViewModel, so this will be the way we'll access our
Now adjust your
templates/helloworld_navbar.jinja2 file to use a
data-bind attribute to set the value from the
settings view model into the
href attribute of the link tag:
You might have noticed the quite ugly way to access our plugin's
url property here:
The reason for this is that we'll make our plugin use the existing
NavigationViewModel which holds the
SettingsViewModel as a property called
settings. So to get to the
settings property of the
NavigationViewModel, we'll need to first "switch" to the
SettingsViewModel using its property name. Hence
the ugly access string.
If you were now to restart OctoPrint and reload the web interface, you'll get the settings dialog placed just fine
in OctoPrint's settings, and the link would also still show up in the navigation bar, but both the input field of the
settings dialog as well as the link's
href attribute would not show our link. The reason for this is that OctoPrint
by default assumes that you'll want to bind your own view models to your templates and hence "unbinds" the included
templates from the templates that are in place at the injected location already. In order to tell OctoPrint to please
don't do this here (since we do want to use both
SettingsViewModel), we'll need to
override the default template configuration using the :class:`~octoprint.plugin.TemplatePlugin`s
:func:`~octoprint.plugin.TemplatePlugin.get_template_configs` method. We'll tell OctoPrint to use no custom bindings
for both our
navbar and our
settings plugin. We'll also remove the override of :func:`octoprint.plugin.TemplatePlugin.get_template_vars`
again since we don't use that anymore:
Restart OctoPrint and shift-reload your browser. Your link in the navigation bar should still point to the URL we
config.yaml earlier. Open the "Settings" and click on the new "Hello World" entry that shows up under
Nice! Edit the value, then click "Save". Your link in the navigation bar should now have been updated as well.
The way we've done our data binding and how OctoPrint currently works, your link's target will update immediately when you update the value in the settings dialog. Even if you click Cancel instead of Save, the change will still be reflected in the UI but will be overwritten again by the stored data upon a reload. This is caused by OctoPrint not storing a copy of the settings data while it is being edited, which might be changed in the future to prevent this unexpected behaviour from occurring.
Congratulations, you've just made your Plugin configurable :)
In the previous section we set that
custom_bindings parameter to
False since we wanted OctoPrint to bind the
SettingsViewModel to our settings dialog and the
NavigationViewModel to our entry in the nav bar.
But what if we want to define our own, with more functionality that is already available? Let's take a look. We'll now add an additional UI component to our OctoPrint interface, a custom tab. It will act as a little internal web browser, showing the website behind the URL from the settings in an IFrame but also allowing the user to load a different URL without having to change the settings.
First let us create the Jinja2 template for our tab. In your plugin's
templates folder create a new file
helloworld_tab.jinja2 like so:
Then we create a new folder in your plugin's root called
static and within that folder another folder by the name of
js. Finally, within that folder create a file
helloworld.js. Our plugin's folder structure should now
look like this:
octoprint_helloworld/ static/ js/ helloworld.js templates/ helloworld_navbar.jinja2 helloworld_settings.jinja2 helloworld_tab.jinja2 __init__.py .editorconfig .gitignore babel.cfg MANIFEST.in README.md requirements.txt setup.py
We need to tell OctoPrint about this new static asset so that it will properly inject it into the page. For this we just need to subclass :class:`~octoprint.plugin.AssetPlugin` and override its method :func:`~octoprint.plugin.AssetPlugin.get_assets` like so:
Note how we did not add another entry to the return value of :func:`~octoprint.plugin.TemplatePlugin.get_template_configs`. Remember how we only added those since we wanted OctoPrint to use existing bindings on our navigation bar and settings menu entries? We don't want this this time, and we named our tab template such that OctoPrint will pick it up automatically so we don't have to do anything here.
Then we'll create our custom Knockout view model in
Take a close look at lines 31 to 42. This is how our plugin tells OctoPrint about our new view model, how to
instantiate it, which dependencies to inject and to which elements in the final page to bind. Since we want to access
the URL from the settings of our plugin, we'll have OctoPrint inject the
SettingsViewModel into our own view model,
which is registered within OctoPrint under the name
settingsViewModel. We'll only bind to our custom tab
for now, which OctoPrint will make available in a container with the id
tab_plugin_helloworld (unless otherwise
Our view model defines two observables:
newUrl, which we bound to the input field in our template, and
which we bound to the
src attribute of the "browser iframe" in our template. There's also a function
which we bound to the click event of the "Go" button in our template.
Restart OctoPrint and shift-reload the browser. You should see a shiny new "Hello World" tab right at the end of the tab bar. Click on it!
The desktop version of that article looks a bit squished in there, so let's enter
into the input field and click the "Go" button. The page inside the iframe should be replaced with the mobile version
of the same article.
So it appears that this stuff is working great already. Only one thing is a bit ugly, let's take another look at
We hardcoded some
style on our
iframe in line 6, to make it look a bit better. It would be nicer if that was actually
located inside a stylesheet instead of directly inside our HTML template. Of course that's no problem, we'll just
add a CSS file to our plugin's provided static assets.
First we'll create a new folder within our plugin's
static folder called
css and within that folders a file
helloworld.css. Our plugin's file structure should now look like this:
octoprint_helloworld/ static/ css/ helloworld.css js/ helloworld.js templates/ helloworld_navbar.jinja2 helloworld_settings.jinja2 helloworld_tab.jinja2 __init__.py .editorconfig .gitignore babel.cfg MANIFEST.in README.md requirements.txt setup.py
Put something like the following into
Don't forget to remove the
style attribute from the
iframe tag in
Then adjust our plugin's
__init__.py so that the :func:`~octoprint.plugin.AssetPlugin.get_assets` method returns
a reference to our CSS file:
load the page. But in order to fully be able to see how what we just did changes how our plugin interacts with OctoPrint
we want to disable that behaviour for now. Open up OctoPrint's
config.yaml and disable bundling of the webassets:
Restart OctoPrint, shift-reload your browser and take a look. Everything should still look like before, but now
OctoPrint included our stylesheet and the style information for the
iframe is taken from that instead of
hardcoded in our template. Way better!
Now, if you had something more complicated than just the couple of line of CSS we used here, you might want to use something like LESS for generating your CSS from. If you use LESS, which is what OctoPrint uses for that purpose, you can even put OctoPrint into a mode where it directly uses your LESS files instead of the generated CSS files (and compiles them on the fly in your browser using lessjs), which makes development so much easier. Let's try that, so you know how it works for future bigger projects.
Add another folder to our
static folder called
less and within that create a file
into that the same content as into our CSS file. Compile that LESS file to CSS , overwriting our old
in the process. The folder structure of our plugin should now look like this:
octoprint_helloworld/ static/ css/ helloworld.css js/ helloworld.js less/ helloworld.less templates/ helloworld_navbar.jinja2 helloworld_settings.jinja2 helloworld_tab.jinja2 __init__.py .editorconfig .gitignore babel.cfg MANIFEST.in README.md requirements.txt setup.py
Then adjust our returned assets to include our LESS file as well:
and enable LESS mode by adjusting one of OctoPrint's
devel flags via the
Restart OctoPrint and shift-reload. Your "Hello World" tab should still look like before. Take a look at the site's
source code. In the
head section of the page you'll see that instead of your
helloworld.css OctoPrint now
helloworld.less file instead:
Switch your config back to CSS mode by either removing the
stylesheet setting we just added to
setting it to
Restart and shift-reload and take another look at the
Now the CSS file is linked and no trace of the LESS links is left in the source. This should help to speed up your development tremendously when you have to work with complex stylesheets, just don't forgot to check the generated CSS file in with the rest of your plugin or people will miss it when trying to run your plugin!
Remember when I mentioned that OctoPrint by default bundles all our assets for us? We adjusted our
stop it from doing that at the start of this section, we should switch this back now:
# [...] devel: stylesheet: css # [...]
Just out of curiosity, restart, shift-reload and take a final look at the
Way more compact, isn't it?
If your plugin only provides CSS files, OctoPrint will detect this when switched to LESS mode and include your CSS files instead of any non-existing LESS files. So you don't really have to use LESS if you don't want, but as soon as you need it just switch over.
The same thing works the other way around too by the way. If your plugin only provides LESS files, OctoPrint will link to those, lessjs will take care of the compilation. Please keep in mind though that also providing CSS files is the cleaner way.
You've now seen how easy it is to add functionality to OctoPrint with this little tutorial. You can find the full source code of the little Hello World plugin we built together here on Github.
But I want to invite you to dive deeper into OctoPrint's plugin system. To get an idea of all the other various plugin types you haven't seen yet, :ref:`take a look at the available plugin mixins <sec-plugins-mixins>`.
For some insight on how to create plugins that react to various events within OctoPrint, the Growl Plugin might be a good example to learn from. For how to add support for a slicer, OctoPrint's own bundled CuraEngine plugin might give some hints. For extending OctoPrint's interface, the NavbarTemp plugin might show what's possible with a few lines of code already. Finally, just take a look at the list of available plugins on the OctoPrint wiki if you are looking for examples.
|||Instead of the |
|||Refer to the LESS documentation on how to do that. If you are developing your plugin under Windows you might also want to give WinLESS a look which will run in the background and keep your CSS files up to date with your various project's LESS files automatically.|