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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 14:31:17 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 14:31:17 +0000 |
commit | 8020f71afd34d7696d7933659df2d763ab05542f (patch) | |
tree | 2fdf1b5447ffd8bdd61e702ca183e814afdcb4fc /collectors/python.d.plugin/README.md | |
parent | Initial commit. (diff) | |
download | netdata-upstream.tar.xz netdata-upstream.zip |
Adding upstream version 1.37.1.upstream/1.37.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'collectors/python.d.plugin/README.md')
-rw-r--r-- | collectors/python.d.plugin/README.md | 270 |
1 files changed, 270 insertions, 0 deletions
diff --git a/collectors/python.d.plugin/README.md b/collectors/python.d.plugin/README.md new file mode 100644 index 0000000..2f5ebfc --- /dev/null +++ b/collectors/python.d.plugin/README.md @@ -0,0 +1,270 @@ +<!-- +title: "python.d.plugin" +custom_edit_url: https://github.com/netdata/netdata/edit/master/collectors/python.d.plugin/README.md +--> + +# python.d.plugin + +`python.d.plugin` is a Netdata external plugin. It is an **orchestrator** for data collection modules written in `python`. + +1. It runs as an independent process `ps fax` shows it +2. It is started and stopped automatically by Netdata +3. It communicates with Netdata via a unidirectional pipe (sending data to the `netdata` daemon) +4. Supports any number of data collection **modules** +5. Allows each **module** to have one or more data collection **jobs** +6. Each **job** is collecting one or more metrics from a single data source + +## Disclaimer + +All third party libraries should be installed system-wide or in `python_modules` directory. +Module configurations are written in YAML and **pyYAML is required**. + +Every configuration file must have one of two formats: + +- Configuration for only one job: + +```yaml +update_every : 2 # update frequency +priority : 20000 # where it is shown on dashboard + +other_var1 : bla # variables passed to module +other_var2 : alb +``` + +- Configuration for many jobs (ex. mysql): + +```yaml +# module defaults: +update_every : 2 +priority : 20000 + +local: # job name + update_every : 5 # job update frequency + other_var1 : some_val # module specific variable + +other_job: + priority : 5 # job position on dashboard + other_var2 : val # module specific variable +``` + +`update_every` and `priority` are always optional. + +## How to debug a python module + +``` +# become user netdata +sudo su -s /bin/bash netdata +``` + +Depending on where Netdata was installed, execute one of the following commands to trace the execution of a python module: + +``` +# execute the plugin in debug mode, for a specific module +/opt/netdata/usr/libexec/netdata/plugins.d/python.d.plugin <module> debug trace +/usr/libexec/netdata/plugins.d/python.d.plugin <module> debug trace +``` + +Where `[module]` is the directory name under <https://github.com/netdata/netdata/tree/master/collectors/python.d.plugin> + +**Note**: If you would like execute a collector in debug mode while it is still running by Netdata, you can pass the `nolock` CLI option to the above commands. + +## How to write a new module + +Writing new python module is simple. You just need to remember to include 5 major things: + +- **ORDER** global list +- **CHART** global dictionary +- **Service** class +- **\_get_data** method + +If you plan to submit the module in a PR, make sure and go through the [PR checklist for new modules](#pull-request-checklist-for-python-plugins) beforehand to make sure you have updated all the files you need to. + +For a quick start, you can look at the [example +plugin](https://raw.githubusercontent.com/netdata/netdata/master/collectors/python.d.plugin/example/example.chart.py). + +**Note**: If you are working 'locally' on a new collector and would like to run it in an already installed and running +Netdata (as opposed to having to install Netdata from source again with your new changes) to can copy over the relevant +file to where Netdata expects it and then either `sudo systemctl restart netdata` to have it be picked up and used by +Netdata or you can just run the updated collector in debug mode by following a process like below (this assumes you have +[installed Netdata from a GitHub fork](https://learn.netdata.cloud/docs/agent/packaging/installer/methods/manual) you +have made to do your development on). + +```bash +# clone your fork (done once at the start but shown here for clarity) +#git clone --branch my-example-collector https://github.com/mygithubusername/netdata.git --depth=100 --recursive +# go into your netdata source folder +cd netdata +# git pull your latest changes (assuming you built from a fork you are using to develop on) +git pull +# instead of running the installer we can just copy over the updated collector files +#sudo ./netdata-installer.sh --dont-wait +# copy over the file you have updated locally (pretending we are working on the 'example' collector) +sudo cp collectors/python.d.plugin/example/example.chart.py /usr/libexec/netdata/python.d/ +# become user netdata +sudo su -s /bin/bash netdata +# run your updated collector in debug mode to see if it works without having to reinstall netdata +/usr/libexec/netdata/plugins.d/python.d.plugin example debug trace nolock +``` + +### Global variables `ORDER` and `CHART` + +`ORDER` list should contain the order of chart ids. Example: + +```py +ORDER = ['first_chart', 'second_chart', 'third_chart'] +``` + +`CHART` dictionary is a little bit trickier. It should contain the chart definition in following format: + +```py +CHART = { + id: { + 'options': [name, title, units, family, context, charttype], + 'lines': [ + [unique_dimension_name, name, algorithm, multiplier, divisor] + ]} +``` + +All names are better explained in the [External Plugins](/collectors/plugins.d/README.md) section. +Parameters like `priority` and `update_every` are handled by `python.d.plugin`. + +### `Service` class + +Every module needs to implement its own `Service` class. This class should inherit from one of the framework classes: + +- `SimpleService` +- `UrlService` +- `SocketService` +- `LogService` +- `ExecutableService` + +Also it needs to invoke the parent class constructor in a specific way as well as assign global variables to class variables. + +Simple example: + +```py +from base import UrlService +class Service(UrlService): + def __init__(self, configuration=None, name=None): + UrlService.__init__(self, configuration=configuration, name=name) + self.order = ORDER + self.definitions = CHARTS +``` + +### `_get_data` collector/parser + +This method should grab raw data from `_get_raw_data`, parse it, and return a dictionary where keys are unique dimension names or `None` if no data is collected. + +Example: + +```py +def _get_data(self): + try: + raw = self._get_raw_data().split(" ") + return {'active': int(raw[2])} + except (ValueError, AttributeError): + return None +``` + +# More about framework classes + +Every framework class has some user-configurable variables which are specific to this particular class. Those variables should have default values initialized in the child class constructor. + +If module needs some additional user-configurable variable, it can be accessed from the `self.configuration` list and assigned in constructor or custom `check` method. Example: + +```py +def __init__(self, configuration=None, name=None): + UrlService.__init__(self, configuration=configuration, name=name) + try: + self.baseurl = str(self.configuration['baseurl']) + except (KeyError, TypeError): + self.baseurl = "http://localhost:5001" +``` + +Classes implement `_get_raw_data` which should be used to grab raw data. This method usually returns a list of strings. + +### `SimpleService` + +_This is last resort class, if a new module cannot be written by using other framework class this one can be used._ + +_Example: `ceph`, `sensors`_ + +It is the lowest-level class which implements most of module logic, like: + +- threading +- handling run times +- chart formatting +- logging +- chart creation and updating + +### `LogService` + +_Examples: `apache_cache`, `nginx_log`_ + +_Variable from config file_: `log_path`. + +Object created from this class reads new lines from file specified in `log_path` variable. It will check if file exists and is readable. Also `_get_raw_data` returns list of strings where each string is one line from file specified in `log_path`. + +### `ExecutableService` + +_Examples: `exim`, `postfix`_ + +_Variable from config file_: `command`. + +This allows to execute a shell command in a secure way. It will check for invalid characters in `command` variable and won't proceed if there is one of: + +- '&' +- '|' +- ';' +- '>' +- '\<' + +For additional security it uses python `subprocess.Popen` (without `shell=True` option) to execute command. Command can be specified with absolute or relative name. When using relative name, it will try to find `command` in `PATH` environment variable as well as in `/sbin` and `/usr/sbin`. + +`_get_raw_data` returns list of decoded lines returned by `command`. + +### UrlService + +_Examples: `apache`, `nginx`, `tomcat`_ + +_Multiple Endpoints (urls) Examples: [`rabbitmq`](/collectors/python.d.plugin/rabbitmq/README.md) (simpler). + + +_Variables from config file_: `url`, `user`, `pass`. + +If data is grabbed by accessing service via HTTP protocol, this class can be used. It can handle HTTP Basic Auth when specified with `user` and `pass` credentials. + +Please note that the config file can use different variables according to the specification of each module. + +`_get_raw_data` returns list of utf-8 decoded strings (lines). + +### SocketService + +_Examples: `dovecot`, `redis`_ + +_Variables from config file_: `unix_socket`, `host`, `port`, `request`. + +Object will try execute `request` using either `unix_socket` or TCP/IP socket with combination of `host` and `port`. This can access unix sockets with SOCK_STREAM or SOCK_DGRAM protocols and TCP/IP sockets in version 4 and 6 with SOCK_STREAM setting. + +Sockets are accessed in non-blocking mode with 15 second timeout. + +After every execution of `_get_raw_data` socket is closed, to prevent this module needs to set `_keep_alive` variable to `True` and implement custom `_check_raw_data` method. + +`_check_raw_data` should take raw data and return `True` if all data is received otherwise it should return `False`. Also it should do it in fast and efficient way. + +## Pull Request Checklist for Python Plugins + +This is a generic checklist for submitting a new Python plugin for Netdata. It is by no means comprehensive. + +At minimum, to be buildable and testable, the PR needs to include: + +- The module itself, following proper naming conventions: `collectors/python.d.plugin/<module_dir>/<module_name>.chart.py` +- A README.md file for the plugin under `collectors/python.d.plugin/<module_dir>`. +- The configuration file for the module: `collectors/python.d.plugin/<module_dir>/<module_name>.conf`. Python config files are in YAML format, and should include comments describing what options are present. The instructions are also needed in the configuration section of the README.md +- A basic configuration for the plugin in the appropriate global config file: `collectors/python.d.plugin/python.d.conf`, which is also in YAML format. Either add a line that reads `# <module_name>: yes` if the module is to be enabled by default, or one that reads `<module_name>: no` if it is to be disabled by default. +- A makefile for the plugin at `collectors/python.d.plugin/<module_dir>/Makefile.inc`. Check an existing plugin for what this should look like. +- A line in `collectors/python.d.plugin/Makefile.am` including the above-mentioned makefile. Place it with the other plugin includes (please keep the includes sorted alphabetically). +- Optionally, chart information in `web/gui/dashboard_info.js`. This generally involves specifying a name and icon for the section, and may include descriptions for the section or individual charts. +- Optionally, some default alarm configurations for your collector in `health/health.d/<module_name>.conf` and a line adding `<module_name>.conf` in `health/Makefile.am`. + + |