tpiperatgod opened a new pull request, #18669:
URL: https://github.com/apache/pulsar/pull/18669
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<!-- Either this PR fixes an issue, -->
Fixes #18533
<!-- or this PR is one task of an issue -->
Master Issue: #18533
### Motivation
The Pulsar functions have the ability to provide the number of instances of
the called function (see, for example, ["Get num
instances"](https://pulsar.apache.org/docs/2.10.x/window-functions-context/#get-num-instances)
), but the data that this function currently relies on needs to be passed in
via command line arguments and cannot be easily changed dynamically. Therefore
we need to provide a more dynamic way of accessing data (mainly
FunctionDetails) for functions, and this way can also serve to pass the
function's other parameters.
This mechanism is aimed at allowing the function to dynamically fetch the
required parameters and data without having to restart the function in order to
load the latest parameters or data.
A more appropriate approach is to provide the function with a local config
file where the data and parameters are stored. The provider of the data and
parameters (usually the initiator of the function, e.g. function-worker) writes
the contents of the parameters and the data (FunctionDetails) to a fixed local
config file, and passes the path of this config file to the function.
```
exec --config-file /path/to/config-file
```
The function determines the value of `--config-file` and determines if the
target config file exists, and parses its contents if it does.
The rules for applying parameters or data to the function are as follows.
- Parameters or data passed in on the command line have a lower priority
than the corresponding parameters or data in the configuration file
- For mandatory parameters or data, if they are not passed in, an exception
is thrown.
- For optional parameters or data, if not passed in, the default value is
used
### Modifications
1. add two arguments
- `enable_live_update`, default is False, which means that
python-function will listen for changes to the configuration file and update
the configuration of the running function instance when it has listened for an
event
- `config_file`, default is None, which means you need to get the
configuration content from `config_file`
2. the priority of command line arguments is higher than the priority of
configuration file arguments during initialization
3. if `args.config_file` and `args.enable_live_update` are enabled, add a
new thread and use the [`watchdog`](https://github.com/gorakhargosh/watchdog)
library to listen to `args.config_file` and update the relevant configuration
after listening to the `on_modified` event
### Verifying this change
- [ ] Make sure that the change passes the CI checks.
*(Please pick either of the following options)*
This change is a trivial rework / code cleanup without any test coverage.
*(or)*
This change is already covered by existing tests, such as *(please describe
tests)*.
*(or)*
This change added tests and can be verified as follows:
*(example:)*
- *Added integration tests for end-to-end deployment with large payloads
(10MB)*
- *Extended integration test for recovery after broker failure*
### Does this pull request potentially affect one of the following parts:
*If the box was checked, please highlight the changes*
- [ ] Dependencies (add or upgrade a dependency)
- [ ] The public API
- [ ] The schema
- [ ] The default values of configurations
- [ ] The threading model
- [ ] The binary protocol
- [ ] The REST endpoints
- [ ] The admin CLI options
- [ ] Anything that affects deployment
### Documentation
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later -->
- [ ] `doc-not-needed` <!-- Your PR changes do not impact docs -->
- [ ] `doc-complete` <!-- Docs have been already added -->
### Matching PR in forked repository
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