Add Documentation 2 (#334)

Add documentation that covers:

- configuration
- prediction

Add Python scripts that support automatic documentation generation for
configuration data defined with pydantic.

Adapt EOS configuration to provide more methods for REST API and
automatic documentation generation.

Adapt REST API to allow for EOS configuration file load and save.
Sort REST API on generation of openapi markdown for docs.

Move logutil to core/logging to allow configuration of logging by standard config.

Make Akkudoktor predictions always start extraction of prediction data at start of day.
Previously extraction started at actual hour. This is to support the code that assumes
prediction data to start at start of day.

Signed-off-by: Bobby Noelte <b0661n0e17e@gmail.com>

docs/akkudoktoreos/configuration.md

@@ -0,0 +1,89 @@
+% SPDX-License-Identifier: Apache-2.0
+
+# Configuration
+
+The configuration controls all aspects of EOS: optimization, prediction, measurement, and energy
+management.
+
+## Storing Configuration
+
+EOS stores configuration data in a **key-value store**, where a `configuration key` refers to the
+unique identifier used to store and retrieve specific configuration data. Note that the key-value
+store is memory-based, meaning all stored data will be lost upon restarting the EOS REST server if
+not saved to the `EOS configuration file`.
+
+Some `configuration keys` are read-only and cannot be altered. These keys are either set up by other
+means, such as environment variables, or determined from other information.
+
+Several endpoints of the EOS REST server allow for the management and retrieval of configuration
+data.
+
+### Save Configuration File
+
+Use endpoint `PUT /v1/config/file` to save the current configuration to the
+`EOS configuration file`.
+
+### Load Configuration File
+
+Use endpoint `POST /v1/config/update` to update the configuration from the `EOS configuration file`.
+
+## Configuration Sources and Priorities
+
+The configuration sources and their priorities are as follows:
+
+1. **Settings**: Provided during runtime by the REST interface
+2. **Environment Variables**: Defined at startup of the REST server and during runtime
+3. **EOS Configuration File**: Read at startup of the REST server and on request
+4. **Default Values**
+
+### Settings
+
+Settings are sets of configuration data that take precedence over all other configuration data from
+different sources. Note that settings are not persistent. To make the current configuration with the
+current settings persistent, save the configuration to the `EOS configuration file`.
+
+Use the following endpoints to change the current configuration settings:
+
+- `PUT /v1/config`: Replaces the entire configuration settings.
+- `PUT /v1/config/value`: Sets a specific configuration option.
+
+### Environment Variables
+
+All `configuration keys` can be set by environment variables with the same name. EOS recognizes the
+following special environment variables:
+
+- `EOS_CONFIG_DIR`: The directory to search for an EOS configuration file.
+- `EOS_DIR`: The directory used by EOS for data, which will also be searched for an EOS
+             configuration file.
+- `EOS_LOGGING_LEVEL`: The logging level to use in EOS.
+
+### EOS Configuration File
+
+The EOS configuration file provides persistent storage for configuration data. It can be modified
+directly or through the REST interface.
+
+If you do not have a configuration file, it will be automatically created on the first startup of
+the REST server in a system-dependent location.
+
+To determine the location of the configuration file used by EOS, ask the REST server. The endpoint
+`GET /v1/config` provides the `config_file_path` configuration key.
+
+EOS searches for the configuration file in the following order:
+
+1. The directory specified by the `EOS_CONFIG_DIR` environment variable
+2. The directory specified by the `EOS_DIR` environment variable
+3. A platform-specific default directory for EOS
+4. The current working directory
+
+The first available configuration file found in these directories is loaded. If no configuration
+file is found, a default configuration file is created in the platform-specific default directory,
+and default settings are loaded into it.
+
+### Default Values
+
+Some of the `configuration keys` have default values by definition. For most of the
+`configuration keys` the default value is just `None`, which means no default value.
+
+```{eval-sh}
+./scripts/generate_config_md.py | ./scripts/extract_markdown.py --input-stdin --heading-level 1
+```