repos/Azure-azure-sdk-for-python-c89899b/sdk/appconfiguration/azure-appconfiguration-provider/README.md

# Azure App Configuration Python Provider client library for Python

Azure App Configuration is a managed service that helps developers centralize their application configurations simply and securely. This provider adds additional functionality above the azure-sdk-for-python.

Using the provider enables loading sets of configurations from an Azure App Configuration store in a managed way.

## Getting started

### Get credentials

Use the [Azure CLI][azure_cli] snippet below to get the connection string from the Configuration Store.

```Powershell
az appconfig credential list --name <config-store-name>
```

Alternatively, get the connection string from the Azure Portal.

### Creating a provider

You can create a client with a connection string:

```python
from azure.appconfiguration.provider import load

config = load(connection_string="your-connection-string")
```

or with AAD:

```python
from azure.appconfiguration.provider import load

config = load(endpoint="your-endpoint", credential=DefaultAzureCredential())
```

these providers will by default load all configurations with `(No Label)` from your configuration store into a dictionary of key/values.

### Features

Currently the Azure App Configuration Provider enables:

* Connecting to an App Configuration Store using a connection string or Azure Active Directory.
* Selecting multiple sets of configurations using `SettingSelector`.
* Loading Feature Flags
* Dynamic Refresh
* Trim prefixes off key names.
* Resolving Key Vault References, requires AAD.
* Secret Resolver, resolve Key Vault References locally without connecting to Key Vault.
* Json Content Type

#### Future Features

List of features we are going to add to the Python Provider in the future.

* Geo-Replication support
* Configuration Placeholders

## Examples

### Selecting configurations

You can refine or expand the configurations loaded from your store by using `SettingSelector`s. Setting selectors provide a way to pass a key filter and label filter into the provider.

```python
from azure.appconfiguration.provider import load, SettingSelector
from azure.identity import DefaultAzureCredential

selects = {SettingSelector(key_filter="*", label_filter="\0"), SettingSelector(key_filter="*", label_filter="dev")}
config = load(endpoint=endpoint, credential=DefaultAzureCredential(), selects=selects)
```

In this example all configuration with empty label and the dev label are loaded. Because the dev selector is listed last, any configurations from dev take priority over those with `(No Label)` when duplicates are found.

## Dynamic Refresh

The provider can be configured to refresh configurations from the store on a set interval. This is done by providing a `refresh_on` to the provider, which is a list of key(s) that will be watched for changes, and when they do change a refresh can happen. `refresh_interval` is the period of time in seconds between refreshes. `on_refresh_success` is a callback that will be called only if a change is detected and no error happens. `on_refresh_error` is a callback that will be called when a refresh fails.

```python
from azure.appconfiguration.provider import load, WatchKey
import os

connection_string = os.environ.get("APPCONFIGURATION_CONNECTION_STRING")

def my_callback_on_success():
    # Do something on success
    ...

def my_callback_on_fail(error):
    # Do something on fail
    ...

config = load(
    connection_string=connection_string,
    refresh_on=[WatchKey("Sentinel")],
    refresh_interval=60,
    on_refresh_success=my_callback_on_success,
    on_refresh_error=my_callback_on_fail,
    **kwargs,
)
```

In this example, the sentinel key will be checked for changes no sooner than every 60 seconds. In order to check for changes, the provider's `refresh` method needs to be called.

```python
config.refresh()
```

Once the provider is refreshed, the configurations can be accessed as normal. And if any changes have been made it will be updated with the latest values. If the `refresh_interval` hasn't passed since the last refresh check, the provider will not check for changes.

For additional info check out [Dynamic Refresh](https://learn.microsoft.com/azure/azure-app-configuration/enable-dynamic-configuration-python) on MS Learn.

### Trimming Keys

You can trim the prefix off of keys by providing a list of trimmed key prefixes to the provider. For example, if you have the key(s) like `/application/message` in your configuration store, you could trim `/application/` from them.

```python
from azure.appconfiguration.provider import load
from azure.identity import DefaultAzureCredential

trim_prefixes={"/application/"}
config = load(endpoint=endpoint, credential=DefaultAzureCredential(), trim_prefixes=trim_prefixes)
print(config["message"])
```

### Resolving Key Vault References

Key Vault References can be resolved by providing credentials to your key vault to the provider using `AzureAppConfigurationKeyVaultOptions`.

#### With Credentials

You can provide `AzureAppConfigurationKeyVaultOptions` with a credential and all key vault references will be resolved with it. The provider will attempt to connect to any key vault referenced with the credential provided.

```python
from azure.appconfiguration.provider import load, AzureAppConfigurationKeyVaultOptions
from azure.identity import DefaultAzureCredential

key_vault_options = AzureAppConfigurationKeyVaultOptions(credential=DefaultAzureCredential())
config = load(endpoint=endpoint, credential=DefaultAzureCredential(), key_vault_options=key_vault_options)
```

### With Clients

You can provide `AzureAppConfigurationKeyVaultOptions` with a list of `SecretClients`.

```python
from azure.appconfiguration.provider import load, AzureAppConfigurationKeyVaultOptions
from azure.identity import DefaultAzureCredential

key_vault_options = AzureAppConfigurationKeyVaultOptions(
    client_configs={key_vault_uri: {'credential': credential}})
config = load(endpoint=endpoint, credential=DefaultAzureCredential(), key_vault_options=key_vault_options)
```

### Secret Resolver

If no Credentials or Clients are provided a secret resolver can be used. Secret resolver provides a way to return any value you want to a key vault reference.

```python
from azure.appconfiguration.provider import load, AzureAppConfigurationKeyVaultOptions
from azure.identity import DefaultAzureCredential

def secret_resolver(uri):
    return "From Secret Resolver"

key_vault_options = AzureAppConfigurationKeyVaultOptions(
    secret_resolver=secret_resolver)
config = load(endpoint=endpoint, credential=DefaultAzureCredential(), key_vault_options=key_vault_options)
```

## Loading Feature Flags

Feature Flags can be loaded from config stores using the provider. Feature flags are loaded as a dictionary of key/value pairs stored in the provider under the `feature_management`, then `feature_flags`.

```python
config = load(endpoint=endpoint, credential=DefaultAzureCredential(), feature_flags_enabled=True)
alpha = config["feature_management"]["feature_flags"]["Alpha"]
print(alpha["enabled"])
```

By default all feature flags with no label are loaded when `feature_flags_enabled` is set to `True`. . If you want to load feature flags with a specific label you can use `SettingSelector` to filter the feature flags.

```python
from azure.appconfiguration.provider import load, SettingSelector

config = load(endpoint=endpoint, credential=DefaultAzureCredential(), feature_flags_enabled=True, feature_flag_selectors=[SettingSelector(key_filter="*", label_filter="dev")])
alpha = config["feature_management"]["feature_flags"]["Alpha"]
print(alpha["enabled"])
```

To enable refresh for feature flags you need to enable refresh. This will allow the provider to refresh feature flags the same way it refreshes configurations. Unlike configurations, all loaded feature flags are monitored for changes and will cause a refresh. Refresh of configuration settings and feature flags are independent of each other. Both are trigged by the `refresh` method, but a feature flag changing will not cause a refresh of configurations and vice versa. Also, if refresh for configuration settings is not enabled, feature flags can still be enabled for refresh.

```python
config = load(endpoint=endpoint, credential=DefaultAzureCredential(), feature_flags_enabled=True, feature_flag_refresh_enabled=True)

...

config.refresh()
```

## Key concepts

## Troubleshooting

## Next steps

Check out our Django and Flask examples to see how to use the provider in a web application.

### [Django](https://github.com/Azure/AppConfiguration/tree/main/examples/Python/python-django-webapp-sample)

### [Flask](https://github.com/Azure/AppConfiguration/tree/main/examples/Python/python-flask-webapp-sample)

## Contributing

This project welcomes contributions and suggestions. Most contributions require
you to agree to a Contributor License Agreement (CLA) declaring that you have
the right to, and actually do, grant us the rights to use your contribution.
For details, visit <https://cla.microsoft.com>.

When you submit a pull request, a CLA-bot will automatically determine whether
you need to provide a CLA and decorate the PR appropriately (e.g., label,
comment). Simply follow the instructions provided by the bot. You will only
need to do this once across all repos using our CLA.

This project has adopted the
[Microsoft Open Source Code of Conduct][code_of_conduct]. For more information,
see the Code of Conduct FAQ or contact <opencode@microsoft.com> with any
additional questions or comments.

[azure_cli]: https://learn.microsoft.com/cli/azure/appconfig
[code_of_conduct]: https://opensource.microsoft.com/codeofconduct/