Azure KeyVault ConfigBuilder

This package provides a config builder that draws its values from an Azure Key Vault. The builder uses DefaultAzureCredential for connecting with the Key Vault service. More comprehensive documentation exists at the MicrosoftConfigBuilders project.

The basic usage of this builder is given below. Parameters inside []s are optional. Parameters grouped in ()s are mutually exclusive. Parameters beginning with @ allow appSettings substitution. The first line of parameters are common to all builders and optional. Their meaning, usage, and defaults are documented here. They are grouped on one line for brevity. When a builder uses a different default value than the project default, the differing value is also listed. Builder-specific settings are listed on each line thereafter followed by a brief explanation.

<add name="AzureKeyVault" [@mode|@enabled="enabled"|@charMap=":=-,_=-,.=-,+=-,\=-"|@prefix|@stripPrefix|tokenPattern|@escapeExpandedValues] (@vaultName="MyVaultName" | @uri="https://MyVaultName.vault.azure.net") [@version="secrets version"] [@preloadSecretNames="true"] type="Microsoft.Configuration.ConfigurationBuilders.AzureKeyVaultConfigBuilder, Microsoft.Configuration.ConfigurationBuilders.Azure" />

• vaultName - This (or uri) is a required attribute. It specifies the name of the vault in your Azure subscription from which to read key/value pairs.
• uri - Connect to non-Azure Key Vault providers with this attribute. If not specified, Azure is the assumed Vault provider. If the uri is specified, then vaultName is no longer a required parameter.
• version - Azure Key Vault provides a versioning feature for secrets. If this is specified, the builder will only retrieve secrets matching this version.
• preloadSecretNames - By default, this builder will query all the key names in the key vault when it is initialized to improve performance. If this is a concern, set this attribute to 'false', and secrets will be retrieved one at a time. This could also be useful if the vault allows "Get" access but not "List" access. (NOTE: Disabling preload is incompatible with Greedy mode.)

Tip: To use versioned secrets, it is not recommended to use the version attribute on the builder. Rather, include the version in the key-name and this builder will know what to do. For example:

<appSettings configBuilders="AzureKeyVault"> <add key="item1" value="Replaced with latest value from the key vault." /> <add key="item2/0123456789abcdefdeadbeefbadf00d" value="Replaced with specific version only, and resulting key is simply 'item2'." /> </appSettings>

V3 Updates:

A more complete list of updates lives here. These are the ones most relevant to this builder:

• :warning: Breaking Change - Expand mode is gone. It has been replaced by Token mode.
• The Azure Config Builders have been updated to require a newer minimum version of Azure.Identity by default which allows for more methods of connecting to Azure, such as User-Assigned Managed Identity, or Client Certificate-based via environment variables. Also a pair of overloads (GetCredential and GetSecretClientOptions/GetConfigurationClientOptions) have been added for users who need something more than DefaultAzureCredential with default client options can provide.
• optional attribute is obsolete => enabled attribute which provides more versatility. (The optional attribute is still parsed and recognized in the absence of the newer enabled attribute, but builders should migrate to use the new attribute name when possible. Installation scripts should try to handle this automatically.)

V2 Updates:

A more complete list of updates lives here. These are the ones most relevant to this builder:

• ConfigBuilder Parameters from AppSettings - This has been one of the most asked for features of these config builders. With V2, it is now possible to read initialization parameters for config builders from appSettings. Read more about it here.
• Updateable Keys - Builders can now massage key names before inserting into config. The AzureKeyVaultConfigBuilder has been updated to use this feature to allow embedding 'version' tags in key names instead of applying a single 'version' tag to the builder. (Note: This is seperate from, and performed after prefix stripping.)
• [[Obsolete]] This has been superceded by the enabled tag. (Base Optional Tag - The optional tag that some of the builders in this project employed in V1 has been moved into the base class and is now available on all key/value config builders.)