3 Ways Referencing Azure Key Vault from Azure Functions

01-kv-reference-1.txt

@Microsoft.KeyVault(SecretUri=https://<key-vault-name>.vault.azure.net/secrets/<secret-name>/<secret-version>)

02-kv-reference-2.txt

@Microsoft.KeyVault(VaultName=<key-vault-name>; SecretName=<secret-name>; SecretVersion=<secret-version>)

03-kv-reference-3.txt

@Microsoft.KeyVault(SecretUri=https://<key-vault-name>.vault.azure.net/secrets/<secret-name>/)

04-appsettings-handler-1.cs

public class AppSettingsHandler
{
    private static Regex regexSecretUri = new Regex(@"\@Microsoft\.KeyVault\(SecretUri\=(.*)\)", RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace);
    private static Regex regexVaultName = new Regex(@"\@Microsoft\.KeyVault\(VaultName\=(.*);\s*SecretName\=(.*);\s*SecretVersion\=(.*)\)", RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace);

    ...
}

05-appsettings-handler-2.cs

public class AppSettingsHandler
{
    ...

    public async Task<string> GetValueAsync(string key)
    {
        var reference = Environment.GetEnvironmentVariable(key);
        if (!this.IsKeyVaultReference(reference))
        {
            return reference;
        }

        ...
    }

    private bool IsKeyVaultReference(string value)
    {
        return value.StartsWith("@Microsoft.KeyVault(");
    }
}

06-appsettings-handler-3.cs

public class AppSettingsHandler
{
    ...

    public async Task<string> GetValueAsync(string key)
    {
        ...

        var bundle = default(SecretBundle);
        var match = regexSecretUri.Match(reference);
        if (match.Success)
        {
            var uri = match.Groups[1].Value;
            bundle = await this._kv.GetSecretAsync(uri).ConfigureAwait(false);

            return bundle.Value;
        }

        ...
    }
}

07-appsettings-handler-4.cs

public class AppSettingsHandler
{
    ...

    public async Task<string> GetValueAsync(string key)
    {
        ...

        match = regexVaultName.Match(reference);
        if (match.Success)
        {
            var vaultName = match.Groups[1].Value;
            var secretName = match.Groups[2].Value;
            var secretVersion = match.Groups[3].Value;
            bundle = await this._kv.GetSecretAsync($"https://{vaultName}.vault.azure.net", secretName, secretVersion).ConfigureAwait(false);

            return bundle.Value;
        }

        ...
    }
}

08-appsettings-handler-5.cs

public class AppSettingsHandler
{
    ...

    public async Task<string> GetValueAsync(string key)
    {
        ...

        return null;
    }
}