private void EnsureOptions(AzureAppConfigurationOptions azconfigOptions)
{
if (azconfigOptions == null)
{
throw new ArgumentNullException(nameof(azconfigOptions));
}
if (azconfigOptions.ConnectionString == null)
{
throw new InvalidOperationException("An Azure App Configuration connection string is required.");
}
OfflineFileCacheOptions options = _options ?? new OfflineFileCacheOptions();
if ((options.Key == null) || (options.SignKey == null) || (options.IV == null))
{
byte[] secret = Convert.FromBase64String(ConnectionStringParser.Parse(azconfigOptions.ConnectionString, "Secret"));
using (SHA256 sha256 = SHA256.Create())
{
byte[] hash = sha256.ComputeHash(secret);
options.Key = options.Key ?? hash;
options.SignKey = options.SignKey ?? hash;
options.IV = options.IV ?? hash.Take(16).ToArray();
}
}
if (string.IsNullOrEmpty(_scopeToken))
{
//
// The default scope token is the configuration store endpoint combined with all of the key-value filters
string endpoint = ConnectionStringParser.Parse(azconfigOptions.ConnectionString, "Endpoint");
if (string.IsNullOrWhiteSpace(endpoint))
{
throw new InvalidOperationException("Invalid connection string format.");
}
var sb = new StringBuilder($"{endpoint}\0");
foreach (var selector in azconfigOptions.KeyValueSelectors)
{
sb.Append($"{selector.KeyFilter}\0{selector.LabelFilter}\0");
}
_scopeToken = sb.ToString();
}
_options = options;
}
/// <summary>
/// A cache used for storing Azure App Configuration data using the file system.
/// Supports encryption of the stored data.
/// </summary>
/// <param name="options">
/// Options dictating the behavior of the offline cache.
/// If the options are null or the encryption keys are omitted, they will be derived from the store's connection string.
/// <see cref="OfflineFileCacheOptions.Path"/> is required unless the application is running inside of an Azure App Service instance, in which case it can be populated automatically.
/// </param>
public OfflineFileCache(OfflineFileCacheOptions options = null)
{
OfflineFileCacheOptions opts = options ?? new OfflineFileCacheOptions();
// If the user does not specify the cache path, we will try to use the default path
// For the moment, default path is only supported when running inside Azure App Service
if (opts.Path == null)
{
// Generate default cache file name under $home/data/azureAppConfigCache/app{instance}-{hash}.json
string homePath = Environment.GetEnvironmentVariable("HOME");
if (Directory.Exists(homePath))
{
string dataPath = Path.Combine(homePath, "data");
if (Directory.Exists(dataPath))
{
string cachePath = Path.Combine(dataPath, "azureAppConfigCache");
if (!Directory.Exists(cachePath))
{
Directory.CreateDirectory(cachePath);
}
string websiteName = Environment.GetEnvironmentVariable("WEBSITE_SITE_NAME");
if (websiteName != null)
{
byte[] hash = new byte[0];
using (var sha = SHA1.Create())
{
hash = sha.ComputeHash(Encoding.UTF8.GetBytes(websiteName));
}
// The instance count will help prevent multiple providers from overwriting each other's cache file
Interlocked.Increment(ref instance);
opts.Path = Path.Combine(cachePath, $"app{instance}-{BitConverter.ToString(hash).Replace("-", String.Empty)}.json");
}
}
}
if (opts.Path == null)
{
throw new ArgumentNullException($"{nameof(OfflineFileCacheOptions)}.{nameof(OfflineFileCacheOptions.Path)}", "Default cache path is only supported when running inside of an Azure App Service.");
}
}
ValidateCachePath(opts.Path);
_localCachePath = opts.Path;
_options = opts;
}