I am looking for a way to use IOptionsMonitor in C# to get and listen for configuration changes, where my configuration is stored in memory. Currently, I understand that IOptionsMonitor is typically used for reading configuration from the file system or environment variables and notifying the application when changes occur. However, my requirement is to dynamically update the configuration during runtime and have IOptionsMonitor be aware of these in-memory changes.
Is there a way to set a custom configuration source to memory and have IOptionsMonitor monitor these in-memory configuration changes? If so, could you provide a simple example or guide me on how to implement this functionality?
Thank you very much!
I have taken the example from Microsoft documentation and modified it to use a MemoryStream . After the configuration is read, I release the stream. It seems unlikely that a closed stream would be able to continue monitoring for changes. I directly modify the IConfiguration ,nothing happens.
<code>HostApplicationBuilder builder = Host.CreateApplicationBuilder(args);
using (MemoryStream memoryStream = new MemoryStream())
using (StreamWriter writer = new StreamWriter(memoryStream))
"SecretKey": "Secret key value",
"TransientFaultHandlingOptions": {
"AutoRetryDelay": "00:00:07"
"Default": "Information",
"Microsoft.Hosting.Lifetime": "Information"
memoryStream.Position = 0;
builder.Configuration.AddJsonStream(writer.BaseStream);
string className = nameof(TransientFaultHandlingOptions);
builder.Services.Configure<TransientFaultHandlingOptions>(builder.Configuration.GetSection(className));
builder.Services.AddSingleton<MonitorService>();
using IHost host = builder.Build();
IConfiguration? con = host.Services.GetRequiredService<IConfiguration>();
var rs = con.GetRequiredSection(className);
MonitorService Monitor = host.Services.GetRequiredService<MonitorService>();
rs["AutoRetryDelay"] = "01:23:45";
rs["AutoRetryDelay"] = "01:02:03";
rs["AutoRetryDelay"] = "66:55:44";
public sealed class MonitorService(IOptionsMonitor<TransientFaultHandlingOptions> monitor)
public void DisplayValues()
TransientFaultHandlingOptions options = monitor.CurrentValue;
monitor.OnChange(Change);
Console.WriteLine($"TransientFaultHandlingOptions.Enabled={options.Enabled}");
Console.WriteLine($"TransientFaultHandlingOptions.AutoRetryDelay={options.AutoRetryDelay}");
static void Change(TransientFaultHandlingOptions options)
Console.WriteLine($"FromChange : TransientFaultHandlingOptions.Enabled={options.Enabled}");
Console.WriteLine($"FromChange : TransientFaultHandlingOptions.AutoRetryDelay={options.AutoRetryDelay}");
public sealed class TransientFaultHandlingOptions
public bool Enabled { get; set; }
public TimeSpan AutoRetryDelay { get; set; }
<code>HostApplicationBuilder builder = Host.CreateApplicationBuilder(args);
using (MemoryStream memoryStream = new MemoryStream())
using (StreamWriter writer = new StreamWriter(memoryStream))
{
string json = """
{
"SecretKey": "Secret key value",
"TransientFaultHandlingOptions": {
"Enabled": true,
"AutoRetryDelay": "00:00:07"
},
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Information"
}
}
}
""";
writer.Write(json);
writer.Flush();
memoryStream.Position = 0;
builder.Configuration.AddJsonStream(writer.BaseStream);
}
string className = nameof(TransientFaultHandlingOptions);
builder.Services.Configure<TransientFaultHandlingOptions>(builder.Configuration.GetSection(className));
builder.Services.AddSingleton<MonitorService>();
using IHost host = builder.Build();
IConfiguration? con = host.Services.GetRequiredService<IConfiguration>();
var rs = con.GetRequiredSection(className);
MonitorService Monitor = host.Services.GetRequiredService<MonitorService>();
Monitor.DisplayValues();
rs["AutoRetryDelay"] = "01:23:45";
rs["AutoRetryDelay"] = "01:02:03";
rs["AutoRetryDelay"] = "66:55:44";
public sealed class MonitorService(IOptionsMonitor<TransientFaultHandlingOptions> monitor)
{
public void DisplayValues()
{
TransientFaultHandlingOptions options = monitor.CurrentValue;
monitor.OnChange(Change);
Console.WriteLine($"TransientFaultHandlingOptions.Enabled={options.Enabled}");
Console.WriteLine($"TransientFaultHandlingOptions.AutoRetryDelay={options.AutoRetryDelay}");
}
static void Change(TransientFaultHandlingOptions options)
{
Console.WriteLine($"FromChange : TransientFaultHandlingOptions.Enabled={options.Enabled}");
Console.WriteLine($"FromChange : TransientFaultHandlingOptions.AutoRetryDelay={options.AutoRetryDelay}");
}
}
public sealed class TransientFaultHandlingOptions
{
public bool Enabled { get; set; }
public TimeSpan AutoRetryDelay { get; set; }
}
</code>
HostApplicationBuilder builder = Host.CreateApplicationBuilder(args);
using (MemoryStream memoryStream = new MemoryStream())
using (StreamWriter writer = new StreamWriter(memoryStream))
{
string json = """
{
"SecretKey": "Secret key value",
"TransientFaultHandlingOptions": {
"Enabled": true,
"AutoRetryDelay": "00:00:07"
},
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Information"
}
}
}
""";
writer.Write(json);
writer.Flush();
memoryStream.Position = 0;
builder.Configuration.AddJsonStream(writer.BaseStream);
}
string className = nameof(TransientFaultHandlingOptions);
builder.Services.Configure<TransientFaultHandlingOptions>(builder.Configuration.GetSection(className));
builder.Services.AddSingleton<MonitorService>();
using IHost host = builder.Build();
IConfiguration? con = host.Services.GetRequiredService<IConfiguration>();
var rs = con.GetRequiredSection(className);
MonitorService Monitor = host.Services.GetRequiredService<MonitorService>();
Monitor.DisplayValues();
rs["AutoRetryDelay"] = "01:23:45";
rs["AutoRetryDelay"] = "01:02:03";
rs["AutoRetryDelay"] = "66:55:44";
public sealed class MonitorService(IOptionsMonitor<TransientFaultHandlingOptions> monitor)
{
public void DisplayValues()
{
TransientFaultHandlingOptions options = monitor.CurrentValue;
monitor.OnChange(Change);
Console.WriteLine($"TransientFaultHandlingOptions.Enabled={options.Enabled}");
Console.WriteLine($"TransientFaultHandlingOptions.AutoRetryDelay={options.AutoRetryDelay}");
}
static void Change(TransientFaultHandlingOptions options)
{
Console.WriteLine($"FromChange : TransientFaultHandlingOptions.Enabled={options.Enabled}");
Console.WriteLine($"FromChange : TransientFaultHandlingOptions.AutoRetryDelay={options.AutoRetryDelay}");
}
}
public sealed class TransientFaultHandlingOptions
{
public bool Enabled { get; set; }
public TimeSpan AutoRetryDelay { get; set; }
}