Asp application configuration file

When you do this, the settings in the Web. You can create a Web. You must create a text file that is named Web. NET application. The Web. At a minimum, the Web. These elements will contain individual configuration elements.

The first line of the Web. This first line must be the same for all. By themselves, these lines do nothing. However, the lines provide a structure that permits you to add future configuration settings. You add the majority of the ASP. These lines mark the beginning and the end of the ASP.

NET configuration settings. The : separator doesn't work with environment variable hierarchical keys on all platforms. The following setx commands can be used to set the environment keys and values on Windows.

Unlike set , setx settings are persisted. To test that the preceding commands override appsettings. Call AddEnvironmentVariables with a string to specify a prefix for environment variables:. NET Core for host and app configuration , but not for user configuration. For more information on host and app configuration, see. NET Generic Host. Azure App Service application settings are:. See Connection string prefixes for information on Azure database connection strings.

Environment variable names reflect the structure of an appsettings. Each element in the hierarchy is separated by a double underscore preferable or a colon. When the element structure includes an array, the array index should be treated as an additional element name in this path. Consider the following appsettings.

Environment variables set in launchSettings. For example, the ASP. NET Core web templates generate a launchSettings. On Linux, the value of URL environment variables must be escaped so systemd can parse it. Use the linux tool systemd-escape which yields httplocalhost The following code displays the environment variables and values on application startup, which can be helpful when debugging environment settings:.

Using the default configuration, the CommandLineConfigurationProvider loads configuration from command-line argument key-value pairs after the following configuration sources:. By default , configuration values set on the command-line override configuration values set with all the other configuration providers. Switch mappings allow key name replacement logic. Provide a dictionary of switch replacements to the AddCommandLine method.

When the switch mappings dictionary is used, the dictionary is checked for a key that matches the key provided by a command-line argument. If the command-line key is found in the dictionary, the dictionary value is passed back to set the key-value pair into the app's configuration. A switch mapping is required for any command-line key prefixed with a single dash -. For apps that use switch mappings, the call to CreateDefaultBuilder shouldn't pass arguments. The CreateDefaultBuilder method's AddCommandLine call doesn't include mapped switches, and there's no way to pass the switch-mapping dictionary to CreateDefaultBuilder.

The solution isn't to pass the arguments to CreateDefaultBuilder but instead to allow the ConfigurationBuilder method's AddCommandLine method to process both the arguments and the switch-mapping dictionary. Environment and command-line arguments can be set in Visual Studio from the launch profiles dialog:. The Configuration API reads hierarchical configuration data by flattening the hierarchical data with the use of a delimiter in the configuration keys.

The sample download contains the following appsettings. The following code from the sample download displays several of the configurations settings:. The preferred way to read hierarchical configuration data is using the options pattern.

For more information, see Bind hierarchical configuration data in this document. GetSection and GetChildren methods are available to isolate sections and children of a section in the configuration data. Configuration sources are read in the order that their configuration providers are specified.

Order configuration providers in code to suit the priorities for the underlying configuration sources that the app requires. A common practice is to add the Command-line configuration provider last in a series of providers to allow command-line arguments to override configuration set by the other providers.

The preceding sequence of providers is used in the default configuration. The Configuration API has special processing rules for four connection string environment variables. These connection strings are involved in configuring Azure connection strings for the app environment. Environment variables with the prefixes shown in the table are loaded into the app with the default configuration or when no prefix is supplied to AddEnvironmentVariables.

When an environment variable is discovered and loaded into configuration with any of the four prefixes shown in the table:. FileConfigurationProvider is the base class for loading configuration from the file system. The following configuration providers derive from FileConfigurationProvider :. The following code clears all the configuration providers and adds several configuration providers:. In the preceding code, settings in the MyIniConfig.

The sample download contains the following MyIniConfig. You typically don't want a custom JSON file overriding values set in the Environment variables configuration provider and the Command-line configuration provider.

Repeating elements that use the same element name work if the name attribute is used to distinguish the elements:. The key is the file name. The value contains the file's contents. The Key-per-file configuration provider is used in Docker hosting scenarios. To activate key-per-file configuration, call the AddKeyPerFile extension method on an instance of ConfigurationBuilder.

The directoryPath to the files must be an absolute path. Call ConfigureAppConfiguration when building the host to specify the app's configuration:. The MemoryConfigurationProvider uses an in-memory collection as configuration key-value pairs.

The following code from the sample download displays the preceding configurations settings:. In the preceding code, config. AddInMemoryCollection Dict is added after the default configuration providers. For an example of ordering the configuration providers, see JSON configuration provider.

See Bind an array for another example using MemoryConfigurationProvider. Kestrel specific endpoint configuration overrides all cross-server endpoint configurations.

Cross-server endpoint configurations include:. When the preceding highlighted markup is used in an ASP. NET Core web app and the app is launched on the command line with the following cross-server endpoint configuration:. Kestrel binds to the endpoint configured specifically for Kestrel in the appsettings.

In the preceding environment variable, Https is the name of the Kestrel specific endpoint. The preceding appsettings. By default , environment variables using the Environment Variables configuration provider are read after appsettings. In the preceding code, if NumberKey isn't found in the configuration, the default value of 99 is used. GetSection returns a configuration subsection with the specified subsection key. GetSection never returns null.

If a matching section isn't found, an empty IConfigurationSection is returned. When GetSection returns a matching section, Value isn't populated.

A Key and Path are returned when the section exists. The following code calls IConfiguration. GetChildren and returns values for section2:subsection0 :. The preceding code calls ConfigurationExtensions. Exists to verify the section exists:. The ConfigurationBinder. Bind supports binding arrays to objects using array indices in configuration keys.

Any array format that exposes a numeric key segment is capable of array binding to a POCO class array. Consider MyArray. In the preceding output, Index 3 has value value40 , corresponding to "4": "value40", in MyArray. The bound array indices are continuous and not bound to the configuration key index.

The configuration binder isn't capable of binding null values or creating null entries in bound objects. The sample app demonstrates how to create a basic configuration provider that reads configuration key-value pairs from a database using Entity Framework EF.

Define an EFConfigurationValue entity for storing configuration values in the database. Create a class that implements IConfigurationSource. Create the custom configuration provider by inheriting from ConfigurationProvider. The configuration provider initializes the database when it's empty. Since configuration keys are case-insensitive, the dictionary used to initialize the database is created with the case-insensitive comparer StringComparer.

In the following code, MyOptions is added to the service container with Configure and bound to configuration:. The following markup uses the inject Razor directive to resolve and display the options values:.

It uses a delegate to configure values for MyOptions :. In the preceding example, the values of Option1 and Option2 are specified in appsettings. Before the app is configured and started, a host is configured and launched. The host is responsible for app startup and lifetime management. Both the app and the host are configured using the configuration providers described in this topic.

Host configuration key-value pairs are also included in the app's configuration. For more information on how the configuration providers are used when the host is built and how configuration sources affect host configuration, see ASP. NET Core fundamentals. NET Core 2. This topic only pertains to app configuration.

Other aspects of running and hosting ASP. NET Core apps are configured using configuration files not covered in this topic:. For more information on migrating app configuration from earlier versions of ASP. An IHostingStartup implementation allows adding enhancements to an app at startup from an external assembly outside of the app's Startup class.

For more information, see Use hosting startup assemblies in ASP. You also have to configure the Nginx web server as a reverse proxy to route the requests to the back-end ASP. NET Core application from port The previous parts in this series showed how to configure Nginx as a reverse proxy and how to troubleshoot an HTTP proxy error. NET Core application wasn't running when Nginx tried to forward traffic to it.

The issue was resolved temporarily by running your ASP. NET Core application manually. But what if the application crashes? Or the server has to be restarted? Manually restarting the ASP. NET Core application every time isn't a practical solution. Therefore, in this section, you'll configure Linux to start your application after it crashes.

So far, you have configured Nginx and ASP. NET Core to work together. Nginx listens on port 80 and routes requests to the ASP. NET Core application that listens on port Although Nginx starts automatically, the ASP. NET Core application must be started manually every time that the server is restarted. Otherwise, the ASP.

NET Core application exits gracefully or crashes. If you run the ASP. NET Core process starts automatically. Another option is to run the ASP. NET Core as a service in Windows so that the auto-start feature can be configured as soon as the computer starts.

Recall that the systemctl command is used to manage the "services", or "daemons". A daemon is a similar concept to that of a Windows service.

Such a service can be restarted automatically when the system starts.