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Runtime Configuration Files
The runtime configuration files store the dependencies of an application (formerly stored in the .deps file). They also include runtime configuration options, such as the Garbage Collector mode. Optionally they can also include data for runtime compilation (compilation settings used to compile the original application, and reference assemblies used by the application).
Note: This document doesn't provide full explanations as to why individual items are needed in this file. That is covered in the host spec and via the Microsoft.Extensions.DependencyModel assembly.
What produces the files and where are they?
There are two runtime configuration files for a particular application. Given a project named MyApp, the compilation process produces the following files (on Windows, other platforms are similar):
MyApp.dll- The managed assembly forMyApp, including an ECMA-compliant entry point token.MyApp.exe- A copy of theapphost.exeexecutable. This is present when the application is self-contained, and in newer functionality (2.1.0+) for framework-dependent applications that wish to support platform-specific (non-portable) executables.MyApp.runtimeconfig.json- An optional configuration file containing runtime configuration settings. This file is required for framework-dependent applications, but not for self-contained apps.MyApp.runtimeconfig.dev.json- An optional configuration file containing runtime configuration settings that typically only exists in a non-published output and thus is used for development-time scenarios. This file typically specifies additional probing paths. Depending on the semantics of each setting, the setting is either combined with or overridden by the values fromMyApp.runtimeconfig.json.MyApp.deps.json- A list of dependencies, compilation dependencies and version information used to address assembly conflicts. Not technically required, but required to use the servicing or package cache/shared package install features, and to assist during roll-forward scenarios to select the newest version of any assembly that exists more than once in the application and framework(s). If the file is not present, all assemblies in the current folder are used instead.
The MyApp.runtimeconfig.json is designed to be user-editable (in the case of an app consumer wanting to change various CLR runtime options for an app, much like the MyApp.exe.config XML file works in .NET 4.x today). However, the MyApp.deps.json file is designed to be processed by automated tools and should not be user-edited. Having the files as separate makes this clearer. We could use a different format for the deps file, but if we're already integrating a JSON parser into the host, it seems most appropriate to re-use that here. Also, there are diagnostic benefits to being able to read the .deps.json file in a simple text editor.
IMPORTANT: Framework-dependent applications have some adjustments to this spec which are covered at the end.
File format
The files are both JSON files stored in UTF-8 encoding. Below are sample files. Note that not all sections are required and some will be opt-in only (see below for more details). The .runtimeconfig.json file is completely optional, and in the .deps.json file, only the runtimeTarget, targets and libraries sections are required (and within the targets section, only the runtime-specific target is required). If no .deps.json exists, all assemblies local to the app will be added as TPA (trusted platform assemblies).
[appname].runtimeconfig.json
{
"runtimeOptions": {
"configProperties": {
"System.GC.Server": true,
"System.GC.Concurrent": true,
"System.Threading.ThreadPool.MinThreads": 4,
"System.Threading.ThreadPool.MaxThreads": 8
},
"framework": {
"name": "Microsoft.NETCore.App",
"version": "2.1.0"
},
"applyPatches": true,
"rollForwardOnNoCandidateFx": 1
}
}
[appname].deps.json
{
"runtimeTarget": {
"name": ".NETCoreApp,Version=v2.0",
"signature": "aafc507050a6c13a0cf2d6d4c3de136e6571da6e"
},
"compilationOptions": {
"defines": [
"TRACE",
"DEBUG"
],
"languageVersion": "",
"platform": "",
"warningsAsErrors": false,
},
"targets": {
".NETCoreApp,Version=v2.0": {
"MyApp/1.0.0": {
"dependencies": {
"System.Banana": "1.0.0"
},
"runtime": {
"MyApp.dll": {}
}
},
"System.Banana/1.0.0": {
"dependencies": {
"System.Foo": "1.0.0"
},
"runtime": {
"lib/netcoreapp2.0/System.Banana.dll": {
"assemblyVersion": "1.0.0.0",
"fileVersion": "1.0.0.0"
}
}
},
"System.Foo/1.0.0": {
"runtime": {
"lib/netcoreapp2.0/System.Foo.dll": {
"assemblyVersion": "1.0.0.0",
"fileVersion": "1.0.0.0"
}
}
}
}
},
"libraries": {
"MyApp/1.0.0": {
"type": "project",
"serviceable": false,
"sha512": ""
},
"System.Banana/1.0.0": {
"type": "package",
"serviceable": true,
"sha512": "sha512-C63ok7q+Fi6O6I/WB4ut3hFibGSraUlE461LxhhwNk5Vcdl4ijDhX1QDupDdp3Cxr7TgwB55Sd4zNtlwT7ksAA==",
"path": "system.banana/1.0.0",
"hashPath": "system.banana.1.0.0.nupkg.sha512"
},
"System.Foo/1.0.0": {
"type": "package",
"serviceable": true,
"sha512": "sha512-avYGOiBQ4U/fJfzEDF7lzPLhk/w6P9/28y0iiQh3AxlWOheuZTgXA/pzuORuAu/s5B2bXHO2BlvQKZN0PfQ2HQ==",
"path": "system.foo/1.0.0",
"hashPath": "system.foo.1.0.0.nupkg.sha512"
}
}
}
Sections
runtimeOptions Section (.runtimeconfig.json)
This section is created when building a project. Settings include:
configProperties- Indicates configuration properties to configure the runtime and the framework- Examples:
- Full list of configuration properties for CoreCLR.
System.GC.Server(old:gcServer) - Boolean indicating if the server GC should be used (Default:true).System.GC.Concurrent(old:gcConcurrent) - Boolean indicating if background garbage collection should be used.
- Examples:
framework- Indicates thename,version, and other properties of the shared framework to use when activating the application includingapplyPathesandrollForwardOnNoCandidateFx. The presence of this section indicates that the application is a framework-dependent app.applyPatches- Whenfalse, the framework version is strictly obeyed by the host. WhenapplyPatchesis unspecified ortrue, the framework from either the same or a higher version that differs only by the patch field will be used.- For example, if
version=1.0.1andapplyPatchesistrue, the host would load the shared framework from1.0.{n}, wheren >= 1, but will not load from1.1.0, even if present. WhenapplyPatchesisfalse, the shared framework will be loaded from1.0.1strictly. - Note: This does not apply to
pre-releaseversions; it applies only toproductionreleases. - Note: This section should not exist self-contained applications because they do not rely upon a shared framework.
- For example, if
rollForwardOnNoCandidateFx- Determines roll-forward behavior of major and minor. Only applies toproductionreleases. Values: 0(Off), 1 (roll forward on [minor]), 2 (Roll forward on [major] and [minor]) See roll-forward-on-no-candidate documentation for more information.
These settings are read by host (apphost or dotnet executable) to determine how to initialize the runtime. All versions of the host must ignore settings in this section that they do not understand (thus allowing new settings to be added in later versions).
compilationOptions Section (.deps.json)
This section is created during build from the project's settings. The exact settings found here are specific to the compiler that produced the original application binary. Some example settings include: defines, languageVersion (e.g. the version of C# or VB), allowUnsafe (a C# option), etc.
runtimeTarget Section (.deps.json)
This property contains the name of the target from targets that should be used by the runtime. This is present to simplify the host so that it does not have to parse or understand target names and the meaning thereof.
targets Section (.deps.json)
This section contains subsetted data from the input project.lock.json.
Each property under targets describes a "target", which is a collection of libraries required by the application when run or compiled in a certain framework and platform context. A target must specify a Framework name, and may specify a Runtime Identifier. Targets without Runtime Identifiers represent the dependencies and assets used for compiling the application for a particular framework. Targets with Runtime Identifiers represent the dependencies and assets used for running the application under a particular framework and on the platform defined by the Runtime Identifier. In the example above, the .NETStandardApp,Version=v1.5 target lists the dependencies and assets used to compile the application for dnxcore50, and the .NETStandardApp,Version=v1.5/osx.10.10-x64 target lists the dependencies and assets used to run the application on dnxcore50 on a 64-bit Mac OS X 10.10 machine.
There will always be two targets in the [appname].runtimeconfig.json file: A compilation target, and a runtime target. The compilation target will be named with the framework name used for the compilation (.NETStandardApp,Version=v1.5 in the example above). The runtime target will be named with the framework name and runtime identifier used to execute the application (.NETStandardApp,Version=v1.5/osx.10.10-x64 in the example above). However, the runtime target will also be identified by name in the runtimeOptions section, so that the host does not need to parse and understand target names.
The content of each target property in the JSON is a JSON object. Each property of that JSON object represents a single dependency required by the application when compiled for/run on that target. The name of the property contains the ID and Version of the dependency in the form [Id]/[Version]. The content of the property is another JSON object containing metadata about the dependency.
The dependencies property of a dependency object defines the ID and Version of direct dependencies of this node. It is a JSON object where the property names are the ID of the dependency and the content of each property is the Version of the dependency.
The runtime property of a dependency object lists the relative paths to Managed Assemblies required to be available at runtime in order to satisfy this dependency. The paths are relative to the location of the Dependency (see below for further details on locating a dependency).
The resources property of a dependency object lists the relative paths and locales of Managed Satellite Assemblies which provide resources for other languages. Each item contains a locale property specifying the IETF Language Tag for the satellite assembly (or more specifically, a value usable in the Culture field for a CLR Assembly Name).
The native property of a dependency object lists the relative paths to Native Libraries required to be available at runtime in order to satisfy this dependency. The paths are relative to the location of the Dependency (see below for further details on locating a dependency).
In compilation targets, the runtime, resources and native properties of a dependency are omitted, because they are not relevant to compilation. Similarly, in runtime targets, the compile property is omitted, because it is not relevant to runtime.
Only dependencies with a type value of package should be considered by the host. There may be other items, used for other purposes (for example, Projects, Reference Assemblies, etc.
libraries Section (.deps.json)
This section contains a union of all the dependencies found in the various targets, and contains common metadata for them. Specifically, it contains the type, as well as a boolean indicating if the library can be serviced (serviceable, only for package-typed libraries) and a SHA-512 hash of the package file (sha512, only for package-typed libraries.
How the file is used
The file is read by two different components:
- The host uses it to determine what to place on the TPA and Native Library Search Path lists, as well as what runtime settings to apply (GC type, etc.). See the host spec.
Microsoft.Extensions.DependencyModeluses it to allow a running managed application to query various data about it's dependencies. For example:- To find all dependencies that depend on a particular package (used by ASP.NET MVC and other plugin-based systems to identify assemblies that should be searched for possible plugin implementations)
- To determine the reference assemblies used by the application when it was compiled in order to allow runtime compilation to use the same reference assemblies (used by ASP.NET Razor to compile views)
- To determine the compilation settings used by the application in order to allow runtime compilation to use the same settings (also used by ASP.NET Razor views).
Opt-In Compilation Data
Some of the sections in the .deps.json file contain data used for runtime compilation. This data is not provided in the file by default. Instead, a project.json setting preserveCompilationContext must be set to true in order to ensure this data is added. Without this setting, the compilationOptions will not be present in the file, and the targets section will contain only the runtime target.
Framework-dependent Deployment Model
An application can be deployed in a "framework-dependent" deployment model. In this case, the RID-specific assets of packages are published within a folder structure that preserves the RID metadata. However the host does not use this folder structure, rather it reads data from the .deps.json file. Also, during deployment, the .exe file (apphost.exe renamed) is not deployed by default.
In the framework-dependent deployment model, the *.runtimeConfig.json file will contain the runtimeOptions.framework section:
{
"runtimeOptions": {
"framework": {
"name": "Microsoft.NETCore.App",
"version": "1.0.1"
}
}
}
This data is used to locate the shared framework folder. The exact mechanics of which version are selected are defined elsewhere, but in general, it locates the shared runtime in the shared folder located beside it by using the relative path shared/[runtimeOptions.framework.name]/[runtimeOptions.framework.version]. Once it has applied any version roll-forward logic and come to a final path to the shared framework, it locates the [runtimeOptions.framework.name].deps.json file within that folder and loads it first.
Next, the deps file from the application is loaded and merged into this deps file (this is conceptual, the host implementation doesn't necessary have to directly merge the data ;)). Data from the app-local deps file trumps data from the shared framework.
The shared framework's deps file will also contain a runtimes section defining the fallback logic for all RIDs known to that shared framework. For example, a shared framework deps file installed into a Ubuntu machine may look something like the following:
{
"runtimeTarget": {
"name": ".NETStandardApp,Version=v1.5",
"portable": false
},
"targets": {
".NETStandardApp,Version=v1.5": {
"System.Runtime/4.0.0": {
"runtime": "lib/netstandard1.5/System.Runtime.dll"
},
"... other libraries ...": {}
}
},
"libraries": {
"System.Runtime/4.0.0": {
"type": "package",
"serviceable": true,
"sha512": "[base64 string]"
},
"... other libraries ...": {}
},
"runtimes": {
"ubuntu.15.04-x64": [ "ubuntu.14.10-x64", "ubuntu.14.04-x64", "debian.8-x64", "linux-x64", "linux", "unix", "any", "base" ],
"ubuntu.14.10-x64": [ "ubuntu.14.04-x64", "debian.8-x64", "linux-x64", "linux", "unix", "any", "base" ],
"ubuntu.14.04-x64": [ "debian.8-x64", "linux-x64", "linux", "unix", "any", "base" ]
}
}
The host will detect the RID at runtime (for example, win10-x64 for Windows 64-bit). It will look up the corresponding entry in the runtimes section to identify what the fallback list is for win10-x64. The fallbacks are identified from most-specific to least-specific. In the case of win10-x64 and the example above, the fallback list is: "win10-x64", "win10", "win81-x64", "win81", "win8-x64", "win8", "win7-x64", "win7", "win-x64", "win", "any", "base" (note that an exact match on the RID itself is the first preference, followed by the first item in the fallback list, then the next item, and so on).
In the app-local deps file for a framework-dependent application, the package entries may have an additional runtimeTargets section detailing RID-specific assets. The host should use this data, along with the current RID and the RID fallback data defined in the runtimes section of the shared framework deps file to select one and only one RID value out of each package individually. The most specific RID present within the package should always be selected.
Consider an application built for ubuntu.14.04-x64 and the following snippet from an app-local deps file (some sections removed for brevity).
{
"targets": {
".NETStandardApp,Version=v1.5": {
"System.Data.SqlClient/4.0.0": {
"compile": {
"ref/netstandard1.5/System.Data.SqlClient.dll": {}
},
"runtimeTargets": {
"runtimes/unix/lib/netstandard1.5/System.Data.SqlClient.dll": {
"assetType": "runtime",
"rid": "unix"
},
"runtimes/win7-x64/lib/netstandard1.5/System.Data.SqlClient.dll": {
"assetType": "runtime",
"rid": "win7-x64"
},
"runtimes/win7-x86/lib/netstandard1.5/System.Data.SqlClient.dll": {
"assetType": "runtime",
"rid": "win7-x86"
},
"runtimes/win7-x64/native/sni.dll": {
"assetType": "native",
"rid": "win7-x64"
},
"runtimes/win7-x86/native/sni.dll": {
"assetType": "native",
"rid": "win7-x86"
}
}
}
}
}
}
When setting up the TPA and native library lists, it will do the following for the System.Data.SqlClient entry in the example above:
- Add all entries from the root
runtimeandnativesections (not present in the example). (Note: This is essentially the current behavior for the existing deps file format) - Add all appropriate entries from the
runtimeTargetssection, based on theridproperty of each item: - Attempt to locate any item for the RID
ubuntu.14.04-x64. If any asset is matched, take only the items matching that RID exactly and add them to the appropriate lists based on theassetTypevalue (runtimefor managed code,nativefor native code) - Reattempt the previous step using the first RID in the list provided by the list in the
runtimes."ubuntu.14.04-x64"section of the shared framework deps file. If any asset is matched, take only the items matching that RID exactly and add them to the appropriate lists - Continue to reattempt the previous search for each RID in the list, from left to right until a match is found or the list is exhausted. Exhausting the list without finding an asset, when a
runtimeTargetssection is present is not an error, it simply indicates that there is no need for a runtime-specific asset for that package.
Note one important aspect about asset resolution: The resolution scope is per-package, not per-application, nor per-asset. For each individual package, the most appropriate RID is selected, and all assets taken from that package must match the selected RID exactly. For example, if a package provides both a linux-x64 and a unix RID (in the ubuntu.14.04-x64 example above), only the linux-x64 asset would be selected for that package. However, if a different package provides only a unix RID, then the asset from the unix RID would be selected.
The path to a runtime-specific asset is resolved in the same way as a normal asset (first check Servicing, then Package Cache, App-Local, Global Packages Location, etc.) with one exception. When searching app-local, rather than just looking for the simple file name in the app-local directory, a runtime-specific asset is expected to be located in a subdirectory matching the relative path information for that asset in the lock file. So the native sni.dll asset for win7-x64 in the System.Data.SqlClient example above would be located at APPROOT/runtimes/win7-x64/native/sni.dll, rather than the normal app-local path of APPROOT/sni.dll.
Opt-In [appname].runtimeconfig.json Explicit Overrides for Framework Settings
In order to address potential issues with compatibility, an application can override a framework's runtimeconfig.json settings. This should only be done with the understanding that any settings specified here have unintended consequences and may prevent future upgrade \ roll-forward compatibility. The settings include version, rollForwardOnNoCandidateFx and applyPatches.
As an example, assume the following framework layering:
- Application
- Microsoft.AspNetCore.All
- Microsoft.AspNetCore.App
- Microsoft.NetCore.App
Except for Microsoft.NetCore.App (since it does not have a lower-level framework), each layer has a runtimeconfig.json setting specifying a single lower-layer framework's name, version and optional rollForwardOnNoCandidateFx and applyPatches.
The normal hierarchy processing for most knobs, such as rollForwardOnNoCandidateFx:
- a) Default value determined by the framework (e.g. roll-forward on [Minor])
- b) Environment variable override (e.g.
DOTNET_ROLL_FORWARD_ON_NO_CANDIDATE_FX) - c) Each layer's
runtimeOptionsoverride setting in its runtimeconfig.json, starting with app (e.g.rollForwardOnNoCandidateFx). Lower layers can override this. - d) The app's
additionalFrameworksoverride section in[appname].runtimeconfig.jsonwhich specifies knobs per-framework. - e) A
--command line value such as--roll-forward-on-no-candidate-fx
In a hypothetical example, Microsoft.AspNetCore.App turns on the ability via mechanism c above to roll-forward Microsoft.NetCore.App on [major] releases by specifying rollForwardOnNoCandidateFx = 2 in its runtimeconfig.json. For example:
{
"runtimeOptions": {
"framework": {
"name": "Microsoft.NetCore.App",
"version": "2.2.0"
},
"rollForwardOnNoCandidateFx": "2"
}
}
However, if that behavior is not wanted by the app, the app has the option of overriding. This cannot be done by the same mechanism c because the app's runtimeconfig settings would be overridden by the sample above since the sample is in a lower layer. Thus to override the setting, mechanism d is used. An example of the additionalFrameworks section for mechanism d:
{
"runtimeOptions": {
"framework": {
"name": "Microsoft.AspNetCore.All",
"version": "1.0.1"
},
"additionalFrameworks": [
{
"name": "Microsoft.AspNetCore.App",
"rollForwardOnNoCandidateFx": "1",
}
]
}
}