Aspire provides two complementary sets of certificate APIs:
HTTPS endpoint APIs: Configure the certificates that resources use for their own HTTPS endpoints (server authentication)
Certificate trust APIs: Configure which certificates resources trust when making outbound HTTPS connections (client authentication)
Both sets of APIs work together to enable secure HTTPS communication during local development. For example, a Vite frontend might use WithHttpsDeveloperCertificate to serve HTTPS traffic, while also using WithDeveloperCertificateTrust to trust the dashboard’s OTLP endpoint certificate.
HTTPS is essential for protecting the security and privacy of data transmitted between services. It encrypts traffic to prevent eavesdropping, tampering, and man-in-the-middle attacks. For production environments, HTTPS is a fundamental security requirement.
However, enabling HTTPS during local development to match the production configuration presents unique challenges. Development environments typically use self-signed certificates that browsers and applications don’t trust by default. Managing these certificates across multiple services, containers, and different language runtimes can be complex and time-consuming, often creating friction in the development workflow.
Aspire simplifies HTTPS configuration for local development by providing APIs to:
Configure HTTPS endpoints with appropriate certificates for server authentication
Manage certificate trust so resources can communicate with services using self-signed certificates
Automatically handle the development certificate (a per-user self-signed certificate valid only for local domains) across different resource types
Many of the certificate features in Aspire rely on a development certificate. Before using these features, you need to ensure that a trusted development certificate is installed on your machine.
The preferred way to manage the development certificate is to use the Aspire CLI. When you run aspire run in an interactive session, the CLI automatically ensures the development certificate is created and trusted. No additional manual steps are required.
For non-C# AppHosts (such as TypeScript or Python AppHosts), the dotnet first-run experience that normally creates the HTTPS development certificate never runs, because these AppHosts launch a prebuilt native binary instead of invoking dotnet. The Aspire CLI fills this gap when aspire run starts and no development certificate exists:
In an interactive session—and on Linux, where establishing trust doesn’t require a prompt—the CLI creates and trusts the certificate, just as it does for C# AppHosts.
In a non-interactive session on macOS or Windows (for example, in CI), the CLI can’t show the macOS Keychain password prompt or the Windows trust dialog, so it generates the certificate without trusting it. This lets servers such as Kestrel load the certificate from the personal store, even though it isn’t trusted. If the certificate can’t be generated, a warning is displayed and the run continues.
To opt out of automatic certificate generation, set the ASPIRE_CLI_GENERATE_HTTPS_CERTIFICATE environment variable to false. This mirrors the .NET SDK’s DOTNET_GENERATE_ASPNET_CERTIFICATE opt-out:
By default, Aspire uses the ASP.NET Core developer certificate to secure communication with its internal Developer Control Plane (DCP) server. This replaces the ephemeral localhost certificate that DCP would otherwise generate itself, and avoids certificate trust errors caused by that certificate not being in the system trust store.
If no trusted developer certificate is found, Aspire automatically falls back to DCP’s ephemeral certificate.
To opt out and use DCP’s default ephemeral certificate instead, set ASPIRE_DCP_USE_DEVELOPER_CERTIFICATE to false in your AppHost’s launchSettings.json or as an environment variable:
HTTPS endpoint configuration determines which certificate a resource presents when serving HTTPS traffic. This is server-side certificate configuration for resources that host HTTPS/TLS endpoints.
For resources that have a certificate configuration defined with WithHttpsCertificateConfiguration, Aspire attempts to configure it to use the development certificate if available. This automatic configuration works for many common resource types including YARP, Redis, and Keycloak containers; Vite based JavaScript apps; and Python apps using Uvicorn.
You can control this behavior using the HTTPS endpoint APIs described below.
Indicates that a resource should use the developer certificate key pair for HTTPS endpoints at run time. Currently this indicates use of the ASP.NET Core developer certificate. The developer certificate will only be used when running in local development scenarios; in publish mode resources will use their default certificate configuration.
withHttpsDeveloperCertificate();
// Use developer certificate with an encrypted private key
Indicates that a resource should use the developer certificate key pair for HTTPS endpoints at run time. Currently this indicates use of the ASP.NET Core developer certificate. The developer certificate will only be used when running in local development scenarios; in publish mode resources will use their default certificate configuration.
For resources that need custom certificate configuration logic, use WithHttpsCertificateConfiguration to specify how certificate files should be passed to the resource:
Certificate trust configuration determines which certificates a resource trusts when making outbound HTTPS connections. This is client-side certificate configuration.
By default, Aspire attempts to add trust for the development certificate to resources that wouldn’t otherwise trust it. This enables resources to communicate with the dashboard OTLP collector endpoint over HTTPS and any other HTTPS endpoints secured by the development certificate.
You can control this behavior per resource using the WithDeveloperCertificateTrust API or through AppHost configuration settings.
Configure development certificate trust per resource
Indicates whether developer certificates should be treated as trusted certificate authorities for the resource at run time. Currently this indicates trust for the ASP.NET Core developer certificate. The developer certificate will only be trusted when running in local development scenarios; in publish mode resources will use their default certificate trust.
Indicates whether developer certificates should be treated as trusted certificate authorities for the resource at run time. Currently this indicates trust for the ASP.NET Core developer certificate. The developer certificate will only be trusted when running in local development scenarios; in publish mode resources will use their default certificate trust.
Certificate authority collections allow you to bundle custom certificates and make them available to resources. You create a collection using the AddCertificateAuthorityCollection method and then reference it from resources that need to trust those certificates.
var certBundle =builder.AddCertificateAuthorityCollection("my-bundle")
.WithCertificates(certificates);
// Apply the certificate bundle to resources
builder.AddNpmApp("my-project","../myapp")
.WithCertificateAuthorityCollection(certBundle);
builder.Build().Run();
In the preceding example, the certificate bundle is created with custom certificates and then applied to a Node.js application, enabling it to trust those certificates.
Certificate trust scopes control how custom certificates interact with a resource’s default trusted certificates. Different scopes provide flexibility in managing certificate trust based on your application’s requirements.
The WithCertificateTrustScope API accepts a CertificateTrustScope value to specify the trust behavior.
Attempts to append the configured certificates to the default trusted certificates for a given resource. This mode is useful when you want to add trust for additional certificates while maintaining trust for the system’s default certificates.
This is the default scope for most resources. For Python resources, only OTEL trust configuration will be applied in this mode.
Attempts to override a resource to only trust the configured certificates, replacing the default trusted certificates entirely. This mode is useful when you need strict control over which certificates are trusted.
AppHost.cs
var builder =DistributedApplication.CreateBuilder(args);
var certBundle =builder.AddCertificateAuthorityCollection("custom-certs")
Attempts to combine the configured certificates with the default system root certificates and use them to override the default trusted certificates for a resource. This mode is intended to support Python and similar runtimes that don’t work well with Append mode.
This is the default scope for Python projects because Python only has mechanisms to fully override certificate trust.
For advanced scenarios, you can specify custom certificate trust behavior using a callback API. This callback allows you to customize the command line arguments and environment variables required to configure certificate trust for different resource types.
The callback receives a CertificateTrustConfigurationCallbackAnnotationContext that provides:
Scope: The CertificateTrustScope for the resource.
Arguments: Command line arguments for the resource. Values can be strings or path providers like CertificateBundlePath or CertificateDirectoriesPath.
EnvironmentVariables: Environment variables for configuring certificate trust. The dictionary key is the environment variable name; values can be strings or path providers. By default, includes SSL_CERT_DIR and may include SSL_CERT_FILE if Override or System scope is configured.
CertificateBundlePath: A value provider that resolves to the path of a custom certificate bundle file.
CertificateDirectoriesPath: A value provider that resolves to paths containing individual certificates.
Default implementations are provided for Node.js, Python, and container resources. Container resources rely on standard OpenSSL configuration options, with default values that support the majority of common Linux distributions.
The WithContainerCertificatePaths API accepts three optional parameters:
customCertificatesDestination: Overrides the base path in the container where custom certificate files are placed. If not set or set to null, the default path of /usr/lib/ssl/aspire is used.
defaultCertificateBundlePaths: Overrides the path(s) in the container where a default certificate authority bundle file is located. When the CertificateTrustScope is Override or System, the custom certificate bundle is additionally written to these paths. If not set or set to null, a set of default certificate paths for common Linux distributions is used.
defaultCertificateDirectoryPaths: Overrides the path(s) in the container where individual trusted certificate files are found. When the CertificateTrustScope is Append, these paths are concatenated with the path to the uploaded certificate artifacts. If not set or set to null, a set of default certificate paths for common Linux distributions is used.
Indicates that a resource should use the developer certificate key pair for HTTPS endpoints at run time. Currently this indicates use of the ASP.NET Core developer certificate. The developer certificate will only be used when running in local development scenarios; in publish mode resources will use their default certificate configuration.
withHttpsDeveloperCertificate()// Server cert for HTTPS endpoints
Indicates whether developer certificates should be treated as trusted certificate authorities for the resource at run time. Currently this indicates trust for the ASP.NET Core developer certificate. The developer certificate will only be trusted when running in local development scenarios; in publish mode resources will use their default certificate trust.
withDeveloperCertificateTrust(true);// Client trust for dashboard
Indicates that a resource should use the developer certificate key pair for HTTPS endpoints at run time. Currently this indicates use of the ASP.NET Core developer certificate. The developer certificate will only be used when running in local development scenarios; in publish mode resources will use their default certificate configuration.