Offline Usage of vcpkg

This document details two robust methods for deploying vcpkg in environments without live internet connectivity.

Method 1: Prebuild and Export Packages

This method uses the export command to create a comprehensive package bundle on an internet-connected system. The process compiles binaries, headers, and all transitive dependencies into a self-contained SDK bundle suitable for offline deployment.

Get started with the Export Tutorial – Creating a self-contained SDK bundle.

Pros and Cons

Pros:

• All necessary components are bundled together into a single archive using the export command.
• Easy to get started.
• Extremely reliable.

Cons:

• Updates and source development must be performed on a connected system.
• Involves additional maintenance when libraries update.
• Handling offline-only private libraries is not possible.
• Does not scale well to multiple diverse consumers -- each needs a separate bundle.

Method 2: Redirect External Resource Access

This strategy enables controlled access to external resources by combining Git URL redirection with asset caching. It is an effective alternative where a complete offline bundle is not essential.

Git Redirection

Git Registries and some port sources are fetched using the git protocol, which may refer to resources outside the offline environment. The Git configuration below demonstrates how to redirect requests from the standard repository to an internal mirror:

[url "https://internal/mirror/of/vcpkg"]
    insteadOf = https://github.com/microsoft/vcpkg

This configuration can also be applied via the command line:

git config --global url."https://internal/mirror/of/vcpkg".insteadOf "https://github.com/microsoft/vcpkg"

See Using Git URL Redirection (insteadOf) in the official Git documentation for more information.

Asset Caching

Asset caching stores downloads locally or on a remote storage solution, enhancing build performance and increasing network security. Detailed instructions are available in both the asset caching tutorial and the asset caching configuration reference.

Pros and Cons

Pros:

• Accelerates builds by reusing cached assets.
• Removes dependency on continuous internet connectivity.
• Enables rebuilding offline, making toolchain or flag changes easier.
• Scales well to multiple diverse consumers with different subsets of libraries.

Cons:

• Involves additional setup.
• Requires maintenance of internal mirrors and caching infrastructure.

Conclusion

Deploying vcpkg in an air-gapped environment can be achieved through:

• Prebuilding and exporting a complete package bundle.
• Configuring Git redirection combined with asset caching for controlled external access.

Choose the method that aligns best with your infrastructure and deployment requirements.

Additional Resources

1. Export Command
2. Asset Caching Configuration Reference
3. Using Git URL Redirection (insteadOf)