TLS certificates
By default, uv loads certificates from the bundled webpki-roots crate. The webpki-roots are a
reliable set of trust roots from Mozilla, and including them in uv improves portability and
performance (especially on macOS, where reading the system trust store incurs a significant delay).
System certificates
In some cases, you may want to use the platform's native certificate store, especially if you're
relying on a corporate trust root (e.g., for a mandatory proxy) that's included in your system's
certificate store. To instruct uv to use the system's trust store, run uv with the --native-tls
command-line flag, or set the UV_NATIVE_TLS environment variable to true.
Custom certificates
If a direct path to the certificate is required (e.g., in CI), set the SSL_CERT_FILE environment
variable to the path of the certificate bundle, to instruct uv to use that file instead of the
system's trust store.
If client certificate authentication (mTLS) is desired, set the SSL_CLIENT_CERT environment
variable to the path of the PEM formatted file containing the certificate followed by the private
key.
Insecure hosts
If you're using a setup in which you want to trust a self-signed certificate or otherwise disable
certificate verification, you can instruct uv to allow insecure connections to dedicated hosts via
the allow-insecure-host configuration option. For example, adding the following to
pyproject.toml will allow insecure connections to example.com:
allow-insecure-host expects to receive a hostname (e.g., localhost) or hostname-port pair (e.g.,
localhost:8080), and is only applicable to HTTPS connections, as HTTP connections are inherently
insecure.
Use allow-insecure-host with caution and only in trusted environments, as it can expose you to
security risks due to the lack of certificate verification.