You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
GatewaysArea: what it touches
ImprovementsKind: in v2.1.321,
ImprovementsSection of the release
What
Claude Code can reach models through Amazon Bedrock, Google Vertex and Microsoft Foundry. A base URL is the address requests are sent to.
The gateway's warning about base-URL environment variables now also covers ANTHROPIC_FOUNDRY_BASE_URL, as well as the Bedrock and Vertex ones.
The warning now says the gateway does not read the variable. Requests for upstreams with no base_url go to the provider's default endpoint. To keep a custom address, copy the URL into base_url. Before, the warning said such requests went to that URL whatever the upstream's region.
Bedrock always gets an explicit address. With no base_url, it uses https://bedrock-runtime.${region}.amazonaws.com built from the profile's region.
Why
If you relied on these environment variables to send requests to a custom address, such as a private endpoint, set base_url instead or requests will go to the provider's default.
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's release notes agreeGateway: Changed Bedrock, Vertex and Foundry upstreams to ignore the ANTHROPIC_*_BASE_URL variables in the gateway's environment. Set…
