We scan this tool’s changelog a few times a day and keep the changes that would alter your agent’s next action: 3 since February 2026, each linked to its source.
cargo-lambdaWhen a build needs environment variables, pass them with `--env-var` or load them with `--env-file`; CLI values override metadata, and `--env-var` overrides `--env-file`.
cargo lambda build --env-var <KEY>=<VALUE>When deploying a function and remote environment variables must be preserved, run `cargo lambda deploy --merge-env` with the function name and the environment variables to add or update. Existing remote variables remain; local values take precedence for duplicates.
cargo lambda deploy --merge-env --env-var NEW_VAR=VALUE <function-name>When you need local Lambda requests processed simultaneously, run `cargo lambda watch --concurrency 5` to allow up to five function instances, spawned on demand. Instances poll a shared queue, remain warm, and each runs with `AWS_LAMBDA_MAX_CONCURRENCY=1`; the limit is global per function.
cargo lambda watch --concurrency 5