nix/doc/manual/source/command-ref/nix-copy-closure.md

Name

nix-copy-closure - copy store objects to or from a remote machine via SSH

Synopsis

nix-copy-closure [--to | --from ] [--gzip] [--include-outputs] [--use-substitutes | -s] [-v] [user@]machine[:port] paths

Description

Given paths from one machine, nix-copy-closure computes the closure of those paths (i.e. all their dependencies in the Nix store), and copies store objects in that closure to another machine via SSH. It doesn’t copy store objects that are already present on the other machine.

Note

While the Nix store to use on the local machine can be specified on the command line with the --store option, the Nix store to be accessed on the remote machine can only be configured statically on that remote machine.

Since nix-copy-closure calls ssh, you may need to authenticate with the remote machine. In fact, you may be asked for authentication twice because nix-copy-closure currently connects twice to the remote machine: first to get the set of paths missing on the target machine, and second to send the dump of those paths. When using public key authentication, you can avoid typing the passphrase with ssh-agent.

Options

• --to

  Copy the closure of paths from a Nix store accessible from the local machine to the Nix store on the remote machine. This is the default behavior.

• --from

  Copy the closure of paths from the Nix store on the remote machine to the local machine's specified Nix store.

• --gzip

  Enable compression of the SSH connection.

• --include-outputs

  Also copy the outputs of store derivations included in the closure.

• --use-substitutes / -s

  Attempt to download missing store objects on the target from substituters. Any store objects that cannot be substituted on the target are still copied normally from the source. This is useful, for instance, if the connection between the source and target machine is slow, but the connection between the target machine and cache.nixos.org (the default binary cache server) is fast.

{{#include ./opt-common.md}}

Environment variables

• NIX_SSHOPTS

  Additional options to be passed to ssh on the command line.

{{#include ./env-common.md}}

Examples

Example

Copy GNU Hello with all its dependencies to a remote machine:

$ storePath="$(nix-build '<nixpkgs>' -I nixpkgs=channel:nixpkgs-unstable -A hello --no-out-link)"
$ nix-copy-closure --to alice@itchy.example.org "$storePath"
copying 5 paths...
copying path '/nix/store/nrwkk6ak3rgkrxbqhsscb01jpzmslf2r-xgcc-13.2.0-libgcc' to 'ssh://alice@itchy.example.org'...
copying path '/nix/store/gm61h1y42pqyl6178g90x8zm22n6pyy5-libunistring-1.1' to 'ssh://alice@itchy.example.org'...
copying path '/nix/store/ddfzjdykw67s20c35i7a6624by3iz5jv-libidn2-2.3.7' to 'ssh://alice@itchy.example.org'...
copying path '/nix/store/apab5i73dqa09wx0q27b6fbhd1r18ihl-glibc-2.39-31' to 'ssh://alice@itchy.example.org'...
copying path '/nix/store/g1n2vryg06amvcc1avb2mcq36faly0mh-hello-2.12.1' to 'ssh://alice@itchy.example.org'...

Example

Copy GNU Hello from a remote machine using a known store path, and run it:

$ storePath="$(nix-instantiate --eval '<nixpkgs>' -I nixpkgs=channel:nixpkgs-unstable -A hello.outPath | tr -d '"')"
$ nix-copy-closure --from alice@itchy.example.org "$storePath"
$ "$storePath"/bin/hello
Hello, world!