Name

       nix flake check - check whether the flake evaluates and run its tests

Synopsis

       nix flake check [option…] flake-url

Examples

       •  Evaluate the flake in the current directory, and build its checks:

       # nix flake check

       •  Verify that the patchelf flake evaluates, but don’t build its checks:

       # nix flake check --no-build github:NixOS/patchelf

Description

       This command verifies that the flake specified by flake reference flake-url can be evaluated successfully
       (as  detailed  below),  and  that  the  derivations  specified  by the flake’s checks output can be built
       successfully.

       If the keep-going option is set to true, Nix will keep evaluating as much as it can and report the errors
       as it encounters them. Otherwise it will stop at the first error.

Evaluation checks

       The following flake output attributes must be derivations:

       •  checks.system.name
       •  defaultPackage.system
       •  devShell.system
       •  devShells.system.name
       •  nixosConfigurations.name.config.system.build.toplevel
       •  packages.system.name

       The following flake output attributes must be app definitions:

       •  apps.system.name
       •  defaultApp.system

       The following flake output attributes must be template definitions:

       •  defaultTemplate
       •  templates.name

       The following flake output attributes must be Nixpkgs overlays:

       •  overlay
       •  overlays.name

       The following flake output attributes must be NixOS modules:

       •  nixosModule
       •  nixosModules.name

       The following flake output attributes must be bundlers:

       •  bundlers.name
       •  defaultBundler

       In addition, the hydraJobs output is evaluated in the same way as  Hydra’s  hydra-eval-jobs  (i.e.  as  a
       arbitrarily  deeply  nested attribute set of derivations). Similarly, the legacyPackages.system output is
       evaluated like nix-env --query --available.

Options

       •  --all-systems

          Check the outputs for all systems.

       •  --no-build

          Do not build checks.

   Common evaluation options
       •  --arg name expr

          Pass the value expr as the argument name to Nix functions.

       •  --arg-from-file name path

          Pass the contents of file path as the argument name to Nix functions.

       •  --arg-from-stdin name

          Pass the contents of stdin as the argument name to Nix functions.

       •  --argstr name string

          Pass the string string as the argument name to Nix functions.

       •  --debugger

          Start an interactive environment if evaluation fails.

       •  --eval-store store-url

          The URL of the Nix store to use for evaluation, i.e. to store  derivations  (.drv  files)  and  inputs
          referenced by them.

       •  --impure

          Allow access to mutable paths and repositories.

       •  --include / -I path

          Add path to search path entries used to resolve lookup paths

          This option may be given multiple times.

          Paths  added  through  -I  take  precedence  over  the nix-path configuration setting and the NIX_PATH
          environment variable.

       •  --override-flake original-ref resolved-ref

          Override the flake registries, redirecting original-ref to resolved-ref.

   Common flake-related options
       •  --commit-lock-file

          Commit changes to the flake’s lock file.

       •  --inputs-from flake-url

          Use the inputs of the specified flake as registry entries.

       •  --no-registries

          Don’t allow lookups in the flake registries.

                 DEPRECATED

                 Use --no-use-registries instead.

       •  --no-update-lock-file

          Do not allow any updates to the flake’s lock file.

       •  --no-write-lock-file

          Do not write the flake’s newly generated lock file.

       •  --output-lock-file flake-lock-path

          Write the given lock file instead of flake.lock within the top-level flake.

       •  --override-input input-path flake-url

          Override a specific flake input (e.g. dwarffs/nixpkgs). This implies --no-write-lock-file.

       •  --recreate-lock-file

          Recreate the flake’s lock file from scratch.

                 DEPRECATED

                 Use nix flake update instead.

       •  --reference-lock-file flake-lock-path

          Read the given lock file instead of flake.lock within the top-level flake.

       •  --update-input input-path

          Update a specific flake input (ignoring its previous entry in the lock file).

                 DEPRECATED

                 Use nix flake update instead.

   Logging-related options
       •  --debug

          Set the logging verbosity level to ‘debug’.

       •  --log-format format

          Set the format of log output; one of raw, internal-json, bar or bar-with-logs.

       •  --print-build-logs / -L

          Print full build logs on standard error.

       •  --quiet

          Decrease the logging verbosity level.

       •  --verbose / -v

          Increase the logging verbosity level.

   Miscellaneous global options
       •  --help

          Show usage information.

       •  --offline

          Disable substituters and consider all previously downloaded files up-to-date.

       •  --option name value

          Set the Nix configuration setting name to value (overriding nix.conf).

       •  --refresh

          Consider all previously downloaded files out-of-date.

       •  --repair

          During evaluation, rewrite missing or corrupted files in  the  Nix  store.  During  building,  rebuild
          missing or corrupted store paths.

       •  --version

          Show version information.

          Note

          See man nix.conf for overriding configuration settings with command line flags.

                                                                                             nix3-flake-check(1)