Warning
This program is experimental and its interface is subject to change.

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.

• --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 the Nix search path. The Nix search path is initialized from the colon-separated NIX_PATH environment variable, and is used to look up the location of Nix expressions using paths enclosed in angle brackets (i.e., <nixpkgs>).

  For instance, passing

  -I /home/eelco/Dev
  -I /etc/nixos
  

  will cause Nix to look for paths relative to /home/eelco/Dev and /etc/nixos, in that order. This is equivalent to setting the NIX_PATH environment variable to

  /home/eelco/Dev:/etc/nixos
  

  It is also possible to match paths against a prefix. For example, passing

  -I nixpkgs=/home/eelco/Dev/nixpkgs-branch
  -I /etc/nixos
  

  will cause Nix to search for <nixpkgs/path> in /home/eelco/Dev/nixpkgs-branch/path and /etc/nixos/nixpkgs/path.

  If a path in the Nix search path starts with http:// or https://, it is interpreted as the URL of a tarball that will be downloaded and unpacked to a temporary location. The tarball must consist of a single top-level directory. For example, passing

  -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/master.tar.gz
  

  tells Nix to download and use the current contents of the master branch in the nixpkgs repository.

  The URLs of the tarballs from the official nixos.org channels (see the manual page for nix-channel) can be abbreviated as channel:<channel-name>. For instance, the following two flags are equivalent:

  -I nixpkgs=channel:nixos-21.05
  -I nixpkgs=https://nixos.org/channels/nixos-21.05/nixexprs.tar.xz
  

  You can also fetch source trees using flake URLs and add them to the search path. For instance,

  -I nixpkgs=flake:nixpkgs
  

  specifies that the prefix nixpkgs shall refer to the source tree downloaded from the nixpkgs entry in the flake registry. Similarly,

  -I nixpkgs=flake:github:NixOS/nixpkgs/nixos-22.05
  

  makes <nixpkgs> refer to a particular branch of the NixOS/nixpkgs repository on GitHub.

• --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. This option is deprecated; use --no-use-registries.

• --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.

• --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).

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.

Options to override configuration settings:

• --accept-flake-config

  Enable the accept-flake-config setting.

• --access-tokens value

  Set the access-tokens setting.

• --allow-dirty

  Enable the allow-dirty setting.

• --allow-import-from-derivation

  Enable the allow-import-from-derivation setting.

• --allow-new-privileges

  Enable the allow-new-privileges setting.

• --allow-symlinked-store

  Enable the allow-symlinked-store setting.

• --allow-unsafe-native-code-during-evaluation

  Enable the allow-unsafe-native-code-during-evaluation setting.

• --allowed-impure-host-deps value

  Set the allowed-impure-host-deps setting.

• --allowed-uris value

  Set the allowed-uris setting.

• --allowed-users value

  Set the allowed-users setting.

• --auto-allocate-uids

  Enable the auto-allocate-uids setting.

• --auto-optimise-store

  Enable the auto-optimise-store setting.

• --bash-prompt value

  Set the bash-prompt setting.

• --bash-prompt-prefix value

  Set the bash-prompt-prefix setting.

• --bash-prompt-suffix value

  Set the bash-prompt-suffix setting.

• --build-hook value

  Set the build-hook setting.

• --build-poll-interval value

  Set the build-poll-interval setting.

• --build-users-group value

  Set the build-users-group setting.

• --builders value

  Set the builders setting.

• --builders-use-substitutes

  Enable the builders-use-substitutes setting.

• --commit-lockfile-summary value

  Set the commit-lockfile-summary setting.

• --compress-build-log

  Enable the compress-build-log setting.

• --connect-timeout value

  Set the connect-timeout setting.

• --cores value

  Set the cores setting.

• --diff-hook value

  Set the diff-hook setting.

• --download-attempts value

  Set the download-attempts setting.

• --download-speed value

  Set the download-speed setting.

• --eval-cache

  Enable the eval-cache setting.

• --experimental-features value

  Set the experimental-features setting.

• --extra-access-tokens value

  Append to the access-tokens setting.

• --extra-allowed-impure-host-deps value

  Append to the allowed-impure-host-deps setting.

• --extra-allowed-uris value

  Append to the allowed-uris setting.

• --extra-allowed-users value

  Append to the allowed-users setting.

• --extra-experimental-features value

  Append to the experimental-features setting.

• --extra-extra-platforms value

  Append to the extra-platforms setting.

• --extra-hashed-mirrors value

  Append to the hashed-mirrors setting.

• --extra-ignored-acls value

  Append to the ignored-acls setting.

• --extra-nix-path value

  Append to the nix-path setting.

• --extra-platforms value

  Set the extra-platforms setting.

• --extra-plugin-files value

  Append to the plugin-files setting.

• --extra-sandbox-paths value

  Append to the sandbox-paths setting.

• --extra-secret-key-files value

  Append to the secret-key-files setting.

• --extra-substituters value

  Append to the substituters setting.

• --extra-system-features value

  Append to the system-features setting.

• --extra-trusted-public-keys value

  Append to the trusted-public-keys setting.

• --extra-trusted-substituters value

  Append to the trusted-substituters setting.

• --extra-trusted-users value

  Append to the trusted-users setting.

• --fallback

  Enable the fallback setting.

• --filter-syscalls

  Enable the filter-syscalls setting.

• --flake-registry value

  Set the flake-registry setting.

• --fsync-metadata

  Enable the fsync-metadata setting.

• --gc-reserved-space value

  Set the gc-reserved-space setting.

• --hashed-mirrors value

  Set the hashed-mirrors setting.

• --http-connections value

  Set the http-connections setting.

• --http2

  Enable the http2 setting.

• --id-count value

  Set the id-count setting.

• --ignore-try

  Enable the ignore-try setting.

• --ignored-acls value

  Set the ignored-acls setting.

• --impersonate-linux-26

  Enable the impersonate-linux-26 setting.

• --keep-build-log

  Enable the keep-build-log setting.

• --keep-derivations

  Enable the keep-derivations setting.

• --keep-env-derivations

  Enable the keep-env-derivations setting.

• --keep-failed

  Enable the keep-failed setting.

• --keep-going

  Enable the keep-going setting.

• --keep-outputs

  Enable the keep-outputs setting.

• --log-lines value

  Set the log-lines setting.

• --max-build-log-size value

  Set the max-build-log-size setting.

• --max-free value

  Set the max-free setting.

• --max-jobs value

  Set the max-jobs setting.

• --max-silent-time value

  Set the max-silent-time setting.

• --max-substitution-jobs value

  Set the max-substitution-jobs setting.

• --min-free value

  Set the min-free setting.

• --min-free-check-interval value

  Set the min-free-check-interval setting.

• --nar-buffer-size value

  Set the nar-buffer-size setting.

• --narinfo-cache-negative-ttl value

  Set the narinfo-cache-negative-ttl setting.

• --narinfo-cache-positive-ttl value

  Set the narinfo-cache-positive-ttl setting.

• --netrc-file value

  Set the netrc-file setting.

• --nix-path value

  Set the nix-path setting.

• --no-accept-flake-config

  Disable the accept-flake-config setting.

• --no-allow-dirty

  Disable the allow-dirty setting.

• --no-allow-import-from-derivation

  Disable the allow-import-from-derivation setting.

• --no-allow-new-privileges

  Disable the allow-new-privileges setting.

• --no-allow-symlinked-store

  Disable the allow-symlinked-store setting.

• --no-allow-unsafe-native-code-during-evaluation

  Disable the allow-unsafe-native-code-during-evaluation setting.

• --no-auto-allocate-uids

  Disable the auto-allocate-uids setting.

• --no-auto-optimise-store

  Disable the auto-optimise-store setting.

• --no-builders-use-substitutes

  Disable the builders-use-substitutes setting.

• --no-compress-build-log

  Disable the compress-build-log setting.

• --no-eval-cache

  Disable the eval-cache setting.

• --no-fallback

  Disable the fallback setting.

• --no-filter-syscalls

  Disable the filter-syscalls setting.

• --no-fsync-metadata

  Disable the fsync-metadata setting.

• --no-http2

  Disable the http2 setting.

• --no-ignore-try

  Disable the ignore-try setting.

• --no-impersonate-linux-26

  Disable the impersonate-linux-26 setting.

• --no-keep-build-log

  Disable the keep-build-log setting.

• --no-keep-derivations

  Disable the keep-derivations setting.

• --no-keep-env-derivations

  Disable the keep-env-derivations setting.

• --no-keep-failed

  Disable the keep-failed setting.

• --no-keep-going

  Disable the keep-going setting.

• --no-keep-outputs

  Disable the keep-outputs setting.

• --no-preallocate-contents

  Disable the preallocate-contents setting.

• --no-print-missing

  Disable the print-missing setting.

• --no-pure-eval

  Disable the pure-eval setting.

• --no-require-sigs

  Disable the require-sigs setting.

• --no-restrict-eval

  Disable the restrict-eval setting.

• --no-run-diff-hook

  Disable the run-diff-hook setting.

• --no-sandbox

  Disable sandboxing.

• --no-sandbox-fallback

  Disable the sandbox-fallback setting.

• --no-show-trace

  Disable the show-trace setting.

• --no-substitute

  Disable the substitute setting.

• --no-sync-before-registering

  Disable the sync-before-registering setting.

• --no-trace-function-calls

  Disable the trace-function-calls setting.

• --no-trace-verbose

  Disable the trace-verbose setting.

• --no-use-case-hack

  Disable the use-case-hack setting.

• --no-use-cgroups

  Disable the use-cgroups setting.

• --no-use-registries

  Disable the use-registries setting.

• --no-use-sqlite-wal

  Disable the use-sqlite-wal setting.

• --no-use-xdg-base-directories

  Disable the use-xdg-base-directories setting.

• --no-warn-dirty

  Disable the warn-dirty setting.

• --plugin-files value

  Set the plugin-files setting.

• --post-build-hook value

  Set the post-build-hook setting.

• --pre-build-hook value

  Set the pre-build-hook setting.

• --preallocate-contents

  Enable the preallocate-contents setting.

• --print-missing

  Enable the print-missing setting.

• --pure-eval

  Enable the pure-eval setting.

• --relaxed-sandbox

  Enable sandboxing, but allow builds to disable it.

• --require-sigs

  Enable the require-sigs setting.

• --restrict-eval

  Enable the restrict-eval setting.

• --run-diff-hook

  Enable the run-diff-hook setting.

• --sandbox

  Enable sandboxing.

• --sandbox-build-dir value

  Set the sandbox-build-dir setting.

• --sandbox-dev-shm-size value

  Set the sandbox-dev-shm-size setting.

• --sandbox-fallback

  Enable the sandbox-fallback setting.

• --sandbox-paths value

  Set the sandbox-paths setting.

• --secret-key-files value

  Set the secret-key-files setting.

• --show-trace

  Enable the show-trace setting.

• --ssl-cert-file value

  Set the ssl-cert-file setting.

• --stalled-download-timeout value

  Set the stalled-download-timeout setting.

• --start-id value

  Set the start-id setting.

• --store value

  Set the store setting.

• --substitute

  Enable the substitute setting.

• --substituters value

  Set the substituters setting.

• --sync-before-registering

  Enable the sync-before-registering setting.

• --system value

  Set the system setting.

• --system-features value

  Set the system-features setting.

• --tarball-ttl value

  Set the tarball-ttl setting.

• --timeout value

  Set the timeout setting.

• --trace-function-calls

  Enable the trace-function-calls setting.

• --trace-verbose

  Enable the trace-verbose setting.

• --trusted-public-keys value

  Set the trusted-public-keys setting.

• --trusted-substituters value

  Set the trusted-substituters setting.

• --trusted-users value

  Set the trusted-users setting.

• --use-case-hack

  Enable the use-case-hack setting.

• --use-cgroups

  Enable the use-cgroups setting.

• --use-registries

  Enable the use-registries setting.

• --use-sqlite-wal

  Enable the use-sqlite-wal setting.

• --use-xdg-base-directories

  Enable the use-xdg-base-directories setting.

• --user-agent-suffix value

  Set the user-agent-suffix setting.

• --warn-dirty

  Enable the warn-dirty setting.