YAML configuration

Stack is configured by the content of YAML files. Stack's YAML configuration options break down into project-specific options and non-project-specific options. They are configured at the project-level or globally.

The project-level configuration file (stack.yaml) contains project-specific options and may contain non-project-specific options.

Stack obtains project-level configuration from one of the following (in order of preference):

A file specified by the --stack-yaml command line option.
A file specified by the STACK_YAML environment variable.
A file named stack.yaml in the current directory or an ancestor directory.
A file name stack.yaml in the global-project directory in the Stack root.

The global configuration file (config.yaml) contains only non-project-specific options.

Stack obtains global configuration from a file named config.yaml:

on Unix-like operating systems only, located in /etc/stack (for system-wide options); and/or
located in the Stack root (for user-specific options).

This page is intended to document fully all YAML configuration options. If you identify any inaccuracies or incompleteness, please update the page, and if you're not sure how, open an issue labeled "question".

If you wish to understand the difference between a stack.yaml files and a Cabal file (named <package_name>.cabal), see the stack.yaml vs a Cabal file documentation.

Project-specific configuration

Project-specific configuration options are valid only in a project-level configuration file (stack.yaml).

Note: We define project to mean a directory that contains a stack.yaml file, which specifies how to build a set of packages. We define package to be a package with a Cabal file or an Hpack package.yaml file.

In your project-specific options, you specify both which local packages to build and which dependencies to use when building these packages. Unlike the user's local packages, these dependencies aren't built by default. They only get built when needed.

Shadowing semantics, described here, are applied to your configuration. So, if you add a package to your packages list, it will be used even if you're using a snapshot that specifies a particular version. Similarly, extra-deps will shadow the version specified in the resolver.

resolver or snapshot

resolver and snapshot are synonyms. Only one of these keys is permitted, not both.

The resolver or snapshot key specifies which snapshot is to be used for this project. A snapshot defines a GHC version, a number of packages available for installation, and various settings like build flags. It is called a resolver since a snapshot states how dependencies are resolved. There are currently four resolver types:

LTS Haskell snapshots, e.g. resolver: lts-19.17
Stackage Nightly snapshots, e.g. resolver: nightly-2002-08-04
No snapshot, just use packages shipped with the compiler. For GHC this looks like resolver: ghc-9.2.4
Custom snapshot, via a URL or relative file path. For further information, see the Pantry documentation.

Each of these resolvers will also determine what constraints are placed on the compiler version. See the compiler-check option for some additional control over compiler version.

The resolver key corresponds to a Pantry snapshot location. For further information, see the Pantry documentation.

packages

Default:

packages:
- .

NOTE From Stack 1.11, Stack moved over to Pantry for managing extra-deps, and removed some legacy syntax for specifying dependencies in packages. Some conversion notes are provided below.

The packages key specifies a list of packages that are part of your local project. These are specified via paths to local directories. The paths are considered relative to the directory containing the stack.yaml file. For example, if your stack.yaml is located at /foo/bar/stack.yaml, and you have:

packages:
- hello
- there/world

Your configuration means "I have packages in /foo/bar/hello and /foo/bar/there/world.

If these packages should be treated as dependencies instead, specify them in extra-deps key, described below.

The packages key is optional. The default item, '.', means that your project has exactly one package, and it is located in the current directory.

Each package directory specified must have a valid Cabal file or Hpack package.yaml file present. The subdirectories of the directory are not searched for Cabal files. Subdirectories will have to be specified as independent items in the list of packages.

Project packages are different from snapshot dependencies (via resolver) and extra dependencies (via extra-deps) in multiple ways, e.g.:

Project packages will be built by default with a stack build without specific targets. Dependencies will only be built if they are depended upon.
Test suites and benchmarks may be run for project packages. They are never run for extra dependencies.

Legacy syntax Prior to Stack 1.11, it was possible to specify dependencies in your packages configuration value as well. This support was removed to simplify the file format. Instead, these values should be moved to extra-deps. As a concrete example, you would convert:

packages:
- .
- location:
    git: https://github.com/bitemyapp/esqueleto.git
    commit: 08c9b4cdf977d5bcd1baba046a007940c1940758
  extra-dep: true
- location:
    git: https://github.com/yesodweb/wai.git
    commit: 6bf765e000c6fd14e09ebdea6c4c5b1510ff5376
    subdirs:
      - wai-extra
  extra-dep: true

extra-deps:
  - streaming-commons-0.2.0.0
  - time-1.9.1
  - yesod-colonnade-1.3.0.1
  - yesod-elements-1.1

into

packages:
- .

extra-deps:
  - streaming-commons-0.2.0.0
  - time-1.9.1
  - yesod-colonnade-1.3.0.1
  - yesod-elements-1.1
  - git: https://github.com/bitemyapp/esqueleto.git
    commit: 08c9b4cdf977d5bcd1baba046a007940c1940758
  - git: https://github.com/yesodweb/wai.git
    commit: 6bf765e000c6fd14e09ebdea6c4c5b1510ff5376
    subdirs:
      - wai-extra

And, in fact, the packages value could be left off entirely since it's using the default value.

extra-deps

Default: []

This key allows you to specify extra dependencies on top of what is defined in your snapshot (specified by the resolver key mentioned above). These dependencies may either come from a local file path or a Pantry package location.

For the local file path case, the same relative path rules as apply to packages apply.

Pantry package locations allow you to include dependencies from three different kinds of sources:

Hackage
Archives (tarballs or zip files, either local or over HTTP or HTTPS)
Git or Mercurial repositories

Here's an example using all of the above:

extra-deps:
- vendor/hashable
- streaming-commons-0.2.0.0
- time-1.9.1
- yesod-colonnade-1.3.0.1
- yesod-elements-1.1
- git: https://github.com/bitemyapp/esqueleto.git
  commit: 08c9b4cdf977d5bcd1baba046a007940c1940758
- url: https://github.com/yesodweb/wai/archive/6bf765e000c6fd14e09ebdea6c4c5b1510ff5376.tar.gz
  subdirs:
    - wai-extra
- github: snoyberg/conduit
  commit: 2e3e41de93821bcfe8ec6210aeca21be3f2087bf
  subdirs:
    - network-conduit-tls

For further information on the format for specifying dependencies, see the Pantry documentation.

flags

Default: {}

Flags can be set for each package separately, e.g.

flags:
  package-name:
    flag-name: true

If a specified flag is different than the one specified for a snapshot package, then the snapshot package will automatically be promoted to be an extra-dep.

drop-packages

(Since 2.0)

Default: []

Packages which, when present in the snapshot specified in resolver, should not be included in our package. This can be used for a few different purposes, e.g.:

Ensure that packages you don't want used in your project cannot be used in a package.yaml file (e.g., for license reasons)
Prevent overriding of a global package like Cabal. For more information, see Stackage issue #4425
When using a custom GHC build, avoid incompatible packages (see this comment).

drop-packages:
- Cabal
- buggy-package
- package-with-unacceptable-license

user-message

If present, specifies a message to be displayed every time the configuration is loaded by Stack. It can serve as a reminder for the user to review the configuration and make any changes if needed. The user can delete this message if the generated configuration is acceptable.

For example, a user-message is inserted by stack init when it omits packages or adds external dependencies, namely:

user-message: ! 'Warning: Some packages were found to be incompatible with the resolver
  and have been left commented out in the packages section.

  Warning: Specified resolver could not satisfy all dependencies. Some external packages
  have been added as dependencies.

  You can omit this message by removing it from stack.yaml

'

custom-preprocessor-extensions

Default: []

In order for Stack to be aware of any custom preprocessors you are using, add their extensions here

custom-preprocessor-extensions:
- erb

TODO: Add a simple example of how to use custom preprocessors.

Non-project-specific configuration

Non-project configuration options are valid in a project-level configuration file (stack.yaml) or in global configuration files (config.yaml). The options below are listed in alphabetic order.

allow-different-user

(Since 1.0.1)

Default: false

Restrictions: POSIX systems only.

Allow users other than the owner of the Stack root to use the Stack installation.

allow-different-user: true

The intention of this option is to prevent file permission problems, for example as the result of a Stack command executed under sudo.

The option is automatically enabled when Stack is re-spawned in a Docker process.

allow-newer

(Since 0.1.7)

Default: false

Whether to ignore version bounds in Cabal files. This also ignores lower bounds. The name allow-newer is chosen to match the commonly-used Cabal option.

allow-newer: true

apply-ghc-options

(Since 0.1.6)

Default: locals

Which packages do ghc-options on the command line get applied to? Before Stack 0.1.6, the default value was targets

apply-ghc-options: locals # all local packages
# apply-ghc-options: targets # all local packages that are targets
# apply-ghc-options: everything # applied even to snapshot and extra-deps

Note that everything is a slightly dangerous value, as it can break invariants about your snapshot database.

arch

Set the architecture for GHC, build directories, etc. Values are those recognized by Cabal, e.g.:

arch: i386, x86_64

This can also be set via the command line.

build

(Since 1.1.0)

Default:

build:
  library-profiling: false
  executable-profiling: false
  copy-bins: false
  prefetch: false
  keep-going: false
  keep-tmp-files: false

  # NOTE: global usage of haddock can cause build failures when documentation is
  # incorrectly formatted.  This could also affect scripts which use Stack.
  haddock: false
  haddock-arguments:
    haddock-args: []      # Additional arguments passed to haddock, --haddock-arguments
    # haddock-args:
    # - "--css=/home/user/my-css"
  open-haddocks: false    # --open
  haddock-deps: false     # if unspecified, defaults to true if haddock is set
  haddock-internal: false

  # These are inadvisable to use in your global configuration, as they make the
  # Stack build command line behave quite differently.
  test: false
  test-arguments:
    rerun-tests: true   # Rerun successful tests
    additional-args: [] # --test-arguments
    # additional-args:
    # - "--fail-fast"
    coverage: false
    no-run-tests: false
  bench: false
  benchmark-opts:
    benchmark-arguments: ""
    # benchmark-arguments: "--csv bench.csv"
    no-run-benchmarks: false
  force-dirty: false
  reconfigure: false
  cabal-verbose: false
  split-objs: false

  # Since 1.8. Starting with 2.0, the default is true
  interleaved-output: true

  # Since 1.10
  ddump-dir: ""

Allows setting build options which are usually specified on the command line.

The meanings of these settings correspond directly with the command line flags of the same name. For further information, see the stack build command documentation and the users guide.

color

This option specifies when to use color in output. The option is used as color: <WHEN>, where <WHEN> is 'always', 'never', or 'auto'. On Windows versions before Windows 10, for terminals that do not support color codes, the default is 'never'; color may work on terminals that support color codes.

The color use can also be set at the command line using the equivalent --color=<WHEN> global option. Color use set at the command line takes precedence over that set in a yaml configuration file.

(The British English spelling (colour) is also accepted. In yaml configuration files, the American spelling is the alternative that has priority.)

compiler

(Since 0.1.7)

Overrides the compiler version in the resolver. Note that the compiler-check flag also applies to the version numbers. This uses the same syntax as compiler resolvers like ghc-9.2.4. This can be used to override the compiler for a Stackage snapshot, like this:

resolver: lts-14.20
compiler: ghc-8.6.4
compiler-check: match-exact

Building GHC from source (experimental)

(Since 2.0)

Stack supports building the GHC compiler from source. The version to build and to use is defined by a a Git commit ID and an Hadrian "flavour" (Hadrian is the build system of GHC) with the following syntax:

compiler: ghc-git-COMMIT-FLAVOUR

In the following example the commit ID is "5be7ad..." and the flavour is "quick":

compiler: ghc-git-5be7ad7861c8d39f60b7101fd8d8e816ff50353a-quick

By default the code is retrieved from the main GHC repository. If you want to select another repository, set the "compiler-repository" option:

compiler-repository: git://my/ghc/repository
# default
# compiler-repository: https://gitlab.haskell.org/ghc/ghc.git

Note that Stack doesn't check the compiler version when it uses a compiler built from source. Moreover it is assumed that the built compiler is recent enough as Stack doesn't enable any known workaround to make older compilers work.

Building the compiler can take a very long time (more than one hour). Hint: for faster build times, use Hadrian flavours that disable documentation generation.

Global packages

The GHC compiler you build from sources may depend on unreleased versions of some global packages (e.g. Cabal). It may be an issue if a package you try to build with this compiler depends on such global packages because Stack may not be able to find versions of those packages (on Hackage, etc.) that are compatible with the compiler.

The easiest way to deal with this issue is to drop the offending packages as follows. Instead of using the packages specified in the resolver, the global packages bundled with GHC will be used.

drop-packages:
- Cabal
- ...

Another way to deal with this issue is to add the relevant packages as extra-deps built from source. To avoid mismatching versions, you can use exactly the same commit id you used to build GHC as follows:

extra-deps:
- git: https://gitlab.haskell.org/ghc/ghc.git
  commit: 5be7ad7861c8d39f60b7101fd8d8e816ff50353a
  subdirs:
    - libraries/Cabal/Cabal
    - libraries/...

Bootstrapping compiler

Building GHC from source requires a working GHC (known as the bootstrap compiler). As we use a Stack based version of Hadrian (hadrian/build-stack in GHC sources), the bootstrap compiler is configured into hadrian/stack.yaml and fully managed by Stack.

compiler-check

(Since 0.1.4)

Default: match-minor

Specifies how the compiler version in the resolver is matched against concrete versions. Valid values:

match-minor: make sure that the first three components match, but allow patch-level differences. For example< 7.8.4.1 and 7.8.4.2 would both match 7.8.4. This is useful to allow for custom patch levels of a compiler.
match-exact: the entire version number must match precisely
newer-minor: the third component can be increased, e.g. if your resolver is ghc-7.10.1, then 7.10.2 will also be allowed. This was the default up through Stack 0.1.3

concurrent-tests

(Since 0.1.2.0)

Default: true

This option specifies whether test suites should be executed concurrently with each other. The default is true since this is usually fine and it often means that tests can complete earlier. However, if some test suites require exclusive access to some resource, or require a great deal of CPU or memory resources, then it makes sense to set this to false.

concurrent-tests: false

configure-options

(Since 2.0)

Options which are passed to the configure step of the Cabal build process. These can either be set by package name, or using the $everything, $targets, and $locals special keys. These special keys have the same meaning as in ghc-options.

configure-options:
  $everything:
  - --with-gcc
  - /some/path
  my-package:
  - --another-flag

connection-count

Default: 8

Integer indicating how many simultaneous downloads are allowed to happen.

default-template

Default: new-template in the stack-templates repository.

This option specifies which template to use with stack new, when none is specified. Other templates are listed in the stack-templates repository. See the output of stack templates.

docker

For further information, see the Docker integration documentation.

dump-logs

(Since 1.3.0)

Default: warning

Control which log output from local non-dependency packages to print to the console. By default, Stack will only do this when building a single target package or if the log contains warnings, to avoid generating unnecessarily verbose output.

dump-logs: none      # don't dump logs even if they contain warnings
dump-logs: warning   # dump logs that contain warnings
dump-logs: all       # dump all logs for local non-dependency packages

extra-include-dirs

Default: []

A list of extra paths to be searched for header files. Paths should be absolute

extra-include-dirs:
- /opt/foo/include

Since these are system-dependent absolute paths, it is recommended that you specify these in your config.yaml file. If you control the build environment in your project's stack.yaml, perhaps through docker or other means, then it may well make sense to include these there as well.

extra-lib-dirs

Default: []

A list of extra paths to be searched for libraries. Paths should be absolute

extra-lib-dirs:
- /opt/foo/lib

Since these are system-dependent absolute paths, it is recommended that you specify these in your config.yaml file. If you control the build environment in your project's stack.yaml, perhaps through docker or other means, then it may well make sense to include these there as well.

extra-path

(Since 0.1.4.0)

This option specifies additional directories to prepend to the PATH. These will be used when resolving the location of executables, and will also be visible in the PATH of processes run by Stack.

For example, to prepend /path-to-some-dep/bin to your PATH:

extra-path:
- /path-to-some-dep/bin

Other paths added by Stack - things like the project's binary directory and the compiler's binary directory - will take precedence over those specified here (the automatic paths get prepended).

ghc-build

(Since 1.3.0)

Specify a specialized architecture bindist to use. Normally this is determined automatically, but you can override the autodetected value here. Possible arguments include standard, gmp4, nopie, tinfo6, tinfo6-nopie, ncurses6, and integersimple.

ghc-options

(Since 0.1.4)

Allows specifying per-package and global GHC options:

ghc-options:
    # All packages
    "$locals": -Wall
    "$targets": -Werror
    "$everything": -O2
    some-package: -DSOME_CPP_FLAG

Since Stack 1.6.0, setting a GHC options for a specific package will automatically promote it to a local package (much like setting a custom package flag). However, setting options via $everything on all flags will not do so (see Github discussion for reasoning). This can lead to unpredictable behavior by affecting your snapshot packages.

The behavior of the $locals, $targets, and $everything special keys mirrors the behavior for the apply-ghc-options setting, which affects command line parameters.

NOTE: Prior to Stack 1.6.0, the $locals, $targets, and $everything keys were not supported. Instead, you could use "*" for the behavior represented now by $everything. It is highly recommended to switch to the new, more expressive, keys.

ghc-variant

(Since 0.1.5)

Default: standard

Specify a variant binary distribution of GHC to use. Known values:

standard: Use the standard GHC binary distribution
integersimple: Use a GHC bindist that uses integer-simple instead of GMP
any other value: Use a custom GHC bindist. You should specify setup-info or setup-info-locations so stack setup knows where to download it, or pass the stack setup --ghc-bindist argument on the command-line

This option is incompatible with system-ghc: true.

hackage-base-url

(Since 1.9.1)

Default: https://hackage.haskell.org/

Sets the address of the Hackage server to upload the package to.

hackage-base-url: https://hackage.example.com/

hide-source-paths

Default: true (since 2.0)

Whether to use the -fhide-source-paths option by default for GHC >= 8.2:

hide-source-paths: false

Build output when enabled:

...
[1 of 2] Compiling Lib
[2 of 2] Compiling Paths_test_pr
...

Build output when disabled:

...
[1 of 2] Compiling Lib              ( src/Lib.hs, .stack-work/dist/x86_64-linux-tinfo6/Cabal-2.4.0.1/build/Lib.o )
...

hide-th-loading

Default: true

Strip out the "Loading ..." lines from GHC build output, produced when using Template Haskell.

ignore-revision-mismatch

(Removed 1.11)

This flag was introduced in Stack 1.6, and removed on the move to Pantry. You will receive a warning if this configuration value is set.

install-ghc

Default: true (since 1.5.0)

Whether or not to automatically install GHC when necessary.

jobs

Default: the number of processors reported by your CPU.

Specifies how many build tasks should be run in parallel. This can be overloaded on the command line via -jN, for example -j2. One usage for this might be to avoid running out of memory by setting it to 1, like this:

jobs: 1

local-bin-path

Default (on Unix-like operating systems): ~/.local/bin

Default (on Windows): %APPDATA%\local\bin

Target directory for stack install and stack build --copy-bins.

local-programs-path

(Since 1.3.0)

Default (on Unix-like operating systems): programs directory in the Stack root.

Default (on Windows): %LOCALAPPDATA%\Programs\stack, if the %LOCALAPPDATA% environment variable exists.

This overrides the location of the Stack 'programs' directory, where tools like GHC and (on Windows) MSYS2 get installed.

NOTE: On Windows, if there is a space character in the %LOCALAPPDATA% path (which may be the case if the relevant user account name and its corresponding user profie path have a space) this may cause problems with building packages that make use of the GNU project's autoconf package and configure shell script files. That may be the case particularly if there is no corresponding short name ('8 dot 3' name) for the directory in the path with the space (which may be the case if '8 dot 3' names have been stripped or their creation not enabled by default). If there are problems building, it will be necessary to override the default location of Stack's 'programs' directory to specify an alternative path that does not contain space characters. Examples of packages on Hackage that make use of configure are network and process.

modify-code-page

(Since 0.1.6)

Default: true

Whether to modify the code page for UTF-8 output when running on Windows.

modify-code-page: false

nix

(since 0.1.10.0)

Default:

nix:
  add-gc-roots: false
  enable: false
  nix-shell-options: []
  packages: []
  path: []
  pure: true
  shell-file:

For further information, see the Nix integration documentation.

os

Set the operating system for GHC, build directories, etc. Values are those recognized by Cabal, e.g.:

os: windows, linux

You are unlikely to want to change the os value.

package-indices

Default:

package-indices:
- download-prefix: https://hackage.haskell.org/
  hackage-security:
    keyids:
    - 0a5c7ea47cd1b15f01f5f51a33adda7e655bc0f0b0615baa8e271f4c3351e21d
    - 1ea9ba32c526d1cc91ab5e5bd364ec5e9e8cb67179a471872f6e26f0ae773d42
    - 280b10153a522681163658cb49f632cde3f38d768b736ddbc901d99a1a772833
    - 2a96b1889dc221c17296fcc2bb34b908ca9734376f0f361660200935916ef201
    - 2c6c3627bd6c982990239487f1abd02e08a02e6cf16edb105a8012d444d870c3
    - 51f0161b906011b52c6613376b1ae937670da69322113a246a09f807c62f6921
    - 772e9f4c7db33d251d5c6e357199c819e569d130857dc225549b40845ff0890d
    - aa315286e6ad281ad61182235533c41e806e5a787e0b6d1e7eef3f09d137d2e9
    - fe331502606802feac15e514d9b9ea83fee8b6ffef71335479a2e68d84adc6b0
    key-threshold: 3 # number of keys required

    # ignore expiration date, see https://github.com/commercialhaskell/stack/pull/4614
    ignore-expiry: true

Since Stack 1.11, this key may only be used to specify a single package index, which must use the Hackage Security format. For the motivation for this change, please see issue #4137. Therefore, this key is most useful for providing an alternate Hackage mirror either for:

Bypassing a firewall
Faster download speeds

If you provide a replacement index which does not mirror Hackage, it is likely that you'll end up with significant breakage, such as most snapshots failing to work.

Note: since Stack v2.1.3, ignore-expiry was changed to true by default. For more information on this change, see issue #4928.

pvp-bounds

(Since 0.1.5)

NOTE As of Stack 1.6.0, this feature does not reliably work, due to issues with the Cabal library's printer. Stack will generate a warning when a lossy conversion occurs, in which case you may need to disable this setting. For further information, see issue #3550.

When using the sdist and upload commands, this setting determines whether the Cabal file's dependencies should be modified to reflect PVP lower and upper bounds. Values are none (unchanged), upper (add upper bounds), lower (add lower bounds), and both (and upper and lower bounds). The algorithm it follows is:

If an upper or lower bound already exists on a dependency, it's left alone
When adding a lower bound, we look at the current version specified by stack.yaml, and set it as the lower bound (e.g., foo >= 1.2.3)
When adding an upper bound, we require less than the next major version (e.g., foo < 1.3)

pvp-bounds: none

For further information, see the announcement blog post.

NOTE Since Stack 1.5.0, each of the values listed above supports adding -revision to the end of each value, e.g. pvp-bounds: both-revision. This means that, when uploading to Hackage, Stack will first upload your tarball with an unmodified Cabal file, and then upload a Cabal file revision with the PVP bounds added. This can be useful - especially combined with the Stackage no-revisions feature - as a method to ensure PVP compliance without having to proactively fix bounds issues for Stackage maintenance.

recommend-stack-upgrade

(Since 2.0)

When Stack notices that a new version of Stack is available, should it notify the user?

recommend-stack-upgrade: true

rebuild-ghc-options

(Since 0.1.6)

Default: false

Should we rebuild a package when its GHC options change? Before Stack 0.1.6, this was a non-configurable true. However, in most cases, the flag is used to affect optimization levels and warning behavior, for which GHC itself doesn't actually recompile the modules anyway. Therefore, the new behavior is to not recompile on an options change, but this behavior can be changed back with the following:

rebuild-ghc-options: true

require-stack-version

Default: "-any"

Require a version of Stack within the specified range (cabal-style) to be used for this project. Example: require-stack-version: "== 0.1.*"

save-hackage-creds

(Since 1.5.0)

Default: true

Controls whether, when using stack upload, the user's Hackage username and password are stored in a local file.

save-hackage-creds: true

setup-info

(Since 0.1.5)

The setup-info dictionary specifies download locations for tools to be installed during set-up, such as GHC or, on Windows, 7z and MSYS2. The dictionary maps ('Tool', 'Platform', 'Version') to the location where it can be obtained. For example, mapping (GHC, 64-bit Windows, 9.2.3) to the URL hosting the archive file for GHC's installation.

Possible usages of this configuration option are:

Using Stack offline or behind a firewall.
Extending the tools known to Stack, such as cutting-edge versions of GHC or builds for custom Linux distributions (for use with the ghc-variant option).

By default, Stack obtains the dictionary from stack-setup-2.yaml.

The setup-info dictionary is constructed in the following order:

setup-info in the YAML configuration - inline configuration
--setup-info-yaml command line arguments - URLs or paths. Multiple locations may be specified.
setup-info-locations in the YAML configuration - URLs or paths. See further below.

The format of this key is the same as in the default stack-setup-2.yaml. For example, GHC 9.2.3 of custom variant myvariant (see further below) on 64-bit Windows:

setup-info:
  ghc:
    windows64-custom-myvariant:
      9.2.3:
        url: "https://example.com/ghc-9.2.3-x86_64-unknown-mingw32-myvariant.tar.xz"

'Platforms' are pairs of an operating system and a machine architecture (for example, 32-bit i386 or 64-bit x86-64) (represented by the Cabal.Distribution.Systems.Platform type). Stack currently (version 2.7.5) supports the following pairs in the format of the setup-info key:

Operating system	I386 arch	X86_64 arch	Other machine architectures
Linux	linux32	linux64	AArch64: linux-aarch64, Arm: linux-armv7, Sparc: linux-sparc
OSX	macosx	macosx
Windows	windows32	windows64
FreeBSD	freebsd32	freebsd64	AArch64: freebsd-aarch64
OpenBSD	openbsd32	openbsd64

For GHC, the distinguishing 'Version' in the key format includes a 'tag' for any (optional) GHC variant (see ghc-variant) and a further 'tag' for any (optional) specialised GHC build (see ghc-build).

The optional variant 'tag' is either -integersimple or -custom-<custom_variant_name>.

For example, for GHC 9.0.2 of specialised GHC build tinfo6 on x86_64 Linux:

setup-info:
  ghc:
    linux64-tinfo6:
      9.0.2:
        url: "http://downloads.haskell.org/~ghc/9.0.2/ghc-9.0.2a-x86_64-fedora27-linux.tar.xz"
        content-length: 237286244
        sha1: affc2aaa3e6a1c446698a884f56a0a13e57f00b4
        sha256: b2670e9f278e10355b0475c2cc3b8842490f1bca3c70c306f104aa60caff37b0

On Windows, the required 7z executable and DLL tools are represented in the format of the setup-info key simply by sevenzexe-info and sevenzdll-info.

This configuration adds the specified setup information metadata to the default. Specifying this configuration does not prevent the default stack-setup-2.yaml from being consulted as a fallback. If, however, you need to replace the default setup-info dictionary, use the following:

setup-info-locations: []

setup-info-locations

(Since 2.3)

By way of introduction, see the setup-info option. This option specifies the location(s) of setup-info dictionaries.

The first location which provides a dictionary that specifies the location of a tool - ('Tool', 'Platform', 'Version') - takes precedence. For example, you can extend the default tools, with a fallback to the default setup-info location, as follows:

setup-info-locations:
- C:/stack-offline/my-stack-setup.yaml
- relative/inside/my/project/setup-info.yaml
- \\smbShare\stack\my-stack-setup.yaml
- http://stack-mirror.com/stack-setup.yaml
# Fallback to the default location
- https://github.com/commercialhaskell/stackage-content/raw/master/stack/stack-setup-2.yaml

Stack only refers to the default setup-info location if no locations are specified in the setup-info-locations configuration or on the command line using the --setup-info-yaml option.

For example, both of the following will cause stack setup not to consult the default setup-info location:

setup-info-locations:
- C:/stack-offline/my-stack-setup.yaml

and

setup-info-locations: []

Relative paths are resolved relative to the stack.yaml file (either the one in the local project or the global stack.yaml).

Relative paths may also be used for the installation paths to tools (such as GHC or 7z). This allows vendoring the tools inside a monorepo (a single respository storing many projects). For example:

Directory structure:

- src/
- installs/
  - my-stack-setup.yaml
  - 7z.exe
  - 7z.dll
  - ghc-9.2.3.tar.xz
- stack.yaml

In the project's stack.yaml:

setup-info-locations:
- installs/my-stack-setup.yaml

In installs/my-stack-setup.yaml:

sevenzexe-info:
  url: "installs/7z.exe"

sevenzdll-info:
  url: "installs/7z.dll"

ghc:
  windows64:
    9.2.3:
      url: "installs/ghc-9.2.3.tar.xz"

skip-ghc-check

Default: false

Should we skip the check to confirm that your system GHC version (on the PATH) matches what your project expects?

skip-msys

(Since 0.1.2.0)

Default: false

Restrictions: Windows systems only

Skips checking for and installing MSYS2 when stack is Setting up the environment. This usually doesn't make sense in project-level configurations, just in config.yaml.

skip-msys: true

snapshot-location-base

(Since 2.5.0)

Default: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/ (as set in the pantry library)

Sets the base location of the LTS Haskell or Stackage Nightly snapshots.

For example:

snapshot-location-base: https://example.com/snapshots/location/

has the following effect:

lts-X.Y expands to https://example.com/snapshots/location/lts/X/Y.yaml
nightly-YYYY-MM-DD expands to https://example.com/snapshots/location/nightly/YYYY/M/D.yaml

This key is convenient in setups that restrict access to GitHub, for instance closed corporate setups. In this setting, it is common for the development environment to have general access to the internet, but not for testing/building environments. To avoid the firewall, one can run a local snapshots mirror and then use a custom snapshot-location-base in the closed environments only.

stack-colors

Stack uses styles to format some of its output. The default styles do not work well with every terminal theme. This option specifies Stack's output styles, allowing new styles to replace the defaults. The option is used as stack-colors: <STYLES>, where <STYLES> is a colon-delimited sequence of key=value, 'key' is a style name and 'value' is a semicolon-delimited list of 'ANSI' SGR (Select Graphic Rendition) control codes (in decimal). Use the command stack ls stack-colors --basic to see the current sequence.

The 'ANSI' standards refer to (1) standard ECMA-48 'Control Functions for Coded Character Sets' (5th edition, 1991); (2) extensions in ITU-T Recommendation (previously CCITT Recommendation) T.416 (03/93) 'Information Technology – Open Document Architecture (ODA) and Interchange Format: Character Content Architectures' (also published as ISO/IEC International Standard 8613-6); and (3) further extensions used by 'XTerm', a terminal emulator for the X Window System. The 'ANSI' SGR codes are described in a Wikipedia article and those codes supported on current versions of Windows in Microsoft's documentation.

For example, users of the popular Solarized Dark terminal theme might wish to set the styles as follows:

stack-colors: error=31:good=32:shell=35:dir=34:recommendation=32:target=95:module=35:package-component=95:secondary=92:highlight=32

The styles can also be set at the command line using the equivalent --stack-colors=<STYLES> global option. Styles set at the command line take precedence over those set in a YAML configuration file. (In respect of styles used in verbose output, some of that output occurs before the configuration file is processed.)

(The British English spelling (colour) is also accepted. In YAML configuration files, the American spelling is the alternative that has priority.)

stack-developer-mode

(Since 2.3.3)

Default (official distributed binaries): false

Default (built from source): true

Turns on a mode where some messages are printed at WARN level instead of DEBUG level, especially useful for developers of Stack itself.

stack-developer-mode: false

system-ghc

Default: false, unless the Docker or Nix integration is enabled.

Enables or disables using the GHC available on the PATH. (Make sure PATH is explicit, i.e., don't use ~.) Useful to enable if you want to save the time, bandwidth or storage space needed to setup an isolated GHC.

In a Nix-enabled configuration, Stack is incompatible with system-ghc: false.

# Turn on system GHC
system-ghc: true

templates

Templates used with stack new have a number of parameters that affect the generated code. These can be set for all new projects you create. The result of them can be observed in the generated LICENSE and Cabal files. The value for all of these parameters must be strings.

The parameters are: author-email, author-name, category, copyright, year and github-username.

author-email - sets the maintainer property in Cabal
author-name - sets the author property in Cabal and the name used in LICENSE
category - sets the category property in Cabal. This is used in Hackage. For examples of categories see Packages by category. It makes sense for category to be set on a per project basis because it is uncommon for all projects a user creates to belong to the same category. The category can be set per project by passing -p "category:value" to the stack new command.
copyright - sets the copyright property in Cabal. It is typically the name of the holder of the copyright on the package and the year(s) from which copyright is claimed. For example: Copyright (c) 2006-2007 Joe Bloggs
year - if copyright is not specified, year and author-name are used to generate the copyright property in Cabal. If year is not specified, it defaults to the current year.
github-username - used to generate homepage and source-repository in Cabal. For instance github-username: myusername and stack new my-project new-template would result:

homepage: http://github.com/myusername/my-project#readme

source-repository head
  type: git
  location: https://github.com/myusername/my-project

These properties can be set in config.yaml as follows:

templates:
  params:
    author-name: Your Name
    author-email: youremail@example.com
    category: Your Projects Category
    copyright: 'Copyright (c) 2022 Your Name'
    github-username: yourusername

Additionally, stack new can automatically initialize source control repositories in the directories it creates. Source control tools can be specified with the scm-init option. At the moment, only git is supported.

templates:
  scm-init: git

urls

Default:

urls:
  latest-snapshot: https://www.stackage.org/download/snapshots.json

Customize the URLs where Stack looks for snapshot build plans.

with-gcc

Specify a path to GCC explicitly, rather than relying on the normal path resolution.

with-gcc: /usr/local/bin/gcc-5

with-hpack

Use an Hpack executable, rather than Stack's in-built version of the Hpack functionality.

with-hpack: /usr/local/bin/hpack

work-dir

(Since 0.1.10.0)

Default: .stack-work

This key specifies the relative path of Stack's 'work' directory. This can also be specified by an environment variable or on the command line. The earlier items in the list below take precedence:

--work-dir DIR passed on the command line
work-dir in a YAML configuration file
STACK_WORK environment variable

Customisation

GHC installation customisation (experimental)

On Unix-like operating systems and Windows, Stack's installation procedure can be fully customised by placing a sh shell script (a 'hook') in the Stack root directory at hooks/ghc-install.sh. On Unix-like operating systems, the script file must be made executable. The script is run by the sh application (which is provided by MSYS2 on Windows).

The script must return an exit code of 0 and the standard output must be the absolute path to the GHC binary that was installed. Otherwise Stack will ignore the script and possibly fall back to its own installation procedure.

The script is not run when system-ghc: true.

When install-ghc: false, the script is still run, which allows you to ensure that only your script will install GHC and Stack won't default to its own installation logic, even when the script fails.

An example script is:

#!/bin/sh

set -eu

case $HOOK_GHC_TYPE in
	bindist)
		# install GHC here, not printing to stdout, e.g.:
		#   command install $HOOK_GHC_VERSION >/dev/null
		;;
	git)
		>&2 echo "Hook doesn't support installing from source"
		exit 1
		;;
	*)
		>&2 echo "Unsupported GHC installation type: $HOOK_GHC_TYPE"
		exit 2
		;;
esac

echo "location/to/ghc/executable"

The following environment variables are always available to the script:

HOOK_GHC_TYPE = "bindist" | "git" | "ghcjs"

For "bindist", additional variables are:

HOOK_GHC_VERSION = <ver>

For "git", additional variables are:

HOOK_GHC_COMMIT = <commit>
HOOK_GHC_FLAVOR = <flavor>

For "ghcjs", additional variables are:

HOOK_GHC_VERSION = <ver>
HOOK_GHCJS_VERSION = <ver>

Since 2.7.x

Files

yaml_configuration.md

Latest commit

History

yaml_configuration.md

File metadata and controls

YAML configuration

Project-specific configuration

resolver or snapshot

packages

extra-deps

flags

drop-packages

user-message

custom-preprocessor-extensions

Non-project-specific configuration

allow-different-user

allow-newer

apply-ghc-options

arch

build

color

compiler

Building GHC from source (experimental)

Global packages

Bootstrapping compiler

compiler-check

concurrent-tests

configure-options

connection-count

default-template

docker

dump-logs

extra-include-dirs

extra-lib-dirs

extra-path

ghc-build

ghc-options

ghc-variant

hackage-base-url

hide-source-paths

hide-th-loading

ignore-revision-mismatch

install-ghc

jobs

local-bin-path

local-programs-path

modify-code-page

nix

os

package-indices

pvp-bounds

recommend-stack-upgrade

rebuild-ghc-options

require-stack-version

save-hackage-creds

setup-info

setup-info-locations

skip-ghc-check

skip-msys

snapshot-location-base

stack-colors

stack-developer-mode

system-ghc

templates

urls

with-gcc

with-hpack

work-dir

Customisation

GHC installation customisation (experimental)