# YAML Configuration This page is intended to fully document all configuration options available in the stack.yaml file. Note that this page is likely to be both *incomplete* and sometimes *inaccurate*. If you see such cases, please update the page, and if you're not sure how, open an issue labeled "question". The stack.yaml configuration options break down into [project-specific](#project-specific-config) options in: - `/stack.yaml` and [non-project-specific](#non-project-specific-config) options in: - `/etc/stack/config.yaml` -- for system global non-project default options - `~/.stack/config.yaml` -- for user non-project default options - The project file itself may also contain non-project specific options *Note:* When stack is invoked outside a stack project it will source project specific options from `~/.stack/global-project/stack.yaml`. When stack is invoked inside a stack project, only options from `/stack.yaml` are used, and `~/.stack/global-project/stack.yaml` is ignored. *Note 2:* A common source of confusion is the distinction between configuration in a `stack.yaml` file versus a cabal file. If you're trying to understand this breakdown, see [stack vs cabal config](stack_yaml_vs_cabal_package_file.md). ## Project-specific config Project-specific options are only valid in the `stack.yaml` file local to a project, not in the user or global config files. > 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 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](http://docs.haskellstack.org/en/stable/architecture/#shadowing), 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 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-2.14` * Stackage Nightly snapshot, e.g. `resolver: nightly-2015-06-16` * No snapshot, just use packages shipped with the compiler * For GHC this looks like `resolver: ghc-7.10.2` * For GHCJS this looks like `resolver: ghcjs-0.1.0_ghc-7.10.2`. * [Custom snapshot](custom_snapshot.md) Each of these resolvers will also determine what constraints are placed on the compiler version. See the [compiler-check](#compiler-check) option for some additional control over compiler version. ### packages and extra-deps _NOTE_ The contents of this section have changed significantly since extensible snapshots were implemented (see: [writeup](https://www.fpcomplete.com/blog/2017/07/stacks-new-extensible-snapshots) and [PR #3249](https://github.com/commercialhaskell/stack/pull/3249)). Most old syntax is still supported with newer versions of Stack, but will not be documented here. Instead, this section contains the recommended syntax as of Stack v1.6.0. There are two types of packages that can be defined in your `stack.yaml` file: * __Project packages__, those which you are actually working on in your current project. These are local file paths in your project directory. * __Extra dependencies__, which are packages provided locally on top of the snapshot definition of available packages. These can come from Hackage (or an alternative package index you've defined, see [package-indices](#package-indices)), an HTTP(S) or local archive, a Git or Mercurial repository, or a local file path. These two sets of packages are both installed into your local package database within your project. However, beyond that, they are completely different: * Project packages will be built by default with a `stack build` without specific targets. Extra 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. The `packages` key is a simple list of file paths, which will be treated as relative to the directory containing your `stack.yaml` file. For example: ```yaml packages: - . - dir1/dir2 ``` Each package directory or location specified must have a valid cabal file or hpack `package.yaml` file present. Note that 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. When the `packages` field is not present, it defaults to looking for a package in the project's root directory: ```yaml packages: - . ``` The `extra-deps` key is given a list of all extra dependencies. If omitted, it is taken as the empty list, e.g.: ```yaml extra-deps: [] ``` It supports four different styles of values: #### Package index Packages can be stated by a name/version combination, which will be looked up in the package index (by default, Hackage). The basic syntax for this is: ```yaml extra-deps: - acme-missiles-0.3 ``` Using this syntax, the most recent Cabal file revision available will be used. For more reproducibility of builds, it is recommended to state the SHA256 hash of the cabal file contents as well, like this: ```yaml extra-deps: - acme-missiles-0.3@sha256:2ba66a092a32593880a87fb00f3213762d7bca65a687d45965778deb8694c5d1 ``` Or a specific revision number, with `0` being the original file: ```yaml extra-deps: - acme-missiles-0.3@rev:0 ``` Note that specifying via SHA256 is slightly more resilient in that it does not rely on correct ordering in the package index, while revision number is likely simpler to use. In practice, both should guarantee equally reproducible build plans. #### Local file path Like `packages`, local file paths can be used in `extra-deps`, and will be relative to the directory containing the `stack.yaml` file. ```yaml extra-deps: - vendor/somelib ``` Note that if a local directory can be parsed as a package identifier, Stack will treat it as a package identifier. In other words, if you have a local directory named `foo-1.2.3`, instead of: ```yaml extra-deps: - foo-1.2.3 ``` You should use the following to be explicit: ```yaml extra-deps: - ./foo-1.2.3 ``` #### Git and Mercurial repos You can give a Git or Mercurial repo at a specific commit, and Stack will clone that repo. ```yaml extra-deps: - git: git@github.com:commercialhaskell/stack.git commit: 6a86ee32e5b869a877151f74064572225e1a0398 - git: git@github.com:snoyberg/http-client.git commit: "a5f4f3" - hg: https://example.com/hg/repo commit: da39a3ee5e6b4b0d3255bfef95601890afd80709 ``` __NOTE__ It is highly recommended that you only use SHA1 values for a Git or Mercurial commit. Other values may work, but they are not officially supported, and may result in unexpected behavior (namely, Stack will not automatically pull to update to new versions). Another problem with this is that your build will not be deterministic, because when someone else tries to build the project they can get a different checkout of the package. A common practice in the Haskell world is to use "megarepos", or repositories with multiple packages in various subdirectories. Some common examples include [wai](https://github.com/yesodweb/wai/) and [digestive-functors](https://github.com/jaspervdj/digestive-functors). To support this, you may also specify `subdirs` for repositories, e.g.: ```yaml extra-deps: - git: git@github.com:yesodweb/wai commit: 2f8a8e1b771829f4a8a77c0111352ce45a14c30f subdirs: - auto-update - wai ``` Since v1.7.1, you can specify packages from GitHub repository name using `github`: ```yaml extra-deps: - github: snoyberg/http-client commit: a5f4f30f01366738f913968163d856366d7e0342 ``` If unspecified, `subdirs` defaults to `['.']` meaning looking for a package in the root of the repo.. Note that if you specify a value of `subdirs`, then `'.'` is _not_ included by default and needs to be explicitly specified if a required package is found in the top-level directory of the repository. #### Archives (HTTP(S) or local filepath) This one's pretty straightforward: you can use HTTP and HTTPS URLs and local filepaths referring to either tarballs or ZIP files. __NOTE__ Stack assumes that these files never change after downloading to avoid needing to make an HTTP request on each build. ```yaml extra-deps: - https://example.com/foo/bar/baz-0.0.2.tar.gz - archive: http://github.com/yesodweb/wai/archive/2f8a8e1b771829f4a8a77c0111352ce45a14c30f.zip subdirs: - wai - warp - archive: ../acme-missiles-0.3.tar.gz sha256: e563d8b524017a06b32768c4db8eff1f822f3fb22a90320b7e414402647b735b ``` Note that HTTP(S) URLs also support `subdirs` like repos to allow for archives of megarepos. In order to leverage this, use `location: http://...`. ### flags Flags can be set for each package separately, e.g. ```yaml 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. ### image The image settings are used for the creation of container images using `stack image container`, e.g. ```yaml image: containers: - base: "fpco/stack-build" add: static: /data/static ``` `base` is the docker image that will be used to built upon. The `add` lines allow you to add additional directories to your image. You can specify the name of the image using `name` (otherwise it defaults to the same as your project). You can also specify `entrypoints`. By default all your executables are placed in `/usr/local/bin`, but you can specify a list using `executables` to only add some. When you specify `entrypoints`, multiple containers will be built: a project container, and one container for each entrypoint. For example the following configuration: ```yaml image: containers: - name: myproject base: fpco/stack-run add: production/app-backend/conf/: /etc/app-backend entrypoints: - app-backend ``` will build one container tagged `myproject:latest` which contains the project including the `/etc/app-backend` configuration data. Another container tagged `myproject-app-backend:latest` based on the `myproject:latest` will additionally contain the logic for starting the `app-backend` entrypoint. ### user-message A user-message is inserted by `stack init` when it omits packages or adds external dependencies. For example: ```yaml 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 ' ``` This messages is displayed every time the config is loaded by stack and serves 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. ## Non-project-specific config Non-project config options may go in the global config (`/etc/stack/config.yaml`) or the user config (`~/.stack/config.yaml`). ### docker See [Docker integration](docker_integration.md#configuration). ### nix (since 0.1.10.0) See [Nix integration](nix_integration.md#configuration). ### connection-count Integer indicating how many simultaneous downloads are allowed to happen Default: `8` ### hide-th-loading Strip out the "Loading ..." lines from GHC build output, produced when using Template Haskell Default: `true` ### latest-snapshot-url URL providing a JSON with information on the latest LTS and Nightly snapshots, used for automatic project configuration. Default: `https://www.stackage.org/download/snapshots.json` ### local-bin-path Target directory for `stack install` and `stack build --copy-bins`. Default: `~/.local/bin` ### package-indices ```yaml package-indices: - name: Hackage download-prefix: https://s3.amazonaws.com/hackage.fpcomplete.com/package/ # HTTP location of the package index http: https://s3.amazonaws.com/hackage.fpcomplete.com/01-index.tar.gz # Or, if using Hackage Security below, give the root URL: http: https://s3.amazonaws.com/hackage.fpcomplete.com/ # optional fields, both default to false require-hashes: false # Starting with stack 1.4, we default to using Hackage Security hackage-security: keyids: ["deadbeef", "12345"] # list of all approved keys key-threshold: 3 # number of keys required ``` One thing you should be aware of: if you change the contents of package-version combination by setting a different package index, this *can* have an effect on other projects by installing into your shared snapshot database. Note that older versions of Stack supported Git-based indices. This feature has since been removed. A line such as: ```yaml git: https://github.com/commercialhaskell/all-cabal-hashes.git gpg-verify: false ``` Will now be ignored. __IMPORTANT__ Hackage and its mirrors typically have two index files available: `00-index.tar.gz` and `01-index.tar.gz`. The former is a legacy file for backwards compatibility. It does not contain the cabal file revisions produced by Hackage, and therefore _will not work_ with most snapshots. Instead, you need to use `01-index.tar.gz` to ensure that exact revisions can be found, ensuring more reproducible builds. ### system-ghc Enables or disables using the GHC available on the PATH. Useful to enable if you want to save the time, bandwidth or storage space needed to setup an isolated GHC. Default is `false` unless the [Docker](docker_integration.md) or [Nix](nix_integration.md) integration is enabled. In a Nix-enabled configuration, stack is incompatible with `system-ghc: false`. ```yaml # Turn on system GHC system-ghc: true ``` ### install-ghc Whether or not to automatically install GHC when necessary. Since Stack 1.5.0, the default is `true`, which means Stack will not ask you before downloading and installing GHC. ### skip-ghc-check Should we skip the check to confirm that your system GHC version (on the PATH) matches what your project expects? Default is `false`. ### require-stack-version Require a version of stack within the specified range ([cabal-style](https://www.haskell.org/cabal/users-guide/developing-packages.html#build-information)) to be used for this project. Example: `require-stack-version: "== 0.1.*"` Default: `"-any"` ### arch/os Set the architecture and operating system for GHC, build directories, etc. Values are those recognized by Cabal, e.g.: arch: i386, x86_64 os: windows, linux You likely only ever want to change the arch value. This can also be set via the command line. ### extra-include-dirs/extra-lib-dirs A list of extra paths to be searched for header files and libraries, respectively. Paths should be absolute ```yaml extra-include-dirs: - /opt/foo/include extra-lib-dirs: - /opt/foo/lib ``` Since these are system-dependent absolute paths, it is recommended that you specify these in your `config.yaml` within the stack root (usually, `~/.stack`). 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. ### with-gcc Specify a path to gcc explicitly, rather than relying on the normal path resolution. ```yaml with-gcc: /usr/local/bin/gcc-5 ``` ### with-hpack Use an Hpack executable, rather than using the bundled Hpack. ```yaml with-hpack: /usr/local/bin/hpack ``` ### compiler-check (Since 0.1.4) 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. This is the default * `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 ### 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-7.10.2` or `ghcjs-0.1.0.20150924_ghc-7.10.2` (version used for the 'old-base' version of GHCJS). While it's useful to override the compiler for a variety of reasons, the main usecase is to use GHCJS with a stackage snapshot, like this: ```yaml resolver: lts-3.10 compiler: ghcjs-0.1.0.20150924_ghc-7.10.2 compiler-check: match-exact ``` ### ghc-options (Since 0.1.4) Allows specifying per-package and global GHC options: ```yaml ghc-options: # All packages "$locals": -Wall "$targets": -Werror "$everything": -O2 some-package: -DSOME_CPP_FLAG ``` Since 1.6.0, setting a GHC options for a specific package will automatically promote it to a local package (much like setting a custom package flag). However, setting options via `$everything` on all flags will not do so (see [Github discussion](https://github.com/commercialhaskell/stack/issues/849#issuecomment-320892095) for reasoning). This can lead to unpredictable behavior by affecting your snapshot packages. The behavior of the `$locals`, `$targets`, and `$everything` special keys mirrors the behavior for the [`apply-ghc-options` setting](#apply-ghc-options), which affects command line parameters. NOTE: Prior to version 1.6.0, the `$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. ### apply-ghc-options (Since 0.1.6) Which packages do ghc-options on the command line get applied to? Before 0.1.6, the default value was `targets` ```yaml apply-ghc-options: locals # all local packages, the default # 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. ### rebuild-ghc-options (Since 0.1.6) Should we rebuild a package when its GHC options change? Before 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: ```yaml rebuild-ghc-options: true ``` ### ghc-variant (Since 0.1.5) Specify a variant binary distribution of GHC to use. Known values: * `standard`: This is the default, uses the standard GHC binary distribution * `integersimple`: Use a GHC bindist that uses [integer-simple instead of GMP](https://ghc.haskell.org/trac/ghc/wiki/ReplacingGMPNotes) * any other value: Use a custom GHC bindist. You should specify [setup-info](#setup-info) 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`. ### 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`, `tinfo6`, and `nopie`. ### setup-info (Since 0.1.5) Allows overriding from where tools like GHC and msys2 (on Windows) are downloaded. Most useful for specifying locations of custom GHC binary distributions (for use with the [ghc-variant](#ghc-variant) option): ```yaml setup-info: ghc: windows32-custom-foo: 7.10.2: url: "https://example.com/ghc-7.10.2-i386-unknown-mingw32-foo.tar.xz" ``` Or without using `ghc-variant`: ```yaml setup-info: "https://raw.githubusercontent.com/fpco/stackage-content/master/stack/stack-setup-2.yaml" ``` `url` may be either URL or (since 1.2.0) absolute file path. ### 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. See [#3550](https://github.com/commercialhaskell/stack/issues/3550) for more information. 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`) ```yaml pvp-bounds: none ``` For more information, see [the announcement blog post](https://www.fpcomplete.com/blog/2015/09/stack-pvp). __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](http://www.snoyman.com/blog/2017/04/stackages-no-revisions-field)—as a method to ensure PVP compliance without having to proactively fix bounds issues for Stackage maintenance. ### modify-code-page (Since 0.1.6) Modify the code page for UTF-8 output when running on Windows. Default behavior is to modify. ```yaml modify-code-page: false ``` ### explicit-setup-deps (Since 0.1.6) Decide whether a custom `Setup.hs` script should be run with an explicit list of dependencies, based on the dependencies of the package itself. It associates the name of a local package with a boolean. When it's `true`, the `Setup.hs` script is built with an explicit list of packages. When it's `false` (default), the `Setup.hs` script is built without access to the local DB, but can access any package in the snapshot / global DB. Note that in the future, this will be unnecessary, once Cabal provides full support for explicit Setup.hs dependencies. ```yaml explicit-setup-deps: "*": true # change the default entropy: false # override the new default for one package ``` NOTE: since 1.4.0, Stack has support for Cabal's `custom-setup` block (introduced in Cabal 1.24). If a `custom-setup` block is provided in a `.cabal` file, it will override the setting of `explicit-setup-deps`, and instead rely on the stated dependencies. ### allow-newer (Since 0.1.7) Ignore version bounds in .cabal files. Default is false. ```yaml allow-newer: true ``` Note that this also ignores lower bounds. The name "allow-newer" is chosen to match the commonly used cabal option. ### allow-different-user (Since 1.0.1) Allow users other than the owner of the stack root directory (typically `~/.stack`) to use the stack installation. The default is `false`. POSIX systems only. ```yaml 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. ### build (Since 1.1.0) Allows setting build options which are usually specified on the CLI. Here are the settings with their defaults: ```yaml 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 CLI 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 interleaved-output: false ``` The meanings of these settings correspond directly with the CLI flags of the same name. See the [build command docs](build_command.md) and the [users guide](GUIDE.md#the-build-command) for more info. ### dump-logs (Since 1.3.0) 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. ```yaml dump-logs: none # don't dump logs even if they contain warnings dump-logs: warning # default: dump logs that contain warnings dump-logs: all # dump all logs for local non-dependency packages ``` ### 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](https://hackage.haskell.org/packages/). 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: ```yaml 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: ```yaml templates: params: author-name: Your Name author-email: youremail@example.com category: Your Projects Category copyright: 'Copyright (c) 2018 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. ```yaml templates: scm-init: git ``` ### save-hackage-creds Controls whether, when using `stack upload`, the user's Hackage username and password are stored in a local file. Default: true. ```yaml save-hackage-creds: true ``` Since 1.5.0 ### hackage-base-url Sets the address of the Hackage server to upload the package to. Default is `https://hackage.haskell.org/`. ```yaml hackage-base-url: https://hackage.example.com/ ``` Since 1.9.1 ### ignore-revision-mismatch Cabal files in packages can be specified via exact revisions to deal with Hackage revision metadata. The default behavior of Stack (since 1.6.0) is to fail if an exact match is not found. In some cases (specifically, when using a legacy `00-index.tar.gz` file), users may wish to allow a mismatch. In such cases, you can change `ignore-revision-mismatch` from `false` to `true`. ```yaml ignore-revision-mismatch: false ``` For more information, see [the Github issue #3520 discussion](https://github.com/commercialhaskell/stack/issues/3520). Since 1.6.0 ### urls Customize the URLs where `stack` looks for snapshot build plans. The default configuration is ```yaml urls: latest-snapshot: https://www.stackage.org/download/snapshots.json lts-build-plans: https://raw.githubusercontent.com/fpco/lts-haskell/master/ nightly-build-plans: https://raw.githubusercontent.com/fpco/stackage-nightly/master/ ``` **Note:** The `latest-snapshot-url` field has been deprecated in favor of `latest-snapshot` and will be removed in a future version of `stack`. ### jobs Specifies how many build tasks should be run in parallel. This can be overloaded on the commandline via `-jN`, for example `-j2`. The default is to use the number of processors reported by your CPU. One usage for this might be to avoid running out of memory by setting it to 1, like this: ```yaml jobs: 1 ``` ### work-dir Specifies relative path of work directory (default is `.stack-work`. This can also be specified by env var or cli flag, in particular, the earlier items in this list take precedence: 1. `--work-dir DIR` passed on the commandline 2. `work-dir` in stack.yaml 3. `STACK_WORK` environment variable Since 0.1.10.0 ### skip-msys Skips checking for and installing msys2 when stack is setting up the environment. This is only useful on Windows machines, and usually doesn't make sense in project configurations, just in `config.yaml`. Defaults to `false`, so if this is used, it only really makes sense to use it like this: ```yaml skip-msys: true ``` Since 0.1.2.0 ### concurrent-tests This option specifies whether test-suites should be executed concurrently with each-other. The default for this 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` (the default is `true`). ```yaml concurrent-tests: false ``` Since 0.1.2.0 ### extra-path This option specifies additional directories to prepend to the PATH environment variable. These will be used when resolving the location of executables, and will also be visible in the `PATH` variable of processes run by stack. For example, to prepend `/path-to-some-dep/bin` to your PATH: ```yaml extra-path: - /path-to-some-dep/bin ``` One thing to note is that other paths added by stack - things like the project's bin dir and the compiler's bin dir - will take precedence over those specified here (the automatic paths get prepended). Since 0.1.4.0 ### local-programs-path This overrides the location of the programs directory, where tools like ghc and msys get installed. On most systems, this defaults to a folder called `programs` within the stack root directory. On windows, if the `LOCALAPPDATA` environment variable exists, then it defaults to `$LOCALAPPDATA/Programs/stack/`, which follows windows conventions. Since 1.3.0 ### default-template This option specifies which template to use with `stack new`, when none is specified. The default is called `new-template`. The other templates are listed in [the stack-templates repo](https://github.com/commercialhaskell/stack-templates/). ### 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: `, where `` 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](http://en.wikipedia.org/wiki/ANSI_escape_code) and those codes supported on current versions of Windows in [Microsoft's documentation](https://docs.microsoft.com/en-us/windows/console/console-virtual-terminal-sequences). For example, users of the popular [Solarized Dark](https://ethanschoonover.com/solarized/) terminal theme might wish to set the styles as follows: ```yaml stack-colors: error=31:good=32:shell=35:dir=34:recommendation=32:target=95:module=35:package-component=95 ``` The styles can also be set at the command line using the equivalent `--stack-colors=` global option. Styles set at the command line take precedence over those set in a yaml configuration file.