Advanced environment configuration¶

Context formatting¶

All environments support the following extra context formatting fields:

Field	Description
`env_name`	The name of the environment
`env_type`	The type of environment
`matrix`	Its modifier selects the value of that matrix variable. If the environment is not part of a matrix or was not generated with the variable, you must specify a default value as an additional modifier e.g. `{matrix:version:v1.0.0}`.
`verbosity`	The integer verbosity value of Hatch. A `flag` modifier is supported that will render the value as a CLI flag e.g. `-2` becomes `-qq`, `1` becomes `-v`, and `0` becomes an empty string. An additional flag integer modifier may be used to adjust the verbosity level. For example, if you wanted to make a command quiet by default, you could use `{verbosity:flag:-1}` within the command.
`args`	For executed commands only, any extra command line arguments with an optional default modifier if none were provided

Matrix¶

Environments can define a series of matrices with the matrix option:

pyproject.toml hatch.toml

[tool.hatch.envs.test]
dependencies = [
  "pytest"
]

[[tool.hatch.envs.test.matrix]]
python = ["3.10", "3.11"]
version = ["42", "3.14"]

[[tool.hatch.envs.test.matrix]]
python = ["3.11", "3.12"]
version = ["9000"]
feature = ["foo", "bar"]

[envs.test]
dependencies = [
  "pytest"
]

[[envs.test.matrix]]
python = ["3.10", "3.11"]
version = ["42", "3.14"]

[[envs.test.matrix]]
python = ["3.11", "3.12"]
version = ["9000"]
feature = ["foo", "bar"]

Doing so will result in the product of each variable combination being its own environment.

Naming¶

The name of the generated environments will be the variable values of each combination separated by hyphens, altogether prefixed by <ENV_NAME>.. For example, the following configuration:

pyproject.toml hatch.toml

[[tool.hatch.envs.test.matrix]]
version = ["42"]
feature = ["foo", "bar"]

[[envs.test.matrix]]
version = ["42"]
feature = ["foo", "bar"]

would indicate the following unique environments:

test.42-foo
test.42-bar

The exceptions to this format are described below.

Python variables¶

If the variables py or python are specified, then they will rank first in the product result and will be prefixed by py if the value is not. For example, the following configuration:

pyproject.toml hatch.toml

[[tool.hatch.envs.test.matrix]]
version = ["42"]
python = ["3.9", "pypy3"]

[[envs.test.matrix]]
version = ["42"]
python = ["3.9", "pypy3"]

would generate the following environments:

test.py3.9-42
test.pypy3-42

Note

The value of this variable sets the Python version.

Name formatting¶

You can set the matrix-name-format option to modify how each variable part is formatted which recognizes the placeholders {variable} and {value}. For example, the following configuration:

pyproject.toml hatch.toml

[tool.hatch.envs.test]
matrix-name-format = "{variable}_{value}"

[[tool.hatch.envs.test.matrix]]
version = ["42"]
feature = ["foo", "bar"]

[envs.test]
matrix-name-format = "{variable}_{value}"

[[envs.test.matrix]]
version = ["42"]
feature = ["foo", "bar"]

would produce the following environments:

test.version_42-feature_foo
test.version_42-feature_bar

By default this option is set to {value}.

Default environment¶

If the default environment defines matrices, then the generated names will not be prefixed by the environment name. This can be useful for projects that only need a single series of matrices without any standalone environments.

Selection¶

Rather than selecting a single generated environment, you can select the root environment to target all of them. For example, if you have the following configuration:

pyproject.toml hatch.toml

[tool.hatch.envs.test]
dependencies = [
  "coverage[toml]",
  "pytest",
  "pytest-cov",
]

[tool.hatch.envs.test.scripts]
cov = 'pytest --cov-report=term-missing --cov-config=pyproject.toml --cov=pkg --cov=tests'

[[tool.hatch.envs.test.matrix]]
python = ["3.11", "3.12"]
version = ["42", "3.14"]

[envs.test]
dependencies = [
  "coverage[toml]",
  "pytest",
  "pytest-cov",
]

[envs.test.scripts]
cov = 'pytest --cov-report=term-missing --cov-config=pyproject.toml --cov=pkg --cov=tests'

[[envs.test.matrix]]
python = ["3.11", "3.12"]
version = ["42", "3.14"]

you could then run your tests consecutively in all 4 environments with:

hatch run test:cov

Option overrides¶

You can modify options based on the conditions of different sources like matrix variables with the overrides table, using dotted key syntax for each declaration:

pyproject.toml hatch.toml

[tool.hatch.envs.<ENV_NAME>.overrides]
<SOURCE>.<CONDITION>.<OPTION> = <VALUE>

[envs.<ENV_NAME>.overrides]
<SOURCE>.<CONDITION>.<OPTION> = <VALUE>

The type of the selected option determines the types of values.

Platform overrides¶

Options can be modified based on the current platform using the platform source.

pyproject.toml hatch.toml

[tool.hatch.envs.test.overrides]
platform.windows.scripts = [
  'run=pytest -m "not io_uring"',
]

[envs.test.overrides]
platform.windows.scripts = [
  'run=pytest -m "not io_uring"',
]

The following platforms are supported:

linux
windows
macos

Environment variable overrides¶

Environment variables can modify options using the env source.

pyproject.toml hatch.toml

[tool.hatch.envs.test.overrides]
env.GITHUB_ACTIONS.dev-mode = { value = false, if = ["true"] }

[envs.test.overrides]
env.GITHUB_ACTIONS.dev-mode = { value = false, if = ["true"] }

Matrix variable overrides¶

The matrix variables used to generate each environment can be used to modify options within using the matrix source.

pyproject.toml hatch.toml

[tool.hatch.envs.test.overrides]
matrix.version.env-vars = "PRODUCT_VERSION"
matrix.auth.features = [
  { value = "oauth", if = ["oauth2"] },
  { value = "kerberos", if = ["kerberos"] },
]

[[tool.hatch.envs.test.matrix]]
python = ["3.11", "3.12"]
version = ["legacy", "latest"]
auth = ["oauth2", "kerberos", "noauth"]

[envs.test.overrides]
matrix.version.env-vars = "PRODUCT_VERSION"
matrix.auth.features = [
  { value = "oauth", if = ["oauth2"] },
  { value = "kerberos", if = ["kerberos"] },
]

[[envs.test.matrix]]
python = ["3.11", "3.12"]
version = ["legacy", "latest"]
auth = ["oauth2", "kerberos", "noauth"]

Name overrides¶

When a matrix is defined, the name source can be used for regular expression matching on the generated name, minus the prefix for non-default environments.

pyproject.toml hatch.toml

[tool.hatch.envs.test.overrides]
name."^0".env-vars = "TESTING_UNSTABLE=true"

[[tool.hatch.envs.test.matrix]]
version = ["0.1.0", "0.2.0", "1.0.0"]

[envs.test.overrides]
name."^0".env-vars = "TESTING_UNSTABLE=true"

[[envs.test.matrix]]
version = ["0.1.0", "0.2.0", "1.0.0"]

Types¶

Literal types like strings for the Python version or booleans for skipping installation can be set using the value itself, an inline table, or an array. For example:

pyproject.toml hatch.toml

[tool.hatch.envs.test.overrides]
matrix.foo.python = "3.10"
matrix.bar.skip-install = { value = true, if = ["..."] }
env.CI.dev-mode = [
  { value = false, if = ["..."] },
  true,
]

[envs.test.overrides]
matrix.foo.python = "3.10"
matrix.bar.skip-install = { value = true, if = ["..."] }
env.CI.dev-mode = [
  { value = false, if = ["..."] },
  true,
]

For arrays, the first allowed value will be used.

Array types like dependencies or commands can be appended to using an array of strings or inline tables. For example:

pyproject.toml hatch.toml

[tool.hatch.envs.test.overrides]
matrix.foo.dependencies = [
  "httpx",
  { value = "cryptography" },
]

[envs.test.overrides]
matrix.foo.dependencies = [
  "httpx",
  { value = "cryptography" },
]

Mapping types like environment variables or scripts can have keys set using a string, or an array of strings or inline tables. For example:

pyproject.toml hatch.toml

[tool.hatch.envs.test.overrides]
matrix.foo.env-vars = "KEY=VALUE"
matrix.bar.env-vars = [
  "KEY1=VALUE1",
  { key = "KEY2", value = "VALUE2" },
]

[envs.test.overrides]
matrix.foo.env-vars = "KEY=VALUE"
matrix.bar.env-vars = [
  "KEY1=VALUE1",
  { key = "KEY2", value = "VALUE2" },
]

If the value is missing (no = for strings, no value key for inline tables), then the value will be set to the value of the source condition.

Overwriting¶

Rather than supplementing the values within mapping types or array types, you can overwrite the option as a whole by prefixing the name with set-:

pyproject.toml hatch.toml

[tool.hatch.envs.test.overrides]
matrix.foo.set-platforms = ["macos", "linux"]

[envs.test.overrides]
matrix.foo.set-platforms = ["macos", "linux"]

When overwriting entire options or keys within mappings, override sources are applied in the following order:

platform
environment variables
matrix variables
names

Conditions¶

You may specify certain extra keys for any inline table that will determine whether or not to apply that entry. These modifiers may be combined with others and any negative evaluation will immediately cause the entry to be skipped.

Allowed values¶

The if key represents the allowed values for that condition. If the value of the condition is not listed, then that entry will not be applied:

pyproject.toml hatch.toml

[tool.hatch.envs.test.overrides]
matrix.version.python = { value = "pypy", if = ["3.14"] }
matrix.version.env-vars = [
  { key = "KEY1", value = "VALUE1", if = ["42"] },
  { key = "KEY2", value = "VALUE2", if = ["3.14"] },
]

[[tool.hatch.envs.test.matrix]]
version = ["42", "3.14"]

[envs.test.overrides]
matrix.version.python = { value = "pypy", if = ["3.14"] }
matrix.version.env-vars = [
  { key = "KEY1", value = "VALUE1", if = ["42"] },
  { key = "KEY2", value = "VALUE2", if = ["3.14"] },
]

[[envs.test.matrix]]
version = ["42", "3.14"]

Specific platforms¶

The platform key represents the desired platforms. If the current platform is not listed, then that entry will not be applied:

pyproject.toml hatch.toml

[tool.hatch.envs.test.overrides]
env.EXPERIMENTAL.python = { value = "pypy", if = ["1"], platform = ["macos"] }
matrix.version.env-vars = [
  { key = "KEY1", value = "VALUE1", if = ["42"], platform = ["linux"] },
  { key = "KEY2", value = "VALUE2", if = ["3.14"] },
]

[[tool.hatch.envs.test.matrix]]
version = ["42", "3.14"]

[envs.test.overrides]
env.EXPERIMENTAL.python = { value = "pypy", if = ["1"], platform = ["macos"] }
matrix.version.env-vars = [
  { key = "KEY1", value = "VALUE1", if = ["42"], platform = ["linux"] },
  { key = "KEY2", value = "VALUE2", if = ["3.14"] },
]

[[envs.test.matrix]]
version = ["42", "3.14"]

Required environment variables¶

The env key represents the required environment variables. If any of the listed environment variables are not set or the defined value does not match, then that entry will not be applied:

pyproject.toml hatch.toml

[tool.hatch.envs.test.overrides]
platform.windows.python = { value = "pypy", env = ["EXPERIMENTAL"] }
matrix.version.env-vars = [
  { key = "KEY1", value = "VALUE1", if = ["42"], env = ["FOO", "BAR=BAZ"] },
  { key = "KEY2", value = "VALUE2", if = ["3.14"] },
]

[[tool.hatch.envs.test.matrix]]
version = ["42", "3.14"]

[envs.test.overrides]
platform.windows.python = { value = "pypy", env = ["EXPERIMENTAL"] }
matrix.version.env-vars = [
  { key = "KEY1", value = "VALUE1", if = ["42"], env = ["FOO", "BAR=BAZ"] },
  { key = "KEY2", value = "VALUE2", if = ["3.14"] },
]

[[envs.test.matrix]]
version = ["42", "3.14"]