src/doc/src/reference/config.md

   1 ## Configuration
   2
   3 This document explains how Cargo’s configuration system works, as well as
   4 available keys or configuration. For configuration of a package through its
   5 manifest, see the [manifest format](manifest.md).
   6
   7 ### Hierarchical structure
   8
   9 Cargo allows local configuration for a particular package as well as global
  10 configuration. It looks for configuration files in the current directory and
  11 all parent directories. If, for example, Cargo were invoked in
  12 `/projects/foo/bar/baz`, then the following configuration files would be
  13 probed for and unified in this order:
  14
  15 * `/projects/foo/bar/baz/.cargo/config.toml`
  16 * `/projects/foo/bar/.cargo/config.toml`
  17 * `/projects/foo/.cargo/config.toml`
  18 * `/projects/.cargo/config.toml`
  19 * `/.cargo/config.toml`
  20 * `$CARGO_HOME/config.toml` which defaults to:
  21     * Windows: `%USERPROFILE%\.cargo\config.toml`
  22     * Unix: `$HOME/.cargo/config.toml`
  23
  24 With this structure, you can specify configuration per-package, and even
  25 possibly check it into version control. You can also specify personal defaults
  26 with a configuration file in your home directory.
  27
  28 If a key is specified in multiple config files, the values will get merged
  29 together. Numbers, strings, and booleans will use the value in the deeper
  30 config directory taking precedence over ancestor directories, where the
  31 home directory is the lowest priority. Arrays will be joined together.
  32
  33 At present, when being invoked from a workspace, Cargo does not read config
  34 files from crates within the workspace. i.e. if a workspace has two crates in
  35 it, named `/projects/foo/bar/baz/mylib` and `/projects/foo/bar/baz/mybin`, and
  36 there are Cargo configs at `/projects/foo/bar/baz/mylib/.cargo/config.toml`
  37 and `/projects/foo/bar/baz/mybin/.cargo/config.toml`, Cargo does not read
  38 those configuration files if it is invoked from the workspace root
  39 (`/projects/foo/bar/baz/`).
  40
  41 > **Note:** Cargo also reads config files without the `.toml` extension, such as
  42 > `.cargo/config`. Support for the `.toml` extension was added in version 1.39
  43 > and is the preferred form. If both files exist, Cargo will use the file
  44 > without the extension.
  45
  46 ### Configuration format
  47
  48 Configuration files are written in the [TOML format][toml] (like the
  49 manifest), with simple key-value pairs inside of sections (tables). The
  50 following is a quick overview of all settings, with detailed descriptions
  51 found below.
  52
  53 ```toml
  54 paths = ["/path/to/override"] # path dependency overrides
  55
  56 [alias]     # command aliases
  57 b = "build"
  58 c = "check"
  59 t = "test"
  60 r = "run"
  61 rr = "run --release"
  62 space_example = ["run", "--release", "--", "\"command list\""]
  63
  64 [build]
  65 jobs = 1                      # number of parallel jobs, defaults to # of CPUs
  66 rustc = "rustc"               # the rust compiler tool
  67 rustc-wrapper = "…"           # run this wrapper instead of `rustc`
  68 rustc-workspace-wrapper = "…" # run this wrapper instead of `rustc` for workspace members
  69 rustdoc = "rustdoc"           # the doc generator tool
  70 target = "triple"             # build for the target triple (ignored by `cargo install`)
  71 target-dir = "target"         # path of where to place all generated artifacts
  72 rustflags = ["…", "…"]        # custom flags to pass to all compiler invocations
  73 rustdocflags = ["…", "…"]     # custom flags to pass to rustdoc
  74 incremental = true            # whether or not to enable incremental compilation
  75 dep-info-basedir = "…"        # path for the base directory for targets in depfiles
  76
  77 [doc]
  78 browser = "chromium"          # browser to use with `cargo doc --open`,
  79                               # overrides the `BROWSER` environment variable
  80
  81 [env]
  82 # Set ENV_VAR_NAME=value for any process run by Cargo
  83 ENV_VAR_NAME = "value"
  84 # Set even if already present in environment
  85 ENV_VAR_NAME_2 = { value = "value", force = true }
  86 # Value is relative to .cargo directory containing `config.toml`, make absolute
  87 ENV_VAR_NAME_3 = { value = "relative/path", relative = true }
  88
  89 [future-incompat-report]
  90 frequency = 'always' # when to display a notification about a future incompat report
  91
  92 [cargo-new]
  93 vcs = "none"              # VCS to use ('git', 'hg', 'pijul', 'fossil', 'none')
  94
  95 [http]
  96 debug = false               # HTTP debugging
  97 proxy = "host:port"         # HTTP proxy in libcurl format
  98 ssl-version = "tlsv1.3"     # TLS version to use
  99 ssl-version.max = "tlsv1.3" # maximum TLS version
 100 ssl-version.min = "tlsv1.1" # minimum TLS version
 101 timeout = 30                # timeout for each HTTP request, in seconds
 102 low-speed-limit = 10        # network timeout threshold (bytes/sec)
 103 cainfo = "cert.pem"         # path to Certificate Authority (CA) bundle
 104 check-revoke = true         # check for SSL certificate revocation
 105 multiplexing = true         # HTTP/2 multiplexing
 106 user-agent = "…"            # the user-agent header
 107
 108 [install]
 109 root = "/some/path"         # `cargo install` destination directory
 110
 111 [net]
 112 retry = 2                   # network retries
 113 git-fetch-with-cli = true   # use the `git` executable for git operations
 114 offline = true              # do not access the network
 115
 116 [patch.<registry>]
 117 # Same keys as for [patch] in Cargo.toml
 118
 119 [profile.<name>]         # Modify profile settings via config.
 120 opt-level = 0            # Optimization level.
 121 debug = true             # Include debug info.
 122 split-debuginfo = '...'  # Debug info splitting behavior.
 123 debug-assertions = true  # Enables debug assertions.
 124 overflow-checks = true   # Enables runtime integer overflow checks.
 125 lto = false              # Sets link-time optimization.
 126 panic = 'unwind'         # The panic strategy.
 127 incremental = true       # Incremental compilation.
 128 codegen-units = 16       # Number of code generation units.
 129 rpath = false            # Sets the rpath linking option.
 130 [profile.<name>.build-override]  # Overrides build-script settings.
 131 # Same keys for a normal profile.
 132 [profile.<name>.package.<name>]  # Override profile for a package.
 133 # Same keys for a normal profile (minus `panic`, `lto`, and `rpath`).
 134
 135 [registries.<name>]  # registries other than crates.io
 136 index = "…"          # URL of the registry index
 137 token = "…"          # authentication token for the registry
 138
 139 [registry]
 140 default = "…"        # name of the default registry
 141 token = "…"          # authentication token for crates.io
 142
 143 [source.<name>]      # source definition and replacement
 144 replace-with = "…"   # replace this source with the given named source
 145 directory = "…"      # path to a directory source
 146 registry = "…"       # URL to a registry source
 147 local-registry = "…" # path to a local registry source
 148 git = "…"            # URL of a git repository source
 149 branch = "…"         # branch name for the git repository
 150 tag = "…"            # tag name for the git repository
 151 rev = "…"            # revision for the git repository
 152
 153 [target.<triple>]
 154 linker = "…"            # linker to use
 155 runner = "…"            # wrapper to run executables
 156 rustflags = ["…", "…"]  # custom flags for `rustc`
 157
 158 [target.<cfg>]
 159 runner = "…"            # wrapper to run executables
 160 rustflags = ["…", "…"]  # custom flags for `rustc`
 161
 162 [target.<triple>.<links>] # `links` build script override
 163 rustc-link-lib = ["foo"]
 164 rustc-link-search = ["/path/to/foo"]
 165 rustc-flags = ["-L", "/some/path"]
 166 rustc-cfg = ['key="value"']
 167 rustc-env = {key = "value"}
 168 rustc-cdylib-link-arg = ["…"]
 169 metadata_key1 = "value"
 170 metadata_key2 = "value"
 171
 172 [term]
 173 quiet = false          # whether cargo output is quiet
 174 verbose = false        # whether cargo provides verbose output
 175 color = 'auto'         # whether cargo colorizes output
 176 progress.when = 'auto' # whether cargo shows progress bar
 177 progress.width = 80    # width of progress bar
 178 ```
 179
 180 ### Environment variables
 181
 182 Cargo can also be configured through environment variables in addition to the
 183 TOML configuration files. For each configuration key of the form `foo.bar` the
 184 environment variable `CARGO_FOO_BAR` can also be used to define the value.
 185 Keys are converted to uppercase, dots and dashes are converted to underscores.
 186 For example the `target.x86_64-unknown-linux-gnu.runner` key can also be
 187 defined by the `CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUNNER` environment
 188 variable.
 189
 190 Environment variables will take precedence over TOML configuration files.
 191 Currently only integer, boolean, string and some array values are supported to
 192 be defined by environment variables. Descriptions below indicate which keys
 193 support environment variables.
 194
 195 In addition to the system above, Cargo recognizes a few other specific
 196 [environment variables][env].
 197
 198 ### Command-line overrides
 199
 200 Cargo also accepts arbitrary configuration overrides through the
 201 `--config` command-line option. The argument should be in TOML syntax of
 202 `KEY=VALUE`:
 203
 204 ```console
 205 cargo --config net.git-fetch-with-cli=true fetch
 206 ```
 207
 208 The `--config` option may be specified multiple times, in which case the
 209 values are merged in left-to-right order, using the same merging logic
 210 that is used when multiple configuration files apply. Configuration
 211 values specified this way take precedence over environment variables,
 212 which take precedence over configuration files.
 213
 214 Some examples of what it looks like using Bourne shell syntax:
 215
 216 ```console
 217 # Most shells will require escaping.
 218 cargo --config http.proxy=\"http://example.com\" …
 219
 220 # Spaces may be used.
 221 cargo --config "net.git-fetch-with-cli = true" …
 222
 223 # TOML array example. Single quotes make it easier to read and write.
 224 cargo --config 'build.rustdocflags = ["--html-in-header", "header.html"]' …
 225
 226 # Example of a complex TOML key.
 227 cargo --config "target.'cfg(all(target_arch = \"arm\", target_os = \"none\"))'.runner = 'my-runner'" …
 228
 229 # Example of overriding a profile setting.
 230 cargo --config profile.dev.package.image.opt-level=3 …
 231 ```
 232
 233 The `--config` option can also be used to pass paths to extra
 234 configuration files that Cargo should use for a specific invocation.
 235 Options from configuration files loaded this way follow the same
 236 precedence rules as other options specified directly with `--config`.
 237
 238 ### Config-relative paths
 239
 240 Paths in config files may be absolute, relative, or a bare name without any
 241 path separators. Paths for executables without a path separator will use the
 242 `PATH` environment variable to search for the executable. Paths for
 243 non-executables will be relative to where the config value is defined. For
 244 config files, that is relative to the parent directory of the `.cargo`
 245 directory where the value was defined. For environment variables it is
 246 relative to the current working directory.
 247
 248 ```toml
 249 # Relative path examples.
 250
 251 [target.x86_64-unknown-linux-gnu]
 252 runner = "foo"  # Searches `PATH` for `foo`.
 253
 254 [source.vendored-sources]
 255 # Directory is relative to the parent where `.cargo/config.toml` is located.
 256 # For example, `/my/project/.cargo/config.toml` would result in `/my/project/vendor`.
 257 directory = "vendor"
 258 ```
 259
 260 ### Executable paths with arguments
 261
 262 Some Cargo commands invoke external programs, which can be configured as a path
 263 and some number of arguments.
 264
 265 The value may be an array of strings like `['/path/to/program', 'somearg']` or
 266 a space-separated string like `'/path/to/program somearg'`. If the path to the
 267 executable contains a space, the list form must be used.
 268
 269 If Cargo is passing other arguments to the program such as a path to open or
 270 run, they will be passed after the last specified argument in the value of an
 271 option of this format. If the specified program does not have path separators,
 272 Cargo will search `PATH` for its executable.
 273
 274 ### Credentials
 275
 276 Configuration values with sensitive information are stored in the
 277 `$CARGO_HOME/credentials.toml` file. This file is automatically created and updated
 278 by [`cargo login`]. It follows the same format as Cargo config files.
 279
 280 ```toml
 281 [registry]
 282 token = "…"   # Access token for crates.io
 283
 284 [registries.<name>]
 285 token = "…"   # Access token for the named registry
 286 ```
 287
 288 Tokens are used by some Cargo commands such as [`cargo publish`] for
 289 authenticating with remote registries. Care should be taken to protect the
 290 tokens and to keep them secret.
 291
 292 As with most other config values, tokens may be specified with environment
 293 variables. The token for [crates.io] may be specified with the
 294 `CARGO_REGISTRY_TOKEN` environment variable. Tokens for other registries may
 295 be specified with environment variables of the form
 296 `CARGO_REGISTRIES_<name>_TOKEN` where `<name>` is the name of the registry in
 297 all capital letters.
 298
 299 ### Configuration keys
 300
 301 This section documents all configuration keys. The description for keys with
 302 variable parts are annotated with angled brackets like `target.<triple>` where
 303 the `<triple>` part can be any target triple like
 304 `target.x86_64-pc-windows-msvc`.
 305
 306 #### `paths`
 307 * Type: array of strings (paths)
 308 * Default: none
 309 * Environment: not supported
 310
 311 An array of paths to local packages which are to be used as overrides for
 312 dependencies. For more information see the [Overriding Dependencies
 313 guide](overriding-dependencies.md#paths-overrides).
 314
 315 #### `[alias]`
 316 * Type: string or array of strings
 317 * Default: see below
 318 * Environment: `CARGO_ALIAS_<name>`
 319
 320 The `[alias]` table defines CLI command aliases. For example, running `cargo
 321 b` is an alias for running `cargo build`. Each key in the table is the
 322 subcommand, and the value is the actual command to run. The value may be an
 323 array of strings, where the first element is the command and the following are
 324 arguments. It may also be a string, which will be split on spaces into
 325 subcommand and arguments. The following aliases are built-in to Cargo:
 326
 327 ```toml
 328 [alias]
 329 b = "build"
 330 c = "check"
 331 d = "doc"
 332 t = "test"
 333 r = "run"
 334 ```
 335
 336 Aliases are not allowed to redefine existing built-in commands.
 337
 338 #### `[build]`
 339
 340 The `[build]` table controls build-time operations and compiler settings.
 341
 342 ##### `build.jobs`
 343 * Type: integer
 344 * Default: number of logical CPUs
 345 * Environment: `CARGO_BUILD_JOBS`
 346
 347 Sets the maximum number of compiler processes to run in parallel.
 348
 349 Can be overridden with the `--jobs` CLI option.
 350
 351 ##### `build.rustc`
 352 * Type: string (program path)
 353 * Default: "rustc"
 354 * Environment: `CARGO_BUILD_RUSTC` or `RUSTC`
 355
 356 Sets the executable to use for `rustc`.
 357
 358 ##### `build.rustc-wrapper`
 359 * Type: string (program path)
 360 * Default: none
 361 * Environment: `CARGO_BUILD_RUSTC_WRAPPER` or `RUSTC_WRAPPER`
 362
 363 Sets a wrapper to execute instead of `rustc`. The first argument passed to the
 364 wrapper is the path to the actual `rustc`.
 365
 366 ##### `build.rustc-workspace-wrapper`
 367 * Type: string (program path)
 368 * Default: none
 369 * Environment: `CARGO_BUILD_RUSTC_WORKSPACE_WRAPPER` or `RUSTC_WORKSPACE_WRAPPER`
 370
 371 Sets a wrapper to execute instead of `rustc`, for workspace members only.
 372 The first argument passed to the wrapper is the path to the actual `rustc`.
 373 It affects the filename hash so that artifacts produced by the wrapper are cached separately.
 374
 375 ##### `build.rustdoc`
 376 * Type: string (program path)
 377 * Default: "rustdoc"
 378 * Environment: `CARGO_BUILD_RUSTDOC` or `RUSTDOC`
 379
 380 Sets the executable to use for `rustdoc`.
 381
 382 ##### `build.target`
 383 * Type: string
 384 * Default: host platform
 385 * Environment: `CARGO_BUILD_TARGET`
 386
 387 The default target platform triple to compile to.
 388
 389 This may also be a relative path to a `.json` target spec file.
 390
 391 Can be overridden with the `--target` CLI option.
 392
 393 ##### `build.target-dir`
 394 * Type: string (path)
 395 * Default: "target"
 396 * Environment: `CARGO_BUILD_TARGET_DIR` or `CARGO_TARGET_DIR`
 397
 398 The path to where all compiler output is placed. The default if not specified
 399 is a directory named `target` located at the root of the workspace.
 400
 401 Can be overridden with the `--target-dir` CLI option.
 402
 403 ##### `build.rustflags`
 404 * Type: string or array of strings
 405 * Default: none
 406 * Environment: `CARGO_BUILD_RUSTFLAGS` or `CARGO_ENCODED_RUSTFLAGS` or `RUSTFLAGS`
 407
 408 Extra command-line flags to pass to `rustc`. The value may be an array of
 409 strings or a space-separated string.
 410
 411 There are four mutually exclusive sources of extra flags. They are checked in
 412 order, with the first one being used:
 413
 414 1. `CARGO_ENCODED_RUSTFLAGS` environment variable.
 415 2. `RUSTFLAGS` environment variable.
 416 3. All matching `target.<triple>.rustflags` and `target.<cfg>.rustflags`
 417    config entries joined together.
 418 4. `build.rustflags` config value.
 419
 420 Additional flags may also be passed with the [`cargo rustc`] command.
 421
 422 If the `--target` flag (or [`build.target`](#buildtarget)) is used, then the
 423 flags will only be passed to the compiler for the target. Things being built
 424 for the host, such as build scripts or proc macros, will not receive the args.
 425 Without `--target`, the flags will be passed to all compiler invocations
 426 (including build scripts and proc macros) because dependencies are shared. If
 427 you have args that you do not want to pass to build scripts or proc macros and
 428 are building for the host, pass `--target` with the host triple.
 429
 430 It is not recommended to pass in flags that Cargo itself usually manages. For
 431 example, the flags driven by [profiles](profiles.md) are best handled by setting the
 432 appropriate profile setting.
 433
 434 > **Caution**: Due to the low-level nature of passing flags directly to the
 435 > compiler, this may cause a conflict with future versions of Cargo which may
 436 > issue the same or similar flags on its own which may interfere with the
 437 > flags you specify. This is an area where Cargo may not always be backwards
 438 > compatible.
 439
 440 ##### `build.rustdocflags`
 441 * Type: string or array of strings
 442 * Default: none
 443 * Environment: `CARGO_BUILD_RUSTDOCFLAGS` or `CARGO_ENCODED_RUSTDOCFLAGS` or `RUSTDOCFLAGS`
 444
 445 Extra command-line flags to pass to `rustdoc`. The value may be an array of
 446 strings or a space-separated string.
 447
 448 There are three mutually exclusive sources of extra flags. They are checked in
 449 order, with the first one being used:
 450
 451 1. `CARGO_ENCODED_RUSTDOCFLAGS` environment variable.
 452 2. `RUSTDOCFLAGS` environment variable.
 453 3. `build.rustdocflags` config value.
 454
 455 Additional flags may also be passed with the [`cargo rustdoc`] command.
 456
 457 ##### `build.incremental`
 458 * Type: bool
 459 * Default: from profile
 460 * Environment: `CARGO_BUILD_INCREMENTAL` or `CARGO_INCREMENTAL`
 461
 462 Whether or not to perform [incremental compilation]. The default if not set is
 463 to use the value from the [profile](profiles.md#incremental). Otherwise this overrides the setting of
 464 all profiles.
 465
 466 The `CARGO_INCREMENTAL` environment variable can be set to `1` to force enable
 467 incremental compilation for all profiles, or `0` to disable it. This env var
 468 overrides the config setting.
 469
 470 ##### `build.dep-info-basedir`
 471 * Type: string (path)
 472 * Default: none
 473 * Environment: `CARGO_BUILD_DEP_INFO_BASEDIR`
 474
 475 Strips the given path prefix from [dep
 476 info](../guide/build-cache.md#dep-info-files) file paths. This config setting
 477 is intended to convert absolute paths to relative paths for tools that require
 478 relative paths.
 479
 480 The setting itself is a config-relative path. So, for example, a value of
 481 `"."` would strip all paths starting with the parent directory of the `.cargo`
 482 directory.
 483
 484 ##### `build.pipelining`
 485
 486 This option is deprecated and unused. Cargo always has pipelining enabled.
 487
 488 #### `[doc]`
 489
 490 The `[doc]` table defines options for the [`cargo doc`] command.
 491
 492 ##### `doc.browser`
 493
 494 * Type: string or array of strings ([program path with args])
 495 * Default: `BROWSER` environment variable, or, if that is missing,
 496   opening the link in a system specific way
 497
 498 This option sets the browser to be used by [`cargo doc`], overriding the
 499 `BROWSER` environment variable when opening documentation with the `--open`
 500 option.
 501
 502 #### `[cargo-new]`
 503
 504 The `[cargo-new]` table defines defaults for the [`cargo new`] command.
 505
 506 ##### `cargo-new.name`
 507
 508 This option is deprecated and unused.
 509
 510 ##### `cargo-new.email`
 511
 512 This option is deprecated and unused.
 513
 514 ##### `cargo-new.vcs`
 515 * Type: string
 516 * Default: "git" or "none"
 517 * Environment: `CARGO_CARGO_NEW_VCS`
 518
 519 Specifies the source control system to use for initializing a new repository.
 520 Valid values are `git`, `hg` (for Mercurial), `pijul`, `fossil` or `none` to
 521 disable this behavior. Defaults to `git`, or `none` if already inside a VCS
 522 repository. Can be overridden with the `--vcs` CLI option.
 523
 524 ### `[env]`
 525
 526 The `[env]` section allows you to set additional environment variables for
 527 build scripts, rustc invocations, `cargo run` and `cargo build`.
 528
 529 ```toml
 530 [env]
 531 OPENSSL_DIR = "/opt/openssl"
 532 ```
 533
 534 By default, the variables specified will not override values that already exist
 535 in the environment. This behavior can be changed by setting the `force` flag.
 536
 537 Setting the `relative` flag evaluates the value as a config-relative path that
 538 is relative to the parent directory of the `.cargo` directory that contains the
 539 `config.toml` file. The value of the environment variable will be the full
 540 absolute path.
 541
 542 ```toml
 543 [env]
 544 TMPDIR = { value = "/home/tmp", force = true }
 545 OPENSSL_DIR = { value = "vendor/openssl", relative = true }
 546 ```
 547
 548 ### `[future-incompat-report]`
 549
 550 The `[future-incompat-report]` table controls setting for [future incompat reporting](future-incompat-report.md)
 551
 552 #### `future-incompat-report.frequency`
 553 * Type: string
 554 * Default: "always"
 555 * Environment: `CARGO_FUTURE_INCOMPAT_REPORT_FREQUENCY`
 556
 557 Controls how often we display a notification to the terminal when a future incompat report is available. Possible values:
 558
 559 * `always` (default): Always display a notification when a command (e.g. `cargo build`) produces a future incompat report
 560 * `never`: Never display a notification
 561
 562 #### `[http]`
 563
 564 The `[http]` table defines settings for HTTP behavior. This includes fetching
 565 crate dependencies and accessing remote git repositories.
 566
 567 ##### `http.debug`
 568 * Type: boolean
 569 * Default: false
 570 * Environment: `CARGO_HTTP_DEBUG`
 571
 572 If `true`, enables debugging of HTTP requests. The debug information can be
 573 seen by setting the `CARGO_LOG=cargo::ops::registry=debug` environment
 574 variable (or use `trace` for even more information).
 575
 576 Be wary when posting logs from this output in a public location. The output
 577 may include headers with authentication tokens which you don't want to leak!
 578 Be sure to review logs before posting them.
 579
 580 ##### `http.proxy`
 581 * Type: string
 582 * Default: none
 583 * Environment: `CARGO_HTTP_PROXY` or `HTTPS_PROXY` or `https_proxy` or `http_proxy`
 584
 585 Sets an HTTP and HTTPS proxy to use. The format is in [libcurl format] as in
 586 `[protocol://]host[:port]`. If not set, Cargo will also check the `http.proxy`
 587 setting in your global git configuration. If none of those are set, the
 588 `HTTPS_PROXY` or `https_proxy` environment variables set the proxy for HTTPS
 589 requests, and `http_proxy` sets it for HTTP requests.
 590
 591 ##### `http.timeout`
 592 * Type: integer
 593 * Default: 30
 594 * Environment: `CARGO_HTTP_TIMEOUT` or `HTTP_TIMEOUT`
 595
 596 Sets the timeout for each HTTP request, in seconds.
 597
 598 ##### `http.cainfo`
 599 * Type: string (path)
 600 * Default: none
 601 * Environment: `CARGO_HTTP_CAINFO`
 602
 603 Path to a Certificate Authority (CA) bundle file, used to verify TLS
 604 certificates. If not specified, Cargo attempts to use the system certificates.
 605
 606 ##### `http.check-revoke`
 607 * Type: boolean
 608 * Default: true (Windows) false (all others)
 609 * Environment: `CARGO_HTTP_CHECK_REVOKE`
 610
 611 This determines whether or not TLS certificate revocation checks should be
 612 performed. This only works on Windows.
 613
 614 ##### `http.ssl-version`
 615 * Type: string or min/max table
 616 * Default: none
 617 * Environment: `CARGO_HTTP_SSL_VERSION`
 618
 619 This sets the minimum TLS version to use. It takes a string, with one of the
 620 possible values of "default", "tlsv1", "tlsv1.0", "tlsv1.1", "tlsv1.2", or
 621 "tlsv1.3".
 622
 623 This may alternatively take a table with two keys, `min` and `max`, which each
 624 take a string value of the same kind that specifies the minimum and maximum
 625 range of TLS versions to use.
 626
 627 The default is a minimum version of "tlsv1.0" and a max of the newest version
 628 supported on your platform, typically "tlsv1.3".
 629
 630 ##### `http.low-speed-limit`
 631 * Type: integer
 632 * Default: 10
 633 * Environment: `CARGO_HTTP_LOW_SPEED_LIMIT`
 634
 635 This setting controls timeout behavior for slow connections. If the average
 636 transfer speed in bytes per second is below the given value for
 637 [`http.timeout`](#httptimeout) seconds (default 30 seconds), then the
 638 connection is considered too slow and Cargo will abort and retry.
 639
 640 ##### `http.multiplexing`
 641 * Type: boolean
 642 * Default: true
 643 * Environment: `CARGO_HTTP_MULTIPLEXING`
 644
 645 When `true`, Cargo will attempt to use the HTTP2 protocol with multiplexing.
 646 This allows multiple requests to use the same connection, usually improving
 647 performance when fetching multiple files. If `false`, Cargo will use HTTP 1.1
 648 without pipelining.
 649
 650 ##### `http.user-agent`
 651 * Type: string
 652 * Default: Cargo's version
 653 * Environment: `CARGO_HTTP_USER_AGENT`
 654
 655 Specifies a custom user-agent header to use. The default if not specified is a
 656 string that includes Cargo's version.
 657
 658 #### `[install]`
 659
 660 The `[install]` table defines defaults for the [`cargo install`] command.
 661
 662 ##### `install.root`
 663 * Type: string (path)
 664 * Default: Cargo's home directory
 665 * Environment: `CARGO_INSTALL_ROOT`
 666
 667 Sets the path to the root directory for installing executables for [`cargo
 668 install`]. Executables go into a `bin` directory underneath the root.
 669
 670 To track information of installed executables, some extra files, such as
 671 `.crates.toml` and `.crates2.json`, are also created under this root.
 672
 673 The default if not specified is Cargo's home directory (default `.cargo` in
 674 your home directory).
 675
 676 Can be overridden with the `--root` command-line option.
 677
 678 #### `[net]`
 679
 680 The `[net]` table controls networking configuration.
 681
 682 ##### `net.retry`
 683 * Type: integer
 684 * Default: 2
 685 * Environment: `CARGO_NET_RETRY`
 686
 687 Number of times to retry possibly spurious network errors.
 688
 689 ##### `net.git-fetch-with-cli`
 690 * Type: boolean
 691 * Default: false
 692 * Environment: `CARGO_NET_GIT_FETCH_WITH_CLI`
 693
 694 If this is `true`, then Cargo will use the `git` executable to fetch registry
 695 indexes and git dependencies. If `false`, then it uses a built-in `git`
 696 library.
 697
 698 Setting this to `true` can be helpful if you have special authentication
 699 requirements that Cargo does not support. See [Git
 700 Authentication](../appendix/git-authentication.md) for more information about
 701 setting up git authentication.
 702
 703 ##### `net.offline`
 704 * Type: boolean
 705 * Default: false
 706 * Environment: `CARGO_NET_OFFLINE`
 707
 708 If this is `true`, then Cargo will avoid accessing the network, and attempt to
 709 proceed with locally cached data. If `false`, Cargo will access the network as
 710 needed, and generate an error if it encounters a network error.
 711
 712 Can be overridden with the `--offline` command-line option.
 713
 714 #### `[patch]`
 715
 716 Just as you can override dependencies using [`[patch]` in
 717 `Cargo.toml`](overriding-dependencies.md#the-patch-section), you can
 718 override them in the cargo configuration file to apply those patches to
 719 any affected build. The format is identical to the one used in
 720 `Cargo.toml`.
 721
 722 Since `.cargo/config.toml` files are not usually checked into source
 723 control, you should prefer patching using `Cargo.toml` where possible to
 724 ensure that other developers can compile your crate in their own
 725 environments. Patching through cargo configuration files is generally
 726 only appropriate when the patch section is automatically generated by an
 727 external build tool.
 728
 729 If a given dependency is patched both in a cargo configuration file and
 730 a `Cargo.toml` file, the patch in the configuration file is used. If
 731 multiple configuration files patch the same dependency, standard cargo
 732 configuration merging is used, which prefers the value defined closest
 733 to the current directory, with `$HOME/.cargo/config.toml` taking the
 734 lowest precedence.
 735
 736 Relative `path` dependencies in such a `[patch]` section are resolved
 737 relative to the configuration file they appear in.
 738
 739 #### `[profile]`
 740
 741 The `[profile]` table can be used to globally change profile settings, and
 742 override settings specified in `Cargo.toml`. It has the same syntax and
 743 options as profiles specified in `Cargo.toml`. See the [Profiles chapter] for
 744 details about the options.
 745
 746 [Profiles chapter]: profiles.md
 747
 748 ##### `[profile.<name>.build-override]`
 749 * Environment: `CARGO_PROFILE_<name>_BUILD_OVERRIDE_<key>`
 750
 751 The build-override table overrides settings for build scripts, proc macros,
 752 and their dependencies. It has the same keys as a normal profile. See the
 753 [overrides section](profiles.md#overrides) for more details.
 754
 755 ##### `[profile.<name>.package.<name>]`
 756 * Environment: not supported
 757
 758 The package table overrides settings for specific packages. It has the same
 759 keys as a normal profile, minus the `panic`, `lto`, and `rpath` settings. See
 760 the [overrides section](profiles.md#overrides) for more details.
 761
 762 ##### `profile.<name>.codegen-units`
 763 * Type: integer
 764 * Default: See profile docs.
 765 * Environment: `CARGO_PROFILE_<name>_CODEGEN_UNITS`
 766
 767 See [codegen-units](profiles.md#codegen-units).
 768
 769 ##### `profile.<name>.debug`
 770 * Type: integer or boolean
 771 * Default: See profile docs.
 772 * Environment: `CARGO_PROFILE_<name>_DEBUG`
 773
 774 See [debug](profiles.md#debug).
 775
 776 ##### `profile.<name>.split-debuginfo`
 777 * Type: string
 778 * Default: See profile docs.
 779 * Environment: `CARGO_PROFILE_<name>_SPLIT_DEBUGINFO`
 780
 781 See [split-debuginfo](profiles.md#split-debuginfo).
 782
 783 ##### `profile.<name>.debug-assertions`
 784 * Type: boolean
 785 * Default: See profile docs.
 786 * Environment: `CARGO_PROFILE_<name>_DEBUG_ASSERTIONS`
 787
 788 See [debug-assertions](profiles.md#debug-assertions).
 789
 790 ##### `profile.<name>.incremental`
 791 * Type: boolean
 792 * Default: See profile docs.
 793 * Environment: `CARGO_PROFILE_<name>_INCREMENTAL`
 794
 795 See [incremental](profiles.md#incremental).
 796
 797 ##### `profile.<name>.lto`
 798 * Type: string or boolean
 799 * Default: See profile docs.
 800 * Environment: `CARGO_PROFILE_<name>_LTO`
 801
 802 See [lto](profiles.md#lto).
 803
 804 ##### `profile.<name>.overflow-checks`
 805 * Type: boolean
 806 * Default: See profile docs.
 807 * Environment: `CARGO_PROFILE_<name>_OVERFLOW_CHECKS`
 808
 809 See [overflow-checks](profiles.md#overflow-checks).
 810
 811 ##### `profile.<name>.opt-level`
 812 * Type: integer or string
 813 * Default: See profile docs.
 814 * Environment: `CARGO_PROFILE_<name>_OPT_LEVEL`
 815
 816 See [opt-level](profiles.md#opt-level).
 817
 818 ##### `profile.<name>.panic`
 819 * Type: string
 820 * default: See profile docs.
 821 * Environment: `CARGO_PROFILE_<name>_PANIC`
 822
 823 See [panic](profiles.md#panic).
 824
 825 ##### `profile.<name>.rpath`
 826 * Type: boolean
 827 * default: See profile docs.
 828 * Environment: `CARGO_PROFILE_<name>_RPATH`
 829
 830 See [rpath](profiles.md#rpath).
 831
 832
 833 #### `[registries]`
 834
 835 The `[registries]` table is used for specifying additional [registries]. It
 836 consists of a sub-table for each named registry.
 837
 838 ##### `registries.<name>.index`
 839 * Type: string (url)
 840 * Default: none
 841 * Environment: `CARGO_REGISTRIES_<name>_INDEX`
 842
 843 Specifies the URL of the git index for the registry.
 844
 845 ##### `registries.<name>.token`
 846 * Type: string
 847 * Default: none
 848 * Environment: `CARGO_REGISTRIES_<name>_TOKEN`
 849
 850 Specifies the authentication token for the given registry. This value should
 851 only appear in the [credentials](#credentials) file. This is used for registry
 852 commands like [`cargo publish`] that require authentication.
 853
 854 Can be overridden with the `--token` command-line option.
 855
 856 #### `[registry]`
 857
 858 The `[registry]` table controls the default registry used when one is not
 859 specified.
 860
 861 ##### `registry.index`
 862
 863 This value is no longer accepted and should not be used.
 864
 865 ##### `registry.default`
 866 * Type: string
 867 * Default: `"crates-io"`
 868 * Environment: `CARGO_REGISTRY_DEFAULT`
 869
 870 The name of the registry (from the [`registries` table](#registries)) to use
 871 by default for registry commands like [`cargo publish`].
 872
 873 Can be overridden with the `--registry` command-line option.
 874
 875 ##### `registry.token`
 876 * Type: string
 877 * Default: none
 878 * Environment: `CARGO_REGISTRY_TOKEN`
 879
 880 Specifies the authentication token for [crates.io]. This value should only
 881 appear in the [credentials](#credentials) file. This is used for registry
 882 commands like [`cargo publish`] that require authentication.
 883
 884 Can be overridden with the `--token` command-line option.
 885
 886 #### `[source]`
 887
 888 The `[source]` table defines the registry sources available. See [Source
 889 Replacement] for more information. It consists of a sub-table for each named
 890 source. A source should only define one kind (directory, registry,
 891 local-registry, or git).
 892
 893 ##### `source.<name>.replace-with`
 894 * Type: string
 895 * Default: none
 896 * Environment: not supported
 897
 898 If set, replace this source with the given named source.
 899
 900 ##### `source.<name>.directory`
 901 * Type: string (path)
 902 * Default: none
 903 * Environment: not supported
 904
 905 Sets the path to a directory to use as a directory source.
 906
 907 ##### `source.<name>.registry`
 908 * Type: string (url)
 909 * Default: none
 910 * Environment: not supported
 911
 912 Sets the URL to use for a registry source.
 913
 914 ##### `source.<name>.local-registry`
 915 * Type: string (path)
 916 * Default: none
 917 * Environment: not supported
 918
 919 Sets the path to a directory to use as a local registry source.
 920
 921 ##### `source.<name>.git`
 922 * Type: string (url)
 923 * Default: none
 924 * Environment: not supported
 925
 926 Sets the URL to use for a git repository source.
 927
 928 ##### `source.<name>.branch`
 929 * Type: string
 930 * Default: none
 931 * Environment: not supported
 932
 933 Sets the branch name to use for a git repository.
 934
 935 If none of `branch`, `tag`, or `rev` is set, defaults to the `master` branch.
 936
 937 ##### `source.<name>.tag`
 938 * Type: string
 939 * Default: none
 940 * Environment: not supported
 941
 942 Sets the tag name to use for a git repository.
 943
 944 If none of `branch`, `tag`, or `rev` is set, defaults to the `master` branch.
 945
 946 ##### `source.<name>.rev`
 947 * Type: string
 948 * Default: none
 949 * Environment: not supported
 950
 951 Sets the [revision] to use for a git repository.
 952
 953 If none of `branch`, `tag`, or `rev` is set, defaults to the `master` branch.
 954
 955
 956 #### `[target]`
 957
 958 The `[target]` table is used for specifying settings for specific platform
 959 targets. It consists of a sub-table which is either a platform triple or a
 960 [`cfg()` expression]. The given values will be used if the target platform
 961 matches either the `<triple>` value or the `<cfg>` expression.
 962
 963 ```toml
 964 [target.thumbv7m-none-eabi]
 965 linker = "arm-none-eabi-gcc"
 966 runner = "my-emulator"
 967 rustflags = ["…", "…"]
 968
 969 [target.'cfg(all(target_arch = "arm", target_os = "none"))']
 970 runner = "my-arm-wrapper"
 971 rustflags = ["…", "…"]
 972 ```
 973
 974 `cfg` values come from those built-in to the compiler (run `rustc --print=cfg`
 975 to view), values set by [build scripts], and extra `--cfg` flags passed to
 976 `rustc` (such as those defined in `RUSTFLAGS`). Do not try to match on
 977 `debug_assertions` or Cargo features like `feature="foo"`.
 978
 979 If using a target spec JSON file, the `<triple>` value is the filename stem.
 980 For example `--target foo/bar.json` would match `[target.bar]`.
 981
 982 ##### `target.<triple>.ar`
 983
 984 This option is deprecated and unused.
 985
 986 ##### `target.<triple>.linker`
 987 * Type: string (program path)
 988 * Default: none
 989 * Environment: `CARGO_TARGET_<triple>_LINKER`
 990
 991 Specifies the linker which is passed to `rustc` (via [`-C linker`]) when the
 992 `<triple>` is being compiled for. By default, the linker is not overridden.
 993
 994 ##### `target.<triple>.runner`
 995 * Type: string or array of strings ([program path with args])
 996 * Default: none
 997 * Environment: `CARGO_TARGET_<triple>_RUNNER`
 998
 999 If a runner is provided, executables for the target `<triple>` will be
1000 executed by invoking the specified runner with the actual executable passed as
1001 an argument. This applies to [`cargo run`], [`cargo test`] and [`cargo bench`]
1002 commands. By default, compiled executables are executed directly.
1003
1004 ##### `target.<cfg>.runner`
1005
1006 This is similar to the [target runner](#targettriplerunner), but using
1007 a [`cfg()` expression]. If both a `<triple>` and `<cfg>` runner match,
1008 the `<triple>` will take precedence. It is an error if more than one
1009 `<cfg>` runner matches the current target.
1010
1011 ##### `target.<triple>.rustflags`
1012 * Type: string or array of strings
1013 * Default: none
1014 * Environment: `CARGO_TARGET_<triple>_RUSTFLAGS`
1015
1016 Passes a set of custom flags to the compiler for this `<triple>`. The value
1017 may be an array of strings or a space-separated string.
1018
1019 See [`build.rustflags`](#buildrustflags) for more details on the different
1020 ways to specific extra flags.
1021
1022 ##### `target.<cfg>.rustflags`
1023
1024 This is similar to the [target rustflags](#targettriplerustflags), but
1025 using a [`cfg()` expression]. If several `<cfg>` and `<triple>` entries
1026 match the current target, the flags are joined together.
1027
1028 ##### `target.<triple>.<links>`
1029
1030 The links sub-table provides a way to [override a build script]. When
1031 specified, the build script for the given `links` library will not be
1032 run, and the given values will be used instead.
1033
1034 ```toml
1035 [target.x86_64-unknown-linux-gnu.foo]
1036 rustc-link-lib = ["foo"]
1037 rustc-link-search = ["/path/to/foo"]
1038 rustc-flags = "-L /some/path"
1039 rustc-cfg = ['key="value"']
1040 rustc-env = {key = "value"}
1041 rustc-cdylib-link-arg = ["…"]
1042 metadata_key1 = "value"
1043 metadata_key2 = "value"
1044 ```
1045
1046 #### `[term]`
1047
1048 The `[term]` table controls terminal output and interaction.
1049
1050 ##### `term.quiet`
1051 * Type: boolean
1052 * Default: false
1053 * Environment: `CARGO_TERM_QUIET`
1054
1055 Controls whether or not log messages are displayed by Cargo.
1056
1057 Specifying the `--quiet` flag will override and force quiet output.
1058 Specifying the `--verbose` flag will override and disable quiet output.
1059
1060 ##### `term.verbose`
1061 * Type: boolean
1062 * Default: false
1063 * Environment: `CARGO_TERM_VERBOSE`
1064
1065 Controls whether or not extra detailed messages are displayed by Cargo.
1066
1067 Specifying the `--quiet` flag will override and disable verbose output.
1068 Specifying the `--verbose` flag will override and force verbose output.
1069
1070 ##### `term.color`
1071 * Type: string
1072 * Default: "auto"
1073 * Environment: `CARGO_TERM_COLOR`
1074
1075 Controls whether or not colored output is used in the terminal. Possible values:
1076
1077 * `auto` (default): Automatically detect if color support is available on the
1078   terminal.
1079 * `always`: Always display colors.
1080 * `never`: Never display colors.
1081
1082 Can be overridden with the `--color` command-line option.
1083
1084 ##### `term.progress.when`
1085 * Type: string
1086 * Default: "auto"
1087 * Environment: `CARGO_TERM_PROGRESS_WHEN`
1088
1089 Controls whether or not progress bar is shown in the terminal. Possible values:
1090
1091 * `auto` (default): Intelligently guess whether to show progress bar.
1092 * `always`: Always show progress bar.
1093 * `never`: Never show progress bar.
1094
1095 ##### `term.progress.width`
1096 * Type: integer
1097 * Default: none
1098 * Environment: `CARGO_TERM_PROGRESS_WIDTH`
1099
1100 Sets the width for progress bar.
1101
1102 [`cargo bench`]: ../commands/cargo-bench.md
1103 [`cargo login`]: ../commands/cargo-login.md
1104 [`cargo doc`]: ../commands/cargo-doc.md
1105 [`cargo new`]: ../commands/cargo-new.md
1106 [`cargo publish`]: ../commands/cargo-publish.md
1107 [`cargo run`]: ../commands/cargo-run.md
1108 [`cargo rustc`]: ../commands/cargo-rustc.md
1109 [`cargo test`]: ../commands/cargo-test.md
1110 [`cargo rustdoc`]: ../commands/cargo-rustdoc.md
1111 [`cargo install`]: ../commands/cargo-install.md
1112 [env]: environment-variables.md
1113 [`cfg()` expression]: ../../reference/conditional-compilation.html
1114 [build scripts]: build-scripts.md
1115 [`-C linker`]: ../../rustc/codegen-options/index.md#linker
1116 [override a build script]: build-scripts.md#overriding-build-scripts
1117 [toml]: https://toml.io/
1118 [incremental compilation]: profiles.md#incremental
1119 [program path with args]: #executable-paths-with-arguments
1120 [libcurl format]: https://everything.curl.dev/libcurl/proxies#proxy-types
1121 [source replacement]: source-replacement.md
1122 [revision]: https://git-scm.com/docs/gitrevisions
1123 [registries]: registries.md
1124 [crates.io]: https://crates.io/