conan lock create

$ conan lock create -h
WARN: Downgrading cache from Conan 2.7.1 to 2.5.0
usage: conan lock create [-h] [-v [V]] [-cc CORE_CONF] [--name NAME]
                         [--version VERSION] [--user USER] [--channel CHANNEL]
                         [--requires REQUIRES] [--tool-requires TOOL_REQUIRES]
                         [-b BUILD] [-r REMOTE | -nr] [-u [UPDATE]]
                         [-pr PROFILE] [-pr:b PROFILE_BUILD]
                         [-pr:h PROFILE_HOST] [-pr:a PROFILE_ALL] [-o OPTIONS]
                         [-o:b OPTIONS_BUILD] [-o:h OPTIONS_HOST]
                         [-o:a OPTIONS_ALL] [-s SETTINGS]
                         [-s:b SETTINGS_BUILD] [-s:h SETTINGS_HOST]
                         [-s:a SETTINGS_ALL] [-c CONF] [-c:b CONF_BUILD]
                         [-c:h CONF_HOST] [-c:a CONF_ALL] [-l LOCKFILE]
                         [--lockfile-partial] [--lockfile-out LOCKFILE_OUT]
                         [--lockfile-clean]
                         [--lockfile-overrides LOCKFILE_OVERRIDES]
                         [--build-require]
                         [path]

Create a lockfile from a conanfile or a reference.

positional arguments:
  path                  Path to a folder containing a recipe (conanfile.py or
                        conanfile.txt) or to a recipe file. e.g.,
                        ./my_project/conanfile.txt.

options:
  -h, --help            show this help message and exit
  -v [V]                Level of detail of the output. Valid options from less
                        verbose to more verbose: -vquiet, -verror, -vwarning,
                        -vnotice, -vstatus, -v or -vverbose, -vv or -vdebug,
                        -vvv or -vtrace
  -cc CORE_CONF, --core-conf CORE_CONF
                        Define core configuration, overwriting global.conf
                        values. E.g.: -cc core:non_interactive=True
  --name NAME           Provide a package name if not specified in conanfile
  --version VERSION     Provide a package version if not specified in
                        conanfile
  --user USER           Provide a user if not specified in conanfile
  --channel CHANNEL     Provide a channel if not specified in conanfile
  --requires REQUIRES   Directly provide requires instead of a conanfile
  --tool-requires TOOL_REQUIRES
                        Directly provide tool-requires instead of a conanfile
  -b BUILD, --build BUILD
                        Optional, specify which packages to build from source.
                        Combining multiple '--build' options on one command
                        line is allowed. Possible values: --build="*" Force
                        build from source for all packages. --build=never
                        Disallow build for all packages, use binary packages
                        or fail if a binary package is not found, it cannot be
                        combined with other '--build' options. --build=missing
                        Build packages from source whose binary package is not
                        found. --build=cascade Build packages from source that
                        have at least one dependency being built from source.
                        --build=[pattern] Build packages from source whose
                        package reference matches the pattern. The pattern
                        uses 'fnmatch' style wildcards. --build=~[pattern]
                        Excluded packages, which will not be built from the
                        source, whose package reference matches the pattern.
                        The pattern uses 'fnmatch' style wildcards.
                        --build=missing:[pattern] Build from source if a
                        compatible binary does not exist, only for packages
                        matching pattern.
  -r REMOTE, --remote REMOTE
                        Look in the specified remote or remotes server
  -nr, --no-remote      Do not use remote, resolve exclusively in the cache
  -u [UPDATE], --update [UPDATE]
                        Will install newer versions and/or revisions in the
                        local cache for the given reference, or all in case no
                        argument is supplied. When using version ranges, it
                        will install the latest version that satisfies the
                        range. Also, if using revisions, it will update to the
                        latest revision for the resolved version range.
  -pr PROFILE, --profile PROFILE
                        Apply the specified profile. By default, or if
                        specifying -pr:h (--profile:host), it applies to the
                        host context. Use -pr:b (--profile:build) to specify
                        the build context, or -pr:a (--profile:all) to specify
                        both contexts at once
  -pr:b PROFILE_BUILD, --profile:build PROFILE_BUILD
  -pr:h PROFILE_HOST, --profile:host PROFILE_HOST
  -pr:a PROFILE_ALL, --profile:all PROFILE_ALL
  -o OPTIONS, --options OPTIONS
                        Apply the specified options. By default, or if
                        specifying -o:h (--options:host), it applies to the
                        host context. Use -o:b (--options:build) to specify
                        the build context, or -o:a (--options:all) to specify
                        both contexts at once. Example: -o pkg:with_qt=true
  -o:b OPTIONS_BUILD, --options:build OPTIONS_BUILD
  -o:h OPTIONS_HOST, --options:host OPTIONS_HOST
  -o:a OPTIONS_ALL, --options:all OPTIONS_ALL
  -s SETTINGS, --settings SETTINGS
                        Apply the specified settings. By default, or if
                        specifying -s:h (--settings:host), it applies to the
                        host context. Use -s:b (--settings:build) to specify
                        the build context, or -s:a (--settings:all) to specify
                        both contexts at once. Example: -s compiler=gcc
  -s:b SETTINGS_BUILD, --settings:build SETTINGS_BUILD
  -s:h SETTINGS_HOST, --settings:host SETTINGS_HOST
  -s:a SETTINGS_ALL, --settings:all SETTINGS_ALL
  -c CONF, --conf CONF  Apply the specified conf. By default, or if specifying
                        -c:h (--conf:host), it applies to the host context.
                        Use -c:b (--conf:build) to specify the build context,
                        or -c:a (--conf:all) to specify both contexts at once.
                        Example: -c tools.cmake.cmaketoolchain:generator=Xcode
  -c:b CONF_BUILD, --conf:build CONF_BUILD
  -c:h CONF_HOST, --conf:host CONF_HOST
  -c:a CONF_ALL, --conf:all CONF_ALL
  -l LOCKFILE, --lockfile LOCKFILE
                        Path to a lockfile. Use --lockfile="" to avoid
                        automatic use of existing 'conan.lock' file
  --lockfile-partial    Do not raise an error if some dependency is not found
                        in lockfile
  --lockfile-out LOCKFILE_OUT
                        Filename of the updated lockfile
  --lockfile-clean      Remove unused entries from the lockfile
  --lockfile-overrides LOCKFILE_OVERRIDES
                        Overwrite lockfile overrides
  --build-require       Whether the provided reference is a build-require

The conan lock create command creates a lockfile for the recipe or reference specified in path or --requires. This command will compute the dependency graph, evaluate which binaries do exist or need to be built, but it will not try to install or build from source those binaries. In that regard, it is equivalent to the conan graph info command. Most of the arguments accepted by this command are the same as conan graph info (and conan install, conan create), because the conan lock create creates or update a lockfile for a given configuration.

A lockfile can be created from scratch, computing a new dependency graph from a local conanfile, or from requires, for example for this conanfile.txt:

conanfile.txt
[requires]
fmt/9.0.0

[tool_requires]
cmake/3.23.5

We can run:

$ conan lock create .

$ cat conan.lock
{
    "version": "0.5",
    "requires": [
        "fmt/9.0.0#ca4ae2047ef0ccd7d2210d8d91bd0e02%1675126491.773"
    ],
    "build_requires": [
        "cmake/3.23.5#5f184bc602682bcea668356d75e7563b%1676913225.027"
    ],
    "python_requires": []
}

conan lock create accepts a --lockfile input lockfile (if a conan.lock default one is found, it will be automatically used), and then it will add new information in the --lockfile-out (by default, also conan.lock). For example if we change the above conanfile.txt, removing the tool_requires, updating fmt to 9.1.0 and adding a new dependency to zlib/1.2.13:

conanfile.txt
[requires]
fmt/9.1.0
zlib/1.2.13

[tool_requires]

We will see how conan lock create extends the existing lockfile with the new configuration, but it doesn’t remove unused versions or packages from it:

$ conan lock create .  # will use the existing conan.lock as base, and rewrite it
# use --lockfile and --lockfile-out to change that behavior

$ cat conan.lock
{
  "version": "0.5",
  "requires": [
      "zlib/1.2.13#13c96f538b52e1600c40b88994de240f%1667396813.733",
      "fmt/9.1.0#e747928f85b03f48aaf227ff897d9634%1675126490.952",
      "fmt/9.0.0#ca4ae2047ef0ccd7d2210d8d91bd0e02%1675126491.773"
  ],
  "build_requires": [
      "cmake/3.23.5#5f184bc602682bcea668356d75e7563b%1676913225.027"
  ],
  "python_requires": []
}

This behavior is very important to be able to capture multiple different configurations (Linux/Windows, shared/static, Debug/Release, etc) that might have different dependency graphs. See the lockfiles tutorial, to read more about lockfiles for multiple configurations.

If we want to trim unused versions and packages we can force it with the --lockfile-clean argument:

$ conan lock create . --lockfile-clean
# will use the existing conan.lock as base, and rewrite it, cleaning unused versions
$ cat conan.lock
{
    "version": "0.5",
    "requires": [
        "zlib/1.2.13#13c96f538b52e1600c40b88994de240f%1667396813.733",
        "fmt/9.1.0#e747928f85b03f48aaf227ff897d9634%1675126490.952"
    ],
    "build_requires": [],
    "python_requires": []
}

See also

The lockfiles tutorial section has more examples and hands on explanations of lockfiles.