Please config file reference

The root of a Please repo is identified by a .plzconfig file. This also has a number of options to control various parts of its behaviour which might be useful to tailor it to your environment.

Please looks in several locations for these files and builds it up bit by bit. In order (from lowest priority to highest):

  • /etc/plzconfig
  • ~/.config/please/plzconfig
  • .plzconfig
  • .plzconfig_<arch> (e.g. .plzconfig_linux_amd64)
  • .plzconfig.<profile> (if the --profile flag is passed)
  • .plzconfig.local
One would normally check in .plzconfig (and arch-specific equivalents if needed).
/etc/plzconfig is there to facilitate per-machine config in cases where the repo is often deleted - this is quite common in CI systems.
Finally you normally add .plzconfig.local to .gitignore to allow people to override settings locally if needed.

The file format is very similar to Git's config; it's broken into sections by headers in square brackets, and each section contains option = value pairs. Comments start with a semicolon.

We'll list out the various options by section. The option names are all case-insensitive, the values are of course case sensitive (except in the case of boolean variables which accept various forms of true, false, yes, no etc).
Various parameters can be repeated (they're noted as such below); this means passing them multiple times in their entirety, e.g.

          buildfilename = BUILD
          buildfilename = BUILD.plz
Comma-separating on the same line won't generally work.


  • Version
    Defines the version of plz that this repo is supposed to use currently. If it's not present or the version matches the currently running version no special action is taken; otherwise if SelfUpdate is set Please will attempt to download an appropriate version, otherwise it will issue a warning and continue.

    Note that if this is not set, you can run plz update to update to the latest version available on the server.
  • Location
    Defines the directory Please is installed into.
    Defaults to ~/.please but you might want it to be somewhere else if you're installing via another method.
  • SelfUpdate (bool)
    Sets whether plz will attempt to update itself when the version set in the config file is different.
  • DownloadLocation
    Defines the location to download Please from when self-updating. Defaults to the Please web server (, but you can point it to some location of your own if you prefer to keep traffic within your network or use home-grown versions.
  • Lang
    Sets the language passed to build rules when building. This can be important for some tools (although hopefully not many) - we've mostly observed it with Sass. Defaults to en_GB.UTF-8.
  • Nonce
    This is an arbitrary string that is added to the hash of every build target. It provides a way to force a rebuild of everything when it's changed.
    We will bump the default of this whenever we think it's required - although it's been a pretty long time now and we hope that'll continue.
  • NumThreads (int)
    Number of parallel build operations to run.
    Is overridden by the equivalent command-line flag, if that's passed. Defaults to the number of CPUs plus two.


  • BuildFileName (repeated string)
    Sets the names that Please uses for its build files. Defaults to BUILD.
    For clarity the documentation refers to them simply as BUILD files but you could reconfigure them here to be something else.
    One case this can be particularly useful is in cases where you have a subdirectory named build on a case-insensitive file system like HFS+.
  • BlacklistDirs (repeated string)
    Directories to blacklist when recursively searching for BUILD files (e.g. when using plz build ... or similar).
    This is generally useful when you have large directories within your repo that don't need to be searched, especially things like node_modules that have come from external package managers.
  • ExperimentalDir (repeated string)
    Directory containing experimental code. This is subject to some extra restrictions:
    • Code in the experimental dir can override normal visibility constraints
    • Code outside the experimental dir can never depend on code inside it
    • Tests are excluded from general detection
  • PreloadBuildDefs (repeated string)
    Files to preload by the parser before loading any BUILD files.
    Since this is done before the first package is parsed they must be files in the repository, they cannot be subinclude() paths.


Contains options relating to display output. These have no impact on build output.

  • UpdateTitle (bool)
    Whether to update the window title as things are built. This is off by default because while many Linux shells will reset it afterwards, others won't and it's not ideal for us to leave it messed up.
  • SystemStats (bool)
    Whether or not to show basic system resource usage in the interactive display. Defaults to False.


  • Arch
    Architecture to compile for. Defaults to the host architecture.
  • Timeout (int)
    Timeout for build operations, in seconds. Defaults to 600 (ten minutes).
  • Path (repeated string)
    The PATH variable that will be passed to the build processes.
    Defaults to /usr/local/bin:/usr/bin:/bin but of course can be modified if you need to get binaries from other locations.
  • Config
    The build config to use when one is not chosen on the command line. Defaults to opt.
  • FallbackConfig
    The build config to use when one is chosen and a required target does not have one by the same name. Also defaults to opt.
  • PassEnv (repeated string)
    A list of environment variables to pass from the current environment to build rules. For example PassEnv = HTTP_PROXY would copy your HTTP_PROXY environment variable to the build env for any rules.
  • Sandbox (bool)
    Activates sandboxing for individual build actions, which isolates them from network access, IPC and some aspects of the filesystem. Currently only works on Linux. Defaults to False.


  • Dir
    Sets the directory to use for the dir cache.
    The default is .plz-cache, if set to the empty string the dir cache will be disabled.
  • DirCacheHighWaterMark (size)
    Starts cleaning the directory cache when it is over this number of bytes.
    Can also be given with human-readable suffixes like 10G, 200MB etc. Defaults to 10GiB.
  • DirCacheLowWaterMark (size)
    When cleaning the directory cache, it's reduced to at most this size. Defaults to 8GiB.
  • HttpUrl
    Base URL of the HTTP cache.
    Not set to anything by default which means the cache will be disabled.
  • HttpWriteable (bool)
    If True this plz instance will write content back to the HTTP cache.
    By default it runs in read-only mode.
  • HttpTimeout (int)
    Timeout for operations contacting the HTTP cache, in seconds.
  • RpcUrl
    Base URL of the RPC cache.
    Not set to anything by default which means the cache will be disabled.
  • RpcWriteable (bool)
    If True this plz instance will write content back to the RPC cache.
    By default it runs in read-only mode.
  • RpcTimeout (int)
    Timeout for operations contacting the RPC cache, in seconds.
  • RpcMaxMsgSize (bytes)
    Maximum size of a single message that we'll send to the RPC server.
    This should agree with the server's limit, if it's higher the artifacts will be rejected.
    The value is given as a byte size so can be suffixed with M, GB, KiB, etc.


  • Timeout (int)
    Sets the default timeout length, in seconds, for any test that isn't explicitly given one. Defaults to 600 (10 minutes).
  • DefaultContainer
    Sets the default type of containerisation to use for tests that are given container = True.
    Currently the only option is "docker" but we intend to add rkt support at some point.
  • Sandbox (bool)
    Activates sandboxing for individual tests, which isolates them from network access, IPC and some aspects of the filesystem. Currently only works on Linux. Defaults to False.


  • FileExtension (repeated string)
    Extensions of files to consider for coverage.
    Defaults to .go, .py, .java, .js, .cc, .h, and .c.
  • ExcludeExtension (repeated string)
    Extensions of files to exclude from coverage.
    Typically this is for generated code; the default is to exclude protobuf extensions like .pb.go, Defaults to .pb.go,,, .pb.h,, _test.go, _pb.go, _bindata.go, and


Options related to metric collection. Currently the only metrics implementation pushes to a Prometheus pushgateway for collection.

  • PushGatewayURL
    The URL of the pushgateway to send metrics to.
  • PushFrequency (duration)
    The frequency to push statistics at. Defaults to 400ms.
  • PushTimeout (duration)
    The timeout for metric pushes. Defaults to 500ms.
  • PerTest (bool)
    Emit per-test duration metrics. Off by default, they can be very useful but generate larger cardinalities of labels in Prometheus.
  • PerUser (bool)
    Emit per-user metric labels. On by default, but turning it off can reduce the amount of data to be stored.


Describes optional labels to attach to metrics.
For technical reasons this is a separate section to the main metrics options.

These are defined as key-value pairs, where the key is the label attached to the metric and the value is a command to run on the system that defines the value to attach.
Hence these labels are run once at startup and constant across all build targets.

For example:

branch = git rev-parse --abbrev-ref HEAD
to attach the current git branch to all metrics reported.

In general it's a good idea not to let the cardinality of your labels become too large, so you might want to filter it to only print whether the user is on master or not.


Options relating to tests that are run inside Docker containers.

  • DefaultImage
    The default image used for any test that doesn't specify another. Defaults to ubuntu:trusty.
  • AllowLocalFallback (bool)
    If True, will attempt to run the test locally if containerised running fails. Defaults to False.
  • Timeout (int)
    Default timeout for Dockerised tests, in seconds. Default is 1200 (twenty minutes).
  • ResultsTimeout (int)
    Timeout to wait when trying to retrieve results from inside the container. Default is 20 seconds.
  • RemoveTimeout (int)
    Timeout to wait when trying to remove a container after running a test. Defaults to 20 seconds.


Options relating to use of plz gc.

  • Keep (build label)
    Marks targets that gc should always keep. Can include meta-targets such as //test/... and //docs:all.
  • KeepLabel
    Defines a target label to be kept; for example, if you set this to go, no Go targets would ever be considered for deletion.


Properties that affect how the various Go build rules work.

  • ImportPath
    String name of the canonical path of this repository.
    This path is used as the prefix of the package name relative to this please build directory. importpath is commonly used to prepend to a project's path.
  • GoPath
    If set, will set the GOPATH environment variable appropriately during build actions.
  • GoTool
    If set, the binary name to use to invoke Go & its subtools with. Defaults to go.
  • GoRoot
    If set, will set the GOROOT environment variable appropriately during build actions.
  • BuildIDTool
    Sets the name of the binary to use to replace Go go tool buildid. Defaults to go_buildid_replacer.
  • TestTool
    Sets the location of the please_go_test tool that is used to template the test main for go_test rules.
  • CgoCCTool
    Sets the location of CC while building cgo_library and cgo_test rules. Defaults to gcc
  • FilterTool
    Sets the location of the please_go_filter tool that is used to filter source files against build constraints.
  • DefaultStatic (bool)
    Sets Go binaries to default to static linking. Note that enabling this may have negative consequences for some code, including Go's DNS lookup code in the net module.


Properties that affect how the various Python build rules work.

  • PipTool
    The tool that is invoked during pip_library rules. Defaults to pip3.
  • PexTool
    The tool that's invoked to build pexes. Defaults to please_pex in the install directory.
  • DefaultInterpreter
    The interpreter used for python_binary and python_test rules when none is specified on the rule itself. Defaults to python3 but you could of course set it to pypy.
  • TestRunner
    The test runner used to discover & run Python tests; one of unittest, pytest or behave. Defaults to unittest.
  • ModuleDir
    Defines a directory containing modules from which they can be imported at the top level.
    By default this is empty but by convention we define our pip_library rules in third_party/python and set this appropriately. Hence any of those third-party libraries that try something like import six will have it work as they expect, even though it's actually in a different location within the .pex.
  • DefaultPipRepo
    Defines a location for a pip repo to download wheels from.
    By default pip_library uses PyPI (although see below on that) but you may well want to use this define another location to upload your own wheels to.
    Is overridden by the repo argument to pip_library.
  • UsePyPI (bool)
    Whether or not to use PyPI for pip_library rules or not. Defaults to True, if you disable this you will presumably want to set DefaultPipRepo to use one of your own.
    Is overridden by the use_pypi argument to pip_library.
  • WheelNameScheme (string)
    Defines a custom templatized wheel naming scheme.
    Templatized variables should be surrounded in curly braces within the scheme, and the available options are: url_base, package_name, and version. The default search pattern is {url_base}/{package_name}-{version}-${{OS}}-${{ARCH}}.whl along with a few common variants.


Properties that affect how the various Java build rules work.

  • JavacTool
    Defines the tool used for the Java compiler. Defaults to javac.
  • JlinkTool
    Defines the tool used for the Java linker. Defaults to jlink.
  • JavaHome
    Defines the Java home folder.
  • JarTool
    Defines the tool used to build a .jar. Defaults to jar.
  • JarcatTool
    Defines the tool used to concatenate .jar files which we use to build the output of java_binary and java_test.Defaults to jarcat in the Please install directory.
    Any resemblance to this or this is purr-ly coincidental.
  • PleaseMavenTool
    Defines the tool used to fetch information from Maven in maven_jars rules.
    Defaults to please_maven in the Please install directory.
  • DefaultMavenRepo
    Default location to load artifacts from in maven_jar rules.
  • JUnitRunner
    Defines the .jar containing the JUnit runner. This is built into all java_test rules since it's necessary to make JUnit do anything useful.
    Defaults to junit_runner.jar in the Please install directory.
  • DefaultTestPackage
    The Java classpath to search for functions annotated with @Test.
  • SourceLevel (int)
    The default Java source level when compiling. Defaults to 8.
  • TargetLevel (int)
    The default Java bytecode level to target. Defaults to 8.
  • ReleaseLevel (int)
    The default Java release level when compiling. SourceLevel and TargetLevel are ignored if this is set. Bear in mind that this flag is only supported in Java version 9+.


Properties that affect how the various C++ build rules work.

  • CCTool
    The tool invoked to compile C code. Defaults to gcc but you might want to set it to clang, for example.
  • CppTool
    The tool invoked to compile C++ code. Defaults to g++ but you might want to set it to clang++, for example.
  • LdTool
    The tool invoked to link object files. Defaults to ld but you could also set it to gold, for example.
  • ArTool
    The tool invoked to archive static libraries. Defaults to ar.
  • AsmTool
    The tool invoked as an assembler. Currently only used on OSX for cc_embed_binary rules and so defaults to nasm.
  • LinkWithLdTool
    If true, instructs Please to use the tool set earlier in ldtool to link binaries instead of cctool.
    This is an esoteric setting that most people don't want; a vanilla ld will not perform all steps necessary here (you'll get lots of missing symbol messages from having no libc etc). Generally best to leave this disabled.
  • DefaultOptCflags
    Compiler flags passed to all C rules during opt builds; these are typically pretty basic things like what language standard you want to target, warning flags, etc.
    Defaults to --std=c99 -O3 -DNDEBUG -Wall -Werror
  • DefaultDbgCflags
    Compiler rules passed to all C rules during dbg builds.
    Defaults to --std=c99 -g3 -DDEBUG -Wall -Werror.
  • DefaultOptCppflags
    Compiler flags passed to all C++ rules during opt builds; these are typically pretty basic things like what language standard you want to target, warning flags, etc.
    Defaults to --std=c++11 -O3 -DNDEBUG -Wall -Werror
  • DefaultDbgCppflags
    Compiler rules passed to all C++ rules during dbg builds.
    Defaults to --std=c++11 -g3 -DDEBUG -Wall -Werror.
  • DefaultLdFlags
    Linker flags passed to all C++ rules.
    By default this is empty.
  • DefaultNamespace
    Namespace passed to all cc_embed_binary rules when not overridden by the namespace argument to that rule.
    Not set by default, if you want to use those rules you'll need to set it or pass it explicitly to each one.
  • Coverage
    If true (the default), coverage will be available for C and C++ build rules.
    This is still a little experimental but should work for GCC. Right now it does not work for Clang (it likely will in Clang 4.0 which will likely support --fprofile-dir) and so this can be useful to disable it.
    It's also useful in some cases for CI systems etc if you'd prefer to avoid the overhead, since the tests have to be compiled with extra instrumentation and without optimisation.


Properties that affect how the proto_library and grpc_library rules work.

As noted elsewhere, these rules are fairly complex and do a bunch of things internally, so they correspondingly have a lot of options here.

Obviously the various gRPC-related properties only apply to grpc_library rules, whereas proto_library rules are affected by all of them.

  • ProtocTool
    The binary invoked to compile .proto files. Defaults to protoc.
  • ProtocGoPlugin
    The binary passed to protoc as a plugin to generate Go code. Defaults to protoc-gen-go.
    We've found this easier to manage with a go_get rule instead though, so you can also pass a build label here. See the Please repo for an example.
  • GrpcPythonPlugin
    The plugin invoked to compile Python code for grpc_library.
    Defaults to grpc_python_plugin.
  • GrpcJavaPlugin
    The plugin invoked to compile Java code for grpc_library.
    Defaults to protoc-gen-grpc-java.
  • Language (repeated string)
    Sets the default set of languages that proto rules are built for.
    Chosen from the set of {cc, java, go, py}.
    Defaults to multiple Language lines, one line for each of the following values: cc, py, java, go, and js.
  • PythonDep
    An in-repo dependency that's applied to any Python targets built. Defaults to //third_party/python:protobuf.
  • JavaDep
    An in-repo dependency that's applied to any Java targets built. Defaults to //third_party/java:protobuf.
  • GoDep
    An in-repo dependency that's applied to any Go targets built. Defaults to //third_party/go:protobuf.
  • PythonGrpcDep
    An in-repo dependency that's applied to any Python gRPC targets built. Defaults to //third_party/python:grpc.
  • JavaGrpcDep
    An in-repo dependency that's applied to any Java gRPC targets built. Defaults to /third_party/java:grpc-all.
  • GoGrpcDep
    An in-repo dependency that's applied to any Go gRPC targets built. Defaults to //third_party/go:grpc.


Please has a limited ability to detect licences from third-party code. We obviously can't be 100% sure of these due to the complex nature of dependency management formats and the many, many different forms each licence can be described as. Hopefully though this should offer some help in cases where licences can be detected.

  • Accept (repeated string)
    Licences that are accepted in this repository.
    When this is empty licences are ignored. As soon as it's set any licence detected or assigned must be accepted explicitly here.
    There's no fuzzy matching, so some package managers (especially PyPI and Maven, but shockingly not npm which rather nicely uses SPDX) will generate a lot of slightly different spellings of the same thing, which will all have to be accepted here. We'd rather that than trying to "cleverly" match them which might result in matching the wrong thing.
  • Reject
    Licences that are explicitly rejected in this repository.
    An astute observer will notice that this is not very different to just not adding it to the accept section, but it does have the advantage of explicitly documenting things that the team aren't allowed to use.


This section lets you define new commands to run at the command line. These are currently implemented as a simple text-based replacement of the original command which limits some applications, but they can still be very useful.

They're written with a simple alias = replacement syntax:

	deploy = run //deployment:deployer --

This would transform plz deploy //src:please into plz run //deployment:deployer -- //src:please.

You can also do subcommands of aliases, with a slightly different syntax:

	[aliases "deploy"]
	dev = run //deployment:deployer -- --env=dev
	prod = run //deployment:deployer -- --env=prod

These are then invoked as plz deploy dev and plz deploy prod respectively.
Due to the limitations of parsing our config format, you can only have one level of subcommand of aliases.


This is (unsurprisingly) very similar to the [Aliases] section, but allows more information to be defined against each one. For example:

	[alias "deploy"]
    cmd = run //deployment:deployer --
    subcommand = dev
    subcommand = prod
    subcommand = real prod
    flag = --force
    flag = -f

This will tab-complete, taking into account the various sub-commands and flags etc.


This section defines some settings to help with limited Bazel compatibility.
We don't aspire to be fully compatible and mimic all the semantics of their system, but we hope to ease migration and cross-testing by being able to parse simple repos.

Currently the only attribute here is compatibility, when that is enabled some aspects of the parser behave a little differently; some of the rule names and flags change, //visibility:public is interpreted specially and WORKSPACE files are parsed to find external dependencies.

There is a --bazel_compat flag to plz init which sets this on initialising a new repo.

We don't have a separate setting for it, but switching this on will also allow limited Buck compatibility. Specifically include_defs becomes available and the various C++ rules gain cxx_ aliases.