Пример #1
0
def build(variant, package_dir, name, repository_url, clean_after_build):
    print("Building package {} variant {}".format(name, variant
                                                  or "<default>"))
    tmpdir = tempfile.TemporaryDirectory(prefix="pkgpanda_repo")
    repository = Repository(tmpdir.name)

    def pkg_abs(name):
        return package_dir + '/' + name

    # Build pkginfo over time, translating fields from buildinfo.
    pkginfo = {}

    # Build up the docker command arguments over time, translating fields as needed.
    cmd = DockerCmd()

    buildinfo = load_buildinfo(package_dir, variant)

    if 'name' in buildinfo:
        raise BuildError(
            "'name' is not allowed in buildinfo.json, it is implicitly the name of the "
            "folder containing the buildinfo.json")

    # Make sure build_script is only set on variants
    if 'build_script' in buildinfo and variant is None:
        raise BuildError("build_script can only be set on package variants")

    # Convert single_source -> sources
    try:
        sources = expand_single_source_alias(name, buildinfo)
    except ValidationError as ex:
        raise BuildError(
            "Invalid buildinfo.json for package: {}".format(ex)) from ex

    # Save the final sources back into buildinfo so it gets written into
    # buildinfo.json. This also means buildinfo.json is always expanded form.
    buildinfo['sources'] = sources

    # Construct the source fetchers, gather the checkout ids from them
    checkout_ids = dict()
    fetchers = dict()
    try:
        for src_name, src_info in sorted(sources.items()):
            if src_info[
                    'kind'] not in pkgpanda.build.src_fetchers.all_fetchers:
                raise ValidationError(
                    "No known way to catch src with kind '{}'. Known kinds: {}"
                    .format(src_info['kind'],
                            pkgpanda.src_fetchers.all_fetchers.keys()))

            cache_dir = pkg_abs("cache")
            if not os.path.exists(cache_dir):
                os.mkdir(cache_dir)

            fetchers[src_name] = pkgpanda.build.src_fetchers.all_fetchers[
                src_info['kind']](src_name, src_info, package_dir)
            checkout_ids[src_name] = fetchers[src_name].get_id()
    except ValidationError as ex:
        raise BuildError(
            "Validation error when fetching sources for package: {}".format(
                ex))

    for src_name, checkout_id in checkout_ids.items():
        # NOTE: single_source buildinfo was expanded above so the src_name is
        # always correct here.
        # Make sure we never accidentally overwrite something which might be
        # important. Fields should match if specified (And that should be
        # tested at some point). For now disallowing identical saves hassle.
        assert_no_duplicate_keys(checkout_id, buildinfo['sources'][src_name])
        buildinfo['sources'][src_name].update(checkout_id)

    # Add the sha1sum of the buildinfo.json + build file to the build ids
    build_ids = {"sources": checkout_ids}
    build_ids['build'] = pkgpanda.util.sha1(pkg_abs("build"))
    build_ids['pkgpanda_version'] = pkgpanda.build.constants.version
    build_ids['variant'] = '' if variant is None else variant

    extra_dir = pkg_abs("extra")
    # Add the "extra" folder inside the package as an additional source if it
    # exists
    if os.path.exists(extra_dir):
        extra_id = hash_folder(extra_dir)
        build_ids['extra_source'] = extra_id
        buildinfo['extra_source'] = extra_id

    # Figure out the docker name.
    docker_name = buildinfo.get('docker', 'dcos-builder:latest')
    cmd.container = docker_name

    # Add the id of the docker build environment to the build_ids.
    try:
        docker_id = get_docker_id(docker_name)
    except CalledProcessError:
        # docker pull the container and try again
        check_call(['docker', 'pull', docker_name])
        docker_id = get_docker_id(docker_name)

    build_ids['docker'] = docker_id

    # TODO(cmaloney): The environment variables should be generated during build
    # not live in buildinfo.json.
    build_ids['environment'] = buildinfo.get('environment', {})

    # Packages need directories inside the fake install root (otherwise docker
    # will try making the directories on a readonly filesystem), so build the
    # install root now, and make the package directories in it as we go.
    install_dir = tempfile.mkdtemp(prefix="pkgpanda-")

    active_packages = list()
    active_package_ids = set()
    active_package_variants = dict()
    auto_deps = set()
    # Verify all requires are in the repository.
    if 'requires' in buildinfo:
        # Final package has the same requires as the build.
        pkginfo['requires'] = buildinfo['requires']

        # TODO(cmaloney): Pull generating the full set of requires a function.
        to_check = copy.deepcopy(buildinfo['requires'])
        if type(to_check) != list:
            raise BuildError(
                "`requires` in buildinfo.json must be an array of dependencies."
            )
        while to_check:
            requires_info = to_check.pop(0)
            requires_name, requires_variant = expand_require(requires_info)

            if requires_name in active_package_variants:
                # TODO(cmaloney): If one package depends on the <default>
                # variant of a package and 1+ others depends on a non-<default>
                # variant then update the dependency to the non-default variant
                # rather than erroring.
                if requires_variant != active_package_variants[requires_name]:
                    # TODO(cmaloney): Make this contain the chains of
                    # dependencies which contain the conflicting packages.
                    # a -> b -> c -> d {foo}
                    # e {bar} -> d {baz}
                    raise BuildError(
                        "Dependncy on multiple variants of the same package {}. "
                        "variants: {} {}".format(
                            requires_name, requires_variant,
                            active_package_variants[requires_name]))

                # The variant has package {requires_name, variant} already is a
                # dependency, don't process it again / move on to the next.
                continue

            active_package_variants[requires_name] = requires_variant

            # Figure out the last build of the dependency, add that as the
            # fully expanded dependency.
            require_package_dir = os.path.normpath(
                pkg_abs('../' + requires_name))
            last_build = require_package_dir + '/' + last_build_filename(
                requires_variant)
            if not os.path.exists(last_build):
                raise BuildError(
                    "No last build file found for dependency {} variant {}. Rebuild "
                    "the dependency".format(requires_name, requires_variant))

            try:
                pkg_id_str = load_string(last_build)
                auto_deps.add(pkg_id_str)
                pkg_buildinfo = load_buildinfo(require_package_dir,
                                               requires_variant)
                pkg_requires = pkg_buildinfo.get('requires', list())
                pkg_path = repository.package_path(pkg_id_str)
                pkg_tar = pkg_id_str + '.tar.xz'
                if not os.path.exists(require_package_dir + '/' + pkg_tar):
                    raise BuildError(
                        "The build tarball {} refered to by the last_build file of the "
                        "dependency {} variant {} doesn't exist. Rebuild the dependency."
                        .format(pkg_tar, requires_name, requires_variant))

                active_package_ids.add(pkg_id_str)

                # Mount the package into the docker container.
                cmd.volumes[
                    pkg_path] = "/opt/mesosphere/packages/{}:ro".format(
                        pkg_id_str)
                os.makedirs(
                    os.path.join(install_dir,
                                 "packages/{}".format(pkg_id_str)))

                # Add the dependencies of the package to the set which will be
                # activated.
                # TODO(cmaloney): All these 'transitive' dependencies shouldn't
                # be available to the package being built, only what depends on
                # them directly.
                to_check += pkg_requires
            except ValidationError as ex:
                raise BuildError(
                    "validating package needed as dependency {0}: {1}".format(
                        requires_name, ex)) from ex
            except PackageError as ex:
                raise BuildError(
                    "loading package needed as dependency {0}: {1}".format(
                        requires_name, ex)) from ex

    # Add requires to the package id, calculate the final package id.
    # NOTE: active_packages isn't fully constructed here since we lazily load
    # packages not already in the repository.
    build_ids['requires'] = list(active_package_ids)
    version_base = hash_checkout(build_ids)
    version = None
    if "version_extra" in buildinfo:
        version = "{0}-{1}".format(buildinfo["version_extra"], version_base)
    else:
        version = version_base
    pkg_id = PackageId.from_parts(name, version)

    # Save the build_ids. Useful for verify exactly what went into the
    # package build hash.
    buildinfo['build_ids'] = build_ids
    buildinfo['package_version'] = version

    # Save the package name and variant. The variant is used when installing
    # packages to validate dependencies.
    buildinfo['name'] = name
    buildinfo['variant'] = variant

    # If the package is already built, don't do anything.
    pkg_path = pkg_abs("{}.tar.xz".format(pkg_id))

    # Done if it exists locally
    if exists(pkg_path):
        print("Package up to date. Not re-building.")

        # TODO(cmaloney): Updating / filling last_build should be moved out of
        # the build function.
        check_call(["mkdir", "-p", pkg_abs("cache")])
        write_string(pkg_abs(last_build_filename(variant)), str(pkg_id))

        return pkg_path

    # Try downloading.
    if repository_url:
        tmp_filename = pkg_path + '.tmp'
        try:
            # Normalize to no trailing slash for repository_url
            repository_url = repository_url.rstrip('/')
            url = repository_url + '/packages/{0}/{1}.tar.xz'.format(
                pkg_id.name, str(pkg_id))
            print("Attempting to download", pkg_id, "from", url)
            download(tmp_filename, url, package_dir)
            os.rename(tmp_filename, pkg_path)

            print(
                "Package up to date. Not re-building. Downloaded from repository-url."
            )
            # TODO(cmaloney): Updating / filling last_build should be moved out of
            # the build function.
            check_call(["mkdir", "-p", pkg_abs("cache")])
            write_string(pkg_abs(last_build_filename(variant)), str(pkg_id))
            return pkg_path
        except FetchError:
            try:
                os.remove(tmp_filename)
            except:
                pass

            # Fall out and do the build since the command errored.
            print("Unable to download from cache. Proceeding to build")

    print("Building package {} with buildinfo: {}".format(
        pkg_id, json.dumps(buildinfo, indent=2, sort_keys=True)))

    # Clean out src, result so later steps can use them freely for building.
    clean(package_dir)

    # Only fresh builds are allowed which don't overlap existing artifacts.
    result_dir = pkg_abs("result")
    if exists(result_dir):
        raise BuildError(
            "result folder must not exist. It will be made when the package is "
            "built. {}".format(result_dir))

    # 'mkpanda add' all implicit dependencies since we actually need to build.
    for dep in auto_deps:
        print("Auto-adding dependency: {}".format(dep))
        # NOTE: Not using the name pkg_id because that overrides the outer one.
        id_obj = PackageId(dep)
        add_to_repository(
            repository, pkg_abs('../{0}/{1}.tar.xz'.format(id_obj.name, dep)))
        package = repository.load(dep)
        active_packages.append(package)

    # Checkout all the sources int their respective 'src/' folders.
    try:
        src_dir = pkg_abs('src')
        if os.path.exists(src_dir):
            raise ValidationError(
                "'src' directory already exists, did you have a previous build? "
                +
                "Currently all builds must be from scratch. Support should be "
                + "added for re-using a src directory when possible. src={}".
                format(src_dir))
        os.mkdir(src_dir)
        for src_name, fetcher in sorted(fetchers.items()):
            root = pkg_abs('src/' + src_name)
            os.mkdir(root)

            fetcher.checkout_to(root)
    except ValidationError as ex:
        raise BuildError(
            "Validation error when fetching sources for package: {}".format(
                ex))

    # Copy over environment settings
    if 'environment' in buildinfo:
        pkginfo['environment'] = buildinfo['environment']

    # Activate the packages so that we have a proper path, environment
    # variables.
    # TODO(cmaloney): RAII type thing for temproary directory so if we
    # don't get all the way through things will be cleaned up?
    install = Install(install_dir, None, True, False, True, True)
    install.activate(active_packages)
    # Rewrite all the symlinks inside the active path because we will
    # be mounting the folder into a docker container, and the absolute
    # paths to the packages will change.
    # TODO(cmaloney): This isn't very clean, it would be much nicer to
    # just run pkgpanda inside the package.
    rewrite_symlinks(install_dir, repository.path, "/opt/mesosphere/packages/")

    print("Building package in docker")

    # TODO(cmaloney): Run as a specific non-root user, make it possible
    # for non-root to cleanup afterwards.
    # Run the build, prepping the environment as necessary.
    mkdir(pkg_abs("result"))

    # Copy the build info to the resulting tarball
    write_json(pkg_abs("src/buildinfo.full.json"), buildinfo)
    write_json(pkg_abs("result/buildinfo.full.json"), buildinfo)

    write_json(pkg_abs("result/pkginfo.json"), pkginfo)

    # Make the folder for the package we are building. If docker does it, it
    # gets auto-created with root permissions and we can't actually delete it.
    os.makedirs(os.path.join(install_dir, "packages", str(pkg_id)))

    # TOOD(cmaloney): Disallow writing to well known files and directories?
    # Source we checked out
    cmd.volumes.update({
        # TODO(cmaloney): src should be read only...
        pkg_abs("src"):
        "/pkg/src:rw",
        # The build script
        pkg_abs(buildinfo.get('build_script', 'build')):
        "/pkg/build:ro",
        # Getting the result out
        pkg_abs("result"):
        "/opt/mesosphere/packages/{}:rw".format(pkg_id),
        install_dir:
        "/opt/mesosphere:ro"
    })

    if os.path.exists(extra_dir):
        cmd.volumes[extra_dir] = "/pkg/extra:ro"

    cmd.environment = {
        "PKG_VERSION": version,
        "PKG_NAME": name,
        "PKG_ID": pkg_id,
        "PKG_PATH": "/opt/mesosphere/packages/{}".format(pkg_id),
        "PKG_VARIANT": variant if variant is not None else "<default>"
    }

    try:
        # TODO(cmaloney): Run a wrapper which sources
        # /opt/mesosphere/environment then runs a build. Also should fix
        # ownership of /opt/mesosphere/packages/{pkg_id} post build.
        cmd.run([
            "/bin/bash", "-o", "nounset", "-o", "pipefail", "-o", "errexit",
            "/pkg/build"
        ])
    except CalledProcessError as ex:
        raise BuildError("docker exited non-zero: {}\nCommand: {}".format(
            ex.returncode, ' '.join(ex.cmd)))

    # Clean up the temporary install dir used for dependencies.
    # TODO(cmaloney): Move to an RAII wrapper.
    check_call(['rm', '-rf', install_dir])

    print("Building package tarball")

    # Check for forbidden services before packaging the tarball:
    try:
        check_forbidden_services(pkg_abs("result"), RESERVED_UNIT_NAMES)
    except ValidationError as ex:
        raise BuildError("Package validation failed: {}".format(ex))

    # TODO(cmaloney): Updating / filling last_build should be moved out of
    # the build function.
    check_call(["mkdir", "-p", pkg_abs("cache")])
    write_string(pkg_abs(last_build_filename(variant)), str(pkg_id))

    # Bundle the artifacts into the pkgpanda package
    tmp_name = pkg_path + "-tmp.tar.xz"
    make_tar(tmp_name, pkg_abs("result"))
    os.rename(tmp_name, pkg_path)
    print("Package built.")
    if clean_after_build:
        clean(package_dir)
    return pkg_path
Пример #2
0
def build(package_store, name, variant, clean_after_build):
    assert isinstance(package_store, PackageStore)
    print("Building package {} variant {}".format(name, pkgpanda.util.variant_str(variant)))
    tmpdir = tempfile.TemporaryDirectory(prefix="pkgpanda_repo")
    repository = Repository(tmpdir.name)

    package_dir = package_store.get_package_folder(name)

    def pkg_abs(name):
        return package_dir + '/' + name

    # Build pkginfo over time, translating fields from buildinfo.
    pkginfo = {}

    # Build up the docker command arguments over time, translating fields as needed.
    cmd = DockerCmd()

    assert (name, variant) in package_store.packages, \
        "Programming error: name, variant should have been validated to be valid before calling build()."
    buildinfo = copy.deepcopy(package_store.get_buildinfo(name, variant))

    if 'name' in buildinfo:
        raise BuildError("'name' is not allowed in buildinfo.json, it is implicitly the name of the "
                         "folder containing the buildinfo.json")

    # Convert single_source -> sources
    try:
        sources = expand_single_source_alias(name, buildinfo)
    except ValidationError as ex:
        raise BuildError("Invalid buildinfo.json for package: {}".format(ex)) from ex

    # Save the final sources back into buildinfo so it gets written into
    # buildinfo.json. This also means buildinfo.json is always expanded form.
    buildinfo['sources'] = sources

    # Construct the source fetchers, gather the checkout ids from them
    checkout_ids = dict()
    fetchers = dict()
    try:
        for src_name, src_info in sorted(sources.items()):
            if src_info['kind'] not in pkgpanda.build.src_fetchers.all_fetchers:
                raise ValidationError("No known way to catch src with kind '{}'. Known kinds: {}".format(
                    src_info['kind'],
                    pkgpanda.src_fetchers.all_fetchers.keys()))

            cache_dir = pkg_abs("cache")
            if not os.path.exists(cache_dir):
                os.mkdir(cache_dir)

            fetchers[src_name] = pkgpanda.build.src_fetchers.all_fetchers[src_info['kind']](src_name,
                                                                                            src_info,
                                                                                            package_dir)
            checkout_ids[src_name] = fetchers[src_name].get_id()
    except ValidationError as ex:
        raise BuildError("Validation error when fetching sources for package: {}".format(ex))

    for src_name, checkout_id in checkout_ids.items():
        # NOTE: single_source buildinfo was expanded above so the src_name is
        # always correct here.
        # Make sure we never accidentally overwrite something which might be
        # important. Fields should match if specified (And that should be
        # tested at some point). For now disallowing identical saves hassle.
        assert_no_duplicate_keys(checkout_id, buildinfo['sources'][src_name])
        buildinfo['sources'][src_name].update(checkout_id)

    # Add the sha1sum of the buildinfo.json + build file to the build ids
    build_ids = {"sources": checkout_ids}
    build_ids['build'] = pkgpanda.util.sha1(pkg_abs(buildinfo['build_script']))
    build_ids['pkgpanda_version'] = pkgpanda.build.constants.version
    build_ids['variant'] = '' if variant is None else variant

    extra_dir = pkg_abs("extra")
    # Add the "extra" folder inside the package as an additional source if it
    # exists
    if os.path.exists(extra_dir):
        extra_id = hash_folder(extra_dir)
        build_ids['extra_source'] = extra_id
        buildinfo['extra_source'] = extra_id

    # Figure out the docker name.
    docker_name = buildinfo['docker']
    cmd.container = docker_name

    # Add the id of the docker build environment to the build_ids.
    try:
        docker_id = get_docker_id(docker_name)
    except CalledProcessError:
        # docker pull the container and try again
        check_call(['docker', 'pull', docker_name])
        docker_id = get_docker_id(docker_name)

    build_ids['docker'] = docker_id

    # TODO(cmaloney): The environment variables should be generated during build
    # not live in buildinfo.json.
    build_ids['environment'] = buildinfo['environment']

    # Packages need directories inside the fake install root (otherwise docker
    # will try making the directories on a readonly filesystem), so build the
    # install root now, and make the package directories in it as we go.
    install_dir = tempfile.mkdtemp(prefix="pkgpanda-")

    active_packages = list()
    active_package_ids = set()
    active_package_variants = dict()
    auto_deps = set()
    # Verify all requires are in the repository.
    if 'requires' in buildinfo:
        # Final package has the same requires as the build.
        pkginfo['requires'] = buildinfo['requires']

        # TODO(cmaloney): Pull generating the full set of requires a function.
        to_check = copy.deepcopy(buildinfo['requires'])
        if type(to_check) != list:
            raise BuildError("`requires` in buildinfo.json must be an array of dependencies.")
        while to_check:
            requires_info = to_check.pop(0)
            requires_name, requires_variant = expand_require(requires_info)

            if requires_name in active_package_variants:
                # TODO(cmaloney): If one package depends on the <default>
                # variant of a package and 1+ others depends on a non-<default>
                # variant then update the dependency to the non-default variant
                # rather than erroring.
                if requires_variant != active_package_variants[requires_name]:
                    # TODO(cmaloney): Make this contain the chains of
                    # dependencies which contain the conflicting packages.
                    # a -> b -> c -> d {foo}
                    # e {bar} -> d {baz}
                    raise BuildError("Dependncy on multiple variants of the same package {}. "
                                     "variants: {} {}".format(
                                        requires_name,
                                        requires_variant,
                                        active_package_variants[requires_name]))

                # The variant has package {requires_name, variant} already is a
                # dependency, don't process it again / move on to the next.
                continue

            active_package_variants[requires_name] = requires_variant

            # Figure out the last build of the dependency, add that as the
            # fully expanded dependency.
            requires_last_build = package_store.get_last_build_filename(requires_name, requires_variant)
            if not os.path.exists(requires_last_build):
                raise BuildError("No last build file found for dependency {} variant {}. Rebuild "
                                 "the dependency".format(requires_name, requires_variant))

            try:
                pkg_id_str = load_string(requires_last_build)
                auto_deps.add(pkg_id_str)
                pkg_buildinfo = package_store.get_buildinfo(requires_name, requires_variant)
                pkg_requires = pkg_buildinfo['requires']
                pkg_path = repository.package_path(pkg_id_str)
                pkg_tar = pkg_id_str + '.tar.xz'
                if not os.path.exists(package_store.get_package_folder(requires_name) + '/' + pkg_tar):
                    raise BuildError("The build tarball {} refered to by the last_build file of the "
                                     "dependency {} variant {} doesn't exist. Rebuild the dependency.".format(
                                        pkg_tar,
                                        requires_name,
                                        requires_variant))

                active_package_ids.add(pkg_id_str)

                # Mount the package into the docker container.
                cmd.volumes[pkg_path] = "/opt/mesosphere/packages/{}:ro".format(pkg_id_str)
                os.makedirs(os.path.join(install_dir, "packages/{}".format(pkg_id_str)))

                # Add the dependencies of the package to the set which will be
                # activated.
                # TODO(cmaloney): All these 'transitive' dependencies shouldn't
                # be available to the package being built, only what depends on
                # them directly.
                to_check += pkg_requires
            except ValidationError as ex:
                raise BuildError("validating package needed as dependency {0}: {1}".format(requires_name, ex)) from ex
            except PackageError as ex:
                raise BuildError("loading package needed as dependency {0}: {1}".format(requires_name, ex)) from ex

    # Add requires to the package id, calculate the final package id.
    # NOTE: active_packages isn't fully constructed here since we lazily load
    # packages not already in the repository.
    build_ids['requires'] = list(active_package_ids)
    version_base = hash_checkout(build_ids)
    version = None
    if "version_extra" in buildinfo:
        version = "{0}-{1}".format(buildinfo["version_extra"], version_base)
    else:
        version = version_base
    pkg_id = PackageId.from_parts(name, version)

    # Save the build_ids. Useful for verify exactly what went into the
    # package build hash.
    buildinfo['build_ids'] = build_ids
    buildinfo['package_version'] = version

    # Save the package name and variant. The variant is used when installing
    # packages to validate dependencies.
    buildinfo['name'] = name
    buildinfo['variant'] = variant

    # If the package is already built, don't do anything.
    pkg_path = pkg_abs("{}.tar.xz".format(pkg_id))

    # Done if it exists locally
    if exists(pkg_path):
        print("Package up to date. Not re-building.")

        # TODO(cmaloney): Updating / filling last_build should be moved out of
        # the build function.
        check_call(["mkdir", "-p", pkg_abs("cache")])
        write_string(pkg_abs(last_build_filename(variant)), str(pkg_id))

        return pkg_path

    # Try downloading.
    dl_path = package_store.try_fetch_by_id(pkg_id)
    if dl_path:
        print("Package up to date. Not re-building. Downloaded from repository-url.")
        # TODO(cmaloney): Updating / filling last_build should be moved out of
        # the build function.
        check_call(["mkdir", "-p", pkg_abs("cache")])
        write_string(pkg_abs(last_build_filename(variant)), str(pkg_id))
        print(dl_path, pkg_path)
        assert dl_path == pkg_path
        return pkg_path

    # Fall out and do the build since it couldn't be downloaded
    print("Unable to download from cache. Proceeding to build")

    print("Building package {} with buildinfo: {}".format(
        pkg_id,
        json.dumps(buildinfo, indent=2, sort_keys=True)))

    # Clean out src, result so later steps can use them freely for building.
    clean(package_dir)

    # Only fresh builds are allowed which don't overlap existing artifacts.
    result_dir = pkg_abs("result")
    if exists(result_dir):
        raise BuildError("result folder must not exist. It will be made when the package is "
                         "built. {}".format(result_dir))

    # 'mkpanda add' all implicit dependencies since we actually need to build.
    for dep in auto_deps:
        print("Auto-adding dependency: {}".format(dep))
        # NOTE: Not using the name pkg_id because that overrides the outer one.
        id_obj = PackageId(dep)
        add_to_repository(repository, pkg_abs('../{0}/{1}.tar.xz'.format(id_obj.name, dep)))
        package = repository.load(dep)
        active_packages.append(package)

    # Checkout all the sources int their respective 'src/' folders.
    try:
        src_dir = pkg_abs('src')
        if os.path.exists(src_dir):
            raise ValidationError(
                "'src' directory already exists, did you have a previous build? " +
                "Currently all builds must be from scratch. Support should be " +
                "added for re-using a src directory when possible. src={}".format(src_dir))
        os.mkdir(src_dir)
        for src_name, fetcher in sorted(fetchers.items()):
            root = pkg_abs('src/' + src_name)
            os.mkdir(root)

            fetcher.checkout_to(root)
    except ValidationError as ex:
        raise BuildError("Validation error when fetching sources for package: {}".format(ex))

    # Copy over environment settings
    pkginfo['environment'] = buildinfo['environment']

    # Activate the packages so that we have a proper path, environment
    # variables.
    # TODO(cmaloney): RAII type thing for temproary directory so if we
    # don't get all the way through things will be cleaned up?
    install = Install(install_dir, None, True, False, True, True)
    install.activate(active_packages)
    # Rewrite all the symlinks inside the active path because we will
    # be mounting the folder into a docker container, and the absolute
    # paths to the packages will change.
    # TODO(cmaloney): This isn't very clean, it would be much nicer to
    # just run pkgpanda inside the package.
    rewrite_symlinks(install_dir, repository.path, "/opt/mesosphere/packages/")

    print("Building package in docker")

    # TODO(cmaloney): Run as a specific non-root user, make it possible
    # for non-root to cleanup afterwards.
    # Run the build, prepping the environment as necessary.
    mkdir(pkg_abs("result"))

    # Copy the build info to the resulting tarball
    write_json(pkg_abs("src/buildinfo.full.json"), buildinfo)
    write_json(pkg_abs("result/buildinfo.full.json"), buildinfo)

    write_json(pkg_abs("result/pkginfo.json"), pkginfo)

    # Make the folder for the package we are building. If docker does it, it
    # gets auto-created with root permissions and we can't actually delete it.
    os.makedirs(os.path.join(install_dir, "packages", str(pkg_id)))

    # TOOD(cmaloney): Disallow writing to well known files and directories?
    # Source we checked out
    cmd.volumes.update({
        # TODO(cmaloney): src should be read only...
        pkg_abs("src"): "/pkg/src:rw",
        # The build script
        pkg_abs(buildinfo['build_script']): "/pkg/build:ro",
        # Getting the result out
        pkg_abs("result"): "/opt/mesosphere/packages/{}:rw".format(pkg_id),
        install_dir: "/opt/mesosphere:ro"
    })

    if os.path.exists(extra_dir):
        cmd.volumes[extra_dir] = "/pkg/extra:ro"

    cmd.environment = {
        "PKG_VERSION": version,
        "PKG_NAME": name,
        "PKG_ID": pkg_id,
        "PKG_PATH": "/opt/mesosphere/packages/{}".format(pkg_id),
        "PKG_VARIANT": variant if variant is not None else "<default>"
    }

    try:
        # TODO(cmaloney): Run a wrapper which sources
        # /opt/mesosphere/environment then runs a build. Also should fix
        # ownership of /opt/mesosphere/packages/{pkg_id} post build.
        cmd.run([
            "/bin/bash",
            "-o", "nounset",
            "-o", "pipefail",
            "-o", "errexit",
            "/pkg/build"])
    except CalledProcessError as ex:
        raise BuildError("docker exited non-zero: {}\nCommand: {}".format(ex.returncode, ' '.join(ex.cmd)))

    # Clean up the temporary install dir used for dependencies.
    # TODO(cmaloney): Move to an RAII wrapper.
    check_call(['rm', '-rf', install_dir])

    print("Building package tarball")

    # Check for forbidden services before packaging the tarball:
    try:
        check_forbidden_services(pkg_abs("result"), RESERVED_UNIT_NAMES)
    except ValidationError as ex:
        raise BuildError("Package validation failed: {}".format(ex))

    # TODO(cmaloney): Updating / filling last_build should be moved out of
    # the build function.
    check_call(["mkdir", "-p", pkg_abs("cache")])
    write_string(pkg_abs(last_build_filename(variant)), str(pkg_id))

    # Bundle the artifacts into the pkgpanda package
    tmp_name = pkg_path + "-tmp.tar.xz"
    make_tar(tmp_name, pkg_abs("result"))
    os.rename(tmp_name, pkg_path)
    print("Package built.")
    if clean_after_build:
        clean(package_dir)
    return pkg_path