release workflow: Add spack command for generating the .gitlab-ci.yml

This spack command adds a new schema for a file which describes the
builder containers available, along with the compilers availabe on
each builder.  The release-jobs command then generates the .gitlab-ci.yml
file by first expanding the release spec set, concretizing each spec
(in an appropriate docker container if --this-machine-only argument is
not provided on command line), and then combining and staging all the
concrete specs as jobs to be run by gitlab.

etc/spack/defaults/release.yaml

@@ -0,0 +1,16 @@
+# -------------------------------------------------------------------------
+# This is the default spack release spec set.
+# -------------------------------------------------------------------------
+spec-set:
+    include: []
+    exclude: []
+    matrix:
+        - packages:
+            xsdk:
+                versions: [0.4.0]
+        - compilers:
+            gcc:
+                versions: [5.5.0]
+            clang:
+                versions: [6.0.0, '6.0.0-1ubuntu2']
+    cdash: ["https://spack.io/cdash/submit.php?project=spack"]

lib/spack/spack/cmd/release_jobs.py

@@ -0,0 +1,607 @@
+# Copyright 2013-2019 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+import argparse
+import json
+import os
+import shutil
+import tempfile
+
+import subprocess
+from jsonschema import validate, ValidationError
+from six import iteritems
+
+import llnl.util.tty as tty
+
+from spack.architecture import sys_type
+from spack.dependency import all_deptypes
+from spack.spec import Spec, CompilerSpec
+from spack.paths import spack_root
+from spack.error import SpackError
+from spack.schema.os_container_mapping import schema as mapping_schema
+from spack.schema.specs_deps import schema as specs_deps_schema
+from spack.spec_set import CombinatorialSpecSet
+import spack.util.spack_yaml as syaml
+
+description = "generate release build set as .gitlab-ci.yml"
+section = "build"
+level = "long"
+
+
+def setup_parser(subparser):
+    subparser.add_argument(
+        '-s', '--spec-set', default=None,
+        help="path to release spec-set yaml file")
+
+    subparser.add_argument(
+        '-m', '--mirror-url', default=None,
+        help="url of binary mirror where builds should be pushed")
+
+    subparser.add_argument(
+        '-o', '--output-file', default=".gitlab-ci.yml",
+        help="path to output file to write")
+
+    subparser.add_argument(
+        '-t', '--shared-runner-tag', default=None,
+        help="tag to add to jobs for shared runner selection")
+
+    subparser.add_argument(
+        '-k', '--signing-key', default=None,
+        help="hash of gpg key to use for package signing")
+
+    subparser.add_argument(
+        '-c', '--cdash-url', default='https://cdash.spack.io',
+        help="Base url of CDash instance jobs should communicate with")
+
+    subparser.add_argument(
+        '-p', '--print-summary', action='store_true', default=False,
+        help="Print summary of staged jobs to standard output")
+
+    subparser.add_argument(
+        '--resolve-deps-locally', action='store_true', default=False,
+        help="Use only the current machine to concretize specs, " +
+        "instead of iterating over items in os-container-mapping.yaml " +
+        "and using docker run.  Assumes the current machine architecure " +
+        "is listed in the os-container-mapping.yaml config file.")
+
+    subparser.add_argument(
+        '--specs-deps-output', default='/dev/stdout',
+        help="A file path to which spec deps should be written.  This " +
+             "argument is generally for internal use, and should not be " +
+             "provided by end-users under normal conditions.")
+
+    subparser.add_argument(
+        'specs', nargs=argparse.REMAINDER,
+        help="These positional arguments are generally for internal use.  " +
+             "The --spec-set argument should be used to identify a yaml " +
+             "file describing the set of release specs to include in the " +
+             ".gitlab-ci.yml file.")
+
+
+def get_job_name(spec, osarch):
+    return '{0} {1} {2} {3}'.format(spec.name, spec.version,
+                                    spec.compiler, osarch)
+
+
+def get_spec_string(spec):
+    format_elements = [
+        '${package}@${version}',
+        '%${compilername}@${compilerversion}',
+    ]
+
+    if spec.architecture:
+        format_elements.append(' arch=${architecture}')
+
+    return spec.format(''.join(format_elements))
+
+
+def spec_deps_key_label(s):
+    return s.dag_hash(), "%s/%s" % (s.name, s.dag_hash(7))
+
+
+def _add_dependency(spec_label, dep_label, deps):
+    if spec_label == dep_label:
+        return
+    if spec_label not in deps:
+        deps[spec_label] = set()
+    deps[spec_label].add(dep_label)
+
+
+def get_deps_using_container(specs, image):
+    image_home_dir = '/home/spackuser'
+    repo_mount_location = '{0}/spack'.format(image_home_dir)
+    temp_dir = tempfile.mkdtemp(dir='/tmp')
+
+    # The paths this module will see (from outside the container)
+    temp_file = os.path.join(temp_dir, 'spec_deps.json')
+    temp_err = os.path.join(temp_dir, 'std_err.log')
+
+    # The paths the bash_command will see inside the container
+    json_output = '/work/spec_deps.json'
+    std_error = '/work/std_err.log'
+
+    specs_arg = ' '.join([str(spec) for spec in specs])
+
+    bash_command = " ".join(["source {0}/share/spack/setup-env.sh ;",
+                             "spack release-jobs",
+                             "--specs-deps-output {1}",
+                             "{2}",
+                             "2> {3}"]).format(
+        repo_mount_location, json_output, specs_arg, std_error)
+
+    docker_cmd_to_run = [
+        'docker', 'run', '--rm',
+        '-v', '{0}:{1}'.format(spack_root, repo_mount_location),
+        '-v', '{0}:{1}'.format(temp_dir, '/work'),
+        '--entrypoint', 'bash',
+        '-t', str(image),
+        '-c',
+        bash_command,
+    ]
+
+    tty.debug('Running subprocess command:')
+    tty.debug(' '.join(docker_cmd_to_run))
+
+    # Docker is going to merge the stdout/stderr from the script and write it
+    # all to the stdout of the running container.  For this reason, we won't
+    # pipe any stdout/stderr from the docker command, but rather write the
+    # output we care about to a file in a mounted directory.  Similarly, any
+    # errors from running the spack command inside the container are redirected
+    # to another file in the mounted directory.
+    proc = subprocess.Popen(docker_cmd_to_run)
+    proc.wait()
+
+    # Check for errors from spack command
+    if os.path.exists(temp_err) and os.path.getsize(temp_err) > 0:
+        # Spack wrote something to stderr inside the container.  We will
+        # print out whatever it is, but attempt to carry on with the process.
+        tty.error('Encountered spack error running command in container:')
+        with open(temp_err, 'r') as err:
+            tty.error(err.read())
+
+    spec_deps_obj = {}
+
+    try:
+        # Finally, try to read/parse the output we really care about: the
+        # specs and dependency edges for the provided spec, as it was
+        # concretized in the appropriate container.
+        with open(temp_file, 'r') as fd:
+            spec_deps_obj = json.loads(fd.read())
+
+    except ValueError as val_err:
+        tty.error('Failed to read json object from spec-deps output file:')
+        tty.error(str(val_err))
+    except IOError as io_err:
+        tty.error('Problem reading from spec-deps json output file:')
+        tty.error(str(io_err))
+    finally:
+        shutil.rmtree(temp_dir)
+
+    return spec_deps_obj
+
+
+def get_spec_dependencies(specs, deps, spec_labels, image=None):
+    if image:
+        spec_deps_obj = get_deps_using_container(specs, image)
+    else:
+        spec_deps_obj = compute_spec_deps(specs)
+
+    try:
+        validate(spec_deps_obj, specs_deps_schema)
+    except ValidationError as val_err:
+        tty.error('Ill-formed specs dependencies JSON object')
+        tty.error(spec_deps_obj)
+        tty.debug(val_err)
+        return
+
+    if spec_deps_obj:
+        dependencies = spec_deps_obj['dependencies']
+        specs = spec_deps_obj['specs']
+
+        for entry in specs:
+            spec_labels[entry['label']] = {
+                'spec': Spec(entry['spec']),
+                'rootSpec': entry['root_spec'],
+            }
+
+        for entry in dependencies:
+            _add_dependency(entry['spec'], entry['depends'], deps)
+
+
+def stage_spec_jobs(spec_set, containers, current_system=None):
+    """Take a set of release specs along with a dictionary describing the
+        available docker containers and what compilers they have, and generate
+        a list of "stages", where the jobs in any stage are dependent only on
+        jobs in previous stages.  This allows us to maximize build parallelism
+        within the gitlab-ci framework.
+
+    Arguments:
+        spec_set (CombinatorialSpecSet): Iterable containing all the specs
+            to build.
+        containers (dict): Describes the docker containers available to use
+            for concretizing specs (and also for the gitlab runners to use
+            for building packages).  The schema can be found at
+            "lib/spack/spack/schema/os_container_mapping.py"
+        current_system (string): If provided, this indicates not to use the
+            containers for concretizing the release specs, but rather just
+            assume the current system is in the "containers" dictionary.  A
+            SpackError will be raised if the current system is not in that
+            dictionary.
+
+    Returns: A tuple of information objects describing the specs, dependencies
+        and stages:
+
+        spec_labels: A dictionary mapping the spec labels which are made of
+            (pkg-name/hash-prefix), to objects containing "rootSpec" and "spec"
+            keys.  The root spec is the spec of which this spec is a dependency
+            and the spec is the formatted spec string for this spec.
+
+        deps: A dictionary where the keys should also have appeared as keys in
+            the spec_labels dictionary, and the values are the set of
+            dependencies for that spec.
+
+        stages: An ordered list of sets, each of which contains all the jobs to
+            built in that stage.  The jobs are expressed in the same format as
+            the keys in the spec_labels and deps objects.
+
+    """
+
+    # The convenience method below, "remove_satisfied_deps()", does not modify
+    # the "deps" parameter.  Instead, it returns a new dictionary where only
+    # dependencies which have not yet been satisfied are included in the
+    # return value.
+    def remove_satisfied_deps(deps, satisfied_list):
+        new_deps = {}
+
+        for key, value in iteritems(deps):
+            new_value = set([v for v in value if v not in satisfied_list])
+            if new_value:
+                new_deps[key] = new_value
+
+        return new_deps
+
+    deps = {}
+    spec_labels = {}
+
+    if current_system:
+        if current_system not in containers:
+            error_msg = ' '.join(['Current system ({0}) does not appear in',
+                                  'os_container_mapping.yaml, ignoring',
+                                  'request']).format(
+                current_system)
+            raise SpackError(error_msg)
+        os_names = [current_system]
+    else:
+        os_names = [name for name in containers]
+
+    container_specs = {}
+    for name in os_names:
+        container_specs[name] = {'image': None, 'specs': []}
+
+    # Collect together all the specs that should be concretized in each
+    # container so they can all be done at once, avoiding the need to
+    # run the docker container for each spec separately.
+    for spec in spec_set:
+        for osname in os_names:
+            container_info = containers[osname]
+            image = None if current_system else container_info['image']
+            if image:
+                container_specs[osname]['image'] = image
+            if 'compilers' in container_info:
+                found_at_least_one = False
+                for item in container_info['compilers']:
+                    container_compiler_spec = CompilerSpec(item['name'])
+                    if spec.compiler == container_compiler_spec:
+                        container_specs[osname]['specs'].append(spec)
+                        found_at_least_one = True
+                if not found_at_least_one:
+                    tty.warn('No compiler in {0} satisfied {1}'.format(
+                        osname, spec.compiler))
+
+    for osname in container_specs:
+        if container_specs[osname]['specs']:
+            image = container_specs[osname]['image']
+            specs = container_specs[osname]['specs']
+            get_spec_dependencies(specs, deps, spec_labels, image)
+
+    # Save the original deps, as we need to return them at the end of the
+    # function.  In the while loop below, the "dependencies" variable is
+    # overwritten rather than being modified each time through the loop,
+    # thus preserving the original value of "deps" saved here.
+    dependencies = deps
+    unstaged = set(spec_labels.keys())
+    stages = []
+
+    while dependencies:
+        dependents = set(dependencies.keys())
+        next_stage = unstaged.difference(dependents)
+        stages.append(next_stage)
+        unstaged.difference_update(next_stage)
+        # Note that "dependencies" is a dictionary mapping each dependent
+        # package to the set of not-yet-handled dependencies.  The final step
+        # below removes all the dependencies that are handled by this stage.
+        dependencies = remove_satisfied_deps(dependencies, next_stage)
+
+    if unstaged:
+        stages.append(unstaged.copy())
+
+    return spec_labels, deps, stages
+
+
+def print_staging_summary(spec_labels, dependencies, stages):
+    if not stages:
+        return
+
+    tty.msg('Staging summary:')
+    stage_index = 0
+    for stage in stages:
+        tty.msg('  stage {0} ({1} jobs):'.format(stage_index, len(stage)))
+
+        for job in sorted(stage):
+            s = spec_labels[job]['spec']
+            tty.msg('    {0} -> {1}'.format(job, get_spec_string(s)))
+
+        stage_index += 1
+
+
+def compute_spec_deps(spec_list, stream_like=None):
+    """
+    Computes all the dependencies for the spec(s) and generates a JSON
+    object which provides both a list of unique spec names as well as a
+    comprehensive list of all the edges in the dependency graph.  For
+    example, given a single spec like 'readline@7.0', this function
+    generates the following JSON object:
+
+    .. code-block:: JSON
+
+       {
+           "dependencies": [
+               {
+                   "depends": "readline/ip6aiun",
+                   "spec": "readline/ip6aiun"
+               },
+               {
+                   "depends": "ncurses/y43rifz",
+                   "spec": "readline/ip6aiun"
+               },
+               {
+                   "depends": "ncurses/y43rifz",
+                   "spec": "readline/ip6aiun"
+               },
+               {
+                   "depends": "pkgconf/eg355zb",
+                   "spec": "ncurses/y43rifz"
+               },
+               {
+                   "depends": "pkgconf/eg355zb",
+                   "spec": "readline/ip6aiun"
+               }
+           ],
+           "specs": [
+               {
+                 "root_spec": "readline@7.0%clang@9.1.0-apple arch=darwin-...",
+                 "spec": "readline@7.0%clang@9.1.0-apple arch=darwin-highs...",
+                 "label": "readline/ip6aiun"
+               },
+               {
+                 "root_spec": "readline@7.0%clang@9.1.0-apple arch=darwin-...",
+                 "spec": "ncurses@6.1%clang@9.1.0-apple arch=darwin-highsi...",
+                 "label": "ncurses/y43rifz"
+               },
+               {
+                 "root_spec": "readline@7.0%clang@9.1.0-apple arch=darwin-...",
+                 "spec": "pkgconf@1.5.4%clang@9.1.0-apple arch=darwin-high...",
+                 "label": "pkgconf/eg355zb"
+               }
+           ]
+       }
+
+    The object can be optionally written out to some stream.  This is
+    useful, for example, when we need to concretize and generate the
+    dependencies of a spec in a specific docker container.
+
+    """
+    deptype = all_deptypes
+    spec_labels = {}
+
+    specs = []
+    dependencies = []
+
+    def append_dep(s, d):
+        dependencies.append({
+            'spec': s,
+            'depends': d,
+        })
+
+    for spec in spec_list:
+        spec.concretize()
+
+        root_spec = get_spec_string(spec)
+
+        rkey, rlabel = spec_deps_key_label(spec)
+
+        for s in spec.traverse(deptype=deptype):
+            skey, slabel = spec_deps_key_label(s)
+            spec_labels[slabel] = {
+                'spec': get_spec_string(s),
+                'root': root_spec,
+            }
+            append_dep(rlabel, slabel)
+
+            for d in s.dependencies(deptype=deptype):
+                dkey, dlabel = spec_deps_key_label(d)
+                append_dep(slabel, dlabel)
+
+    for l, d in spec_labels.items():
+        specs.append({
+            'label': l,
+            'spec': d['spec'],
+            'root_spec': d['root'],
+        })
+
+    deps_json_obj = {
+        'specs': specs,
+        'dependencies': dependencies,
+    }
+
+    if stream_like:
+        stream_like.write(json.dumps(deps_json_obj))
+
+    return deps_json_obj
+
+
+def release_jobs(parser, args):
+    share_path = os.path.join(spack_root, 'share', 'spack', 'docker')
+    os_container_mapping_path = os.path.join(
+        share_path, 'os-container-mapping.yaml')
+
+    with open(os_container_mapping_path, 'r') as fin:
+        os_container_mapping = syaml.load(fin)
+
+    try:
+        validate(os_container_mapping, mapping_schema)
+    except ValidationError as val_err:
+        tty.error('Ill-formed os-container-mapping configuration object')
+        tty.error(os_container_mapping)
+        tty.debug(val_err)
+        return
+
+    containers = os_container_mapping['containers']
+
+    if args.specs:
+        # Just print out the spec labels and all dependency edges in
+        # a json format.
+        spec_list = [Spec(s) for s in args.specs]
+        with open(args.specs_deps_output, 'w') as out:
+            compute_spec_deps(spec_list, out)
+        return
+
+    current_system = sys_type() if args.resolve_deps_locally else None
+
+    release_specs_path = args.spec_set
+    if not release_specs_path:
+        raise SpackError('Must provide path to release spec-set')
+
+    release_spec_set = CombinatorialSpecSet.from_file(release_specs_path)
+
+    mirror_url = args.mirror_url
+
+    if not mirror_url:
+        raise SpackError('Must provide url of target binary mirror')
+
+    cdash_url = args.cdash_url
+
+    spec_labels, dependencies, stages = stage_spec_jobs(
+        release_spec_set, containers, current_system)
+
+    if not stages:
+        tty.msg('No jobs staged, exiting.')
+        return
+
+    if args.print_summary:
+        print_staging_summary(spec_labels, dependencies, stages)
+
+    output_object = {}
+    job_count = 0
+
+    stage_names = ['stage-{0}'.format(i) for i in range(len(stages))]
+    stage = 0
+
+    for stage_jobs in stages:
+        stage_name = stage_names[stage]
+
+        for spec_label in stage_jobs:
+            release_spec = spec_labels[spec_label]['spec']
+            root_spec = spec_labels[spec_label]['rootSpec']
+
+            pkg_compiler = release_spec.compiler
+            pkg_hash = release_spec.dag_hash()
+
+            osname = str(release_spec.architecture)
+            job_name = get_job_name(release_spec, osname)
+            container_info = containers[osname]
+            build_image = container_info['image']
+
+            job_scripts = ['./bin/rebuild-package.sh']
+
+            if 'setup_script' in container_info:
+                job_scripts.insert(
+                    0, container_info['setup_script'] % pkg_compiler)
+
+            job_dependencies = []
+            if spec_label in dependencies:
+                job_dependencies = (
+                    [get_job_name(spec_labels[dep_label]['spec'], osname)
+                        for dep_label in dependencies[spec_label]])
+
+            job_object = {
+                'stage': stage_name,
+                'variables': {
+                    'MIRROR_URL': mirror_url,
+                    'CDASH_BASE_URL': cdash_url,
+                    'HASH': pkg_hash,
+                    'DEPENDENCIES': ';'.join(job_dependencies),
+                    'ROOT_SPEC': str(root_spec),
+                },
+                'script': job_scripts,
+                'image': build_image,
+                'artifacts': {
+                    'paths': [
+                        'local_mirror/build_cache',
+                        'jobs_scratch_dir',
+                        'cdash_report',
+                    ],
+                    'when': 'always',
+                },
+                'dependencies': job_dependencies,
+            }
+
+            # If we see 'compilers' in the container iformation, it's a
+            # filter for the compilers this container can handle, else we
+            # assume it can handle any compiler
+            if 'compilers' in container_info:
+                do_job = False
+                for item in container_info['compilers']:
+                    container_compiler_spec = CompilerSpec(item['name'])
+                    if pkg_compiler == container_compiler_spec:
+                        do_job = True
+            else:
+                do_job = True
+
+            if args.shared_runner_tag:
+                job_object['tags'] = [args.shared_runner_tag]
+
+            if args.signing_key:
+                job_object['variables']['SIGN_KEY_HASH'] = args.signing_key
+
+            if do_job:
+                output_object[job_name] = job_object
+                job_count += 1
+
+        stage += 1
+
+    tty.msg('{0} build jobs generated in {1} stages'.format(
+        job_count, len(stages)))
+
+    final_stage = 'stage-rebuild-index'
+
+    final_job = {
+        'stage': final_stage,
+        'variables': {
+            'MIRROR_URL': mirror_url,
+        },
+        'image': build_image,
+        'script': './bin/rebuild-index.sh',
+    }
+
+    if args.shared_runner_tag:
+        final_job['tags'] = [args.shared_runner_tag]
+
+    output_object['rebuild-index'] = final_job
+    stage_names.append(final_stage)
+    output_object['stages'] = stage_names
+
+    with open(args.output_file, 'w') as outf:
+        outf.write(syaml.dump(output_object))

lib/spack/spack/schema/os_container_mapping.py

@@ -0,0 +1,50 @@
+# Copyright 2013-2019 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+"""Schema for os-container-mapping.yaml configuration file.
+
+.. literalinclude:: ../spack/schema/os_container_mapping.py
+   :lines: 32-
+"""
+
+
+schema = {
+    '$schema': 'http://json-schema.org/schema#',
+    'title': 'Spack release builds os/container mapping config file schema',
+    'type': 'object',
+    'additionalProperties': False,
+    'patternProperties': {
+        r'containers': {
+            'type': 'object',
+            'default': {},
+            'patternProperties': {
+                r'[\w\d\-_\.]+': {
+                    'type': 'object',
+                    'default': {},
+                    'additionalProperties': False,
+                    'required': ['image'],
+                    'properties': {
+                        'image': {'type': 'string'},
+                        'setup_script': {'type': 'string'},
+                        'compilers': {
+                            'type': 'array',
+                            'default': [],
+                            'items': {
+                                'type': 'object',
+                                'default': {},
+                                'additionalProperties': False,
+                                'required': ['name'],
+                                'properties': {
+                                    'name': {'type': 'string'},
+                                    'path': {'type': 'string'},
+                                },
+                            },
+                        },
+                    },
+                },
+            },
+        },
+    },
+}

lib/spack/spack/schema/specs_deps.py

@@ -0,0 +1,48 @@
+# Copyright 2013-2019 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+"""Schema for expressing dependencies of a set of specs in a JSON file
+
+.. literalinclude:: ../spack/schema/specs_deps.py
+   :lines: 32-
+"""
+
+
+schema = {
+    '$schema': 'http://json-schema.org/schema#',
+    'title': 'Spack schema for the dependencies of a set of specs',
+    'type': 'object',
+    'additionalProperties': False,
+    'required': ['specs'],
+    'properties': {
+        r'dependencies': {
+            'type': 'array',
+            'default': [],
+            'items': {
+                'type': 'object',
+                'additionalProperties': False,
+                'required': ['depends', 'spec'],
+                'properties': {
+                    r'depends': {'type': 'string'},
+                    r'spec': {'type': 'string'},
+                },
+            },
+        },
+        r'specs': {
+            'type': 'array',
+            'default': [],
+            'items': {
+                'type': 'object',
+                'additionalProperties': False,
+                'required': ['root_spec', 'spec', 'label'],
+                'properties': {
+                    r'root_spec': {'type': 'string'},
+                    r'spec': {'type': 'string'},
+                    r'label': {'type': 'string'},
+                }
+            },
+        },
+    },
+}

lib/spack/spack/test/cmd/release_jobs.py

@@ -0,0 +1,118 @@
+# Copyright 2013-2019 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+import json
+
+from jsonschema import validate
+
+from spack import repo
+from spack.architecture import sys_type
+from spack.cmd.release_jobs import stage_spec_jobs, spec_deps_key_label
+from spack.main import SpackCommand
+from spack.schema.specs_deps import schema as specs_deps_schema
+from spack.spec import Spec
+from spack.test.conftest import MockPackage, MockPackageMultiRepo
+
+
+release_jobs = SpackCommand('release-jobs')
+
+
+def test_specs_deps(tmpdir, config):
+    """If we ask for the specs dependencies to be written to disk, then make
+    sure we get a file of the correct format."""
+
+    output_path = str(tmpdir.mkdir('json').join('spec_deps.json'))
+    release_jobs('--specs-deps-output', output_path, 'readline')
+
+    deps_object = None
+
+    with open(output_path, 'r') as fd:
+        deps_object = json.loads(fd.read())
+
+    assert (deps_object is not None)
+
+    validate(deps_object, specs_deps_schema)
+
+
+def test_specs_staging(config):
+    """Make sure we achieve the best possible staging for the following
+spec DAG::
+
+        a
+       /|
+      c b
+        |\
+        e d
+          |\
+          f g
+
+In this case, we would expect 'c', 'e', 'f', and 'g' to be in the first stage,
+and then 'd', 'b', and 'a' to be put in the next three stages, respectively.
+
+"""
+    current_system = sys_type()
+
+    config_compilers = config.get_config('compilers')
+    first_compiler = config_compilers[0]
+    compiler_spec = first_compiler['compiler']['spec']
+
+    # Whatever that first compiler in the configuration was, let's make sure
+    # we mock up an entry like we'd find in os-container-mapping.yaml which
+    # has that compiler.
+    mock_containers = {}
+    mock_containers[current_system] = {
+        "image": "dontcare",
+        "compilers": [
+            {
+                "name": compiler_spec,
+            }
+        ],
+    }
+
+    default = ('build', 'link')
+
+    g = MockPackage('g', [], [])
+    f = MockPackage('f', [], [])
+    e = MockPackage('e', [], [])
+    d = MockPackage('d', [f, g], [default, default])
+    c = MockPackage('c', [], [])
+    b = MockPackage('b', [d, e], [default, default])
+    a = MockPackage('a', [b, c], [default, default])
+
+    mock_repo = MockPackageMultiRepo([a, b, c, d, e, f, g])
+
+    with repo.swap(mock_repo):
+        # Now we'll ask for the root package to be compiled with whatever that
+        # first compiler in the configuration was.
+        spec_a = Spec('a%{0}'.format(compiler_spec))
+        spec_a.concretize()
+
+        spec_a_label = spec_deps_key_label(spec_a)[1]
+        spec_b_label = spec_deps_key_label(spec_a['b'])[1]
+        spec_c_label = spec_deps_key_label(spec_a['c'])[1]
+        spec_d_label = spec_deps_key_label(spec_a['d'])[1]
+        spec_e_label = spec_deps_key_label(spec_a['e'])[1]
+        spec_f_label = spec_deps_key_label(spec_a['f'])[1]
+        spec_g_label = spec_deps_key_label(spec_a['g'])[1]
+
+        spec_labels, dependencies, stages = stage_spec_jobs(
+            [spec_a], mock_containers, current_system)
+
+        assert (len(stages) == 4)
+
+        assert (len(stages[0]) == 4)
+        assert (spec_c_label in stages[0])
+        assert (spec_e_label in stages[0])
+        assert (spec_f_label in stages[0])
+        assert (spec_g_label in stages[0])
+
+        assert (len(stages[1]) == 1)
+        assert (spec_d_label in stages[1])
+
+        assert (len(stages[2]) == 1)
+        assert (spec_b_label in stages[2])
+
+        assert (len(stages[3]) == 1)
+        assert (spec_a_label in stages[3])

share/spack/docker/os-container-mapping.yaml

@@ -0,0 +1,11 @@
+containers:
+  linux-ubuntu18.04-x86_64:
+    image: scottwittenburg/spack_builder_ubuntu_18.04
+    compilers:
+      - name: gcc@5.5.0
+      - name: clang@6.0.0-1ubuntu2
+  linux-centos7-x86_64:
+    image: scottwittenburg/spack_builder_centos_7
+    compilers:
+      - name: gcc@5.5.0
+      - name: clang@6.0.0