Add `spack --bootstrap` option for accessing bootstrap store (#25601)

We can see what is in the bootstrap store with `spack find -b`, and you can clean it with `spack
clean -b`, but we can't do much else with it, and if there are bootstrap issues they can be hard to
debug.

We already have `spack --mock`, which allows you to swap in the mock packages from the command
line. This PR introduces `spack -b` / `spack --bootstrap`, which runs all of spack with
`ensure_bootstrap_configuration()` set. This means that you can run `spack -b find`, `spack -b
install`, `spack -b spec`, etc. to see what *would* happen with bootstrap configuration, to remove
specific bootstrap packages, etc. This will hopefully make developers' lives easier as they deal
with bootstrap packages.

This PR also uses a `nullcontext` context manager. `nullcontext` has been implemented in several
other places in Spack, and this PR consolidates them to `llnl.util.lang`, with a note that we can
delete the function if we ever reqyire a new enough Python.

- [x] introduce `spack --bootstrap` option
- [x] consolidated all `nullcontext` usages to `llnl.util.lang`

5 files changed, 64 insertions, 58 deletions

diff --git a/lib/spack/llnl/util/lang.py b/lib/spack/llnl/util/lang.py
index c806cab1d7..c0b8c863d4 100644
--- a/lib/spack/llnl/util/lang.py
+++ b/lib/spack/llnl/util/lang.py
@@ -5,6 +5,7 @@
 
 from __future__ import division
 
+import contextlib
 import functools
 import inspect
 import os
@@ -921,3 +922,11 @@ def elide_list(line_list, max_num=10):
         return line_list[:max_num - 1] + ['...'] + line_list[-1:]
     else:
         return line_list
+
+
+@contextlib.contextmanager
+def nullcontext(*args, **kwargs):
+    """Empty context manager.
+    TODO: replace with contextlib.nullcontext() if we ever require python 3.7.
+    """
+    yield
diff --git a/lib/spack/spack/cmd/spec.py b/lib/spack/spack/cmd/spec.py
index d15d63bb82..d908944976 100644
--- a/lib/spack/spack/cmd/spec.py
+++ b/lib/spack/spack/cmd/spec.py
@@ -5,9 +5,9 @@
 
 from __future__ import print_function
 
-import contextlib
 import sys
 
+import llnl.util.lang as lang
 import llnl.util.tty as tty
 
 import spack
@@ -59,14 +59,6 @@ for further documentation regarding the spec syntax, see:
     spack.cmd.common.arguments.add_concretizer_args(subparser)
 
 
-@contextlib.contextmanager
-def nullcontext():
-    """Empty context manager.
-    TODO: replace with contextlib.nullcontext() if we ever require python 3.7.
-    """
-    yield
-
-
 def spec(parser, args):
     name_fmt = '{namespace}.{name}' if args.namespaces else '{name}'
     fmt = '{@version}{%compiler}{compiler_flags}{variants}{arch=architecture}'
@@ -81,7 +73,7 @@ def spec(parser, args):
 
     # use a read transaction if we are getting install status for every
     # spec in the DAG.  This avoids repeatedly querying the DB.
-    tree_context = nullcontext
+    tree_context = lang.nullcontext
     if args.install_status:
         tree_context = spack.store.db.read_transaction
 
diff --git a/lib/spack/spack/database.py b/lib/spack/spack/database.py
index 152b2e2c0e..53b5ec2ab2 100644
--- a/lib/spack/spack/database.py
+++ b/lib/spack/spack/database.py
@@ -38,6 +38,7 @@ except ImportError:
     pass
 
 import llnl.util.filesystem as fs
+import llnl.util.lang as lang
 import llnl.util.tty as tty
 
 import spack.hash_types as ht
@@ -52,12 +53,6 @@ from spack.filesystem_view import YamlFilesystemView
 from spack.util.crypto import bit_length
 from spack.version import Version
 
-
-@contextlib.contextmanager
-def nullcontext(*args, **kwargs):
-    yield
-
-
 # TODO: Provide an API automatically retyring a build after detecting and
 # TODO: clearing a failure.
 
@@ -404,8 +399,8 @@ class Database(object):
             self._write_transaction_impl = lk.WriteTransaction
             self._read_transaction_impl = lk.ReadTransaction
         else:
-            self._write_transaction_impl = nullcontext
-            self._read_transaction_impl = nullcontext
+            self._write_transaction_impl = lang.nullcontext
+            self._read_transaction_impl = lang.nullcontext
 
         self._record_fields = record_fields
 
diff --git a/lib/spack/spack/main.py b/lib/spack/spack/main.py
index 34ba3c3349..b3e0b8a971 100644
--- a/lib/spack/spack/main.py
+++ b/lib/spack/spack/main.py
@@ -448,6 +448,9 @@ def make_argument_parser(**kwargs):
         '-m', '--mock', action='store_true',
         help="use mock packages instead of real ones")
     parser.add_argument(
+        '-b', '--bootstrap', action='store_true',
+        help="use bootstrap configuration (bootstrap store, config, externals)")
+    parser.add_argument(
         '-p', '--profile', action='store_true', dest='spack_profile',
         help="profile execution using cProfile")
     parser.add_argument(
@@ -856,9 +859,22 @@ def _main(argv=None):
     cmd_name = args.command[0]
     cmd_name = aliases.get(cmd_name, cmd_name)
 
-    command = parser.add_command(cmd_name)
+    # set up a bootstrap context, if asked.
+    # bootstrap context needs to include parsing the command, b/c things
+    # like `ConstraintAction` and `ConfigSetAction` happen at parse time.
+    bootstrap_context = llnl.util.lang.nullcontext()
+    if args.bootstrap:
+        import spack.bootstrap as bootstrap  # avoid circular imports
+        bootstrap_context = bootstrap.ensure_bootstrap_configuration()
+
+    with bootstrap_context:
+        finish_parse_and_run(parser, cmd_name, env_format_error)
 
-    # Re-parse with the proper sub-parser added.
+
+def finish_parse_and_run(parser, cmd_name, env_format_error):
+    """Finish parsing after we know the command to run."""
+    # add the found command to the parser and re-run then re-parse
+    command = parser.add_command(cmd_name)
     args, unknown = parser.parse_known_args()
 
     # Now that we know what command this is and what its args are, determine
diff --git a/lib/spack/spack/test/llnl/util/tty/log.py b/lib/spack/spack/test/llnl/util/tty/log.py
index 7e5e728eb0..8d44c1f577 100644
--- a/lib/spack/spack/test/llnl/util/tty/log.py
+++ b/lib/spack/spack/test/llnl/util/tty/log.py
@@ -18,10 +18,9 @@ if TYPE_CHECKING:
 
 import pytest
 
-import llnl.util.tty.log
-from llnl.util.lang import uniq
-from llnl.util.tty.log import log_output
-from llnl.util.tty.pty import PseudoShell
+import llnl.util.tty.log as log
+import llnl.util.lang as lang
+import llnl.util.tty.pty as pty
 
 from spack.util.executable import which
 
@@ -33,14 +32,9 @@ except ImportError:
     pass
 
 
-@contextlib.contextmanager
-def nullcontext():
-    yield
-
-
 def test_log_python_output_with_echo(capfd, tmpdir):
     with tmpdir.as_cwd():
-        with log_output('foo.txt', echo=True):
+        with log.log_output('foo.txt', echo=True):
             print('logged')
 
         # foo.txt has output
@@ -53,7 +47,7 @@ def test_log_python_output_with_echo(capfd, tmpdir):
 
 def test_log_python_output_without_echo(capfd, tmpdir):
     with tmpdir.as_cwd():
-        with log_output('foo.txt'):
+        with log.log_output('foo.txt'):
             print('logged')
 
         # foo.txt has output
@@ -66,7 +60,7 @@ def test_log_python_output_without_echo(capfd, tmpdir):
 
 def test_log_python_output_with_invalid_utf8(capfd, tmpdir):
     with tmpdir.as_cwd():
-        with log_output('foo.txt'):
+        with log.log_output('foo.txt'):
             sys.stdout.buffer.write(b'\xc3\x28\n')
 
         # python2 and 3 treat invalid UTF-8 differently
@@ -85,7 +79,7 @@ def test_log_python_output_with_invalid_utf8(capfd, tmpdir):
 def test_log_python_output_and_echo_output(capfd, tmpdir):
     with tmpdir.as_cwd():
         # echo two lines
-        with log_output('foo.txt') as logger:
+        with log.log_output('foo.txt') as logger:
             with logger.force_echo():
                 print('force echo')
             print('logged')
@@ -104,7 +98,7 @@ def _log_filter_fn(string):
 
 def test_log_output_with_filter(capfd, tmpdir):
     with tmpdir.as_cwd():
-        with log_output('foo.txt', filter_fn=_log_filter_fn):
+        with log.log_output('foo.txt', filter_fn=_log_filter_fn):
             print('foo blah')
             print('blah foo')
             print('foo foo')
@@ -118,7 +112,7 @@ def test_log_output_with_filter(capfd, tmpdir):
 
     # now try with echo
     with tmpdir.as_cwd():
-        with log_output('foo.txt', echo=True, filter_fn=_log_filter_fn):
+        with log.log_output('foo.txt', echo=True, filter_fn=_log_filter_fn):
             print('foo blah')
             print('blah foo')
             print('foo foo')
@@ -140,7 +134,7 @@ def test_log_subproc_and_echo_output_no_capfd(capfd, tmpdir):
     # here, and echoing in test_log_subproc_and_echo_output_capfd below.
     with capfd.disabled():
         with tmpdir.as_cwd():
-            with log_output('foo.txt') as logger:
+            with log.log_output('foo.txt') as logger:
                 with logger.force_echo():
                     echo('echo')
                 print('logged')
@@ -157,7 +151,7 @@ def test_log_subproc_and_echo_output_capfd(capfd, tmpdir):
     # interferes with the logged data. See
     # test_log_subproc_and_echo_output_no_capfd for tests on the logfile.
     with tmpdir.as_cwd():
-        with log_output('foo.txt') as logger:
+        with log.log_output('foo.txt') as logger:
             with logger.force_echo():
                 echo('echo')
             print('logged')
@@ -177,7 +171,7 @@ def simple_logger(**kwargs):
     signal.signal(signal.SIGUSR1, handler)
 
     log_path = kwargs["log_path"]
-    with log_output(log_path):
+    with log.log_output(log_path):
         while running[0]:
             print("line")
             time.sleep(1e-3)
@@ -306,25 +300,25 @@ def mock_shell_fg_bg_no_termios(proc, ctl, **kwargs):
 
 @contextlib.contextmanager
 def no_termios():
-    saved = llnl.util.tty.log.termios
-    llnl.util.tty.log.termios = None
+    saved = log.termios
+    log.termios = None
     try:
         yield
     finally:
-        llnl.util.tty.log.termios = saved
+        log.termios = saved
 
 
 @pytest.mark.skipif(not which("ps"), reason="requires ps utility")
 @pytest.mark.skipif(not termios, reason="requires termios support")
 @pytest.mark.parametrize('test_fn,termios_on_or_off', [
     # tests with termios
-    (mock_shell_fg, nullcontext),
-    (mock_shell_bg, nullcontext),
-    (mock_shell_bg_fg, nullcontext),
-    (mock_shell_fg_bg, nullcontext),
-    (mock_shell_tstp_cont, nullcontext),
-    (mock_shell_tstp_tstp_cont, nullcontext),
-    (mock_shell_tstp_tstp_cont_cont, nullcontext),
+    (mock_shell_fg, lang.nullcontext),
+    (mock_shell_bg, lang.nullcontext),
+    (mock_shell_bg_fg, lang.nullcontext),
+    (mock_shell_fg_bg, lang.nullcontext),
+    (mock_shell_tstp_cont, lang.nullcontext),
+    (mock_shell_tstp_tstp_cont, lang.nullcontext),
+    (mock_shell_tstp_tstp_cont_cont, lang.nullcontext),
     # tests without termios
     (mock_shell_fg_no_termios, no_termios),
     (mock_shell_bg, no_termios),
@@ -342,7 +336,7 @@ def test_foreground_background(test_fn, termios_on_or_off, tmpdir):
     process stop and start.
 
     """
-    shell = PseudoShell(test_fn, simple_logger)
+    shell = pty.PseudoShell(test_fn, simple_logger)
     log_path = str(tmpdir.join("log.txt"))
 
     # run the shell test
@@ -375,7 +369,7 @@ def synchronized_logger(**kwargs):
     v_lock = kwargs["v_lock"]
 
     sys.stderr.write(os.getcwd() + "\n")
-    with log_output(log_path) as logger:
+    with log.log_output(log_path) as logger:
         with logger.force_echo():
             print("forced output")
 
@@ -446,7 +440,7 @@ def mock_shell_v_v_no_termios(proc, ctl, **kwargs):
 @pytest.mark.skipif(not which("ps"), reason="requires ps utility")
 @pytest.mark.skipif(not termios, reason="requires termios support")
 @pytest.mark.parametrize('test_fn,termios_on_or_off', [
-    (mock_shell_v_v, nullcontext),
+    (mock_shell_v_v, lang.nullcontext),
     (mock_shell_v_v_no_termios, no_termios),
 ])
 def test_foreground_background_output(
@@ -457,7 +451,7 @@ def test_foreground_background_output(
 
         return
 
-    shell = PseudoShell(test_fn, synchronized_logger)
+    shell = pty.PseudoShell(test_fn, synchronized_logger)
     log_path = str(tmpdir.join("log.txt"))
 
     # Locks for synchronizing with minion
@@ -485,8 +479,8 @@ def test_foreground_background_output(
 
     # also get lines of log file
     assert os.path.exists(log_path)
-    with open(log_path) as log:
-        log = log.read().strip().split("\n")
+    with open(log_path) as logfile:
+        log_data = logfile.read().strip().split("\n")
 
     # Controller and minion process coordinate with locks such that the
     # minion writes "off" when echo is off, and "on" when echo is on. The
@@ -494,12 +488,12 @@ def test_foreground_background_output(
     # lines if the controller is slow. The important thing to observe
     # here is that we started seeing 'on' in the end.
     assert (
-        ['forced output', 'on'] == uniq(output) or
-        ['forced output', 'off', 'on'] == uniq(output)
+        ['forced output', 'on'] == lang.uniq(output) or
+        ['forced output', 'off', 'on'] == lang.uniq(output)
     )
 
     # log should be off for a while, then on, then off
     assert (
-        ['forced output', 'off', 'on', 'off'] == uniq(log) and
-        log.count("off") > 2  # ensure some "off" lines were omitted
+        ['forced output', 'off', 'on', 'off'] == lang.uniq(log_data) and
+        log_data.count("off") > 2  # ensure some "off" lines were omitted
     )