Integrate alembic check into basic server tests

Starting with Alembic v1.9.0 the command, `alembic check` is available
which will succeed if no migrations are required, and fail if it detects
that a migration is necessary.

We also remove the unused `alembic/alembic.ini`, drop the need for a
separate `tox` environment, remove the need for a `pbench-server.cfg`
file entirely by reverting to the original env.py as generated by
`alembic init alembic`.

We also collapse the existing migrations to one since we just need one
to move from an empty database to our current schema.

exec-tests

@@ -228,6 +228,11 @@ if [[ "${major}" == "all" || "${major}" == "server" ]]; then
         ${_ECHO} verify_make_source_tree server || rc=1
     fi
 
+    # Verify no database migrations would be generated.
+    if [[ "${subtst:-alembic}" == "alembic" && ${rc} -eq 0 ]]; then
+        (cd lib/pbench/server/database && ${ECHO} alembic check) || rc=1
+    fi
+
     # Run the server functional tests
     if [[ "${subtst}" == "functional" && ${rc} -eq 0 ]]; then
         server_arg=${1}

lib/pbench/server/database/alembic.ini

@@ -7,8 +7,14 @@ script_location = alembic
 # template used to generate migration files
 # file_template = %%(rev)s_%%(slug)s
 
-# timezone to use when rendering the date
-# within the migration file as well as the filename.
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.
+prepend_sys_path = .
+
+# timezone to use when rendering the date within the migration file
+# as well as the filename.
+# If specified, requires the python-dateutil library that can be
+# installed by adding `alembic[tz]` to the pip requirements
 # string value is passed to dateutil.tz.gettz()
 # leave blank for localtime
 # timezone =
@@ -26,10 +32,19 @@ script_location = alembic
 # versions/ directory
 # sourceless = false
 
-# version location specification; this defaults
+# version location specification; This defaults
 # to alembic/versions.  When using multiple version
-# directories, initial revisions must be specified with --version-path
-# version_locations = %(here)s/bar %(here)s/bat alembic/versions
+# directories, initial revisions must be specified with --version-path.
+# The path separator used here should be the separator specified by "version_path_separator"
+# version_locations = %(here)s/bar:%(here)s/bat:alembic/versions
+
+# version path separator; As mentioned above, this is the character used to split
+# version_locations. Valid values are:
+#
+# version_path_separator = :
+# version_path_separator = ;
+# version_path_separator = space
+version_path_separator = os  # default: use os.pathsep
 
 # the output encoding used when revision files
 # are written from script.py.mako
@@ -44,17 +59,17 @@ sqlalchemy.url = postgresql://pbench:pbench@localhost:5432/pbench
 # detail and examples
 
 # format using "black" - use the console_scripts runner, against the "black" entrypoint
-# hooks=black
-# black.type=console_scripts
-# black.entrypoint=black
-# black.options=-l 79
+# hooks = black
+# black.type = console_scripts
+# black.entrypoint = black
+# black.options = -l 79 REVISION_SCRIPT_FILENAME
 
 # Logging configuration
 [loggers]
 keys = root,sqlalchemy,alembic
 
 [handlers]
-keys = console, fileHandler
+keys = console
 
 [formatters]
 keys = generic

lib/pbench/server/database/alembic/env.py

@@ -1,62 +1,28 @@
-"""Alembic Migration Driver
-
-This file was auto generated by `alembic init alembic` but was manually altered
-to suit the needs of the Pbench server. Re-running `alembic init alembic` will
-overwrite these changes!
-
-This Python script runs whenever the alembic migration tool is invoked in
-/opt/pbench-server/lib/server/database; it contains instructions to configure
-and generate a SQLAlchemy engine, procure a connection from that engine along
-with a transaction, and then invoke the migration engine, using the connection
-as a source of database connectivity.
-
-This requires access to Pbench library modules and the Pbench server config file
-and thus must be run with
-
-    export PYTHONPATH=/opt/pbench-server/lib:${PYTHONPATH}
-    export _PBENCH_SERVER_CONFIG=/opt/pbench-server/lib/config/pbench-server.cfg
-
-Examples:
-
-   alembic upgrade head     # upgrade database to the latest
-   alembic downgrade base   # downgrade to the original tracked state
-"""
-import logging
-import sys
+from logging.config import fileConfig
 
 from alembic import context
-from sqlalchemy import create_engine
+from sqlalchemy import engine_from_config, pool
 
-from pbench.server.api import get_server_config
 from pbench.server.database.database import Database
 
-# this is the Alembic Config object, which provides
-# access to the values within the .ini file in use.
+# This is the Alembic Config object, which provides access to the values within
+# the .ini file in use.
 config = context.config
 
-# Add syslog handler to send logs to journald
-log = logging.getLogger("alembic")
-handler = logging.handlers.SysLogHandler("/dev/log")
-log.addHandler(handler)
-
-# add your model's MetaData object here for 'autogenerate' support:
+# Interpret the config file for Python logging and setup the loggers.
+fileConfig(config.config_file_name)
 
+# Add your model's MetaData object here for 'autogenerate' support:
+#     from myapp import mymodel
+#     target_metadata = mymodel.Base.metadata
 target_metadata = Database.Base.metadata
 
-# other values from the config, defined by the needs of env.py,
-# can be acquired:
-# my_important_option = config.get_main_option("my_important_option")
-# ... etc.
-
-try:
-    server_config = get_server_config()
-    url = Database.get_engine_uri(server_config)
-except Exception as e:
-    print(e)
-    sys.exit(1)
+# Other values from the config, defined by the needs of env.py, can be acquired:
+#     my_important_option = config.get_main_option("my_important_option")
+#     ... etc.
 
 
-def run_migrations_offline(url: str):
+def run_migrations_offline():
     """Run migrations in 'offline' mode.
 
     This configures the context with just a URL and not an Engine, though an
@@ -65,6 +31,7 @@ def run_migrations_offline(url: str):
 
     Calls to context.execute() here emit the given string to the script output.
     """
+    url = config.get_main_option("sqlalchemy.url")
     context.configure(
         url=url,
         target_metadata=target_metadata,
@@ -76,14 +43,17 @@ def run_migrations_offline(url: str):
         context.run_migrations()
 
 
-def run_migrations_online(url: str):
+def run_migrations_online():
     """Run migrations in 'online' mode.
 
     In this scenario we need to create an Engine and associate a connection with
     the context.
     """
-
-    connectable = create_engine(url)
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
 
     with connectable.connect() as connection:
         context.configure(connection=connection, target_metadata=target_metadata)
@@ -93,8 +63,6 @@ def run_migrations_online(url: str):
 
 
 if context.is_offline_mode():
-    print("running migration offline")
-    run_migrations_offline(url)
+    run_migrations_offline()
 else:
-    print("running migration online")
-    run_migrations_online(url)
+    run_migrations_online()

lib/pbench/server/database/alembic/versions/274bab07e3f8_initial_tables.py → lib/pbench/server/database/alembic/versions/fa12f45a2a5a_initial_database_schema.py

@@ -1,23 +1,23 @@
-"""Initial tables
+"""Initial database schema
 
-Revision ID: 274bab07e3f8
-Revises: 62eddcec4817
-Create Date: 2023-01-16 05:54:33.496244
+Revision ID: fa12f45a2a5a
+Revises:
+Create Date: 2023-01-16 18:33:29.144835
 
 Since we are adding Alembic migrations after we have already been using our
-database in various contexts, this "Initial tables" migration describes how to
-bring an empty database up to the state of the database as of commit 6a764f154.
-That commit was the latest working version of the Pbench Server deployed in Red
-Hat's staging environment.
+database in various contexts, this "Initial database schema" migration describes
+how to bring an empty database up to the state of the database as of commit
+6a764f154.  That commit was the latest working version of the Pbench Server
+deployed in Red Hat's staging environment.
 """
 from alembic import op
 import sqlalchemy as sa
 
 from pbench.server.database.models import TZDateTime
 
 # revision identifiers, used by Alembic.
-revision = "274bab07e3f8"
-down_revision = "62eddcec4817"
+revision = "fa12f45a2a5a"
+down_revision = None
 branch_labels = None
 depends_on = None
 
@@ -60,7 +60,7 @@ def upgrade():
     op.create_table(
         "datasets",
         sa.Column("id", sa.Integer(), autoincrement=True, nullable=False),
-        sa.Column("name", sa.String(length=255), nullable=False),
+        sa.Column("name", sa.String(length=1024), nullable=False),
         sa.Column("owner_id", sa.String(length=255), nullable=False),
         sa.Column("access", sa.String(length=255), nullable=False),
         sa.Column("resource_id", sa.String(length=255), nullable=False),