Support for database schema migrations using alembic

gns3server/alembic.ini

@@ -0,0 +1,103 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts
+script_location = db_migrations
+
+# template used to generate migration file names; The default value is %%(rev)s_%%(slug)s
+# Uncomment the line below if you want the files to be prepended with date and time
+# file_template = %%(year)d_%%(month).2d_%%(day).2d_%%(hour).2d%%(minute).2d-%%(rev)s_%%(slug)s
+
+# 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 =
+
+# max length of characters to apply to the
+# "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; This defaults
+# to db_migrations/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path.
+# The path separator used here should be the separator specified by "version_path_separator" below.
+# version_locations = %(here)s/bar:%(here)s/bat:db_migrations/versions
+
+# version path separator; As mentioned above, this is the character used to split
+# version_locations. The default within new alembic.ini files is "os", which uses os.pathsep.
+# If this key is omitted entirely, it falls back to the legacy behavior of splitting on spaces and/or commas.
+# Valid values for version_path_separator are:
+#
+# version_path_separator = :
+# version_path_separator = ;
+# version_path_separator = space
+version_path_separator = os  # Use os.pathsep. Default configuration used for new projects.
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+sqlalchemy.url =
+
+
+[post_write_hooks]
+# post_write_hooks defines scripts or Python functions that are run
+# on newly generated revision scripts.  See the documentation for further
+# 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 REVISION_SCRIPT_FILENAME
+
+# Logging configuration
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

gns3server/db/tasks.py

@@ -28,6 +28,10 @@ from sqlalchemy import event
 from sqlalchemy.engine import Engine
 from sqlalchemy.exc import SQLAlchemyError
 from sqlalchemy.ext.asyncio import create_async_engine, AsyncSession
+from alembic import command, config
+from alembic.script import ScriptDirectory
+from alembic.runtime.migration import MigrationContext
+
 from gns3server.db.repositories.computes import ComputesRepository
 from gns3server.db.repositories.images import ImagesRepository
 from gns3server.utils.images import discover_images, check_valid_image_header, read_image_info, default_images_directory, InvalidImageError
@@ -41,15 +45,46 @@ import logging
 log = logging.getLogger(__name__)
 
 
+def run_upgrade(connection, cfg):
+
+    cfg.attributes["connection"] = connection
+    command.upgrade(cfg, "head")
+
+
+def run_stamp(connection, cfg):
+
+    cfg.attributes["connection"] = connection
+    command.stamp(cfg, 'head')
+
+
+def check_revision(connection, cfg):
+
+    script = ScriptDirectory.from_config(cfg)
+    head_rev = script.get_revision("head").revision
+    context = MigrationContext.configure(connection)
+    current_rev = context.get_current_revision()
+    return current_rev, head_rev
+
+
 async def connect_to_db(app: FastAPI) -> None:
 
     db_path = os.path.join(Config.instance().config_dir, "gns3_controller.db")
     db_url = os.environ.get("GNS3_DATABASE_URI", f"sqlite+aiosqlite:///{db_path}")
     engine = create_async_engine(db_url, connect_args={"check_same_thread": False}, future=True)
+    alembic_cfg = config.Config()
+    alembic_cfg.set_main_option("script_location", "gns3server:db_migrations")
+    #alembic_cfg.set_main_option('sqlalchemy.url', db_url)
     try:
         async with engine.connect() as conn:
-            await conn.run_sync(Base.metadata.create_all)
-            log.info(f"Successfully connected to database '{db_url}'")
+            current_rev, head_rev = await conn.run_sync(check_revision, alembic_cfg)
+            log.info(f"Current database revision is {current_rev}")
+            if current_rev is None:
+                await conn.run_sync(Base.metadata.create_all)
+                await conn.run_sync(run_stamp, alembic_cfg)
+            elif current_rev != head_rev:
+                # upgrade the database if needed
+                await conn.run_sync(run_upgrade, alembic_cfg)
+                await conn.commit()
         app.state._db_engine = engine
     except SQLAlchemyError as e:
         log.fatal(f"Error while connecting to database '{db_url}: {e}")

gns3server/db_migrations/README

@@ -0,0 +1,4 @@
+Generic single-database configuration with an async dbapi.
+
+# Command to generate a revision
+alembic revision --autogenerate -m "add fields in table"

gns3server/db_migrations/env.py

@@ -0,0 +1,101 @@
+import asyncio
+import os
+from logging.config import fileConfig
+
+from sqlalchemy import pool
+from sqlalchemy.ext.asyncio import async_engine_from_config
+
+from alembic import context
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+from gns3server.db.models.base import Base
+target_metadata = 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.
+
+
+def run_migrations_offline() -> None:
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    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,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def do_run_migrations(connection):
+    context.configure(connection=connection, target_metadata=target_metadata)
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+async def run_async_migrations():
+
+    from gns3server.config import Config as GNS3Config
+    db_path = os.path.join(GNS3Config.instance().config_dir, "gns3_controller.db")
+    db_url = os.environ.get("GNS3_DATABASE_URI", f"sqlite+aiosqlite:///{db_path}")
+    config.set_main_option('sqlalchemy.url', db_url)
+
+    connectable = async_engine_from_config(
+        config.get_section(config.config_ini_section),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    async with connectable.connect() as connection:
+        await connection.run_sync(do_run_migrations)
+
+    await connectable.dispose()
+
+
+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 = config.attributes.get("connection", None)
+
+    if connectable is None:
+        asyncio.run(run_async_migrations())
+    else:
+        do_run_migrations(connectable)
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

gns3server/db_migrations/script.py.mako

@@ -0,0 +1,24 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = ${repr(branch_labels)}
+depends_on = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

gns3server/db_migrations/versions/7ceeddd9c9a8_init.py

@@ -0,0 +1,28 @@
+"""init
+
+Revision ID: 7ceeddd9c9a8
+Revises: 
+Create Date: 2023-01-11 08:55:25.116126
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '7ceeddd9c9a8'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    pass
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    pass
+    # ### end Alembic commands ###

requirements.txt

@@ -12,6 +12,7 @@ distro>=1.7.0
 py-cpuinfo==9.0.0
 sqlalchemy==1.4.45
 aiosqlite==0.18.0
+alembic==1.9.1
 passlib[bcrypt]==1.7.4
 python-jose==3.3.0
 email-validator==1.3.0