From 7ce43a2bfef3d021924ee2834c9e3db7d0da125a Mon Sep 17 00:00:00 2001
From: binaryDiv <lexi@binarydiv.dev>
Date: Fri, 15 Apr 2022 16:10:38 +0200
Subject: [PATCH] Add Alembic to project for database migrations

---
 Makefile                                      | 36 +++++++++--
 Pipfile                                       |  2 +
 Pipfile.lock                                  | 34 +++++++++-
 alembic.ini                                   | 50 +++++++++++++++
 docker-compose.yml                            |  2 +-
 migrations/env.py                             | 63 +++++++++++++++++++
 migrations/script.py.mako                     | 25 ++++++++
 ...4_15_1605-716726b4a1fe_initial_revision.py | 34 ++++++++++
 tofu_api/app.py                               |  6 +-
 tofu_api/common/database/__init__.py          |  2 -
 tofu_api/common/database/model.py             | 10 ---
 tofu_api/common/database/sqlalchemy.py        | 22 +------
 tofu_api/models/__init__.py                   |  4 ++
 .../database/metadata.py => models/base.py}   | 11 +++-
 tofu_api/models/task.py                       |  4 +-
 15 files changed, 256 insertions(+), 49 deletions(-)
 create mode 100644 alembic.ini
 create mode 100644 migrations/env.py
 create mode 100644 migrations/script.py.mako
 create mode 100644 migrations/versions/2022_04_15_1605-716726b4a1fe_initial_revision.py
 delete mode 100644 tofu_api/common/database/model.py
 rename tofu_api/{common/database/metadata.py => models/base.py} (54%)

diff --git a/Makefile b/Makefile
index 7815e2a..348df78 100644
--- a/Makefile
+++ b/Makefile
@@ -2,9 +2,17 @@
 DOCKER_COMPOSE = docker-compose
 DOCKER_RUN = $(DOCKER_COMPOSE) run --rm backend
 
+
+# General
+# -------
+
 # Default target
-.PHONY: all
-all: docker-up
+.PHONY: up
+up: docker-up
+
+# Shortcut for first start (initializing database, etc.)
+.PHONY: first-start
+first-start: docker-build db-upgrade docker-up
 
 
 # Container management
@@ -16,7 +24,7 @@ docker-up:
 
 .PHONY: docker-down
 docker-down:
-	$(DOCKER_COMPOSE) down
+	$(DOCKER_COMPOSE) down --remove-orphans
 
 .PHONY: docker-build
 docker-build:
@@ -28,7 +36,7 @@ docker-rebuild:
 
 .PHONY: docker-purge
 docker-purge:
-	$(DOCKER_COMPOSE) down --volumes
+	$(DOCKER_COMPOSE) down --remove-orphans --volumes
 
 .PHONY: docker-restart
 docker-restart:
@@ -45,3 +53,23 @@ docker-run:
 .PHONY: docker-shell
 docker-shell:
 	$(DOCKER_RUN) bash
+
+
+# Database management
+# -------------------
+
+# Run migrations to upgrade the database to the head revision (set REVISION parameter to override)
+.PHONY: db-upgrade
+db-upgrade:
+	$(DOCKER_RUN) alembic upgrade $(or $(REVISION),head)
+
+# Run migrations to downgrade the database to the previous revision (set REVISION parameter to override)
+.PHONY: db-downgrade
+db-downgrade:
+	$(DOCKER_RUN) alembic downgrade $(or $(REVISION),-1)
+
+# Autogenerate a revision for database migration (requires MESSAGE parameter to set the revision message)
+.PHONY: db-generate-migration
+db-generate-migration:
+	@test -n "$(MESSAGE)" || (echo "Please set the revision message: make db-generate-migration MESSAGE=\"...\""; exit 1)
+	$(DOCKER_RUN) alembic revision --autogenerate -m "$(MESSAGE)"
diff --git a/Pipfile b/Pipfile
index 5ab3763..d5f298d 100644
--- a/Pipfile
+++ b/Pipfile
@@ -10,6 +10,8 @@ flask = "~=2.0"
 pyyaml = "*"
 sqlalchemy = "~=1.4"
 pymysql = "*"
+alembic = "~=1.7"
+python-dateutil = "*"
 
 [dev-packages]
 
diff --git a/Pipfile.lock b/Pipfile.lock
index 30839be..88d65a4 100644
--- a/Pipfile.lock
+++ b/Pipfile.lock
@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "b0c979ea7ddef64da26c3f7537dbadaa9de352c7a8f6cde551f7ce85519de503"
+            "sha256": "f63a254c353bc5c8e6cbe2a920f8402ba0da5bec775bfff91f64fa485e9bf95c"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -16,6 +16,14 @@
         ]
     },
     "default": {
+        "alembic": {
+            "hashes": [
+                "sha256:29be0856ec7591c39f4e1cb10f198045d890e6e2274cf8da80cb5e721a09642b",
+                "sha256:4961248173ead7ce8a21efb3de378f13b8398e6630fab0eb258dc74a8af24c58"
+            ],
+            "index": "pypi",
+            "version": "==1.7.7"
+        },
         "click": {
             "hashes": [
                 "sha256:24e1a4a9ec5bf6299411369b208c1df2188d9eb8d916302fe6bf03faed227f1e",
@@ -117,6 +125,14 @@
             "markers": "python_version >= '3.7'",
             "version": "==3.1.1"
         },
+        "mako": {
+            "hashes": [
+                "sha256:23aab11fdbbb0f1051b93793a58323ff937e98e34aece1c4219675122e57e4ba",
+                "sha256:9a7c7e922b87db3686210cf49d5d767033a41d4010b284e747682c92bddd8b39"
+            ],
+            "markers": "python_version >= '3.7'",
+            "version": "==1.2.0"
+        },
         "markupsafe": {
             "hashes": [
                 "sha256:0212a68688482dc52b2d45013df70d169f542b7394fc744c02a57374a4207003",
@@ -171,6 +187,14 @@
             "index": "pypi",
             "version": "==1.0.2"
         },
+        "python-dateutil": {
+            "hashes": [
+                "sha256:0123cacc1627ae19ddf3c27a5de5bd67ee4586fbdd6440d9748f8abb483d3e86",
+                "sha256:961d03dc3453ebbc59dbdea9e4e11c5651520a876d0f4db161e8674aae935da9"
+            ],
+            "index": "pypi",
+            "version": "==2.8.2"
+        },
         "pyyaml": {
             "hashes": [
                 "sha256:0283c35a6a9fbf047493e3a0ce8d79ef5030852c51e9d911a27badfde0605293",
@@ -218,6 +242,14 @@
             "markers": "python_version >= '3.7'",
             "version": "==62.1.0"
         },
+        "six": {
+            "hashes": [
+                "sha256:1e61c37477a1626458e36f7b1d82aa5c9b094fa4802892072e49de9c60c4c926",
+                "sha256:8abb2f1d86890a2dfb989f9a77cfcfd3e47c2a354b01111771326f8aa26e0254"
+            ],
+            "markers": "python_version >= '2.7' and python_version not in '3.0, 3.1, 3.2, 3.3'",
+            "version": "==1.16.0"
+        },
         "sqlalchemy": {
             "hashes": [
                 "sha256:093b3109c2747d5dc0fa4314b1caf4c7ca336d5c8c831e3cfbec06a7e861e1e6",
diff --git a/alembic.ini b/alembic.ini
new file mode 100644
index 0000000..3d12391
--- /dev/null
+++ b/alembic.ini
@@ -0,0 +1,50 @@
+[alembic]
+# Path to migration scripts
+script_location = migrations
+
+# Add project root directory to the import path
+prepend_sys_path = .
+
+# String template for migration filenames
+file_template = %%(year)d_%%(month).2d_%%(day).2d_%%(hour).2d%%(minute).2d-%%(rev)s_%%(slug)s
+
+# Timezone for the date within the migration files and filenames
+timezone = Europe/Berlin
+
+# Max length for the "slug" field in filenames
+truncate_slug_length = 24
+
+# 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
diff --git a/docker-compose.yml b/docker-compose.yml
index d1c5f1f..7bf9fcd 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -34,7 +34,7 @@ services:
       timeout: 1s
       retries: 20
 
-  adminer:
+  phpmyadmin:
     image: phpmyadmin
     ports:
       - '8099:80'
diff --git a/migrations/env.py b/migrations/env.py
new file mode 100644
index 0000000..bd16fa2
--- /dev/null
+++ b/migrations/env.py
@@ -0,0 +1,63 @@
+from logging.config import fileConfig
+
+from alembic import context
+
+from tofu_api.app import create_app
+from tofu_api.models import BaseModel
+
+# This is the Alembic Config object, which provides access to the values within the .ini file in use.
+alembic_config = context.config
+
+# Interpret the config file for Python logging. This line sets up loggers basically.
+if alembic_config.config_file_name is not None:
+    fileConfig(alembic_config.config_file_name)
+
+# Create Flask app, which loads the app config and initializes the database engine.
+app = create_app()
+db = app.dependencies.get_sqlalchemy()
+
+
+def process_revision_directives(_context, _revision, directives):
+    """
+    Callback used to prevent generating empty migrations with autogenerate.
+    Source: https://alembic.sqlalchemy.org/en/latest/cookbook.html#don-t-generate-empty-migrations-with-autogenerate
+    """
+    if alembic_config.cmd_opts.autogenerate and directives[0].upgrade_ops.is_empty():
+        directives[:] = []
+
+
+def run_migrations_offline():
+    """
+    Run migrations in 'offline' mode, which does not require an actual database engine and can be used to generate SQL scripts.
+    """
+    context.configure(
+        url=app.config.sqlalchemy_database_uri,
+        target_metadata=BaseModel.metadata,
+        process_revision_directives=process_revision_directives,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online():
+    """
+    Run migrations in 'online' mode, which requires a database engine.
+    """
+    with db.engine.connect() as connection:
+        context.configure(
+            connection=connection,
+            target_metadata=BaseModel.metadata,
+            process_revision_directives=process_revision_directives,
+        )
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()
diff --git a/migrations/script.py.mako b/migrations/script.py.mako
new file mode 100644
index 0000000..0b72244
--- /dev/null
+++ b/migrations/script.py.mako
@@ -0,0 +1,25 @@
+"""
+${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():
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade():
+    ${downgrades if downgrades else "pass"}
diff --git a/migrations/versions/2022_04_15_1605-716726b4a1fe_initial_revision.py b/migrations/versions/2022_04_15_1605-716726b4a1fe_initial_revision.py
new file mode 100644
index 0000000..ca8bee8
--- /dev/null
+++ b/migrations/versions/2022_04_15_1605-716726b4a1fe_initial_revision.py
@@ -0,0 +1,34 @@
+"""
+Initial revision
+
+Revision ID: 716726b4a1fe
+Revises: 
+Create Date: 2022-04-15 16:05:29.358429+02:00
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+# Revision identifiers, used by Alembic.
+revision = '716726b4a1fe'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table(
+        'tasks',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('title', sa.String(length=255), nullable=False),
+        sa.Column('description', sa.Text(), nullable=False),
+        sa.PrimaryKeyConstraint('id', name=op.f('pk_tasks'))
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_table('tasks')
+    # ### end Alembic commands ###
diff --git a/tofu_api/app.py b/tofu_api/app.py
index d7a6237..c7f079a 100644
--- a/tofu_api/app.py
+++ b/tofu_api/app.py
@@ -60,12 +60,8 @@ class App(Flask):
         # Import models to fill the metadata object
         import tofu_api.models  # noqa (unused import)
 
-        # Create all tables
-        # TODO: Use migrations instead
-        db.create_all_tables()
 
-
-def create_app() -> Flask:
+def create_app() -> App:
     """
     App factory, returns a Flask app object.
     """
diff --git a/tofu_api/common/database/__init__.py b/tofu_api/common/database/__init__.py
index c46d890..479c708 100644
--- a/tofu_api/common/database/__init__.py
+++ b/tofu_api/common/database/__init__.py
@@ -1,3 +1 @@
-from .metadata import metadata_obj
-from .model import Model
 from .sqlalchemy import SQLAlchemy
diff --git a/tofu_api/common/database/model.py b/tofu_api/common/database/model.py
deleted file mode 100644
index 905bd25..0000000
--- a/tofu_api/common/database/model.py
+++ /dev/null
@@ -1,10 +0,0 @@
-from sqlalchemy.orm import declarative_base
-
-from .metadata import metadata_obj
-
-__all__ = [
-    'Model',
-]
-
-# Generate declarative base class for database models
-Model = declarative_base(name='Model', metadata=metadata_obj)
diff --git a/tofu_api/common/database/sqlalchemy.py b/tofu_api/common/database/sqlalchemy.py
index 1d1cbe9..55c6ec3 100644
--- a/tofu_api/common/database/sqlalchemy.py
+++ b/tofu_api/common/database/sqlalchemy.py
@@ -1,12 +1,11 @@
 from typing import Optional, cast
 
 from flask import Flask
-from sqlalchemy import MetaData, create_engine
+from sqlalchemy import create_engine
 from sqlalchemy.engine import Engine
 from sqlalchemy.orm import Session, scoped_session, sessionmaker
 
 from tofu_api.common.config import Config
-from .metadata import metadata_obj
 
 __all__ = [
     'SQLAlchemy',
@@ -70,22 +69,3 @@ class SQLAlchemy:
         # For all further purposes, the scoped session should be treated like a regular Session object.
         # Use cast() so we can use Session as the type annotation.
         return cast(Session, self._scoped_session)
-
-    @property
-    def metadata(self) -> MetaData:
-        """
-        Database metadata object.
-        """
-        return metadata_obj
-
-    def create_all_tables(self) -> None:
-        """
-        Create tables in the database for all models defined in the metadata.
-        """
-        self.metadata.create_all(self.engine)
-
-    def drop_all_tables(self) -> None:
-        """
-        Delete tables in the database for all models defined in the metadata.
-        """
-        self.metadata.drop_all(self.engine)
diff --git a/tofu_api/models/__init__.py b/tofu_api/models/__init__.py
index 280e6a2..55d01aa 100644
--- a/tofu_api/models/__init__.py
+++ b/tofu_api/models/__init__.py
@@ -1 +1,5 @@
+# Base model first
+from .base import metadata, BaseModel
+
+# Data models
 from .task import Task
diff --git a/tofu_api/common/database/metadata.py b/tofu_api/models/base.py
similarity index 54%
rename from tofu_api/common/database/metadata.py
rename to tofu_api/models/base.py
index 3e5f2ad..e611329 100644
--- a/tofu_api/common/database/metadata.py
+++ b/tofu_api/models/base.py
@@ -1,7 +1,9 @@
 from sqlalchemy import MetaData
+from sqlalchemy.orm import declarative_base
 
 __all__ = [
-    'metadata_obj',
+    'metadata',
+    'BaseModel',
 ]
 
 # Define naming convention for constraints
@@ -13,5 +15,8 @@ _naming_convention = {
     "pk": "pk_%(table_name)s"
 }
 
-# Create global metadata object for database schemas
-metadata_obj = MetaData(naming_convention=_naming_convention)
+# Create metadata object for database schemas
+metadata = MetaData(naming_convention=_naming_convention)
+
+# Generate declarative base class for database models
+BaseModel = declarative_base(name='BaseModel', metadata=metadata)
diff --git a/tofu_api/models/task.py b/tofu_api/models/task.py
index b8acdd5..af8bc11 100644
--- a/tofu_api/models/task.py
+++ b/tofu_api/models/task.py
@@ -1,9 +1,9 @@
 from sqlalchemy import Column, Integer, String, Text
 
-from tofu_api.common.database import Model
+from .base import BaseModel
 
 
-class Task(Model):
+class Task(BaseModel):
     """
     Database model for tasks.
     """