diff --git a/.idea/misc.xml b/.idea/misc.xml
index a4652f3..6a48157 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -1,4 +1,4 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
-  <component name="ProjectRootManager" version="2" project-jdk-name="Python 3.10 (venv)" project-jdk-type="Python SDK" />
+  <component name="ProjectRootManager" version="2" project-jdk-name="Python 3.10 (djangoProject)" project-jdk-type="Python SDK" />
 </project>
\ No newline at end of file
diff --git a/.idea/recipe-app-api.iml b/.idea/recipe-app-api.iml
index d0876a7..1a23ee9 100644
--- a/.idea/recipe-app-api.iml
+++ b/.idea/recipe-app-api.iml
@@ -1,8 +1,8 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<module type="PYTHON_MODULE" version="4">
-  <component name="NewModuleRootManager">
-    <content url="file://$MODULE_DIR$" />
-    <orderEntry type="inheritedJdk" />
-    <orderEntry type="sourceFolder" forTests="false" />
-  </component>
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="PYTHON_MODULE" version="4">
+  <component name="NewModuleRootManager">
+    <content url="file://$MODULE_DIR$" />
+    <orderEntry type="jdk" jdkName="Python 3.10 (djangoProject)" jdkType="Python SDK" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
 </module>
\ No newline at end of file
diff --git a/Dockerfile b/Dockerfile
index 8144c23..5670b01 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,28 +1,32 @@
-FROM python:3.9-alpine3.13
-LABEL maintainer="artem.vasylchuck@gmail.com"
-
-ENV PYTHONUNBUFFERED 1
-
-COPY ./requirements.txt /tmp/requirements.txt
-COPY ./requirements.dev.txt /tmp/requirements.dev.txt
-COPY ./app /app
-WORKDIR /app
-EXPOSE 8000
-
-ARG DEV=false
-RUN python -m venv /py && \
-    /py/bin/pip install --upgrade pip && \
-    /py/bin/pip install -r /tmp/requirements.txt && \
-    if [ $DEV = "true" ]; \
-        then /py/bin/pip install -r /tmp/requirements.dev.txt ; \
-    fi && \
-    rm -rf /tmp && \
-    adduser \
-        --disabled-password \
-        --no-create-home \
-        django-user
-
-ENV PATH="/py/bin:$PATH"
-
-USER django-user
-
+FROM python:3.9-alpine3.13
+LABEL maintainer="artem.vasylchuck@gmail.com"
+
+ENV PYTHONUNBUFFERED 1
+
+COPY ./requirements.txt /tmp/requirements.txt
+COPY ./requirements.dev.txt /tmp/requirements.dev.txt
+COPY ./app /app
+WORKDIR /app
+EXPOSE 8000
+
+ARG DEV=false
+RUN python -m venv /py && \
+    /py/bin/pip install --upgrade pip && \
+    apk add --update --no-cache postgresql-client && \
+    apk add --update --no-cache --virtual .tmp-build-deps \
+        build-base postgresql-dev musl-dev && \
+    /py/bin/pip install -r /tmp/requirements.txt && \
+    if [ $DEV = "true" ]; \
+        then /py/bin/pip install -r /tmp/requirements.dev.txt ; \
+    fi && \
+    rm -rf /tmp && \
+    apk del .tmp-build-deps && \
+    adduser \
+        --disabled-password \
+        --no-create-home \
+        django-user
+
+ENV PATH="/py/bin:$PATH"
+
+USER django-user
+
diff --git a/app/app/calc.py b/app/app/calc.py
new file mode 100644
index 0000000..fa9dcfa
--- /dev/null
+++ b/app/app/calc.py
@@ -0,0 +1,13 @@
+"""
+Calculator functions
+"""
+
+
+def add(x, y):
+    """ Add two numbers."""
+    return x + y
+
+
+def subtract(x, y):
+    """ Subtracting x from y """
+    return x - y
diff --git a/app/app/tests.py b/app/app/tests.py
new file mode 100644
index 0000000..8fff507
--- /dev/null
+++ b/app/app/tests.py
@@ -0,0 +1,20 @@
+"""
+Sample tests
+"""
+from django.test import SimpleTestCase
+
+from . import calc
+
+
+class CalculatorTests(SimpleTestCase):
+    """ Test the calc module """
+    def test_add_numbers(self):
+        """ Test adding two numbers """
+        res = calc.add(3, 6)
+        self.assertEqual(res, 9)
+
+    def test_subtract_numbers(self):
+        """ Testing subtracting two numbers """
+        res = calc.subtract(10, 5)
+
+        self.assertEqual(res, 5)
diff --git a/docker-compose.yml b/docker-compose.yml
index 2cd1bb9..3116425 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,15 +1,34 @@
-version: "3.9"
-
-services:
-  app:
-    build:
-      context: .
-      args:
-        - DEV=true
-    ports:
-      - "8000:8000"
-    volumes:
-      - ./app:/app
-    command: >
-      sh -c "python manage.py runserver 0.0.0.0:8000"
-
+version: "3.9"
+
+services:
+  app:
+    build:
+      context: .
+      args:
+        - DEV=true
+    ports:
+      - "8000:8000"
+    volumes:
+      - ./app:/app
+    command: >
+      sh -c "python manage.py runserver 0.0.0.0:8000"
+    environment:
+      - DB_HOST=db
+      - DB_NAME=devdb
+      - DB_USER=devuser
+      - DB_PASS=changeme
+    depends_on:
+      - db
+
+
+  db:
+    image: postgres:13-alpine
+    volumes:
+      - dev-db-data:/var/lib/postgresql/data
+    environment:
+      - POSTGRES_DB=devdb
+      - POSTGRES_USER=devuser
+      - POSTGRES_PASSWORD=changeme
+
+volumes:
+  dev-db-data:
diff --git a/requirements.txt b/requirements.txt
index ba00276..e78ea71 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,3 @@
-Django>=3.2.4,<3.3
-djangorestframework>=3.12.4,<3.13
\ No newline at end of file
+Django>=3.2.4,<3.3
+djangorestframework>=3.12.4,<3.13
+psycopg2>=2.8.6,<2.9
\ No newline at end of file