diff --git a/.flake8 b/.flake8
new file mode 100644
index 0000000000000000000000000000000000000000..a529cce01dc7b64e37c0b2532fd77aa9cca02e55
--- /dev/null
+++ b/.flake8
@@ -0,0 +1,3 @@
+[flake8]
+max-line-length = 88
+ignore = E203, E731
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 082ccae7fc5d91ca0a9e044a9b13d88b2045f9fd..9771ddf32b2c3bcdfda5a4d4dbb94993f6a277b8 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -8,11 +8,10 @@ variables:
   PUBLISH_URL: ota.ecloud.global
   DOCKER_TLS_CERTDIR: "/certs"
 
-services:
-- docker:19.03.1-dind
-
 build:
   stage: build
+  services:
+    - docker:19.03.1-dind
   script:
   - docker pull $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_NAME || true
   - docker login -u gitlab-ci-token -p $CI_BUILD_TOKEN $CI_REGISTRY
@@ -21,6 +20,52 @@ build:
   - if [ "${CI_COMMIT_REF_NAME}" = master ] ; then docker push $CI_REGISTRY_IMAGE:latest ; fi
   tags:
     - generic_privileged
+  rules:
+    - if: '$CI_PIPELINE_SOURCE != "schedule"'
+
+check:rules:tests:
+  stage: build
+  image: python:3.11-slim
+  before_script:
+    - pip install black==22.10.0 flake8==5.0.4 isort==5.10.1
+  script:
+    - cd tests/functional
+    - black --check .
+    - flake8 .
+    - isort --check .
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+      changes:
+        - tests/functional/*
+
+.tests:functional:
+  stage: test
+  image: python:3.11-slim
+  variables:
+    PYTEST_ADDOPTS: "--junitxml=report.xml"
+  before_script:
+    - cd tests/functional/
+    - pip install -r requirements.txt
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "schedule"'
+    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+      changes:
+        - tests/functional/*
+  artifacts:
+    when: always
+    reports:
+      junit: tests/functional/report.xml
+
+
+tests:functional:staging:
+  extends: .tests:functional
+  script:
+    - pytest --ota-domain "test.${PUBLISH_URL}"
+
+tests:functional:production:
+  extends: .tests:functional
+  script:
+    - pytest --ota-domain "${PUBLISH_URL}"
 
 # Deploy stage
 .deploy:image:
@@ -44,15 +89,17 @@ build:
 
 deploy:staging:
   extends: .deploy:image
-  when: manual
+  rules:
+    - if: '$CI_COMMIT_REF_NAME != "production" && $CI_PIPELINE_SOURCE != "schedule"'
+      when: manual
   environment:
     name: staging
     url: https://ota.eeo.one
 
 deploy:production:
   extends: .deploy:image
-  only:
-    - production
+  rules:
+    - if: '$CI_COMMIT_REF_NAME == "production" && $CI_PIPELINE_SOURCE != "schedule"'
   environment:
     name: production
     url: https://ota.ecloud.global
diff --git a/tests/functional/conftest.py b/tests/functional/conftest.py
new file mode 100644
index 0000000000000000000000000000000000000000..15b01544cdac319afbd2006f463539639737ee50
--- /dev/null
+++ b/tests/functional/conftest.py
@@ -0,0 +1,28 @@
+import pytest
+
+
+class Context:
+    def __init__(self, config):
+        self.domain = config.getoption("--ota-domain")
+        assert self.domain is not None, "OTA server domain has to be defined"
+        self.device = config.getoption("--ota-device")
+        self.channel = config.getoption("--ota-channel")
+        self.url = f"https://{self.domain}"
+
+
+def pytest_addoption(parser):
+    parser.addoption(
+        "--ota-domain", action="store", default=None, help="OTA server domain"
+    )
+    parser.addoption(
+        "--ota-device", action="store", default="FP3", help="OTA device name"
+    )
+    parser.addoption(
+        "--ota-channel", action="store", default="stable", help="OTA channel name"
+    )
+
+
+@pytest.fixture
+def ctx(request):
+    context = Context(request.config)
+    yield context
diff --git a/tests/functional/requirements.txt b/tests/functional/requirements.txt
new file mode 100644
index 0000000000000000000000000000000000000000..65a64119a6db32f128471e7b4cc2cf1408056170
--- /dev/null
+++ b/tests/functional/requirements.txt
@@ -0,0 +1,2 @@
+pytest==7.2.0
+httpx==0.23.1
diff --git a/tests/functional/test_api.py b/tests/functional/test_api.py
new file mode 100644
index 0000000000000000000000000000000000000000..8b266b82feb4ba1f6776f39927328b7ae8ced999
--- /dev/null
+++ b/tests/functional/test_api.py
@@ -0,0 +1,69 @@
+import httpx
+import pytest
+
+
+@pytest.fixture
+def ctx(ctx):
+    ctx.cli = httpx.Client(base_url=f"{ctx.url}/api/v1", timeout=60)
+    yield ctx
+
+
+def test_list_device_builds(ctx):
+    res = ctx.cli.get(f"/{ctx.device}/{ctx.channel}")
+    assert res.status_code == httpx.codes.OK
+    data = res.json()
+    assert not data["error"]
+    assert len(data["response"])
+    build = data["response"][-1]
+    assert build["channel"] == ctx.channel
+    assert build["romtype"] == ctx.channel
+    assert build["url"].startswith(ctx.url)
+    assert build["filename"].startswith("e-")
+
+
+def test_list_build_with_incremental_update_field(ctx):
+    # list and sort all builds by datetime
+    res = ctx.cli.get(f"/{ctx.device}/{ctx.channel}")
+    assert res.status_code == httpx.codes.OK
+    data = sorted(res.json()["response"], key=lambda d: d["datetime"])
+    assert len(data) >= 2
+
+    # list build with incremental field
+    build = data[-2]
+    res = ctx.cli.get(f"/{ctx.device}/{ctx.channel}/{build['incremental']}")
+    assert res.status_code == httpx.codes.OK
+    data = res.json()
+    assert len(data["response"]) == 1
+
+
+def test_FP4_upgrade_from_given_build(ctx):
+    """FP4 A12 upgrade is allowed only from 1.5-r build"""
+    # create a map about /e/OS builds
+    res = ctx.cli.get("/FP4/stable")
+    assert res.status_code == httpx.codes.OK
+    assert len(res.json()["response"])
+    builds = {
+        f"{d['version']}-{d['pre_version']}-{d['android_version']}": d
+        for d in res.json()["response"]
+    }
+
+    # ensure that A12 builds are not listed with version <= 1.4-r
+    build14r = builds["1.4--11"]
+    res = ctx.cli.get(f"/FP4/stable/{build14r['incremental']}")
+    assert res.status_code == httpx.codes.OK
+    data = res.json()["response"]
+    a12builds = [d for d in data if d["android_version"] == "12"]
+    assert len(a12builds) == 0
+
+    # ensure that A12 builds are listed with version == 1.5-r
+    build15r = builds["1.5--11"]
+    res = ctx.cli.get(
+        f"/FP4/stable/{build15r['incremental']}",
+        headers={"User-Agent": "eOS v1.5"},
+    )
+    assert res.status_code == httpx.codes.OK
+    data = res.json()["response"]
+    a12builds = [d for d in data if d["android_version"] == "12"]
+    a11builds = [d for d in data if d["android_version"] == "11"]
+    assert len(a11builds) == 0
+    assert len(a12builds) >= 1