Add url and change to POST

isitup/__init__.py

@@ -69,7 +69,7 @@ async def all_url_checks(check: Union[http.CheckUrl, dns.CheckDomain]) -> list[d
     return results
 
 
-@app.get("/check/prometheus")
-async def prometheus_checks() -> None:
+@app.post("/check/prometheus")
+async def prometheus_checks(prometheusUrl: prometheus.PrometheusUrl) -> None:
     checker = retrieve_check("prometheus")
-    return await checker()
+    return await checker(prometheusUrl)

isitup/prometheus.py

-async def check_prometheus() -> None:
+import httpx
+import pydantic
+from httpx import AsyncClient
+
+from isitup.checks import CheckErrorException
+
+
+class PrometheusUrl(pydantic.BaseModel):
+    prometheusUrl: pydantic.AnyHttpUrl = pydantic.Field(
+        ..., title="Prometheus Url", description="Prometheus server to query"
+    )
+
+    class Config:
+        schema_extra = {"example": {"PrometheusUrl": "https://prometheus.example.com",}}
+
+
+async def check_prometheus(prometheusUrl: PrometheusUrl) -> None:
+    healthy = await prometheus_is_healthy(prometheusUrl.prometheusUrl)
+    if not healthy:
+        raise CheckErrorException(status_code=502, detail="Prometheus is not reachable")
     return 1
 
 
+def get_client():
+    return AsyncClient()
+
+
+async def prometheus_is_healthy(url: str) -> bool:
+    healthcheck_url = url + "/-/healthy"
+    ready_url = url + "/-/ready"
+    async with get_client() as client:
+        response = await client.get(healthcheck_url)
+        if response.status_code == 200 and b"Prometheus is Healthy." in response.read():
+            response = await client.get(ready_url)
+            if (
+                response.status_code == 200
+                and b"Prometheus is Ready." in response.read()
+            ):
+                return True
+        return False
+
+
 def register(register_callback: callable) -> None:
     register_callback(check_prometheus, "prometheus")

requirements-dev.txt

@@ -3,7 +3,9 @@ black==20.8b1
 asgi_lifespan
 pytest==6.2.1
 pytest-asyncio
+pytest-httpserver
 pytest-mock
+pytest-raises
 pre-commit
 pytest-watch
 pytest-cov

tests/test_api.py

+import re
 from unittest import mock
 
 import pytest
 from httpx import AsyncClient
+from pytest_httpserver import HTTPServer
 from pytest_mock import MockerFixture
 from starlette.status import (
     HTTP_200_OK,
@@ -10,6 +12,8 @@ from starlette.status import (
 )
 
 import isitup
+from isitup.checks import CheckErrorException
+from isitup.prometheus import PrometheusUrl, check_prometheus, prometheus_is_healthy
 
 
 class TestHttpChecks:
@@ -59,10 +63,20 @@ class TestDnsChecks:
 
 class TestPrometheusChecks:
     @pytest.mark.asyncio
-    async def test_check_prometheus_is_reachable(
-        self, api: AsyncClient, base_url: str
+    async def test_check_prometheus_requires_post(
+        self,
+        api: AsyncClient,
+        httpserver: HTTPServer,
+        mocker: MockerFixture,
+        base_url: str,
     ) -> None:
         res = await api.get("/check/prometheus/")
+        assert res.status_code == 405
+        mock_function = mock.AsyncMock(return_value=True)
+        mocker.patch("isitup.prometheus.prometheus_is_healthy", mock_function)
+        res = await api.post(
+            "/check/prometheus/", json={"prometheusUrl": "https://ignored.net"}
+        )
         assert res.status_code == 200
 
     @pytest.mark.asyncio
@@ -71,5 +85,34 @@ class TestPrometheusChecks:
     ) -> None:
         mock_function = mock.AsyncMock()
         mocker.patch("isitup.prometheus.check_prometheus", mock_function)
-        res = await api.get("/check/prometheus/")
+        res = await api.post("/check/prometheus/")
         mock_function.call_count == 1
+
+    @pytest.mark.asyncio
+    async def test_prometheus_check_function_executes_healthcheck(
+        self, api: AsyncClient, httpserver: HTTPServer, base_url: str
+    ) -> None:
+        health = await prometheus_is_healthy(httpserver.url_for(""))  # returns 500
+        assert health == False
+        httpserver.expect_request("/-/healthy").respond_with_data(
+            "Prometheus is Healthy."
+        )
+        httpserver.expect_oneshot_request("/-/ready").respond_with_data(
+            "Prometheus is Ready."
+        )
+        health = await prometheus_is_healthy(httpserver.url_for(""))
+        assert health == True
+        health = await prometheus_is_healthy(
+            httpserver.url_for("")
+        )  # ready returns 500 now
+        assert health == False
+
+    @pytest.mark.asyncio
+    @pytest.mark.raises(exception=CheckErrorException)
+    async def test_check_prometheus_raises_exception_when_prometheus_not_healthy(
+        self, api: AsyncClient, mocker: MockerFixture, base_url: str
+    ) -> None:
+        mocker.patch("isitup.prometheus.prometheus_is_healthy", return_value=False)
+        ignored = PrometheusUrl
+        ignored.prometheusUrl = "ignored"
+        await check_prometheus(ignored)