Alerting: Fetch all applied alerting configurations (#65728)

* WIP

* skip invalid historic configurations instead of erroring

* add warning log when bad historic config is found

* remove unused custom marshaller for GettableHistoricUserConfig

* add id to historic user config, move limit check to store, fix typo

* swagger spec

pkg/services/ngalert/api/api_alertmanager_test.go

@@ -291,6 +291,96 @@ func TestAlertmanagerConfig(t *testing.T) {
 	})
 }
 
+func TestRouteGetAlertingConfigHistory(t *testing.T) {
+	sut := createSut(t, nil)
+
+	t.Run("assert 200 and empty slice when no applied configurations are found", func(tt *testing.T) {
+		req, err := http.NewRequest(http.MethodGet, "https://grafana.net", nil)
+		require.NoError(tt, err)
+		q := req.URL.Query()
+		q.Add("limit", "10")
+		req.URL.RawQuery = q.Encode()
+
+		rc := createRequestCtxInOrg(10)
+
+		response := sut.RouteGetAlertingConfigHistory(rc)
+		require.Equal(tt, 200, response.Status())
+
+		var configs []apimodels.GettableHistoricUserConfig
+		err = json.Unmarshal(response.Body(), &configs)
+		require.NoError(tt, err)
+
+		require.Len(tt, configs, 0)
+	})
+
+	t.Run("assert 200 and one config in the response for an org that has one successfully applied configuration", func(tt *testing.T) {
+		req, err := http.NewRequest(http.MethodGet, "https://grafana.net", nil)
+		require.NoError(tt, err)
+		q := req.URL.Query()
+		q.Add("limit", "10")
+		req.URL.RawQuery = q.Encode()
+
+		rc := createRequestCtxInOrg(1)
+
+		response := sut.RouteGetAlertingConfigHistory(rc)
+		require.Equal(tt, 200, response.Status())
+
+		var configs []apimodels.GettableHistoricUserConfig
+		err = json.Unmarshal(response.Body(), &configs)
+		require.NoError(tt, err)
+
+		require.Len(tt, configs, 1)
+	})
+
+	t.Run("assert 200 when no limit is provided", func(tt *testing.T) {
+		rc := createRequestCtxInOrg(1)
+
+		response := sut.RouteGetAlertingConfigHistory(rc)
+		require.Equal(tt, 200, response.Status())
+
+		configs := asGettableHistoricUserConfigs(tt, response)
+		for _, config := range configs {
+			require.NotZero(tt, config.LastApplied)
+		}
+	})
+
+	t.Run("assert 200 when limit is < 1", func(tt *testing.T) {
+		req, err := http.NewRequest(http.MethodGet, "https://grafana.net", nil)
+		require.NoError(tt, err)
+		q := req.URL.Query()
+		q.Add("limit", "0")
+		req.URL.RawQuery = q.Encode()
+
+		rc := createRequestCtxInOrg(1)
+
+		response := sut.RouteGetAlertingConfigHistory(rc)
+		require.Equal(tt, 200, response.Status())
+
+		configs := asGettableHistoricUserConfigs(tt, response)
+		for _, config := range configs {
+			require.NotZero(tt, config.LastApplied)
+		}
+	})
+
+	t.Run("assert 200 when limit is > 100", func(tt *testing.T) {
+		req, err := http.NewRequest(http.MethodGet, "https://grafana.net", nil)
+		require.NoError(tt, err)
+		q := req.URL.Query()
+		q.Add("limit", "1000")
+		req.URL.RawQuery = q.Encode()
+
+		rc := createRequestCtxInOrg(1)
+
+		response := sut.RouteGetAlertingConfigHistory(rc)
+		require.Equal(tt, 200, response.Status())
+
+		configs := asGettableHistoricUserConfigs(tt, response)
+		for _, config := range configs {
+			require.NotZero(tt, config.LastApplied)
+		}
+	})
+}
+
 func TestSilenceCreate(t *testing.T) {
 	makeSilence := func(comment string, createdBy string,
 		startsAt, endsAt strfmt.DateTime, matchers amv2.Matchers) amv2.Silence {
@@ -661,3 +751,11 @@ func asGettableUserConfig(t *testing.T, r response.Response) *apimodels.Gettable
 	require.NoError(t, err)
 	return body
 }
+
+func asGettableHistoricUserConfigs(t *testing.T, r response.Response) []apimodels.GettableHistoricUserConfig {
+	t.Helper()
+	var body []apimodels.GettableHistoricUserConfig
+	err := json.Unmarshal(r.Body(), &body)
+	require.NoError(t, err)
+	return body
+}