diff --git a/go.mod b/go.mod
index 80ee601c8..020d6395d 100644
--- a/go.mod
+++ b/go.mod
@@ -62,6 +62,7 @@ require (
 	google.golang.org/genproto v0.0.0-20200312145019-da6875a35672 // indirect
 	google.golang.org/grpc v1.28.0 // indirect
 	gopkg.in/ini.v1 v1.54.0 // indirect
+	gopkg.in/yaml.v2 v2.2.8 // indirect
 	gotest.tools/v3 v3.0.2 // indirect
 	helm.sh/helm/v3 v3.1.2
 	k8s.io/api v0.18.0
diff --git a/pkg/components/prometheus-operator/component_conversion_test.go b/pkg/components/prometheus-operator/component_conversion_test.go
new file mode 100644
index 000000000..1c45e7fd2
--- /dev/null
+++ b/pkg/components/prometheus-operator/component_conversion_test.go
@@ -0,0 +1,167 @@
+package prometheus //nolint:testpackage
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/hashicorp/hcl/v2"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	yamlserializer "k8s.io/apimachinery/pkg/runtime/serializer/yaml"
+	"k8s.io/client-go/util/jsonpath"
+
+	"github.com/kinvolk/lokomotive/pkg/components/util"
+)
+
+func renderManifests(t *testing.T, configHCL string) map[string]string {
+	name := "prometheus-operator"
+
+	component := newComponent()
+
+	body, diagnostics := util.GetComponentBody(configHCL, name)
+	if diagnostics.HasErrors() {
+		t.Fatalf("Getting component body: %v", diagnostics.Errs())
+	}
+
+	diagnostics = component.LoadConfig(body, &hcl.EvalContext{})
+	if diagnostics.HasErrors() {
+		t.Fatalf("Valid config should not return an error, got: %v", diagnostics)
+	}
+
+	ret, err := component.RenderManifests()
+	if err != nil {
+		t.Fatalf("Rendering manifests with valid config should succeed, got: %s", err)
+	}
+
+	return ret
+}
+
+//nolint:funlen
+func TestConversion(t *testing.T) {
+	testCases := []struct {
+		Name                   string
+		InputConfig            string
+		ExpectedConfigFileName string
+		Expected               reflect.Value
+		JSONPath               string
+	}{
+		{
+			Name: "use external_url param",
+			InputConfig: `
+component "prometheus-operator" {
+  prometheus {
+    external_url = "https://prometheus.externalurl.net"
+  }
+}
+`,
+			ExpectedConfigFileName: "prometheus-operator/templates/prometheus/prometheus.yaml",
+			Expected:               reflect.ValueOf("https://prometheus.externalurl.net"),
+			JSONPath:               "{.spec.externalUrl}",
+		},
+		{
+			Name: "no external_url param",
+			InputConfig: `
+		component "prometheus-operator" {
+		  prometheus {
+		    ingress {
+		      host                       = "prometheus.mydomain.net"
+		      class                      = "contour"
+		      certmanager_cluster_issuer = "letsencrypt-production"
+		    }
+		  }
+		}
+		`,
+			ExpectedConfigFileName: "prometheus-operator/templates/prometheus/prometheus.yaml",
+			Expected:               reflect.ValueOf("https://prometheus.mydomain.net"),
+			JSONPath:               "{.spec.externalUrl}",
+		},
+		{
+			Name: "ingress creation for prometheus",
+			InputConfig: `
+		component "prometheus-operator" {
+		  prometheus {
+		    ingress {
+		      host                       = "prometheus.mydomain.net"
+		      class                      = "contour"
+		      certmanager_cluster_issuer = "letsencrypt-production"
+		    }
+		  }
+		}
+		`,
+			ExpectedConfigFileName: "prometheus-operator/templates/prometheus/ingress.yaml",
+			Expected:               reflect.ValueOf("prometheus.mydomain.net"),
+			JSONPath:               "{.spec.rules[0].host}",
+		},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(tc.Name, func(t *testing.T) {
+			t.Parallel()
+
+			m := renderManifests(t, tc.InputConfig)
+			if len(m) == 0 {
+				t.Fatalf("Rendered manifests shouldn't be empty")
+			}
+
+			gotConfig, ok := m[tc.ExpectedConfigFileName]
+			if !ok {
+				t.Fatalf("Config not found with filename: %q", tc.ExpectedConfigFileName)
+			}
+
+			u := getUnstructredObj(t, gotConfig)
+			got := getValFromObject(t, tc.JSONPath, u)
+
+			switch got.Kind() { //nolint:exhaustive
+			case reflect.Interface:
+				switch gotVal := got.Interface().(type) {
+				// Add more cases as the expected values become heterogeneous.
+				// case bool:
+				case string:
+					expVal, ok := tc.Expected.Interface().(string)
+					if !ok {
+						t.Fatalf("expected value is not string")
+					}
+
+					if gotVal != expVal {
+						t.Fatalf("expected: %s, got: %s", expVal, gotVal)
+					}
+
+				default:
+					t.Fatalf("Unknown type of the interface object: %T", got.Interface())
+				}
+			default:
+				t.Fatalf("Unknown type of the object extracted from the converted YAML: %v", got.Kind())
+			}
+		})
+	}
+}
+
+func getUnstructredObj(t *testing.T, yamlObj string) *unstructured.Unstructured {
+	u := &unstructured.Unstructured{}
+
+	// Decode YAML into `unstructured.Unstructured`.
+	dec := yamlserializer.NewDecodingSerializer(unstructured.UnstructuredJSONScheme)
+	if _, _, err := dec.Decode([]byte(yamlObj), nil, u); err != nil {
+		t.Fatalf("Converting config to unstructured.Unstructured: %v", err)
+	}
+
+	return u
+}
+
+func getValFromObject(t *testing.T, jp string, obj *unstructured.Unstructured) reflect.Value {
+	jPath := jsonpath.New("parse")
+	if err := jPath.Parse(jp); err != nil {
+		t.Fatalf("Parsing JSONPath: %v", err)
+	}
+
+	v, err := jPath.FindResults(obj.Object)
+	if err != nil {
+		t.Fatalf("Finding results using JSONPath in the YAML file: %v", err)
+	}
+
+	if len(v) == 0 || len(v[0]) == 0 {
+		t.Fatalf("No result found")
+	}
+
+	return v[0][0]
+}
diff --git a/pkg/components/prometheus-operator/component_test.go b/pkg/components/prometheus-operator/component_test.go
index 8de992256..9f996c555 100644
--- a/pkg/components/prometheus-operator/component_test.go
+++ b/pkg/components/prometheus-operator/component_test.go
@@ -62,6 +62,34 @@ component "prometheus-operator" {
 }`,
 			wantErr: true,
 		},
+		{
+			desc: "prometheus ingress and external_url given and are different",
+			hcl: `
+component "prometheus-operator" {
+  prometheus {
+	external_url = "https://prometheus.notmydomain.net"
+    ingress {
+      host = "prometheus.mydomain.net"
+    }
+  }
+}
+`,
+			wantErr: true,
+		},
+		{
+			desc: "prometheus ingress and external_url given and are same",
+			hcl: `
+component "prometheus-operator" {
+  prometheus {
+	external_url = "https://prometheus.mydomain.net"
+    ingress {
+      host = "prometheus.mydomain.net"
+    }
+  }
+}
+`,
+			wantErr: false,
+		},
 	}
 
 	for _, tc := range tests {
diff --git a/vendor/k8s.io/apimachinery/pkg/runtime/serializer/yaml/yaml.go b/vendor/k8s.io/apimachinery/pkg/runtime/serializer/yaml/yaml.go
new file mode 100644
index 000000000..2fdd1d43d
--- /dev/null
+++ b/vendor/k8s.io/apimachinery/pkg/runtime/serializer/yaml/yaml.go
@@ -0,0 +1,46 @@
+/*
+Copyright 2014 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package yaml
+
+import (
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/util/yaml"
+)
+
+// yamlSerializer converts YAML passed to the Decoder methods to JSON.
+type yamlSerializer struct {
+	// the nested serializer
+	runtime.Serializer
+}
+
+// yamlSerializer implements Serializer
+var _ runtime.Serializer = yamlSerializer{}
+
+// NewDecodingSerializer adds YAML decoding support to a serializer that supports JSON.
+func NewDecodingSerializer(jsonSerializer runtime.Serializer) runtime.Serializer {
+	return &yamlSerializer{jsonSerializer}
+}
+
+func (c yamlSerializer) Decode(data []byte, gvk *schema.GroupVersionKind, into runtime.Object) (runtime.Object, *schema.GroupVersionKind, error) {
+	out, err := yaml.ToJSON(data)
+	if err != nil {
+		return nil, nil, err
+	}
+	data = out
+	return c.Serializer.Decode(data, gvk, into)
+}
diff --git a/vendor/modules.txt b/vendor/modules.txt
index 8ae88d736..8067f30a5 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -575,6 +575,7 @@ k8s.io/apimachinery/pkg/runtime/serializer/protobuf
 k8s.io/apimachinery/pkg/runtime/serializer/recognizer
 k8s.io/apimachinery/pkg/runtime/serializer/streaming
 k8s.io/apimachinery/pkg/runtime/serializer/versioning
+k8s.io/apimachinery/pkg/runtime/serializer/yaml
 k8s.io/apimachinery/pkg/selection
 k8s.io/apimachinery/pkg/types
 k8s.io/apimachinery/pkg/util/cache