feat(spec): add support for health

Add support for providing things like livenessProbe and readinessProbe.
Add a new field in container level called health which has readinessProbe
and livenessProbe. These fields are identical to the way we define
livenessProbe or readinessProbe in kubernetes. So no new extra field has
been added, everything that k8s supports works with the health option in
OpenCompose.

fixes #24

Author: surajssd

examples/wordpress/health.yaml

@@ -0,0 +1,47 @@
+version: '0.1-dev'
+
+services:
+- name: database
+  containers:
+  - image: mariadb:10
+    env:
+    - name: MYSQL_ROOT_PASSWORD
+      value: rootpasswd
+    - name: MYSQL_DATABASE
+      value: wordpress
+    - name: MYSQL_USER
+      value: wordpress
+    - name: MYSQL_PASSWORD
+      value: wordpress
+    ports:
+    - port: 3306
+    mounts:
+    - volumeRef: database
+      mountPath: /var/lib/mysql
+
+- name: web
+  containers:
+  - image: wordpress:4
+    env:
+    - name: WORDPRESS_DB_HOST
+      value: database:3306
+    - name: WORDPRESS_DB_PASSWORD
+      value: wordpress
+    - name: WORDPRESS_DB_USER
+      value: wordpress
+    - name: WORDPRESS_DB_NAME
+      value: wordpress
+    ports:
+    - port: 80
+      type: external
+    health:
+      readinessProbe:
+        httpGet:
+          port: 80
+          path: /v1
+        initialDelaySeconds: 10
+
+volumes:
+- name: database
+  size: 100Mi
+  accessMode: ReadWriteOnce

pkg/encoding/util/util.go

@@ -122,3 +122,23 @@ func ValidateRequiredFields(i interface{}) error {
 
 	return nil
 }
+
+// Converts the yaml read into empty interface to JSONified
+// empty interface, this can be used to marshal into actual
+// JSON and from there if you want it you can read it into
+// Took help from https://stackoverflow.com/a/40737676/3848679
+func InterfaceToJSON(i interface{}) interface{} {
+	switch x := i.(type) {
+	case map[interface{}]interface{}:
+		m2 := map[string]interface{}{}
+		for k, v := range x {
+			m2[k.(string)] = InterfaceToJSON(v)
+		}
+		return m2
+	case []interface{}:
+		for i, v := range x {
+			x[i] = InterfaceToJSON(v)
+		}
+	}
+	return i
+}

pkg/encoding/util/util_test.go

@@ -4,6 +4,8 @@ import (
 	"errors"
 	"reflect"
 	"testing"
+
+	"gopkg.in/yaml.v2"
 )
 
 type S struct {
@@ -135,3 +137,59 @@ func TestValidateRequiredFields(t *testing.T) {
 		}
 	}
 }
+
+func TestInterfaceToJSON(t *testing.T) {
+	tests := []struct {
+		input  string
+		output map[string]interface{}
+	}{
+		{
+			input:  `foo: bar`,
+			output: map[string]interface{}{"foo": "bar"},
+		},
+		{
+			input: `
+one:
+- 1
+- 2
+- 3
+two: four`,
+			output: map[string]interface{}{
+				"two": "four",
+				"one": []interface{}{1, 2, 3},
+			},
+		},
+		{
+			input: `
+one:
+  two:
+    three: four
+five: six
+seven:
+- eight
+- nine`,
+			output: map[string]interface{}{
+				"one": map[string]interface{}{
+					"two": map[string]interface{}{
+						"three": "four",
+					},
+				},
+				"five":  "six",
+				"seven": []interface{}{"eight", "nine"},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		var input interface{}
+		err := yaml.Unmarshal([]byte(test.input), &input)
+		if err != nil {
+			t.Fatalf("failed unmarshalling: %v", err)
+		}
+		gotOutput := InterfaceToJSON(input)
+
+		if !reflect.DeepEqual(test.output, gotOutput) {
+			t.Errorf("Expected: %#v\nGot: %#v", test.output, gotOutput)
+		}
+	}
+}

pkg/encoding/v1/encoding.go

@@ -1,6 +1,7 @@
 package v1
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"strconv"
@@ -10,6 +11,8 @@ import (
 	"github.com/redhat-developer/opencompose/pkg/goutil"
 	"github.com/redhat-developer/opencompose/pkg/object"
 	"gopkg.in/yaml.v2"
+
+	api_v1 "k8s.io/client-go/pkg/api/v1"
 )
 
 const (
@@ -219,11 +222,85 @@ func (m *Mount) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	return nil
 }
 
+type Health struct {
+	// Data holder for ReadinessProbe while parsing
+	// Data from the yaml file will be read into this field
+	ReadinessProbeData interface{} `yaml:"readinessProbe,omitempty"`
+	// After certain processing the data in ReadinessProbeData
+	// will be populated into ReadinessProbe for further use
+	ReadinessProbe *api_v1.Probe
+
+	LivenessProbeData interface{} `yaml:"livenessProbe,omitempty"`
+	LivenessProbe     *api_v1.Probe
+}
+
+// If given an interface which has JSONified data of type Probe
+// this function will read the interface and give concrete
+// data strcuture pointer.
+func interfaceToProbe(i interface{}) (*api_v1.Probe, error) {
+	i = util.InterfaceToJSON(i)
+
+	var b []byte
+	var err error
+	if b, err = json.Marshal(i); err != nil {
+		return nil, fmt.Errorf("error: marshalling interface to bytes: %v", err)
+	}
+	var p api_v1.Probe
+	if err = json.Unmarshal(b, &p); err != nil {
+		return nil, fmt.Errorf("error: unmarshalling bytes to Probe: %v", err)
+	}
+	return &p, nil
+}
+
+func (h *Health) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type HealthAlias Health
+	var st struct {
+		HealthAlias `yaml:",inline"`
+		Leftovers   map[string]interface{} `yaml:",inline"` // Catches all undefined fields and must be empty after parsing.
+	}
+
+	err := unmarshal(&st)
+	if err != nil {
+		return err
+	}
+
+	if len(st.Leftovers) > 0 {
+		return util.NewExcessKeysErrorFromMap("Health", st.Leftovers)
+	}
+
+	*h = Health(st.HealthAlias)
+
+	// extract the data from interface into concrete data type 'Probe'
+	if h.ReadinessProbeData != nil {
+		h.ReadinessProbe, err = interfaceToProbe(h.ReadinessProbeData)
+		if err != nil {
+			return fmt.Errorf("readinessProbe: %v", err)
+		}
+		h.ReadinessProbeData = interface{}(nil)
+	}
+
+	// extract the data from interface into concrete data type 'Probe'
+	if h.LivenessProbeData != nil {
+		h.LivenessProbe, err = interfaceToProbe(h.LivenessProbeData)
+		if err != nil {
+			return fmt.Errorf("livenessProbe: %v", err)
+		}
+		h.LivenessProbeData = interface{}(nil)
+	}
+
+	// TODO: Right now we have no way of finding if the excess keys are given
+	// by the user, since we are doing the whole conversion from YAML to JSON
+	// and then parsing it into the internal k8s structs
+
+	return nil
+}
+
 type Container struct {
 	Image  ImageRef      `yaml:"image"`
 	Env    []EnvVariable `yaml:"env,omitempty"`
 	Ports  []Port        `yaml:"ports,omitempty"`
 	Mounts []Mount       `yaml:"mounts,omitempty"`
+	Health *Health       `yaml:"health,omitempty"`
 }
 
 func (c *Container) UnmarshalYAML(unmarshal func(interface{}) error) error {
@@ -443,6 +520,11 @@ func (d *Decoder) Decode(data []byte) (*object.OpenCompose, error) {
 				oc.Mounts = append(oc.Mounts, mount)
 			}
 
+			if c.Health != nil {
+				oc.Health.LivenessProbe = c.Health.LivenessProbe
+				oc.Health.ReadinessProbe = c.Health.ReadinessProbe
+			}
+
 			// convert env
 			for _, e := range c.Env {
 				oc.Environment = append(oc.Environment, object.EnvVariable{