envsvc: added pod spec env lookup

env.go

@@ -505,5 +505,10 @@ func Visit(fn func(*Var)) {
 
 // Parse parses variables from the process environment.
 func Parse() error {
-	return CmdVar.Parse(osLookup{})
+	return ParseWithGetter(osLookup{})
+}
+
+// ParseWithGetter parses variables via the given Getter.
+func ParseWithGetter(g Getter) error {
+	return CmdVar.Parse(g)
 }

envsvc/envsvc.go

@@ -33,8 +33,24 @@ func ParseWithExitFn(exitFn func(int)) {
 	envDumpJSON := flag.Bool("env-dump-json", false, "dump env variables in JSON format")
 	envDumpCUE := flag.Bool("env-dump-cue", false, "dump env variables as CUE schema")
 
+	envPodYAML := flag.String("env-pod-spec", "", "path to pod YAML to read env from")
+	envPodYAMLContainerName := flag.String("env-pod-spec-container-name", "", "extract env from container `name` in the pod spec (required if more than one container is in the pod)")
+
 	flag.Parse()
 
+	var g Getter = osLookup{}
+
+	if *envPodYAML != "" {
+		f, err := os.Open(*envPodYAML)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "could not open pod spec %q: %v", *envPodYAML, err)
+		}
+		g, err = PodENVLookup(f, *envPodYAMLContainerName)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "could not read pod spec: %v", err)
+		}
+	}
+
 	var outWriter io.Writer = os.Stderr
 
 	if *envDumpJSON {
@@ -45,15 +61,15 @@ func ParseWithExitFn(exitFn func(int)) {
 				fmt.Fprintf(outWriter, ",\n")
 			}
 			first = false
-			fmt.Fprintf(outWriter, "    %q: %q", v.Name, os.Getenv(v.Name))
+			fmt.Fprintf(outWriter, "    %q: %q", v.Name, get(g, v.Name))
 		})
 		fmt.Fprintf(outWriter, "\n}\n")
 		exitFn(0)
 	}
 
 	if *envDumpYAML {
 		env.Visit(func(v *env.Var) {
-			fmt.Fprintf(outWriter, "- name: %v\n  value: %q\n", v.Name, os.Getenv(v.Name))
+			fmt.Fprintf(outWriter, "- name: %v\n  value: %q\n", v.Name, get(g, v.Name))
 		})
 		exitFn(0)
 	}
@@ -76,7 +92,7 @@ func ParseWithExitFn(exitFn func(int)) {
 				fmt.Fprintf(outWriter, "\n")
 			}
 			first = false
-			fmt.Fprintf(outWriter, "# %v\nexport %v=%q\n", v.Usage, v.Name, os.Getenv(v.Name))
+			fmt.Fprintf(outWriter, "# %v\nexport %v=%q\n", v.Usage, v.Name, get(g, v.Name))
 		})
 		exitFn(0)
 	}

envsvc/http.go

@@ -55,7 +55,3 @@ func detailHandler(w io.Writer) {
 	})
 	fmt.Fprintf(w, "\n    ]\n}\n")
 }
-
-func init() {
-	http.HandleFunc("/debug/env", envHandler)
-}

envsvc/podspec.go

@@ -0,0 +1,89 @@
+package envsvc
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+
+	"gopkg.in/yaml.v3"
+)
+
+type pod struct {
+	Spec struct {
+		Containers []struct {
+			Name string `yaml:"name"`
+			Env  []struct {
+				Name  string `yaml:"name"`
+				Value string `yaml:"value"`
+			} `yaml:"env"`
+		} `yaml:"containers"`
+	} `yaml:"spec"`
+}
+
+type Getter interface {
+	Get(string) (string, bool)
+}
+
+// PodENVLookup creates a lookup Getter from the given Pod YAML.
+// Set name if there is more than one container in the pod.
+func PodENVLookup(r io.Reader, name string) (Getter, error) {
+	dec := yaml.NewDecoder(r)
+	p := &pod{}
+	if err := dec.Decode(p); err != nil {
+		return nil, err
+	}
+
+	if len(p.Spec.Containers) == 0 {
+		return nil, errors.New("no containers in pod spec")
+	}
+
+	if name == "" {
+		if len(p.Spec.Containers) != 1 {
+			return nil, fmt.Errorf("name empty but %d containers in pod spec, must set name", len(p.Spec.Containers))
+		}
+		return lookupFromContainerEnv(p, 0), nil
+	}
+
+	for i, c := range p.Spec.Containers {
+		if c.Name == name {
+			return lookupFromContainerEnv(p, i), nil
+		}
+	}
+	return nil, fmt.Errorf("no container for name %q", name)
+}
+
+func lookupFromContainerEnv(p *pod, n int) *lookup {
+	m := make(map[string]string)
+	for _, x := range p.Spec.Containers[n].Env {
+		m[x.Name] = x.Value
+	}
+	return &lookup{
+		g: osLookup{},
+		m: m,
+	}
+}
+
+type lookup struct {
+	g Getter
+	m map[string]string
+}
+
+func (l lookup) Get(x string) (string, bool) {
+	z, ok := l.g.Get(x)
+	if ok {
+		return z, ok
+	}
+
+	z, ok = l.m[x]
+	return z, ok
+}
+
+type osLookup struct{}
+
+func (osLookup) Get(x string) (string, bool) { return os.LookupEnv(x) }
+
+func get(g Getter, x string) string {
+	z, _ := g.Get(x)
+	return z
+}

envsvc/podspec_test.go

@@ -0,0 +1,129 @@
+package envsvc_test
+
+import (
+	"strings"
+	"testing"
+
+	"code.sajari.com/env/envsvc"
+)
+
+const singleInput = `apiVersion: v1
+kind: Pod
+metadata:
+  name: podname
+  labels:
+    name: podname
+spec:
+  containers:
+  - name: one
+    image: one
+    ports:
+    - name: grpc
+      protocol: TCP
+      containerPort: 50551
+    resources:
+      requests:
+        cpu: 100m
+        memory: 50Mi
+      limits:
+        cpu: "1"
+        memory: 50Mi
+    env:
+    - name: ONE_BOOLEAN
+      value: "false"
+    - name: ONE_STRING
+      value: "string value"
+    - name: ONE_INTEGER
+      value: "1"`
+
+const multipleInput = `apiVersion: v1
+kind: Pod
+metadata:
+  name: podname
+  labels:
+    name: podname
+spec:
+  containers:
+  - name: one
+    image: one
+    ports:
+    - name: grpc
+      protocol: TCP
+      containerPort: 50551
+    resources:
+      requests:
+        cpu: 100m
+        memory: 50Mi
+      limits:
+        cpu: "1"
+        memory: 50Mi
+    env:
+    - name: ONE_BOOLEAN
+      value: "false"
+    - name: ONE_STRING
+      value: "string value"
+    - name: ONE_INTEGER
+      value: "1"
+  - name: two
+    image: two
+    ports:
+    - name: grpc
+      protocol: TCP
+      containerPort: 50552
+    env:
+    - name: TWO_BOOLEAN
+      value: "true"
+    - name: TWO_STRING
+      value: "string value two"
+    - name: TWO_INTEGER
+      value: "2"`
+
+func TestPodENVLookup(t *testing.T) {
+	t.Run("single_container", func(t *testing.T) {
+		x, err := envsvc.PodENVLookup(strings.NewReader(singleInput), "")
+		must(t, err)
+
+		expectValue(t, x, "ONE_BOOLEAN", "false")
+		expectValue(t, x, "ONE_STRING", "string value")
+		expectValue(t, x, "ONE_INTEGER", "1")
+
+		// Using the name should be fine (for 1 container also).
+		x, err = envsvc.PodENVLookup(strings.NewReader(singleInput), "one")
+		must(t, err)
+
+		expectValue(t, x, "ONE_BOOLEAN", "false")
+		expectValue(t, x, "ONE_STRING", "string value")
+		expectValue(t, x, "ONE_INTEGER", "1")
+	})
+
+	t.Run("multiple_containers", func(t *testing.T) {
+		x, err := envsvc.PodENVLookup(strings.NewReader(multipleInput), "two")
+		must(t, err)
+
+		expectValue(t, x, "TWO_BOOLEAN", "true")
+		expectValue(t, x, "TWO_STRING", "string value two")
+		expectValue(t, x, "TWO_INTEGER", "2")
+	})
+
+}
+
+func expectValue(t *testing.T, g envsvc.Getter, name, value string) {
+	t.Helper()
+
+	x, ok := g.Get(name)
+	if !ok {
+		t.Errorf("expected value for %q", name)
+		return
+	}
+	if x != value {
+		t.Errorf("g.Get(%q) = %q, want %q", name, x, value)
+	}
+}
+
+func must(t *testing.T, err error) {
+	t.Helper()
+
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}

go.mod

@@ -1,3 +1,5 @@
 module code.sajari.com/env
 
 go 1.15
+
+require gopkg.in/yaml.v3 v3.0.1

go.sum

@@ -0,0 +1,4 @@
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=