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Allow composing env var from existing env vars. (#643)

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Example:
env name:  FOO
    value: "foo"
    name:  BAR
    value: "bar"
    name:  FOOBAR
    value: "${FOO}${BAR}" <-- should expand to: "foobar"

Added testcase for the same as well.
Change is based on kubelet_pods.go.
Simplified some of the existing code.
This commit is contained in:
Yash Desai
2019-06-01 09:41:10 -07:00
committed by Brian Goff
parent 71546a908f
commit 1542c4d2f4
4 changed files with 219 additions and 56 deletions
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104
vkubelet/env.go
View File

@@ -16,6 +16,7 @@ import (
v1helper "k8s.io/kubernetes/pkg/apis/core/v1/helper"
fieldpath "k8s.io/kubernetes/pkg/fieldpath"
"k8s.io/kubernetes/pkg/kubelet/envvars"
"k8s.io/kubernetes/third_party/forked/golang/expansion"
"github.com/virtual-kubelet/virtual-kubelet/log"
"github.com/virtual-kubelet/virtual-kubelet/manager"
@@ -78,12 +79,13 @@ func populateEnvironmentVariables(ctx context.Context, pod *corev1.Pod, rm *mana
// populateContainerEnvironment populates the environment of a single container in the specified pod.
func populateContainerEnvironment(ctx context.Context, pod *corev1.Pod, container *corev1.Container, rm *manager.ResourceManager, recorder record.EventRecorder) error {
// Create an "environment map" based on the value of the specified container's ".envFrom" field.
envFrom, err := makeEnvironmentMapBasedOnEnvFrom(ctx, pod, container, rm, recorder)
tmpEnv, err := makeEnvironmentMapBasedOnEnvFrom(ctx, pod, container, rm, recorder)
if err != nil {
return err
}
// Create an "environment map" based on the value of the specified container's ".env" field.
env, err := makeEnvironmentMapBasedOnEnv(ctx, pod, container, rm, recorder)
// Create the final "environment map" for the container using the ".env" and ".envFrom" field
// and service environment variables.
err = makeEnvironmentMap(ctx, pod, container, rm, recorder, tmpEnv)
if err != nil {
return err
}
@@ -92,7 +94,17 @@ func populateContainerEnvironment(ctx context.Context, pod *corev1.Pod, containe
// This is in accordance with what the Kubelet itself does.
// https://github.com/kubernetes/kubernetes/blob/v1.13.1/pkg/kubelet/kubelet_pods.go#L557-L558
container.EnvFrom = []corev1.EnvFromSource{}
container.Env = mergeEnvironments(envFrom, env)
res := make([]corev1.EnvVar, 0)
for key, val := range tmpEnv {
res = append(res, corev1.EnvVar{
Name: key,
Value: val,
})
}
container.Env = res
return nil
}
@@ -265,17 +277,37 @@ loop:
return res, nil
}
// makeEnvironmentMapBasedOnEnv returns a map representing the resolved environment of the specified container after being populated from the entries in the ".env" field.
func makeEnvironmentMapBasedOnEnv(ctx context.Context, pod *corev1.Pod, container *corev1.Container, rm *manager.ResourceManager, recorder record.EventRecorder) (map[string]string, error) {
// Create a map to hold the resolved environment variables.
res := make(map[string]string, len(container.Env))
// makeEnvironmentMap returns a map representing the resolved environment of the specified container after being populated from the entries in the ".env" and ".envFrom" field.
func makeEnvironmentMap(ctx context.Context, pod *corev1.Pod, container *corev1.Container, rm *manager.ResourceManager, recorder record.EventRecorder, res map[string]string) error {
// TODO If pod.Spec.EnableServiceLinks is nil then fail as per 1.14 kubelet.
enableServiceLinks := corev1.DefaultEnableServiceLinks
if pod.Spec.EnableServiceLinks != nil {
enableServiceLinks = *pod.Spec.EnableServiceLinks
}
// Note that there is a race between Kubelet seeing the pod and kubelet seeing the service.
// To avoid this users can: (1) wait between starting a service and starting; or (2) detect
// missing service env var and exit and be restarted; or (3) use DNS instead of env vars
// and keep trying to resolve the DNS name of the service (recommended).
svcEnv, err := getServiceEnvVarMap(rm, pod.Namespace, enableServiceLinks)
if err != nil {
return err
}
// If the variable's Value is set, expand the `$(var)` references to other
// variables in the .Value field; the sources of variables are the declared
// variables of the container and the service environment variables.
mappingFunc := expansion.MappingFuncFor(res, svcEnv)
// Iterate over environment variables in order to populate the map.
loop:
for _, env := range container.Env {
switch {
// Handle values that have been directly provided.
case env.Value != "":
res[env.Name] = env.Value
// Expand variable references
res[env.Name] = expansion.Expand(env.Value, mappingFunc)
continue loop
// Handle population from a configmap key.
case env.ValueFrom != nil && env.ValueFrom.ConfigMapKeyRef != nil:
@@ -303,10 +335,10 @@ loop:
// Hence, we should return a meaningful error.
if errors.IsNotFound(err) {
recorder.Eventf(pod, corev1.EventTypeWarning, ReasonMandatoryConfigMapNotFound, "configmap %q not found", vf.Name)
return nil, fmt.Errorf("configmap %q not found", vf.Name)
return fmt.Errorf("configmap %q not found", vf.Name)
}
recorder.Eventf(pod, corev1.EventTypeWarning, ReasonFailedToReadMandatoryConfigMap, "failed to read configmap %q", vf.Name)
return nil, fmt.Errorf("failed to read configmap %q: %v", vf.Name, err)
return fmt.Errorf("failed to read configmap %q: %v", vf.Name, err)
}
// At this point we have successfully fetched the target configmap.
// We must now try to grab the requested key.
@@ -325,7 +357,7 @@ loop:
// At this point we know the key reference is mandatory.
// Hence, we should fail.
recorder.Eventf(pod, corev1.EventTypeWarning, ReasonMandatoryConfigMapKeyNotFound, "key %q does not exist in configmap %q", vf.Key, vf.Name)
return nil, fmt.Errorf("configmap %q doesn't contain the %q key required by pod %s", vf.Name, vf.Key, pod.Name)
return fmt.Errorf("configmap %q doesn't contain the %q key required by pod %s", vf.Name, vf.Key, pod.Name)
}
// Populate the environment variable and continue on to the next reference.
res[env.Name] = keyValue
@@ -355,10 +387,10 @@ loop:
// Hence, we should return a meaningful error.
if errors.IsNotFound(err) {
recorder.Eventf(pod, corev1.EventTypeWarning, ReasonMandatorySecretNotFound, "secret %q not found", vf.Name)
return nil, fmt.Errorf("secret %q not found", vf.Name)
return fmt.Errorf("secret %q not found", vf.Name)
}
recorder.Eventf(pod, corev1.EventTypeWarning, ReasonFailedToReadMandatorySecret, "failed to read secret %q", vf.Name)
return nil, fmt.Errorf("failed to read secret %q: %v", vf.Name, err)
return fmt.Errorf("failed to read secret %q: %v", vf.Name, err)
}
// At this point we have successfully fetched the target secret.
// We must now try to grab the requested key.
@@ -377,7 +409,7 @@ loop:
// At this point we know the key reference is mandatory.
// Hence, we should fail.
recorder.Eventf(pod, corev1.EventTypeWarning, ReasonMandatorySecretKeyNotFound, "key %q does not exist in secret %q", vf.Key, vf.Name)
return nil, fmt.Errorf("secret %q doesn't contain the %q key required by pod %s", vf.Name, vf.Key, pod.Name)
return fmt.Errorf("secret %q doesn't contain the %q key required by pod %s", vf.Name, vf.Key, pod.Name)
}
// Populate the environment variable and continue on to the next reference.
res[env.Name] = string(keyValue)
@@ -389,7 +421,7 @@ loop:
runtimeVal, err := podFieldSelectorRuntimeValue(vf, pod)
if err != nil {
return res, err
return err
}
res[env.Name] = runtimeVal
@@ -402,21 +434,6 @@ loop:
}
}
// TODO If pod.Spec.EnableServiceLinks is nil then fail as per 1.14 kubelet.
enableServiceLinks := corev1.DefaultEnableServiceLinks
if pod.Spec.EnableServiceLinks != nil {
enableServiceLinks = *pod.Spec.EnableServiceLinks
}
// Note that there is a race between Kubelet seeing the pod and kubelet seeing the service.
// To avoid this users can: (1) wait between starting a service and starting; or (2) detect
// missing service env var and exit and be restarted; or (3) use DNS instead of env vars
// and keep trying to resolve the DNS name of the service (recommended).
svcEnv, err := getServiceEnvVarMap(rm, pod.Namespace, enableServiceLinks)
if err != nil {
return nil, err
}
// Append service env vars.
for k, v := range svcEnv {
if _, present := res[k]; !present {
@@ -424,8 +441,7 @@ loop:
}
}
// Return the populated environment.
return res, nil
return nil
}
// podFieldSelectorRuntimeValue returns the runtime value of the given
@@ -444,25 +460,3 @@ func podFieldSelectorRuntimeValue(fs *corev1.ObjectFieldSelector, pod *corev1.Po
}
return fieldpath.ExtractFieldPathAsString(pod, internalFieldPath)
}
// mergeEnvironments creates the final environment for a container by merging "envFrom" and "env".
// Values in "env" override any values with the same key defined in "envFrom".
// This is in accordance with what the Kubelet itself does.
// https://github.com/kubernetes/kubernetes/blob/v1.13.1/pkg/kubelet/kubelet_pods.go#L557-L558
func mergeEnvironments(envFrom map[string]string, env map[string]string) []corev1.EnvVar {
tmp := make(map[string]string, 0)
res := make([]corev1.EnvVar, 0)
for key, val := range envFrom {
tmp[key] = val
}
for key, val := range env {
tmp[key] = val
}
for key, val := range tmp {
res = append(res, corev1.EnvVar{
Name: key,
Value: val,
})
}
return res
}

65
vkubelet/env_internal_test.go
View File

@@ -23,6 +23,10 @@ const (
envVarValue1 = "foo_value"
// envVarName2 is a string that can be used as the name of an environment value.
envVarName2 = "BAR"
// envVarValue2 is a string meant to be used as the value of the "envVarName2" environment value.
envVarValue2 = "bar_value"
// envVarName12 is a key that can be used as the name of an environment variable.
envVarName12 = "FOOBAR"
// envVarName3 is a string that can be used as the name of an environment value.
envVarName3 = "CHO"
// envVarName4 is a string that can be used as the name of an environment value.
@@ -1011,3 +1015,64 @@ func TestServiceEnvVar(t *testing.T) {
}
}
// TestComposingEnv tests that env var can be composed from the existing env vars.
func TestComposingEnv(t *testing.T) {
rm := testutil.FakeResourceManager()
er := testutil.FakeEventRecorder(defaultEventRecorderBufferSize)
// Create a pod object having a single container.
// The container's third environment variable is composed of the previous two.
pod := &corev1.Pod{
ObjectMeta: metav1.ObjectMeta{
Namespace: namespace,
Name: "pod-0",
},
Spec: corev1.PodSpec{
Containers: []corev1.Container{
{
Env: []corev1.EnvVar{
{
Name: envVarName1,
Value: envVarValue1,
},
{
Name: envVarName2,
Value: envVarValue2,
},
{
Name: envVarName12,
Value: "$(" + envVarName1 + ")$(" + envVarName2 + ")", // "$(envVarName1)$(envVarName2)"
},
},
},
},
EnableServiceLinks: &bFalse,
},
}
// Populate the pods's environment.
err := populateEnvironmentVariables(context.Background(), pod, rm, er)
assert.Check(t, err)
// Make sure that the container's environment contains all the expected keys and values.
assert.Check(t, is.DeepEqual(pod.Spec.Containers[0].Env, []corev1.EnvVar{
{
Name: envVarName1,
Value: envVarValue1,
},
{
Name: envVarName2,
Value: envVarValue2,
},
{
Name: envVarName12,
Value: envVarValue1 + envVarValue2,
},
},
sortOpt,
))
// Make sure that no events have been recorded.
assert.Check(t, is.Len(er.Events, 0))
}