I have a kubectl config map like below.
apiVersion: v1
data:
server.properties: |+
server.hostname=test.com
kind: ConfigMap
metadata:
name: my-config
And I tried to read this config inside a container.
containers:
- name: testserver
env:
- name: server.hostname
valueFrom:
configMapKeyRef:
name: my-config
key: server.properties.server.hostname
However, these configs are not passing to the container properly. Do I need do any changes to my configs?
What you have in there isn't the right key. ConfigMaps are strictly 1 level of k/v pairs. The |+ syntax is YAML for a multiline string but the fact the data inside that is also YAML is not something the system knows. As far as Kubernetes is concerned you have one key there, server.properties, with a string value that is opaque.
Related
I'm trying to figure it out, how to change one string inside configmap in Kubernetes. I have pretty simple configmap:
apiVersion: v1
data:
config.cfg: |-
[authentication]
USERNAME=user
PASSWORD=password
[podname]
PODNAME=metadata.podName
kind: ConfigMap
metadata:
name: name_here
And I need to mount the configmap inside a couple of pods. But PODNAME should be matched to current podname. Is it possible in any another way? thanks!
I do not think it could be done with ConfigMap. But you can set environment variables in your pod spec that references a pod fields.
apiVersion: v1
kind: Pod
metadata:
name: test-ref-pod-name
spec:
containers:
- name: test-container
image: busybox
command: [ "sh", "-c"]
args:
- env | grep PODNAME
env:
- name: PODNAME
valueFrom:
fieldRef:
fieldPath: metadata.name
restartPolicy: Never
See official documentation: https://kubernetes.io/docs/tasks/inject-data-application/environment-variable-expose-pod-information/#use-pod-fields-as-values-for-environment-variables
This doesn't answer you question exactly but the pod name normally ends up as the host name inside the pod and can be accessed as a standard environment variable
echo $HOSTNAME
I have two ConfigMap files. One is supposed to be "secret" values and the other has regular values and should import the secrets.
Here's the sample secret ConfigMap:
kind: ConfigMap
metadata:
name: secret-cm
data:
MY_SEKRET: 'SEKRET'
And the regular ConfigMap file:
kind: ConfigMap
metadata:
name: regular-cm
data:
SOME_CONFIG: 123
USING_SEKRET: $(MY_SEKRET)
And my deployment is as follows:
kind: Deployment
spec:
template:
spec:
containers:
- name: my_container
envFrom:
- configMapRef:
name: secret-cm
- configMapRef:
name: regular-cm
I was hoping that my variable USING_SEKRET would be "SEKRET" because of the order the envFrom files are imported but they just appear as "$(MY_SEKRET)" on the Pods.
I've also tried setting the dependent variable as an env directly at the Deployment but it results on the same problem:
kind: Deployment
...
env:
- name: MY_SEKRET
# Not the expected result because the variable is openly visible but should be hidden
value: 'SEKRET'
I was trying to follow the documentation guides, based on the Define an environment dependent variable for a container but I haven't seen examples similar to what I want to do.
Is there a way to do this?
EDIT:
To explain my idea behind this structure, secret-cm whole file will be encrypted at the repository so not all peers will be able to see its contents.
On the other hand, I still want to be able to show everyone where its variables are used, hence the dependency on regular-cm.
With that, authorized peers can run kubectl commands and variable replacements of secret-cm would work properly but for everyone else the file is hidden.
You did not explain why you want to define two configmap (one getting value from another) but I am assuming that you want the env parameter name define in confgimap be independent of paramter name used by your container in pod. If that is the case then create your configmap
kind: ConfigMap metadata: name: secret-cm data: MY_SEKRET: 'SEKRET'
Then in your deployment use the env variable from configmap
kind: Deployment
spec:
template:
spec:
containers:
- name: my_container
env:
- name: USING_SEKRET
valueFrom:
configMapKeyRef:
name: secret-cm
key: MY_SEKRET
Now when you access env variable $USING_SEKRET, it will show value as 'SEKRET'
incase your requirement is different then ignore this response and provide more details.
I have been trying to figure out how to consume a ConfigMap created using a ConfigMap generator via Kustomize.
When created using Kustomize generators, the configMaps are named with a special suffix. See here:
https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#create-a-configmap-from-generator
Question is how can this be referenced?
You don't reference it yourself. Kustomize recognizes where the configMap is used in the other resources (like a Deployment) and changes those references to use the name+hash.
The reason for this is so that if you change the configMap, Kustomize generates a new hash and updates the Deployment, causing a rolling restart of the Pods.
If you don't want this behavior, you can add the following to your kustomization.yaml file:
generatorOptions:
disableNameSuffixHash: true
It is specified there in the doc. When you do kubectl apply -k . a configmap created named game-config-4-m9dm2f92bt.
You can check that the ConfigMap was created like this: kubectl get configmap. This ConfigMap will contains a field data where your given datas will belong.
Now as usual you can use this configmap in a pod. Like below:
Ex from k8s:
apiVersion: v1
kind: Pod
metadata:
name: test-pod
spec:
containers:
- name: test-container
image: k8s.gcr.io/busybox
command: [ "/bin/sh", "-c", "env" ]
env:
# Define the environment variable
- name: SPECIAL_LEVEL_KEY
valueFrom:
configMapKeyRef:
# The ConfigMap containing the value you want to assign to SPECIAL_LEVEL_KEY
name: special-config
# Specify the key associated with the value
key: special.how
restartPolicy: Never
You can use ConfigMap as volume also, like this example from k8s doc:
apiVersion: v1
kind: Pod
metadata:
name: configmap-demo-pod
spec:
containers:
- name: demo
image: alpine
command: ["sleep", "3600"]
env:
# Define the environment variable
- name: PLAYER_INITIAL_LIVES # Notice that the case is different here
# from the key name in the ConfigMap.
valueFrom:
configMapKeyRef:
name: game-demo # The ConfigMap this value comes from.
key: player_initial_lives # The key to fetch.
- name: UI_PROPERTIES_FILE_NAME
valueFrom:
configMapKeyRef:
name: game-demo
key: ui_properties_file_name
volumeMounts:
- name: config
mountPath: "/config"
readOnly: true
volumes:
# You set volumes at the Pod level, then mount them into containers inside that Pod
- name: config
configMap:
# Provide the name of the ConfigMap you want to mount.
name: game-demo
# An array of keys from the ConfigMap to create as files
items:
- key: "game.properties"
path: "game.properties"
- key: "user-interface.properties"
path: "user-interface.properties
You can see k8s official doc
I was struggling with this too. I could not figure out why kustomize was not updating the configmap name for the volume in the deployment to include the hash. What solved this for me was to add namespace: <namespace> in the kustomization.yaml for both the base and overlay.
I am working on operator-sdk, in the controller, we often need to create a Deployment object, and Deployment resource has a lot of configuration items, such as environment variables or ports definition or others as following. I am wondering what is best way to get these values, I don't want to hard code them, for example, variable_a or variable_b.
Probably, you can put them in the CRD as spec, then pass them to Operator Controller; Or maybe you can put them in the configmap, then pass configmap name to Operator Controller, Operator Controller can access configmap to get them; Or maybe you can put in the template file, then in the Operator Controller, controller has to read that template file.
What is best way or best practice to deal with this situation? Thanks for sharing your ideas or points.
deployment := &appsv1.Deployment{
ObjectMeta: metav1.ObjectMeta{
Name: m.Name,
Namespace: m.Namespace,
Labels: ls,
},
Spec: appsv1.DeploymentSpec{
Replicas: &replicas,
Selector: &metav1.LabelSelector{
MatchLabels: ls,
},
Template: corev1.PodTemplateSpec{
ObjectMeta: metav1.ObjectMeta{
Labels: ls,
},
Spec: corev1.PodSpec{
Containers: []corev1.Container{{
Image: "....",
Name: m.Name,
Ports: []corev1.ContainerPort{{
ContainerPort: port_a,
Name: "tcpport",
}},
Env: []corev1.EnvVar{
{
Name: "aaaa",
Value: variable_a,
},
{
Name: "bbbb",
Value: variable_b,
},
Using enviroment variables
It can be convenient that your app gets your data as environment variables.
Environment variables from ConfigMap
For non-sensitive data, you can store your variables in a ConfigMap and then define container environment variables using the ConfigMap data.
Example from Kubernetes docs:
Create the ConfigMap first. File configmaps.yaml:
apiVersion: v1
kind: ConfigMap
metadata:
name: special-config
namespace: default
data:
special.how: very
---
apiVersion: v1
kind: ConfigMap
metadata:
name: env-config
namespace: default
data:
log_level: INFO
Create the ConfigMap:
kubectl create -f ./configmaps.yaml
Then define the environment variables in the Pod specification, pod-multiple-configmap-env-variable.yaml:
apiVersion: v1
kind: Pod
metadata:
name: dapi-test-pod
spec:
containers:
- name: test-container
image: k8s.gcr.io/busybox
command: [ "/bin/sh", "-c", "env" ]
env:
- name: SPECIAL_LEVEL_KEY
valueFrom:
configMapKeyRef:
name: special-config
key: special.how
- name: LOG_LEVEL
valueFrom:
configMapKeyRef:
name: env-config
key: log_level
restartPolicy: Never
Create the Pod:
kubectl create -f ./pod-multiple-configmap-env-variable.yaml
Now in your controller you can read these environment variables SPECIAL_LEVEL_KEY (which will give you special.how value from special-config ConfigMap) and LOG_LEVEL (which will give you log_level value from env-config ConfigMap):
For example:
specialLevelKey := os.Getenv("SPECIAL_LEVEL_KEY")
logLevel := os.Getenv("LOG_LEVEL")
fmt.Println("SPECIAL_LEVEL_KEY:", specialLevelKey)
fmt.Println("LOG_LEVEL:", logLevel)
Environment variables from Secret
If your data is sensitive, you can store it in a Secret and then use the Secret as environment variables.
To create a Secret manually:
You'll first need to encode your strings using base64.
# encode username
$ echo -n 'admin' | base64
YWRtaW4=
# encode password
$ echo -n '1f2d1e2e67df' | base64
MWYyZDFlMmU2N2Rm
Then create a Secret with the above data:
apiVersion: v1
kind: Secret
metadata:
name: mysecret
type: Opaque
data:
username: YWRtaW4=
password: MWYyZDFlMmU2N2Rm
Create a Secret with kubectl apply:
$ kubectl apply -f ./secret.yaml
Please notice that there are other ways to create a secret, pick one that works best for you:
Creating a Secret using kubectl
Creating a Secret from a generator
Creating a Secret from files
Creating a Secret from string literals
Now you can use this created Secret for environment variables.
To use a secret in an environment variable in a Pod:
Create a secret or use an existing one. Multiple Pods can reference the same secret.
Modify your Pod definition in each container that you wish to consume the value of a secret key to add an environment variable for each secret key you wish to consume. The environment variable that consumes the secret key should populate the secret's name and key in env[].valueFrom.secretKeyRef.
Modify your image and/or command line so that the program looks for values in the specified environment variables.
Here is a Pod example from Kubernetes docs that shows how to use a Secret for environment variables:
apiVersion: v1
kind: Pod
metadata:
name: secret-env-pod
spec:
containers:
- name: mycontainer
image: redis
env:
- name: SECRET_USERNAME
valueFrom:
secretKeyRef:
name: mysecret
key: username
- name: SECRET_PASSWORD
valueFrom:
secretKeyRef:
name: mysecret
key: password
restartPolicy: Never
Finally, as stated in the docs:
Inside a container that consumes a secret in an environment variables, the secret keys appear as normal environment variables containing the base64 decoded values of the secret data.
Now in your controller you can read these environment variables SECRET_USERNAME (which will give you username value from mysecret Secret) and SECRET_PASSWORD (which will give you password value from mysecret Secret):
For example:
username := os.Getenv("SECRET_USERNAME")
password := os.Getenv("SECRET_PASSWORD")
Using volumes
You can also mount both ConfigMap and Secret as a volume to you pods.
Populate a Volume with data stored in a ConfigMap:
apiVersion: v1
kind: Pod
metadata:
name: dapi-test-pod
spec:
containers:
- name: test-container
image: k8s.gcr.io/busybox
command: [ "/bin/sh", "-c", "ls /etc/config/" ]
volumeMounts:
- name: config-volume
mountPath: /etc/config
volumes:
- name: config-volume
configMap:
# Provide the name of the ConfigMap containing the files you want
# to add to the container
name: special-config
restartPolicy: Never
Using Secrets as files from a Pod:
To consume a Secret in a volume in a Pod:
Create a secret or use an existing one. Multiple Pods can reference the same secret.
Modify your Pod definition to add a volume under .spec.volumes[]. Name the volume anything, and have a .spec.volumes[].secret.secretName field equal to the name of the Secret object.
Add a .spec.containers[].volumeMounts[] to each container that needs the secret. Specify .spec.containers[].volumeMounts[].readOnly = true and .spec.containers[].volumeMounts[].mountPath to an unused directory name where you would like the secrets to appear.
Modify your image or command line so that the program looks for files in that directory. Each key in the secret data map becomes the filename under mountPath.
An example of a Pod that mounts a Secret in a volume:
apiVersion: v1
kind: Pod
metadata:
name: mypod
spec:
containers:
- name: mypod
image: redis
volumeMounts:
- name: foo
mountPath: "/etc/foo"
readOnly: true
volumes:
- name: foo
secret:
secretName: mysecret
I have an application in a container which reads a YAML file which contains data like
initializationCount=0
port=980
Now that I want to remove those hard coded values inside the application and get them out of the container. Hence I created a configMap with all configuration values. I used the config map keys as environmental variables while deploying the pod.
My issue is that, If I want to use these environment variables in my yaml file like
initializationCount=${iCount}
port=${port}
The API which reads this YAML file throws number format Exception since the env variables are always strings. I do not have control over the API which reads my yaml file.
I have tried
initializationCount=!!int ${iCount}
but it does not work.
Rather than pulling in the configmap values as environment variables, try mounting the configmap as a volume at runtime.
The configmap should have one key which is the name of your YAML file. the value for that key should be the contents of the file.
This data will be mounted to the container's filesystem when the pod initializes. That way your app will read the config YAML the same way it has been, but the values will be externalized in the configmap.
Something like this:
apiVersion: v1
kind: Pod
metadata:
name: my-pod
spec:
containers:
- name: my-app
image: my-app:latest
volumeMounts:
- name: config-volume
mountPath: /etc/config
volumes:
- name: config-volume
configMap:
name: app-config
apiVersion: v1
kind: ConfigMap
metadata:
name: app-config
data:
config.yaml: |
initializationCount=0
port=980
Kubernetes docs here