Merge pull request #47180 from windsonsea/viacon
Clean up updating-configuration-via-a-configmap.mdpull/47184/head
Kubernetes Prow Robot
GitHub
commit
d043a5e5da
|
|
@ -7,7 +7,7 @@ weight: 20
|
|||
<!-- overview -->
|
||||
This page provides a step-by-step example of updating configuration within a Pod via a ConfigMap
|
||||
and builds upon the [Configure a Pod to Use a ConfigMap](/docs/tasks/configure-pod-container/configure-pod-configmap/) task.
|
||||
At the end of this tutorial, you will understand how to change the configuration for a running application.
|
||||
At the end of this tutorial, you will understand how to change the configuration for a running application.
|
||||
This tutorial uses the `alpine` and `nginx` images as examples.
|
||||
|
||||
## {{% heading "prerequisites" %}}
|
||||
|
|
@ -27,27 +27,32 @@ documentation for your local operating system.
|
|||
|
||||
## Update configuration via a ConfigMap mounted as a Volume {#rollout-configmap-volume}
|
||||
|
||||
Use the `kubectl create configmap` command to create a ConfigMap from [literal values](/docs/tasks/configure-pod-container/configure-pod-configmap/#create-configmaps-from-literal-values):
|
||||
Use the `kubectl create configmap` command to create a ConfigMap from
|
||||
[literal values](/docs/tasks/configure-pod-container/configure-pod-configmap/#create-configmaps-from-literal-values):
|
||||
|
||||
```shell
|
||||
kubectl create configmap sport --from-literal=sport=football
|
||||
```
|
||||
|
||||
Below is an example of a Deployment manifest with the ConfigMap `sport` mounted as a
|
||||
{{< glossary_tooltip text="volume" term_id="volume" >}} into the Pod's only container.
|
||||
{{% code_sample file="deployments/deployment-with-configmap-as-volume.yaml" %}}
|
||||
|
||||
Create the Deployment:
|
||||
|
||||
```shell
|
||||
kubectl apply -f https://k8s.io/examples/deployments/deployment-with-configmap-as-volume.yaml
|
||||
```
|
||||
|
||||
Check the pods for this Deployment to ensure they are ready (matching by
|
||||
{{< glossary_tooltip text="selector" term_id="selector" >}}):
|
||||
|
||||
```shell
|
||||
kubectl get pods --selector=app.kubernetes.io/name=configmap-volume
|
||||
```
|
||||
|
||||
You should see an output similar to:
|
||||
|
||||
```
|
||||
NAME READY STATUS RESTARTS AGE
|
||||
configmap-volume-6b976dfdcf-qxvbm 1/1 Running 0 72s
|
||||
|
|
@ -55,18 +60,20 @@ configmap-volume-6b976dfdcf-skpvm 1/1 Running 0 72s
|
|||
configmap-volume-6b976dfdcf-tbc6r 1/1 Running 0 72s
|
||||
```
|
||||
|
||||
On each node where one of these Pods is running, the kubelet fetches the data for
|
||||
that ConfigMap and translates it to files in a local volume.
|
||||
The kubelet then mounts that volume into the container, as specified in the Pod template.
|
||||
The code running in that container loads the information from the file
|
||||
and uses it to print a report to stdout.
|
||||
On each node where one of these Pods is running, the kubelet fetches the data for
|
||||
that ConfigMap and translates it to files in a local volume.
|
||||
The kubelet then mounts that volume into the container, as specified in the Pod template.
|
||||
The code running in that container loads the information from the file
|
||||
and uses it to print a report to stdout.
|
||||
You can check this report by viewing the logs for one of the Pods in that Deployment:
|
||||
|
||||
```shell
|
||||
# Pick one Pod that belongs to the Deployment, and view its logs
|
||||
kubectl logs deployments/configmap-volume
|
||||
```
|
||||
|
||||
You should see an output similar to:
|
||||
|
||||
```
|
||||
Found 3 pods, using pod/configmap-volume-76d9c5678f-x5rgj
|
||||
Thu Jan 4 14:06:46 UTC 2024 My preferred sport is football
|
||||
|
|
@ -77,6 +84,7 @@ Thu Jan 4 14:07:26 UTC 2024 My preferred sport is football
|
|||
```
|
||||
|
||||
Edit the ConfigMap:
|
||||
|
||||
```shell
|
||||
kubectl edit configmap sport
|
||||
```
|
||||
|
|
@ -102,15 +110,19 @@ metadata:
|
|||
```
|
||||
|
||||
You should see the following output:
|
||||
|
||||
```
|
||||
configmap/sport edited
|
||||
```
|
||||
|
||||
Tail (follow the latest entries in) the logs of one of the pods that belongs to this Deployment:
|
||||
|
||||
```shell
|
||||
kubectl logs deployments/configmap-volume --follow
|
||||
```
|
||||
|
||||
After few seconds, you should see the log output change as follows:
|
||||
|
||||
```
|
||||
Thu Jan 4 14:11:36 UTC 2024 My preferred sport is football
|
||||
Thu Jan 4 14:11:46 UTC 2024 My preferred sport is football
|
||||
|
|
@ -119,42 +131,47 @@ Thu Jan 4 14:12:06 UTC 2024 My preferred sport is cricket
|
|||
Thu Jan 4 14:12:16 UTC 2024 My preferred sport is cricket
|
||||
```
|
||||
|
||||
When you have a ConfigMap that is mapped into a running Pod using either a
|
||||
`configMap` volume or a `projected` volume, and you update that ConfigMap,
|
||||
When you have a ConfigMap that is mapped into a running Pod using either a
|
||||
`configMap` volume or a `projected` volume, and you update that ConfigMap,
|
||||
the running Pod sees the update almost immediately.
|
||||
However, your application only sees the change if it is written to either poll for changes,
|
||||
However, your application only sees the change if it is written to either poll for changes,
|
||||
or watch for file updates.
|
||||
An application that loads its configuration once at startup will not notice a change.
|
||||
|
||||
|
||||
{{< note >}}
|
||||
The total delay from the moment when the ConfigMap is updated to the moment when
|
||||
The total delay from the moment when the ConfigMap is updated to the moment when
|
||||
new keys are projected to the Pod can be as long as kubelet sync period.
|
||||
Also check [Mounted ConfigMaps are updated automatically](/docs/tasks/configure-pod-container/configure-pod-configmap/#mounted-configmaps-are-updated-automatically).
|
||||
{{< /note >}}
|
||||
|
||||
## Update environment variables of a Pod via a ConfigMap {#rollout-configmap-env}
|
||||
Use the `kubectl create configmap` command to create a ConfigMap from [literal values](/docs/tasks/configure-pod-container/configure-pod-configmap/#create-configmaps-from-literal-values):
|
||||
|
||||
Use the `kubectl create configmap` command to create a ConfigMap from
|
||||
[literal values](/docs/tasks/configure-pod-container/configure-pod-configmap/#create-configmaps-from-literal-values):
|
||||
|
||||
```shell
|
||||
kubectl create configmap fruits --from-literal=fruits=apples
|
||||
```
|
||||
|
||||
Below is an example of a Deployment manifest with an environment variable configured via the ConfigMap `fruits`.
|
||||
|
||||
{{% code_sample file="deployments/deployment-with-configmap-as-envvar.yaml" %}}
|
||||
|
||||
Create the Deployment:
|
||||
|
||||
```shell
|
||||
kubectl apply -f https://k8s.io/examples/deployments/deployment-with-configmap-as-envvar.yaml
|
||||
```
|
||||
|
||||
Check the pods for this Deployment to ensure they are ready (matching by
|
||||
{{< glossary_tooltip text="selector" term_id="selector" >}}):
|
||||
|
||||
```shell
|
||||
kubectl get pods --selector=app.kubernetes.io/name=configmap-env-var
|
||||
```
|
||||
|
||||
You should see an output similar to:
|
||||
|
||||
```
|
||||
NAME READY STATUS RESTARTS AGE
|
||||
configmap-env-var-59cfc64f7d-74d7z 1/1 Running 0 46s
|
||||
|
|
@ -164,11 +181,13 @@ configmap-env-var-59cfc64f7d-dpr98 1/1 Running 0 46s
|
|||
|
||||
The key-value pair in the ConfigMap is configured as an environment variable in the container of the Pod.
|
||||
Check this by viewing the logs of one Pod that belongs to the Deployment.
|
||||
|
||||
```shell
|
||||
kubectl logs deployment/configmap-env-var
|
||||
```
|
||||
|
||||
You should see an output similar to:
|
||||
|
||||
```
|
||||
Found 3 pods, using pod/configmap-env-var-7c994f7769-l74nq
|
||||
Thu Jan 4 16:07:06 UTC 2024 The basket is full of apples
|
||||
|
|
@ -177,6 +196,7 @@ Thu Jan 4 16:07:26 UTC 2024 The basket is full of apples
|
|||
```
|
||||
|
||||
Edit the ConfigMap:
|
||||
|
||||
```shell
|
||||
kubectl edit configmap fruits
|
||||
```
|
||||
|
|
@ -185,6 +205,7 @@ In the editor that appears, change the value of key `fruits` from `apples` to `m
|
|||
The kubectl tool updates the ConfigMap accordingly (if you see an error, try again).
|
||||
|
||||
Here's an example of how that manifest could look after you edit it:
|
||||
|
||||
```yaml
|
||||
apiVersion: v1
|
||||
data:
|
||||
|
|
@ -197,21 +218,23 @@ metadata:
|
|||
name: fruits
|
||||
namespace: default
|
||||
resourceVersion: "1749472"
|
||||
|
||||
```
|
||||
|
||||
You should see the following output:
|
||||
|
||||
```
|
||||
configmap/fruits edited
|
||||
```
|
||||
|
||||
Tail the logs of the Deployment and observe the output for few seconds:
|
||||
|
||||
```shell
|
||||
# As the text explains, the output does NOT change
|
||||
kubectl logs deployments/configmap-env-var --follow
|
||||
```
|
||||
|
||||
Notice that the output remains **unchanged**, even though you edited the ConfigMap:
|
||||
|
||||
```
|
||||
Thu Jan 4 16:12:56 UTC 2024 The basket is full of apples
|
||||
Thu Jan 4 16:13:06 UTC 2024 The basket is full of apples
|
||||
|
|
@ -220,11 +243,16 @@ Thu Jan 4 16:13:26 UTC 2024 The basket is full of apples
|
|||
```
|
||||
|
||||
{{< note >}}
|
||||
Although the value of the key inside the ConfigMap has changed, the environment variable in the Pod still shows the earlier value. This is because environment variables for a process running inside a Pod are **not** updated when the source data changes; if you wanted to force an update, you would need to have Kubernetes replace your existing Pods. The new Pods would then run with the updated information.
|
||||
Although the value of the key inside the ConfigMap has changed, the environment variable
|
||||
in the Pod still shows the earlier value. This is because environment variables for a
|
||||
process running inside a Pod are **not** updated when the source data changes; if you
|
||||
wanted to force an update, you would need to have Kubernetes replace your existing Pods.
|
||||
The new Pods would then run with the updated information.
|
||||
{{< /note >}}
|
||||
|
||||
You can trigger that replacement. Perform a rollout for the Deployment, using
|
||||
[`kubectl rollout`](/docs/reference/kubectl/generated/kubectl_rollout/):
|
||||
|
||||
```shell
|
||||
# Trigger the rollout
|
||||
kubectl rollout restart deployment configmap-env-var
|
||||
|
|
@ -234,22 +262,28 @@ kubectl rollout status deployment configmap-env-var --watch=true
|
|||
```
|
||||
|
||||
Next, check the Deployment:
|
||||
|
||||
```shell
|
||||
kubectl get deployment configmap-env-var
|
||||
```
|
||||
|
||||
You should see an output similar to:
|
||||
|
||||
```
|
||||
NAME READY UP-TO-DATE AVAILABLE AGE
|
||||
configmap-env-var 3/3 3 3 12m
|
||||
```
|
||||
|
||||
Check the Pods:
|
||||
|
||||
```shell
|
||||
kubectl get pods --selector=app.kubernetes.io/name=configmap-env-var
|
||||
```
|
||||
|
||||
The rollout causes Kubernetes to make a new {{< glossary_tooltip term_id="replica-set" text="ReplicaSet" >}} for the Deployment; that means the existing Pods eventually terminate, and new ones are created. After few seconds, you should see an output similar to:
|
||||
The rollout causes Kubernetes to make a new {{< glossary_tooltip term_id="replica-set" text="ReplicaSet" >}}
|
||||
for the Deployment; that means the existing Pods eventually terminate, and new ones are created.
|
||||
After few seconds, you should see an output similar to:
|
||||
|
||||
```
|
||||
NAME READY STATUS RESTARTS AGE
|
||||
configmap-env-var-6d94d89bf5-2ph2l 1/1 Running 0 13s
|
||||
|
|
@ -262,12 +296,14 @@ Please wait for the older Pods to fully terminate before proceeding with the nex
|
|||
{{< /note >}}
|
||||
|
||||
View the logs for a Pod in this Deployment:
|
||||
|
||||
```shell
|
||||
# Pick one Pod that belongs to the Deployment, and view its logs
|
||||
kubectl logs deployment/configmap-env-var
|
||||
```
|
||||
|
||||
You should see an output similar to the below:
|
||||
|
||||
```
|
||||
Found 3 pods, using pod/configmap-env-var-6d9ff89fb6-bzcf6
|
||||
Thu Jan 4 16:30:35 UTC 2024 The basket is full of mangoes
|
||||
|
|
@ -281,59 +317,74 @@ rollout. If Pods get created for another reason, such as scaling up the Deployme
|
|||
also use the latest configuration values; if you don't trigger a rollout, then you might find that your
|
||||
app is running with a mix of old and new environment variable values.
|
||||
|
||||
|
||||
## Update configuration via a ConfigMap in a multi-container Pod {#rollout-configmap-multiple-containers}
|
||||
|
||||
Use the `kubectl create configmap` command to create a ConfigMap from [literal values](/docs/tasks/configure-pod-container/configure-pod-configmap/#create-configmaps-from-literal-values):
|
||||
Use the `kubectl create configmap` command to create a ConfigMap from
|
||||
[literal values](/docs/tasks/configure-pod-container/configure-pod-configmap/#create-configmaps-from-literal-values):
|
||||
|
||||
```shell
|
||||
kubectl create configmap color --from-literal=color=red
|
||||
```
|
||||
Below is an example manifest for a Deployment that manages a set of Pods, each with two containers. The two containers share an `emptyDir` volume that they use to communicate.
|
||||
The first container runs a web server (`nginx`). The mount path for the shared volume in the web server container is `/usr/share/nginx/html`. The second helper container is based on `alpine`, and for this container the `emptyDir` volume is mounted at `/pod-data`. The helper container writes a file in HTML that has its content based on a ConfigMap. The web server container serves the HTML via HTTP.
|
||||
|
||||
Below is an example manifest for a Deployment that manages a set of Pods, each with two containers.
|
||||
The two containers share an `emptyDir` volume that they use to communicate.
|
||||
The first container runs a web server (`nginx`). The mount path for the shared volume in the
|
||||
web server container is `/usr/share/nginx/html`. The second helper container is based on `alpine`,
|
||||
and for this container the `emptyDir` volume is mounted at `/pod-data`. The helper container writes
|
||||
a file in HTML that has its content based on a ConfigMap. The web server container serves the HTML via HTTP.
|
||||
|
||||
{{% code_sample file="deployments/deployment-with-configmap-two-containers.yaml" %}}
|
||||
|
||||
Create the Deployment:
|
||||
|
||||
```shell
|
||||
kubectl apply -f https://k8s.io/examples/deployments/deployment-with-configmap-two-containers.yaml
|
||||
```
|
||||
|
||||
Check the pods for this Deployment to ensure they are ready (matching by
|
||||
{{< glossary_tooltip text="selector" term_id="selector" >}}):
|
||||
|
||||
```shell
|
||||
kubectl get pods --selector=app.kubernetes.io/name=configmap-two-containers
|
||||
```
|
||||
|
||||
You should see an output similar to:
|
||||
|
||||
```
|
||||
NAME READY STATUS RESTARTS AGE
|
||||
configmap-two-containers-565fb6d4f4-2xhxf 2/2 Running 0 20s
|
||||
configmap-two-containers-565fb6d4f4-g5v4j 2/2 Running 0 20s
|
||||
configmap-two-containers-565fb6d4f4-mzsmf 2/2 Running 0 20s
|
||||
````
|
||||
```
|
||||
|
||||
Expose the Deployment (the `kubectl` tool creates a
|
||||
{{<glossary_tooltip text="Service" term_id="service">}} for you):
|
||||
{{<glossary_tooltip text="Service" term_id="service">}} for you):
|
||||
|
||||
```shell
|
||||
kubectl expose deployment configmap-two-containers --name=configmap-service --port=8080 --target-port=80
|
||||
```
|
||||
|
||||
Use `kubectl` to forward the port:
|
||||
|
||||
```shell
|
||||
kubectl port-forward service/configmap-service 8080:8080 & # this stays running in the background
|
||||
# this stays running in the background
|
||||
kubectl port-forward service/configmap-service 8080:8080 &
|
||||
```
|
||||
|
||||
Access the service.
|
||||
|
||||
```shell
|
||||
curl http://localhost:8080
|
||||
```
|
||||
|
||||
You should see an output similar to:
|
||||
|
||||
```
|
||||
Fri Jan 5 08:08:22 UTC 2024 My preferred color is red
|
||||
```
|
||||
|
||||
Edit the ConfigMap:
|
||||
|
||||
```shell
|
||||
kubectl edit configmap color
|
||||
```
|
||||
|
|
@ -358,13 +409,15 @@ metadata:
|
|||
uid: 80d33e4a-cbb4-4bc9-ba8c-544c68e425d6
|
||||
```
|
||||
|
||||
Loop over the service URL for few seconds.
|
||||
Loop over the service URL for few seconds.
|
||||
|
||||
```shell
|
||||
# Cancel this when you're happy with it (Ctrl-C)
|
||||
while true; do curl --connect-timeout 7.5 http://localhost:8080; sleep 10; done
|
||||
```
|
||||
|
||||
You should see the output change as follows:
|
||||
|
||||
```
|
||||
Fri Jan 5 08:14:00 UTC 2024 My preferred color is red
|
||||
Fri Jan 5 08:14:02 UTC 2024 My preferred color is red
|
||||
|
|
@ -377,63 +430,79 @@ Fri Jan 5 08:15:00 UTC 2024 My preferred color is blue
|
|||
|
||||
## Update configuration via a ConfigMap in a Pod possessing a sidecar container {#rollout-configmap-sidecar}
|
||||
|
||||
The above scenario can be replicated by using a [Sidecar Container](/docs/concepts/workloads/pods/sidecar-containers/) as a helper container to write the HTML file.
|
||||
The above scenario can be replicated by using a [Sidecar Container](/docs/concepts/workloads/pods/sidecar-containers/)
|
||||
as a helper container to write the HTML file.
|
||||
As a Sidecar Container is conceptually an Init Container, it is guaranteed to start before the main web server container.
|
||||
This ensures that the HTML file is always available when the web server is ready to serve it.
|
||||
Please see [Enabling sidecar containers](/docs/concepts/workloads/pods/sidecar-containers/#enabling-sidecar-containers) to utilize this feature.
|
||||
|
||||
If you are continuing from the previous scenario, you can reuse the ConfigMap named `color` for this scenario.
|
||||
If you are executing this scenario independently, use the `kubectl create configmap` command to create a ConfigMap from [literal values](/docs/tasks/configure-pod-container/configure-pod-configmap/#create-configmaps-from-literal-values):
|
||||
If you are executing this scenario independently, use the `kubectl create configmap` command to create a ConfigMap
|
||||
from [literal values](/docs/tasks/configure-pod-container/configure-pod-configmap/#create-configmaps-from-literal-values):
|
||||
|
||||
```shell
|
||||
kubectl create configmap color --from-literal=color=blue
|
||||
```
|
||||
|
||||
Below is an example manifest for a Deployment that manages a set of Pods, each with a main container and a sidecar container. The two containers share an `emptyDir` volume that they use to communicate.
|
||||
The main container runs a web server (NGINX). The mount path for the shared volume in the web server container is `/usr/share/nginx/html`. The second container is a Sidecar Container based on Alpine Linux which acts as a helper container. For this container the `emptyDir` volume is mounted at `/pod-data`. The Sidecar Container writes a file in HTML that has its content based on a ConfigMap. The web server container serves the HTML via HTTP.
|
||||
Below is an example manifest for a Deployment that manages a set of Pods, each with a main container and
|
||||
a sidecar container. The two containers share an `emptyDir` volume that they use to communicate.
|
||||
The main container runs a web server (NGINX). The mount path for the shared volume in the web server container
|
||||
is `/usr/share/nginx/html`. The second container is a Sidecar Container based on Alpine Linux which acts as
|
||||
a helper container. For this container the `emptyDir` volume is mounted at `/pod-data`. The Sidecar Container
|
||||
writes a file in HTML that has its content based on a ConfigMap. The web server container serves the HTML via HTTP.
|
||||
|
||||
{{% code_sample file="deployments/deployment-with-configmap-and-sidecar-container.yaml" %}}
|
||||
|
||||
Create the Deployment:
|
||||
|
||||
```shell
|
||||
kubectl apply -f https://k8s.io/examples/deployments/deployment-with-configmap-and-sidecar-container.yaml
|
||||
```
|
||||
|
||||
Check the pods for this Deployment to ensure they are ready (matching by
|
||||
{{< glossary_tooltip text="selector" term_id="selector" >}}):
|
||||
|
||||
```shell
|
||||
kubectl get pods --selector=app.kubernetes.io/name=configmap-sidecar-container
|
||||
```
|
||||
|
||||
You should see an output similar to:
|
||||
|
||||
```
|
||||
NAME READY STATUS RESTARTS AGE
|
||||
configmap-sidecar-container-5fb59f558b-87rp7 2/2 Running 0 94s
|
||||
configmap-sidecar-container-5fb59f558b-ccs7s 2/2 Running 0 94s
|
||||
configmap-sidecar-container-5fb59f558b-wnmgk 2/2 Running 0 94s
|
||||
````
|
||||
```
|
||||
|
||||
Expose the Deployment (the `kubectl` tool creates a
|
||||
{{<glossary_tooltip text="Service" term_id="service">}} for you):
|
||||
{{<glossary_tooltip text="Service" term_id="service">}} for you):
|
||||
|
||||
```shell
|
||||
kubectl expose deployment configmap-sidecar-container --name=configmap-sidecar-service --port=8081 --target-port=80
|
||||
```
|
||||
|
||||
Use ```kubectl``` to forward the port:
|
||||
Use `kubectl` to forward the port:
|
||||
|
||||
```shell
|
||||
kubectl port-forward service/configmap-sidecar-service 8081:8081 & # this stays running in the background
|
||||
# this stays running in the background
|
||||
kubectl port-forward service/configmap-sidecar-service 8081:8081 &
|
||||
```
|
||||
|
||||
Access the service.
|
||||
|
||||
```shell
|
||||
curl http://localhost:8081
|
||||
```
|
||||
|
||||
You should see an output similar to:
|
||||
|
||||
```
|
||||
Sat Feb 17 13:09:05 UTC 2024 My preferred color is blue
|
||||
```
|
||||
|
||||
Edit the ConfigMap:
|
||||
|
||||
```shell
|
||||
kubectl edit configmap color
|
||||
```
|
||||
|
|
@ -459,12 +528,14 @@ metadata:
|
|||
```
|
||||
|
||||
Loop over the service URL for few seconds.
|
||||
|
||||
```shell
|
||||
# Cancel this when you're happy with it (Ctrl-C)
|
||||
while true; do curl --connect-timeout 7.5 http://localhost:8081; sleep 10; done
|
||||
```
|
||||
|
||||
You should see the output change as follows:
|
||||
|
||||
```
|
||||
Sat Feb 17 13:12:35 UTC 2024 My preferred color is blue
|
||||
Sat Feb 17 13:12:45 UTC 2024 My preferred color is blue
|
||||
|
|
@ -478,9 +549,11 @@ Sat Feb 17 13:13:35 UTC 2024 My preferred color is green
|
|||
## Update configuration via an immutable ConfigMap that is mounted as a volume {#rollout-configmap-immutable-volume}
|
||||
|
||||
{{< note >}}
|
||||
Immutable ConfigMaps are especially used for configuration that is constant and is **not** expected to change over time. Marking a ConfigMap as immutable allows a performance improvement where the kubelet does not watch for changes.
|
||||
Immutable ConfigMaps are especially used for configuration that is constant and is **not** expected
|
||||
to change over time. Marking a ConfigMap as immutable allows a performance improvement where the kubelet does not watch for changes.
|
||||
|
||||
If you do need to make a change, you should plan to either:
|
||||
|
||||
- change the name of the ConfigMap, and switch to running Pods that reference the new name
|
||||
- replace all the nodes in your cluster that have previously run a Pod that used the old value
|
||||
- restart the kubelet on any node where the kubelet previously loaded the old ConfigMap
|
||||
|
|
@ -490,26 +563,31 @@ An example manifest for an [Immutable ConfigMap](/docs/concepts/configuration/co
|
|||
{{% code_sample file="configmap/immutable-configmap.yaml" %}}
|
||||
|
||||
Create the Immutable ConfigMap:
|
||||
|
||||
```shell
|
||||
kubectl apply -f https://k8s.io/examples/configmap/immutable-configmap.yaml
|
||||
```
|
||||
|
||||
Below is an example of a Deployment manifest with the Immutable ConfigMap `company-name-20150801` mounted as a
|
||||
{{< glossary_tooltip text="volume" term_id="volume" >}} into the Pod's only container.
|
||||
|
||||
{{% code_sample file="deployments/deployment-with-immutable-configmap-as-volume.yaml" %}}
|
||||
|
||||
Create the Deployment:
|
||||
|
||||
```shell
|
||||
kubectl apply -f https://k8s.io/examples/deployments/deployment-with-immutable-configmap-as-volume.yaml
|
||||
```
|
||||
|
||||
Check the pods for this Deployment to ensure they are ready (matching by
|
||||
{{< glossary_tooltip text="selector" term_id="selector" >}}):
|
||||
|
||||
```shell
|
||||
kubectl get pods --selector=app.kubernetes.io/name=immutable-configmap-volume
|
||||
```
|
||||
|
||||
You should see an output similar to:
|
||||
|
||||
```
|
||||
NAME READY STATUS RESTARTS AGE
|
||||
immutable-configmap-volume-78b6fbff95-5gsfh 1/1 Running 0 62s
|
||||
|
|
@ -517,13 +595,16 @@ immutable-configmap-volume-78b6fbff95-7vcj4 1/1 Running 0 62s
|
|||
immutable-configmap-volume-78b6fbff95-vdslm 1/1 Running 0 62s
|
||||
```
|
||||
|
||||
The Pod's container refers to the data defined in the ConfigMap and uses it to print a report to stdout. You can check this report by viewing the logs for one of the Pods in that Deployment:
|
||||
The Pod's container refers to the data defined in the ConfigMap and uses it to print a report to stdout.
|
||||
You can check this report by viewing the logs for one of the Pods in that Deployment:
|
||||
|
||||
```shell
|
||||
# Pick one Pod that belongs to the Deployment, and view its logs
|
||||
kubectl logs deployments/immutable-configmap-volume
|
||||
```
|
||||
|
||||
You should see an output similar to:
|
||||
|
||||
```
|
||||
Found 3 pods, using pod/immutable-configmap-volume-78b6fbff95-5gsfh
|
||||
Wed Mar 20 03:52:34 UTC 2024 The name of the company is ACME, Inc.
|
||||
|
|
@ -532,14 +613,15 @@ Wed Mar 20 03:52:54 UTC 2024 The name of the company is ACME, Inc.
|
|||
```
|
||||
|
||||
{{< note >}}
|
||||
Once a ConfigMap is marked as immutable, it is not possible to revert this change
|
||||
Once a ConfigMap is marked as immutable, it is not possible to revert this change
|
||||
nor to mutate the contents of the data or the binaryData field.
|
||||
In order to modify the behavior of the Pods that use this configuration,
|
||||
you will create a new immutable ConfigMap and edit the Deployment
|
||||
In order to modify the behavior of the Pods that use this configuration,
|
||||
you will create a new immutable ConfigMap and edit the Deployment
|
||||
to define a slightly different pod template, referencing the new ConfigMap.
|
||||
{{< /note >}}
|
||||
|
||||
Create a new immutable ConfigMap by using the manifest shown below:
|
||||
|
||||
{{% code_sample file="configmap/new-immutable-configmap.yaml" %}}
|
||||
|
||||
```shell
|
||||
|
|
@ -547,6 +629,7 @@ kubectl apply -f https://k8s.io/examples/configmap/new-immutable-configmap.yaml
|
|||
```
|
||||
|
||||
You should see an output similar to:
|
||||
|
||||
```
|
||||
configmap/company-name-20240312 created
|
||||
```
|
||||
|
|
@ -558,15 +641,17 @@ kubectl get configmap
|
|||
```
|
||||
|
||||
You should see an output displaying both the old and new ConfigMaps:
|
||||
|
||||
```
|
||||
NAME DATA AGE
|
||||
company-name-20150801 1 22m
|
||||
company-name-20240312 1 24s
|
||||
```
|
||||
|
||||
Modify the Deployment to reference the new ConfigMap.
|
||||
Modify the Deployment to reference the new ConfigMap.
|
||||
|
||||
Edit the Deployment:
|
||||
|
||||
```shell
|
||||
kubectl edit deployment immutable-configmap-volume
|
||||
```
|
||||
|
|
@ -580,7 +665,9 @@ volumes:
|
|||
name: company-name-20240312 # Update this field
|
||||
name: config-volume
|
||||
```
|
||||
|
||||
You should see the following output:
|
||||
|
||||
```
|
||||
deployment.apps/immutable-configmap-volume edited
|
||||
```
|
||||
|
|
@ -588,6 +675,7 @@ deployment.apps/immutable-configmap-volume edited
|
|||
This will trigger a rollout. Wait for all the previous Pods to terminate and the new Pods to be in a ready state.
|
||||
|
||||
Monitor the status of the Pods:
|
||||
|
||||
```shell
|
||||
kubectl get pods --selector=app.kubernetes.io/name=immutable-configmap-volume
|
||||
```
|
||||
|
|
@ -600,10 +688,10 @@ immutable-configmap-volume-5fdb88fcc8-n5jx4 1/1 Running 0 1
|
|||
immutable-configmap-volume-78b6fbff95-5gsfh 1/1 Terminating 0 32m
|
||||
immutable-configmap-volume-78b6fbff95-7vcj4 1/1 Terminating 0 32m
|
||||
immutable-configmap-volume-78b6fbff95-vdslm 1/1 Terminating 0 32m
|
||||
|
||||
```
|
||||
|
||||
You should eventually see an output similar to:
|
||||
|
||||
```
|
||||
NAME READY STATUS RESTARTS AGE
|
||||
immutable-configmap-volume-5fdb88fcc8-29v8n 1/1 Running 0 43s
|
||||
|
|
@ -612,12 +700,14 @@ immutable-configmap-volume-5fdb88fcc8-n5jx4 1/1 Running 0 45s
|
|||
```
|
||||
|
||||
View the logs for a Pod in this Deployment:
|
||||
|
||||
```shell
|
||||
# Pick one Pod that belongs to the Deployment, and view its logs
|
||||
kubectl logs deployment/immutable-configmap-volume
|
||||
```
|
||||
|
||||
You should see an output similar to the below:
|
||||
|
||||
```
|
||||
Found 3 pods, using pod/immutable-configmap-volume-5fdb88fcc8-n5jx4
|
||||
Wed Mar 20 04:24:17 UTC 2024 The name of the company is Fiktivesunternehmen GmbH
|
||||
|
|
@ -628,7 +718,7 @@ Wed Mar 20 04:24:37 UTC 2024 The name of the company is Fiktivesunternehmen GmbH
|
|||
Once all the deployments have migrated to use the new immutable ConfigMap, it is advised to delete the old one.
|
||||
|
||||
```shell
|
||||
kubectl delete configmap company-name-20150801
|
||||
kubectl delete configmap company-name-20150801
|
||||
```
|
||||
|
||||
## Summary
|
||||
|
|
@ -637,18 +727,23 @@ Changes to a ConfigMap mounted as a Volume on a Pod are available seamlessly aft
|
|||
|
||||
Changes to a ConfigMap that configures environment variables for a Pod are available after the subsequent rollout for the Pod.
|
||||
|
||||
Once a ConfigMap is marked as immutable, it is not possible to revert this change (you cannot make an immutable ConfigMap mutable), and you also cannot make any change to the contents of the `data` or the `binaryData` field. You can delete and recreate the ConfigMap, or you can make a new different ConfigMap. When you delete a ConfigMap, running containers
|
||||
and their Pods maintain a mount point to any volume that referenced that existing ConfigMap.
|
||||
|
||||
Once a ConfigMap is marked as immutable, it is not possible to revert this change
|
||||
(you cannot make an immutable ConfigMap mutable), and you also cannot make any change
|
||||
to the contents of the `data` or the `binaryData` field. You can delete and recreate
|
||||
the ConfigMap, or you can make a new different ConfigMap. When you delete a ConfigMap,
|
||||
running containers and their Pods maintain a mount point to any volume that referenced
|
||||
that existing ConfigMap.
|
||||
|
||||
## {{% heading "cleanup" %}}
|
||||
|
||||
Terminate the `kubectl port-forward` commands in case they are running.
|
||||
|
||||
Delete the resources created during the tutorial:
|
||||
|
||||
```shell
|
||||
kubectl delete deployment configmap-volume configmap-env-var configmap-two-containers configmap-sidecar-container immutable-configmap-volume
|
||||
kubectl delete service configmap-service configmap-sidecar-service
|
||||
kubectl delete configmap sport fruits color company-name-20240312
|
||||
|
||||
kubectl delete configmap company-name-20150801 # In case it was not handled during the task execution
|
||||
```
|
||||
```
|
||||
|
|
|
|||
Loading…
Reference in New Issue