ConfigMaps in K8s

摘要

ConfigMaps是Kubernetes（K8s）中用于存储应用程序配置信息的一种资源对象。它将key-value对存储为Kubernetes集群中的一个资源，并可以在Pod中以卷或环境变量的形式使用。

ConfigMaps的设计目的是将应用程序配置与应用程序本身解耦。它可以存储应用程序所需的任何配置信息，例如数据库连接字符串、API密钥、日志级别等。通过使用ConfigMaps，可以在不重新构建或重新部署应用程序的情况下更改配置，这使得配置管理变得更加灵活和可维护。

ConfigMaps的寿命是根据其创建方式和使用方式而定的。

创建方式：

  1. 在集群中使用kubectl create configmap命令创建的ConfigMaps将在集群中持久存在，直到被手动删除。
  2. 如果使用ConfigMap的定义文件来创建ConfigMap，并将其提交给Kubernetes API，那么ConfigMap将持久存在，直到手动删除。

使用方式：

  1. 将ConfigMap作为卷挂载到Pod中，该Pod将与ConfigMap的生命周期保持一致。如果ConfigMap被删除，Pod将无法访问ConfigMap中的配置。
  2. 将ConfigMap中的数据作为环境变量注入到Pod中，ConfigMap的寿命与Pod的寿命无关。即使删除了ConfigMap，Pod仍然可以继续使用ConfigMap中的配置。但是，如果重启Pod或启动新的Pod，它们将无法访问被删除的ConfigMap中的数据。

总结起来，通过使用kubectl create或定义文件创建ConfigMaps，并将其作为卷挂载到Pod中，可以保证ConfigMap的寿命与Pod的寿命相同。如果将ConfigMap的数据作为环境变量注入到Pod中，ConfigMap的寿命与Pod的寿命无关，并且即使配置Map被删除，Pod仍然可以使用之前注入的配置。

Simply

ConfigMaps in Kubernetes (K8s) are designed to store application configuration information. They are a resource object that stores key-value pairs as a resource in the Kubernetes cluster, and can be used in Pods as volumes or environment variables.

The design of ConfigMaps aims to decouple application configuration from the application itself. It can store any configuration information required by an application, such as database connection strings, API keys, log levels, etc. By using ConfigMaps, configurations can be changed without rebuilding or redeploying the application, making configuration management more flexible and maintainable.

The lifespan of ConfigMaps depends on how they are created and used:

Creation:

  1. ConfigMaps created using the kubectl create configmap command will persist in the cluster until manually deleted.
  2. If a ConfigMap is created using a ConfigMap definition file and submitted to the Kubernetes API, it will persist until manually deleted.

Usage:

  1. If a ConfigMap is mounted as a volume in a Pod, the lifespan of the ConfigMap will be tied to the Pod. If the ConfigMap is deleted, the Pod will lose access to the configuration stored in the ConfigMap.
  2. If the data from a ConfigMap is injected into a Pod as environment variables, the lifespan of the ConfigMap is independent of the Pod. Even if the ConfigMap is deleted, the Pod can still use the injected configuration. However, if the Pod is restarted or a new Pod is started, it will not be able to access the deleted ConfigMap data.

To summarize, ConfigMaps created using kubectl create or a definition file and mounted as volumes in Pods will have the same lifespan as the Pods. If the ConfigMap’s data is injected as environment variables in a Pod, the ConfigMap’s lifespan is independent of the Pod’s lifespan, and the Pod can still use the injected configuration even if the ConfigMap is deleted.

Example

ConfigMaps是Kubernetes（K8s）中用于存储配置数据的一种资源对象。它允许您将配置数据从容器镜像中分离出来，以便在运行时进行动态配置。

以下是一个使用示例：

  1. 首先，创建一个名为my-configmap.yaml的配置文件，其中包含ConfigMap的定义：
apiVersion: v1
kind: ConfigMap
metadata:
  name: my-configmap
data:
  config.yaml: |
    key1: value1
    key2: value2
    key3: value3

在这个示例中，我们创建了一个名为my-configmap的ConfigMap对象，并将一个config.yaml键关联到一个包含一些键值对的配置数据的值。

  1. 使用kubectl命令将ConfigMap创建到集群中：
kubectl apply -f my-configmap.yaml
  1. 在Deployment或Pod的配置中使用ConfigMap。
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
  replicas: 1
  template:
    spec:
      containers:
      - name: my-container
        image: nginx
        volumeMounts:
        - name: config-volume
          mountPath: /etc/config
      volumes:
      - name: config-volume
        configMap:
          name: my-configmap

在这个示例中，我们将ConfigMap挂载到了Deployment的Pod中的/etc/config路径下，并将ConfigMap的数据映射到了容器内。

  1. 部署Deployment到集群中：
kubectl apply-f my-deployment.yaml

这样，当Pod启动时，ConfigMap的数据将被挂载到容器中，并可以在容器内的/etc/config路径下访问。

另一种使用ConfigMap的方法是通过环境变量注入配置数据：

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
  replicas: 1
  template:
    spec:
      containers:
        - name: my-container
          image: nginx
          env:
            - name: CONFIG_KEY
              valueFrom:
                configMapKeyRef:
                  name: my-configmap
                  key: key1

在这个示例中，我们使用valueFrom字段指定了ConfigMap的名称和键，将ConfigMap中的key1对应的值注入到了Pod的环境变量CONFIG_KEY中。

总结来说，ConfigMaps是Kubernetes中一种用于存储配置数据的资源对象。通过将配置数据分离出容器镜像，您可以在不重新构建和重新部署容器的情况下修改和管理配置。这使得应用程序的部署和管理更加灵活和可维护。

On the other hand

In a distant future, where space exploration and colonization have become the norm, ConfigMaps have taken on a crucial role in the operation of advanced space stations and interstellar vessels. These ConfigMaps are sophisticated devices that contain all necessary information and parameters to control and configure the various systems on board.

Imagine a stunning, massive space station floating gracefully at the edge of a nebula. Within its sleek corridors, humans and advanced artificial intelligence coexist in perfect harmony. This advanced society has harnessed the power of ConfigMaps to create a seamless integration between human intuition and machine intelligence.

Onboard the space station, ConfigMaps are meticulously maintained and regularly updated by skilled engineers. These engineers are responsible for inputting the precise instructions, algorithms, and protocols needed to ensure the smooth operation of all onboard systems. They carefully configure the ConfigMaps to regulate life support systems, power distribution networks, communication protocols, and even the station’s defensive capabilities.

As the space station embarks on its mission to explore uncharted galaxies, ConfigMaps become even more critical. They ensure the seamless adaptability of the space station in ever-changing environments. The ConfigMaps contain detailed mappings of the cosmic radiation levels, gravitational forces, and atmospheric conditions of each celestial body. With this information, the ConfigMaps are constantly updated to optimize the station’s performance and safeguard the lives of its inhabitants.

In this future, ConfigMaps are not limited to space stations alone. Interstellar vessels, capable of traveling vast distances within the blink of an eye, utilize ConfigMaps as well. These ConfigMaps provide the necessary data to navigate through treacherous asteroid fields, evade hostile alien species, and perform intricate docking maneuvers with other ships.

To ensure the security and reliability of ConfigMaps, advanced encryption algorithms and artificial intelligence are deployed. The ConfigMaps are safeguarded against unauthorized access and tampering, guaranteeing the integrity of their contents. Only authorized personnel can modify or update the ConfigMaps, ensuring that every change is carefully evaluated and approved.

ConfigMaps have become the backbone of space exploration in this futuristic world, enabling humanity to venture into the farthest reaches of the universe. Through their advanced configuration capabilities, these devices ensure the seamless operation of space stations and interstellar vessels, making the impossible possible.

As humans and machines continue to push the boundaries of knowledge and explore new frontiers, ConfigMaps will evolve and adapt, becoming even more advanced and indispensable. They will continue to serve as the bridge between human ingenuity and the limitless potential of technology, enabling us to uncover the mysteries of the cosmos, one ConfigMap at a time.