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ConfigMaps e Secrets para configuração

Gerencie com segurança a configuração da aplicação e os dados confidenciais usando ConfigMaps e Secrets no Kubernetes.

ConfigMaps e Secrets para configuração é uma aula grátis de Docker & Kubernetes for Developers no CoddyKit. Esta é a aula 3 de 4. Você pode ler a aula completa abaixo gratuitamente — depois pratica ao vivo no navegador com um editor de código integrado e um tutor de IA 24/7. Faz parte do caminho de aprendizado de Docker & Kubernetes for Developers, e seu progresso é sincronizado entre a web e o app CoddyKit. O curso de Docker & Kubernetes for Developers inclui 4 aulas no total.

Partes desta aula ainda não foram traduzidas e aparecem em inglês.

Configuration Challenges

Managing application configuration and sensitive data can be tricky, especially in dynamic environments like Kubernetes.

Hardcoding values into images makes them less reusable. Storing secrets directly in Git is a security risk.

Kubernetes offers two powerful resources to solve these challenges: ConfigMaps and Secrets.

Meet ConfigMaps

A ConfigMap is an API object used to store non-sensitive configuration data in key-value pairs.

Think of it as a central place for settings like database hostnames, logging levels, or API endpoints.

  • Separates configuration from application code.
  • Allows easy updates without rebuilding images.
  • Can be consumed as environment variables or mounted files.

ConfigMap: Literal Values

You can create a ConfigMap directly from literal key-value pairs using YAML. This is great for simple, direct settings.

Here's an example for an application's settings:

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-settings
data:
  log_level: INFO
  feature_flag_a: "true"
  api_url: http://backend-service/api

ConfigMap: From Files

For more complex configurations, you can create a ConfigMap from an entire file.

If you have a config.properties file, its content can be directly embedded into the ConfigMap. The resulting ConfigMap would look like this:

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config-from-file
data:
  config.properties: |
    database.host=db-service
    database.port=5432
    application.name=MyWebApp

ConfigMap as Env Vars

The most common way to use a ConfigMap is by injecting its data as environment variables into your Pods.

This allows your application to read configuration values directly.

apiVersion: v1
kind: Pod
metadata:
  name: my-app-pod
spec:
  containers:
  - name: my-container
    image: nginx
    env:
    - name: LOG_LEVEL
      valueFrom:
        configMapKeyRef:
          name: app-settings
          key: log_level
    - name: API_URL
      valueFrom:
        configMapKeyRef:
          name: app-settings
          key: api_url

ConfigMap as Volume Mounts

ConfigMap data can also be mounted as files into a Pod's filesystem. This is ideal for applications that read configuration from files.

Each key in the ConfigMap becomes a file in the specified mountPath. For example, log_level would be at /etc/config/log_level.

apiVersion: v1
kind: Pod
metadata:
  name: my-app-pod-volume
spec:
  containers:
  - name: my-container
    image: nginx
    volumeMounts:
    - name: config-volume
      mountPath: "/etc/config"
  volumes:
  - name: config-volume
    configMap:
      name: app-settings

Introducing Secrets

A Secret is similar to a ConfigMap but is designed for sensitive data like passwords, API keys, or TLS certificates.

Secrets are stored in Kubernetes in base64 encoded format, but this is NOT encryption. It's just encoding for safe transport.

  • Provides a mechanism to distribute sensitive data.
  • Accessed like ConfigMaps (env vars or volume mounts).
  • Should always be managed with care and access controls.

Secret: Literal Values

Secrets are created similarly to ConfigMaps, but their data values are base64 encoded. This encoding is for safe transport, not encryption.

For example, if your password is "my-secure-password", its base64 encoding is "bXktc2VjdXJlLXBhc3N3b3Jk".

apiVersion: v1
kind: Secret
metadata:
  name: db-credentials
type: Opaque
data:
  username: dXNlcg== # 'user' base64 encoded
  password: bXktc2VjdXJlLXBhc3N3b3Jk # 'my-secure-password' base64 encoded

Secret as Env Vars

Secrets can be consumed as environment variables, just like ConfigMaps. Kubernetes automatically decodes the base64 value for the container.

This makes sensitive data available to your application without hardcoding it directly in the image.

apiVersion: v1
kind: Pod
metadata:
  name: my-db-app
spec:
  containers:
  - name: my-container
    image: my-app:1.0
    env:
    - name: DB_USERNAME
      valueFrom:
        secretKeyRef:
          name: db-credentials
          key: username
    - name: DB_PASSWORD
      valueFrom:
        secretKeyRef:
          name: db-credentials
          key: password

Secret as Volume Mounts

Mounting Secrets as files is often preferred for sensitive data, as it limits the exposure of the secret to the application process.

The mounted files will contain the decoded (plain-text) secret values, and you can set them to be read-only.

apiVersion: v1
kind: Pod
metadata:
  name: my-secure-app
spec:
  containers:
  - name: my-container
    image: my-app:1.0
    volumeMounts:
    - name: secret-volume
      mountPath: "/etc/secrets"
      readOnly: true
  volumes:
  - name: secret-volume
    secret:
      secretName: db-credentials

ConfigMaps vs. Secrets

You need to store an API key for a third-party service and a configuration setting for your application's logging level. Which Kubernetes resources would you use for each?

Recap: Config & Secrets

We've learned how ConfigMaps and Secrets help manage configuration and sensitive data in Kubernetes.

  • ConfigMaps store non-sensitive key-value pairs.
  • Secrets store sensitive data, base64 encoded (not encrypted).
  • Both can be consumed as environment variables or mounted files in Pods.
  • Using them separates configuration from application logic, improving flexibility and security.

Perguntas Frequentes

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O que vou aprender em “ConfigMaps e Secrets para configuração”?

Gerencie com segurança a configuração da aplicação e os dados confidenciais usando ConfigMaps e Secrets no Kubernetes. Você pratica Docker & Kubernetes for Developers com código prático que executa diretamente no navegador, e um tutor de IA 24/7 responde suas dúvidas enquanto trabalha na aula.

Preciso ter experiência prévia para começar Docker & Kubernetes for Developers?

Nenhuma experiência prévia é necessária. Docker & Kubernetes for Developers no CoddyKit é estruturado para alunos iniciantes até avançados, então você pode começar aqui ou desde o início e aprender no seu ritmo. Esta é a aula 3 de 4.

Quanto tempo leva a aula “ConfigMaps e Secrets para configuração”?

A maioria das aulas CoddyKit leva cerca de 5–10 minutos. Cada uma é compacta e interativa, então você faz progresso constante e retoma exatamente de onde parou entre web e app.

Posso escrever e executar código nesta aula de Docker & Kubernetes for Developers?

Sim. Cada aula de Docker & Kubernetes for Developers inclui um editor de código integrado, então você escreve e executa código real direto no navegador e recebe feedback de IA instantaneamente — nenhuma configuração local necessária.

Todas as aulas deste curso

  1. Volumes persistentes e solicitações de volumes persistentes
  2. Gerenciamento de aplicações com estado usando StatefulSets
  3. ConfigMaps e Secrets para configuração
  4. Classes de armazenamento e provisionamento dinâmico
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