180 lines
9.5 KiB
Markdown
180 lines
9.5 KiB
Markdown
---
|
||
title: 容器镜像的垃圾收集
|
||
content_type: concept
|
||
weight: 70
|
||
---
|
||
|
||
<!--
|
||
title: Garbage collection for container images
|
||
content_type: concept
|
||
weight: 70
|
||
-->
|
||
|
||
<!-- overview -->
|
||
|
||
<!--
|
||
Garbage collection is a helpful function of kubelet that will clean up unused [images](/docs/concepts/containers/#container-images) and unused [containers](/docs/concepts/containers/). Kubelet will perform garbage collection for containers every minute and garbage collection for images every five minutes.
|
||
|
||
External garbage collection tools are not recommended as these tools can potentially break the behavior of kubelet by removing containers expected to exist.
|
||
-->
|
||
|
||
垃圾回收是 kubelet 的一个有用功能，它将清理未使用的[镜像](/zh/docs/concepts/containers/#container-images)和[容器](/zh/docs/concepts/containers/)。
|
||
Kubelet 将每分钟对容器执行一次垃圾回收，每五分钟对镜像执行一次垃圾回收。
|
||
|
||
不建议使用外部垃圾收集工具，因为这些工具可能会删除原本期望存在的容器进而破坏 kubelet 的行为。
|
||
|
||
<!-- body -->
|
||
|
||
<!--
|
||
## Image Collection
|
||
|
||
Kubernetes manages lifecycle of all images through imageManager, with the cooperation
|
||
of cadvisor.
|
||
|
||
The policy for garbage collecting images takes two factors into consideration:
|
||
`HighThresholdPercent` and `LowThresholdPercent`. Disk usage above the high threshold
|
||
will trigger garbage collection. The garbage collection will delete least recently used
|
||
images until the low threshold has been met.
|
||
-->
|
||
## 镜像回收 {#image-collection}
|
||
|
||
Kubernetes 借助于 cadvisor 通过 imageManager 来管理所有镜像的生命周期。
|
||
|
||
镜像垃圾回收策略只考虑两个因素：`HighThresholdPercent` 和 `LowThresholdPercent`。
|
||
磁盘使用率超过上限阈值（HighThresholdPercent）将触发垃圾回收。
|
||
垃圾回收将删除最近最少使用的镜像，直到磁盘使用率满足下限阈值（LowThresholdPercent）。
|
||
|
||
<!--
|
||
## Container Collection
|
||
|
||
The policy for garbage collecting containers considers three user-defined variables. `MinAge` is the minimum age at which a container can be garbage collected. `MaxPerPodContainer` is the maximum number of dead containers every single
|
||
pod (UID, container name) pair is allowed to have. `MaxContainers` is the maximum number of total dead containers. These variables can be individually disabled by setting `MinAge` to zero and setting `MaxPerPodContainer` and `MaxContainers` respectively to less than zero.
|
||
-->
|
||
## 容器回收 {#container-collection}
|
||
|
||
容器垃圾回收策略考虑三个用户定义变量。
|
||
`MinAge` 是容器可以被执行垃圾回收的最小生命周期。
|
||
`MaxPerPodContainer` 是每个 pod 内允许存在的死亡容器的最大数量。
|
||
`MaxContainers` 是全部死亡容器的最大数量。
|
||
可以分别独立地通过将 `MinAge` 设置为 0，以及将 `MaxPerPodContainer` 和 `MaxContainers`
|
||
设置为小于 0 来禁用这些变量。
|
||
|
||
<!--
|
||
Kubelet will act on containers that are unidentified, deleted, or outside of the boundaries set by the previously mentioned flags. The oldest containers will generally be removed first. `MaxPerPodContainer` and `MaxContainer` may potentially conflict with each other in situations where retaining the maximum number of containers per pod (`MaxPerPodContainer`) would go outside the allowable range of global dead containers (`MaxContainers`). `MaxPerPodContainer` would be adjusted in this situation: A worst case scenario would be to downgrade `MaxPerPodContainer` to 1 and evict the oldest containers. Additionally, containers owned by pods that have been deleted are removed once they are older than `MinAge`.
|
||
-->
|
||
`kubelet` 将处理无法辨识的、已删除的以及超出前面提到的参数所设置范围的容器。
|
||
最老的容器通常会先被移除。
|
||
`MaxPerPodContainer` 和 `MaxContainer` 在某些场景下可能会存在冲突，
|
||
例如在保证每个 pod 内死亡容器的最大数量（`MaxPerPodContainer`）的条件下可能会超过
|
||
允许存在的全部死亡容器的最大数量（`MaxContainer`）。
|
||
`MaxPerPodContainer` 在这种情况下会被进行调整：
|
||
最坏的情况是将 `MaxPerPodContainer` 降级为 1，并驱逐最老的容器。
|
||
此外，pod 内已经被删除的容器一旦年龄超过 `MinAge` 就会被清理。
|
||
|
||
<!--
|
||
Containers that are not managed by kubelet are not subject to container garbage collection.
|
||
-->
|
||
不被 kubelet 管理的容器不受容器垃圾回收的约束。
|
||
|
||
<!--
|
||
## User Configuration
|
||
|
||
Users can adjust the following thresholds to tune image garbage collection with the following kubelet flags :
|
||
-->
|
||
## 用户配置 {#user-configuration}
|
||
|
||
用户可以使用以下 kubelet 参数调整相关阈值来优化镜像垃圾回收：
|
||
|
||
<!--
|
||
1. `image-gc-high-threshold`, the percent of disk usage which triggers image garbage collection.
|
||
Default is 85%.
|
||
|
||
2. `image-gc-low-threshold`, the percent of disk usage to which image garbage collection attempts
|
||
to free. Default is 80%.
|
||
-->
|
||
|
||
1. `image-gc-high-threshold`，触发镜像垃圾回收的磁盘使用率百分比。默认值为 85%。
|
||
2. `image-gc-low-threshold`，镜像垃圾回收试图释放资源后达到的磁盘使用率百分比。默认值为 80%。
|
||
|
||
<!--
|
||
We also allow users to customize garbage collection policy through the following kubelet flags:
|
||
-->
|
||
我们还允许用户通过以下 kubelet 参数自定义垃圾收集策略：
|
||
|
||
<!--
|
||
1. `minimum-container-ttl-duration`, minimum age for a finished container before it is
|
||
garbage collected. Default is 0 minute, which means every finished container will be garbage collected.
|
||
|
||
2. `maximum-dead-containers-per-container`, maximum number of old instances to be retained
|
||
per container. Default is 1.
|
||
|
||
3. `maximum-dead-containers`, maximum number of old instances of containers to retain globally.
|
||
Default is -1, which means there is no global limit.
|
||
-->
|
||
|
||
1. `minimum-container-ttl-duration`，完成的容器在被垃圾回收之前的最小年龄，默认是 0 分钟。
|
||
这意味着每个完成的容器都会被执行垃圾回收。
|
||
|
||
2. `maximum-dead-containers-per-container`，每个容器要保留的旧实例的最大数量。默认值为 1。
|
||
|
||
3. `maximum-dead-containers`，要全局保留的旧容器实例的最大数量。
|
||
默认值是 -1，意味着没有全局限制。
|
||
|
||
<!--
|
||
Containers can potentially be garbage collected before their usefulness has expired. These containers
|
||
can contain logs and other data that can be useful for troubleshooting. A sufficiently large value for
|
||
`maximum-dead-containers-per-container` is highly recommended to allow at least 1 dead container to be
|
||
retained per expected container. A larger value for `maximum-dead-containers` is also recommended for a
|
||
similar reason.
|
||
|
||
See [this issue](https://github.com/kubernetes/kubernetes/issues/13287) for more details.
|
||
-->
|
||
容器可能会在其效用过期之前被垃圾回收。这些容器可能包含日志和其他对故障诊断有用的数据。
|
||
强烈建议为 `maximum-dead-containers-per-container` 设置一个足够大的值，以便每个预期容器至少保留一个死亡容器。
|
||
由于同样的原因，`maximum-dead-containers` 也建议使用一个足够大的值。
|
||
|
||
查阅[这个 Issue](https://github.com/kubernetes/kubernetes/issues/13287) 获取更多细节。
|
||
|
||
<!--
|
||
## Deprecation
|
||
|
||
Some kubelet Garbage Collection features in this doc will be replaced by kubelet eviction in the future.
|
||
|
||
Including:
|
||
-->
|
||
## 弃用 {#deprecation}
|
||
|
||
这篇文档中的一些 kubelet 垃圾收集（Garbage Collection）功能将在未来被 kubelet 驱逐回收（eviction）所替代。
|
||
|
||
包括:
|
||
|
||
<!--
|
||
| Existing Flag | New Flag | Rationale |
|
||
| ------------- | -------- | --------- |
|
||
| `--image-gc-high-threshold` | `--eviction-hard` or `--eviction-soft` | existing eviction signals can trigger image garbage collection |
|
||
| `--image-gc-low-threshold` | `--eviction-minimum-reclaim` | eviction reclaims achieve the same behavior |
|
||
| `--maximum-dead-containers` | | deprecated once old logs are stored outside of container's context |
|
||
| `--maximum-dead-containers-per-container` | | deprecated once old logs are stored outside of container's context |
|
||
| `--minimum-container-ttl-duration` | | deprecated once old logs are stored outside of container's context |
|
||
| `--low-diskspace-threshold-mb` | `--eviction-hard` or `eviction-soft` | eviction generalizes disk thresholds to other resources |
|
||
| `--outofdisk-transition-frequency` | `--eviction-pressure-transition-period` | eviction generalizes disk pressure transition to other resources |
|
||
-->
|
||
| 现存参数 | 新参数 | 解释 |
|
||
| ------------- | -------- | --------- |
|
||
| `--image-gc-high-threshold` | `--eviction-hard` 或 `--eviction-soft` | 现存的驱逐回收信号可以触发镜像垃圾回收 |
|
||
| `--image-gc-low-threshold` | `--eviction-minimum-reclaim` | 驱逐回收实现相同行为 |
|
||
| `--maximum-dead-containers` | | 一旦旧日志存储在容器上下文之外，就会被弃用 |
|
||
| `--maximum-dead-containers-per-container` | | 一旦旧日志存储在容器上下文之外，就会被弃用 |
|
||
| `--minimum-container-ttl-duration` | | 一旦旧日志存储在容器上下文之外，就会被弃用 |
|
||
| `--low-diskspace-threshold-mb` | `--eviction-hard` or `eviction-soft` | 驱逐回收将磁盘阈值泛化到其他资源 |
|
||
| `--outofdisk-transition-frequency` | `--eviction-pressure-transition-period` | 驱逐回收将磁盘压力转换到其他资源 |
|
||
|
||
## {{% heading "whatsnext" %}}
|
||
|
||
<!--
|
||
See [Configuring Out Of Resource Handling](/docs/tasks/administer-cluster/out-of-resource/) for more details.
|
||
-->
|
||
|
||
查阅[配置资源不足情况的处理](/zh/docs/tasks/administer-cluster/out-of-resource/)了解更多细节。
|
||
|