/etc/docker where

### Purpose of the `/etc/docker` directory in Linux The `/etc/docker` directory is primarily used to store Docker's configuration files on a Linux system. This directory contains key files that influence how the Docker daemon operates, including settings for security, networking, logging, and registry mirrors. One of the most commonly configured files within this directory is `daemon.json`. This file allows users to customize the behavior of the Docker daemon at startup. For instance, it can be used to specify registry mirrors, adjust default network settings, or configure advanced storage drivers. An example of using `daemon.json` is setting up an image acceleration service by specifying mirror URLs under the `"registry-mirrors"` key [^1]. ### Common Files and Their Purposes - **daemon.json**: This is the primary configuration file for the Docker daemon. If this file exists, Docker will use its contents to override default configurations. It is often used to set options such as: - Registry mirrors (`"registry-mirrors"`): A list of URLs pointing to alternative registries that Docker clients may use to pull images from. - Insecure registries (`"insecure-registries"`): Allows connections to registries without valid TLS certificates. - Debug mode (`"debug"`): Enables debug mode for more verbose logging output. - **key.json**: This file is less commonly modified directly but plays a role in managing keys for secure communication between Docker components. - **daemon.log** (optional): While not always present, some setups might include a log file here if logging is explicitly configured to write logs to a specific location. ### Managing Configuration To apply changes made in the `daemon.json` file, the Docker service must be reloaded and restarted using commands like `systemctl daemon-reload` followed by `systemctl restart docker`. This ensures that any new settings take effect immediately without requiring a full system reboot [^1]. Here’s an example snippet showing what the `daemon.json` might look like: ```json { "registry-mirrors": ["https://fil0uwf5.mirror.aliyuncs.com"], "insecure-registries": ["myregistry.local:5000"] } ``` This JSON structure demonstrates how one could configure both a registry mirror and an insecure registry entry within the `daemon.json` file.