# Alpine Linux 快速参考

*包管理、服务、网络、Docker 基础镜像*

> Source: Alpine Linux Documentation (wiki.alpinelinux.org) · MIT

## 包管理

### apk 基础

```
apk update               # refresh package index
apk upgrade              # upgrade all packages
apk add curl git vim     # install packages
apk del curl             # remove a package
apk search nginx         # search for packages
```

### 包信息

```
apk info                 # list installed packages
apk info -a nginx        # detailed package info
apk info -L nginx        # list files in package
apk policy nginx         # show available versions
```

### 虚拟包

```
# Install build deps as a group, remove later
apk add --virtual .build-deps gcc musl-dev
make && make install
apk del .build-deps
```

### 软件源

```
# /etc/apk/repositories
https://dl-cdn.alpinelinux.org/alpine/v3.20/main
https://dl-cdn.alpinelinux.org/alpine/v3.20/community
@edge https://dl-cdn.alpinelinux.org/alpine/edge/testing
```

## 服务管理

### OpenRC 服务管理

```
rc-service nginx start    # start service
rc-service nginx stop     # stop service
rc-service nginx restart  # restart service
rc-service nginx status   # check status
```

### 运行级别管理

```
rc-update add nginx default   # enable at boot
rc-update del nginx default   # disable at boot
rc-update show               # list all services
rc-status                    # show running services
```

### 运行级别

| Command | Description |
|---------|-------------|
| `sysinit` | 系统初始化（文件系统、时钟） |
| `boot` | 基础系统服务（网络、syslog） |
| `default` | 普通服务（Web 服务器、守护进程） |
| `shutdown` | 关机任务 |

## 配置

### 关键配置文件

| Command | Description |
|---------|-------------|
| `/etc/apk/repositories` | 软件源 URL 列表 |
| `/etc/hostname` | 系统主机名 |
| `/etc/network/interfaces` | 网络接口配置 |
| `/etc/conf.d/` | 各服务专属配置 |
| `/etc/motd` | 登录提示信息 |

### 系统初始化

```
setup-alpine             # interactive full setup
setup-timezone           # set timezone
setup-keymap             # configure keyboard layout
setup-hostname myhost    # set hostname
```

### 时区设置

```
apk add tzdata
cp /usr/share/zoneinfo/US/Eastern /etc/localtime
echo "US/Eastern" > /etc/timezone
apk del tzdata          # optional: remove to save space
```

## 网络

### 接口配置

```
# /etc/network/interfaces
auto eth0
iface eth0 inet dhcp
# --- static ---
iface eth0 inet static
  address 192.168.1.10/24
  gateway 192.168.1.1
```

### 网络命令

```
ip addr show             # show IP addresses
ip route show            # show routing table
ip link set eth0 up     # bring interface up
setup-interfaces         # interactive net config
```

### DNS 与防火墙

```
# DNS: /etc/resolv.conf
nameserver 1.1.1.1
nameserver 8.8.8.8
# Firewall
apk add iptables
iptables -L -n           # list rules
```

## 用户管理

### 用户操作

```
adduser alice             # create user (interactive)
adduser -D -s /bin/sh bob # non-interactive, set shell
deluser alice             # delete user
passwd alice              # set/change password
```

### 用户组与 sudo

```
addgroup devs             # create group
addgroup alice devs       # add user to group
apk add doas              # lightweight sudo alternative
# /etc/doas.conf
permit persist alice as root
```

### 系统用户

```
adduser -S -D -H -s /sbin/nologin myapp
# -S system user  -D no password
# -H no home dir  -s no shell
```

## 磁盘与存储

### 文件系统命令

```
df -h                    # disk usage summary
du -sh /var/log          # directory size
lsblk                    # list block devices
mount /dev/sda1 /mnt     # mount device
umount /mnt              # unmount
```

### LBU（Alpine 本地备份）

```
# For diskless/data modes — persist changes across reboots
lbu status               # show uncommitted changes
lbu commit               # save changes to boot media
lbu list                 # list backed-up files
lbu include /etc/myconf  # add path to backup
```

### 磁盘安装

```
setup-disk               # interactive disk install
setup-disk /dev/sda      # install to specific disk
# Modes: sys (traditional), data, diskless
```

## Docker 基础镜像

### 为何选 Alpine 做 Docker 基础镜像

| Command | Description |
|---------|-------------|
| `~5 MB base image` | 对比 Debian slim 约 80 MB |
| `musl libc` | 比 glibc 更小（部分兼容性问题） |
| `apk package manager` | 快速，默认不留缓存 |
| `Minimal attack surface` | 包越少，CVE 越少 |

### 最简 Dockerfile

```
FROM alpine:3.20
RUN apk add --no-cache python3 py3-pip
COPY app.py /app/
CMD ["python3", "/app/app.py"]
```

### 多阶段构建

```
FROM golang:1.22-alpine AS builder
WORKDIR /src
COPY . .
RUN go build -o /app
FROM alpine:3.20
COPY --from=builder /app /app
CMD ["/app"]
```

### 常见坑

| Command | Description |
|---------|-------------|
| `--no-cache` | 务必加，保持镜像小 |
| `musl vs glibc` | 部分二进制需要 gcompat 包 |
| `No bash by default` | 用 /bin/sh 或 apk add bash |
| `Timezone missing` | 需要时安装 tzdata |

## 常用模式

### 安装构建工具

```
apk add --no-cache build-base   # gcc, make, etc.
apk add --no-cache python3-dev  # Python headers
apk add --no-cache linux-headers # kernel headers
```

### 定时任务

```
# Add a cron job
echo "*/5 * * * * /usr/local/bin/task.sh" \
  | crontab -
rc-service crond start
rc-update add crond default
```

### 启用 SSH

```
apk add openssh
rc-service sshd start
rc-update add sshd default
# Config: /etc/ssh/sshd_config
```

### 升级 Alpine 版本

```
# Edit /etc/apk/repositories: change v3.19 → v3.20
apk update
apk upgrade --available
sync && reboot
```