Install Alpine Linux on your Linode

Alpine Linux is a small, security-oriented Linux distro. It’s regularly updated with security patches, and runs on the grsecurity kernel. All binaries are statically linked and built against musl libc.

Before You Begin

1. Familiarize yourself with Lish, as most of this guide will require an out-of-band connection.

2. Installing Alpine in this manner will destroy all existing data on the installation target disks. Back up all data on the disks which you intend to install Alpine on.

3. The initial portion of this guide involves creating the disk images, so you make sure you have plenty of free space for them. A minimal installation of Alpine requires less than 1 GB, but depending on your needs, you may want to allow for more.

4. This guide assumes a consistent present working directory, meaning all commands should be run from the same directory. In most cases, it will be /alpine or a chroot of said directory.

Prepare the Linode

Disk Images

In this section, we’ll create the disk images necessary to install Alpine Linux. Although it is not strictly necessary, giving each disk a descriptive name upon creation will make it easier to keep track of its role in the system.

1. Log in to the Linode Manager and select the Linode to install Alpine Linux on.

2. Create your boot disk image by selecting Create a new Disk under the Disks section. The size should be between 128 and 256 MB, and the type should be ext4.

   Note

   Boot drives (disk images) will need to store your kernel and your initramfs. Currently, Alpine will need about 21 MB for each kernel/initramfs combination, so even 128 MB is enough for several kernel versions, just remember to keep an eye on the available storage in /boot when you perform upgrades of the kernel.

3. Create your root disk image with as much space as you need, although if you want a swap disk image, make sure you leave room for it. The root disk image should be of the ext4 type as well.

4. Optionally, create a swap disk image with type swap.

   Note

   Between 256 and 512 MB of swap is a good estimate. Many sources recommend much more than this, but a new installation of Alpine will use less than 50 MB of RAM when fully booted.

Configuration Profile

Create a new configuration profile for your Linode. Choose GRUB 2 from the kernel menu, which will use the GRUB 2 bootloader to boot Alpine’s kernel from your disk image. Set your boot disk image as /dev/sda, your root disk image as /dev/sdb, and your swap disk image, if you created one, as /dev/sdc.

Turn off all the Filesystem/Boot Helpers. The rest of the settings can be left at their default values.

Install Alpine Linux

Boot into Rescue Mode

1. From the Linode Cloud Manager, boot your Linode into Rescue Mode, with your boot disk image as /dev/sda, your root disk image as /dev/sdb, and your swap as /dev/sdc.

2. Once the Linode has booted, connect to it via Lish. If you are not familiar with Lish, there is a simple web interface for it in the Linode Cloud Manager. Access it by clicking the Launch Console link from the Linode’s dashboard.

Mount Drives

1. Create the /alpine directory. This will serve as a mount point for the root disk image:

   mkdir /alpine
   

2. Mount the root disk to the new /alpine directory and navigate to it:

   mount /dev/sdb /alpine
   cd /alpine
   

3. Create a boot directory and mount the boot disk image to it:

   mkdir boot
   mount /dev/sda /alpine/boot
   

Download APK Tools

1. Update the CA Certificates package so curl can verify the download:

   update-ca-certificates
   

2. Select your desired Alpine Linux release. In most cases, you can use the latest stable release

3. Identify the current version of the apk-tools-static package. You will need to navigate into the main/x86_64 directory of your chosen release in your web browser.

   For example, the latest stable version’s apk-tools-static package can be found at http://nl.alpinelinux.org/alpine/latest-stable/main/x86_64/. From there, simply search for apk-tools-static. Once you’ve found it, copy the file’s location. To do this in most browsers, right click the filename and select Copy Link Address.

4. Download and extract the apk-tools-static package to your Linode. You should still be working in the /alpine directory when performing this step. Replace address in the following command with the address you copied in the previous step:

   curl -s address | tar xz
   

5. Perform the initial distro installation. This will use the latest stable build of Alpine:

   ./sbin/apk.static --repository https://nl.alpinelinux.org/alpine/latest-stable/main/ --update-cache --allow-untrusted --root /alpine --initdb add alpine-base alpine-mirrors
   

   This should output a series of installation messages, followed by a message showing how many packages were installed and their sizes.

System Configuration

In this section, we will modify critical system files. It is recommended that you make backup copies before making changes.

1. Configure your filesystem table (fstab), entering a single hard tab between each column. This file specifies how each disk is initialized or mounted into the overall filesystem:

   File: /alpine/etc/fstab

   1 2 3

   /dev/sdb / ext4 defaults,noatime 0 0 /dev/sda /boot ext4 defaults,noatime 0 1 /dev/sdc swap swap defaults 0 0

2. Uncomment the line below to enable a serial console output. This gives you visibility over Lish when booting the installed system.

   File: /alpine/etc/inittab

   1 2	# Put a getty on the serial port ttyS0::respawn:/sbin/getty -L ttyS0 115200 vt100

3. Create the GRUB 2 boot configuration directory:

   mkdir /alpine/boot/grub
   

   Create a new file, grub.cfg within this directory, and add the following contents. This file specifies configuration options for GRUB 2 to use during the boot process:

   File: /alpine/boot/grub/grub.cfg

   1 2 3 4 5 6 7 8

   set root=(hd0) set default="Alpine Linux" set timeout=0 menuentry "Alpine Linux" { linux /vmlinuz-vanilla root=/dev/sdb modules=sd-mod,usb-storage,ext4 console=ttyS0 quiet initrd /initramfs-vanilla }

4. Create a mkinitfs directory:

   mkdir /alpine/etc/mkinitfs
   

   Create a new file, mkinitfs.conf, within this directory and add the following contents. This file specifies options for building the initial RAM file system (initramfs):

   File: /alpine/etc/mkinitfs/mkinitfs.conf

   1	features="ata ide scsi virtio base ext4"

5. Copy the recovery system’s resolv.conf file into /alpine/etc. Optionally, you can fill in your own choice of DNS resolvers.

   cp /etc/resolv.conf /alpine/etc
   

6. If you want to allow root logins over Lish, add ttyS0 to securetty:

   echo ttyS0 >> /alpine/etc/securetty
   

Install the Kernel

1. Bind the /proc and /dev directories to the /alpine directory:

   mount --bind /proc /alpine/proc
   mount --bind /dev /alpine/dev
   

2. Enter the Alpine chroot jail:

   chroot /alpine /bin/sh
   

3. Select a mirror to use when downloading or updating packages:

   setup-apkrepos
   

   You can select a mirror by entering its corresponding number, or f to automatically pick the fastest mirror.

4. Update your packages:

   apk update
   

5. Set your hostname, replacing example with a hostname of your choice:

   setup-hostname -n example
   

6. Configure important services to start automatically using Alpine’s OpenRC init system:

   rc-update add networking boot
   rc-update add urandom boot
   rc-update add crond
   

   If you’ll need other services, you can also add them now. The above is intended to serve as a starting point.

7. Install the kernel:

   apk add linux-vanilla
   

8. Exit the chroot jail:

   exit
   

Configure Alpine Linux

Reboot into Alpine

1. Reboot into the Alpine Linux configuration you made earlier by selecting the button next to the profile in the Linode Manager and clicking Reboot. If this is the only configuration profile, this can also be accomplished directly in Lish using the boot 1 command. If there are other profiles, you can substitute 1 with the list position of your Alpine profile.

   Note

   During boot, the output in Lish that networking fails to start. This is expected, and will be fixed shortly.

2. Use Lish to log in as root. You will not be prompted for a password since it has not yet been set.

Configuration

1. Set up and start networking. Alpine has a handy script that will configure the network interface file for you and guide you through the various options. It’s capable of advanced configuration, like bridging and bonding, but for a basic setup, its defaults should be sufficient.

   setup-interfaces
   

   Press enter 3 times to accept the defaults of eth0, dhcp, and no, then restart the networking service:

   service networking restart
   

   Your Linode should now have a functional network connection.

2. Set a root password:

   passwd
   

3. Create a limited user account to avoid using root for all commands. Replace example-user with a username of your choice:

   adduser example-user
   

4. Install the sudo package:

   apk add sudo
   

5. Add your new user to the wheel group:

   adduser example-user wheel
   

6. Allow the wheel group to temporarily elevate their privileges with sudo:

   sed -i '/%wheel/s/^# //' /etc/sudoers
   

7. Install and configure the SSH daemon (SSHD). Alpine has a simple setup script to handle this:

   setup-sshd
   

   We recommend the openssh server if you want full SFTP access. dropbear is a more lightweight option, although it only provides SSH access.

Next Steps

At this point, you should be able to connect to your server via SSH. Alpine is very lightweight, and doesn’t install very much unless you ask it to.

Install Packages

Alpine’s website provides a searchable library of available packages.

A few packages to consider:

• Text editor: nano or vim
• Web server: lighttpd, apache2, or nginx
• Scripting languages: php, perl, or python
• Database servers: mysql or postgresql

Note that some of these combinations may require additional dependencies. To install a new package, use the following command, replacing package with the package name(s):

apk add package

For example, to add Apache, PHP, and MySQL:

apk add apache2 php mysql

For more information, see Alpine’s wiki page on package management.

Secure Your Server

Before using your Linode in a development or production capacity, make sure you’ve taken some basic security precautions. Our Securing Your Server guide provides a good starting point but you should also research additional, Alpine-specific security options. Keep in mind that most security packages (e.g. iptables.) will need to be installed.

For more information, refer to their wiki page on security.

More Information

You may wish to consult the following resources for additional information on this topic. While these are provided in the hope that they will be useful, please note that we cannot vouch for the accuracy or timeliness of externally hosted materials.

• Alpine Linux