An Alpine diskless overlay for your very own satellite ground station!
You will need the following things:
- A SD card, obviously. You shouldn't need more than 2GB.
- A Raspberry Pi, obviously. 2GBs of RAM are fine but more is always better. Also, it should be able to run
aarch64. That means only RPi 3B+ and up will work. - The overlay, obviously.
- Alpine Linux. Make sure you get the Raspberry Pi
aarch64specific image and it's the one ending with.tar.gz, not.img.gz.
First, find your SD: lsblk
➜ ~ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
sda 8:0 1 7.4G 0 disk
├─sda1 8:1 1 256M 0 part
└─sda2 8:2 1 7.2G 0 part
<snip>
In my case I have inserted the SD card into an USB adapter. If you have a SD card slot you may see something like mmcblk0pX where X denotes the partition number. For this guide we will assume that the SD card is at /dev/sda.
Alternatively, execute sudo dmesg right after inserting the SD card. For example:
➜ ~ sudo dmesg
<snip>
[ 6493.015685] usb-storage 1-4:1.0: USB Mass Storage device detected
[ 6493.016321] scsi host4: usb-storage 1-4:1.0
[ 6494.041392] scsi 4:0:0:0: Direct-Access Mass Storage Device 1.00 PQ: 0 ANSI: 0 CCS
[ 6494.041994] sd 4:0:0:0: Attached scsi generic sg0 type 0
[ 6494.416634] sd 4:0:0:0: [sda] 15601664 512-byte logical blocks: (7.99 GB/7.44 GiB)
[ 6494.417014] sd 4:0:0:0: [sda] Write Protect is off
[ 6494.417024] sd 4:0:0:0: [sda] Mode Sense: 03 00 00 00
[ 6494.417239] sd 4:0:0:0: [sda] No Caching mode page found
[ 6494.417248] sd 4:0:0:0: [sda] Assuming drive cache: write through
[ 6494.420866] sda: sda1 sda2
Now that we are at it: make a backup of anything important!
Next up is formatting the SD card. We will do that using the fdisk tool. If you get a command not found you'll have to install it. It's sudo apt install fdisk for Debian-based systems.
➜ ~ sudo fdisk /dev/sda
Welcome to fdisk (util-linux 2.38.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help):
Create a new DOS (MBR) partition table by typing o (WARNING: this will delete everything upon writing your changes. There's no confirmation.)
Command (m for help): o
Created a new DOS (MBR) disklabel with disk identifier 0xb3a7fb94.
Now create the boot partition:
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): <Enter>
First sector (2048-15601663, default 2048): <Enter>
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-15601663, default 15601663): +256M (You could make it just +100M, which are 100MB, if you feel like living on the edge.)
Created a new partition 1 of type 'Linux' and of size 256 MiB.
You may see something like this:
Partition #1 contains a vfat signature.
Do you want to remove the signature? [Y]es/[N]o: y
The signature will be removed by a write command.
If you've made a backup there's nothing to worry about. You made a backup, right? Right?
Cool! Now create your "data" partition:
Command (m for help): n
Partition type
p primary (1 primary, 0 extended, 3 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (2-4, default 2): <Enter>
First sector (526336-15601663, default 526336): <Enter>
Last sector, +/-sectors or +/-size{K,M,G,T,P} (526336-15601663, default 15601663): <Enter> (Or specify the size. You shouldn't need more than +1G, which is equivalent to 1GB.)
Created a new partition 2 of type 'Linux' and of size 7.2 GiB.
Partition #2 contains a ext4 signature.
Do you want to remove the signature? [Y]es/[N]o: y
The signature will be removed by a write command.
Good. The worst part is over. Making the whole thing bootable is rather easy:
Command (m for help): a
Partition number (1,2, default 2): 1
The bootable flag on partition 1 is enabled now.
You should choose partition 1 here because this is your boot partition.
Almost there! So the Raspi can "see" the boot partition, it needs to be of a specific type. Remember that a partition and a filesystem are two completely different things. Setting a partition type has nothing to do with the filesystem.
You can change the type like so:
Command (m for help): t
Partition number (1,2, default 2): 1
Hex code or alias (type L to list all): c
Changed type of partition 'Linux' to 'W95 FAT32 (LBA)'.
Now, there's only one last thing to do:
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
➜ ~
Writing! If you didn't make a backup until now, then you, my friend, fucked up.
That's it for fdisk! Now create the filesystems.
- First must be FAT32. This is where Alpine boots from.
➜ ~ sudo mkfs.vfat /dev/sda1
mkfs.fat 4.2 (2021-01-31)
Easy as that.
- You can choose any filesystem that Alpine supports here. I chose
ext4because why not and because Alpine uses it by default. One thing to note is that^has_journal. This turns offext4's "journaling" feature. That means that never ever something get written to the SD card by Alpine and therefore extending its insulting lifespan.
➜ ~ sudo mkfs.ext4 -O ^has_journal /dev/sda2
mke2fs 1.47.0 (5-Feb-2023)
Creating filesystem with 1884416 4k blocks and 471424 inodes
Filesystem UUID: bd211573-c4e3-4d7f-a1f5-f874553d0c9f
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632
Allocating group tables: done
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
I've just used my DEs archive tool but if you are keen on it you can do it like that on the console (not tested):
sudo mount /dev/sda1 /mnt
cd /mnt
sudo tar xzf /path/to/your/alpine.tar.gz
cd ~
sudo umount /mnt
If you're using your DEs archive tool too, make sure you don't create a folder. All files and folders inside the .tar.gz must be in the partition's root.
sudo mount /dev/sda2 /mnt
cd /mnt
sudo cp ~/Downloads/asgs.sdrgeek.local.apkovl.tar.gz .
You need to create a cache directory for your apks.
sudo mkdir cache
Now you'll need to create your wifi credentials file:
wpa_passphrase <SSID> | sudo tee wpa_supplicant.conf
Don't forget to unmount and you're GTG.
cd ~
sudo umount /mnt
You thought you're done? HAHAHAHA, nope.
Let's move on with the post-installation. First boot the Raspberry Pi and connect to it. You can find it's IP address in 3 ways:
- You don't: just
ssh root@asgs.sdrgeek.local. Note that not all networks support this kind of setup. - Open your router's web interface and look for it in the DHCP client list using either the hostname or MAC address. (MACs may start with:
D8-3A-DD,DC-A6-32,E4-5F-01,28-CD-C1,B8-27-EBor2C-CF-67) - Connect a monitor to your Pi. It'll tell you it's IP address during boot.
Connect to it using ssh root@<IP or hostname>. The password is asgs.
You'll have to change some things, namely the credentials and URL to your cloud, it's certificate and your coordinates.
Let's start with the easy stuff: credentials and URL. You can find the credentials inside /etc/davfs2/secrets.
nano /etc/davfs2/secrets
Scroll down until you see a line starting with /root/asgs-data. Replace the username and password with your own. You can exit nano using Ctrl+o, then Enter and Ctrl+x
Next up: the URL. Unfortunately that's in another file.
nano /etc/fstab
On the last line only change the URL and leave the rest as is. Note that your cloud must support WebDAV (NextCloud).
Now the certificate. You only need to do this step if your cloud supports HTTPS (it really should) and isn't signed by a known authority (Let's Encrypt).
openssl s_client -connect HOSTNAME.at:443 -showcerts </dev/null 2>/dev/null | openssl x509 -outform PEM > cloud_cert.pem
sudo cp cloud_cert.pem /etc/davfs2/certs/
The last step is to change your coordinates used by SatDump. Just nano /root/autotrack.json and change lines 11-13.
Up until now everything is saved in RAM. That means if you would reboot now, everything you just did would be gone. You can save your changes using lbu commit. This takes around 10 seconds.
And finally: reboot now
You can find the logs over at /var/log/satdump.err.
The service file is inside /etc/init.d/satdump and you can control it using service satdump start/stop/restart/status.
You can contact me directly or find me in the SatDump space.