Increase disk size

[southpolemonkey]

Scenario

The pulled images only has 2G disk space which is set in qemu-img resize raspbian-lite.qcow2 +4G \, and get easily out of space after installing some apps.

pi@raspberrypi:/dev $ df --human-readable
Filesystem      Size  Used Avail Use% Mounted on
/dev/root       1.5G  1.4G  4.2M 100% /
devtmpfs        124M     0  124M   0% /dev
tmpfs           124M     0  124M   0% /dev/shm
tmpfs           124M  1.9M  122M   2% /run
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           124M     0  124M   0% /sys/fs/cgroup
/dev/sda1       253M   53M  200M  21% /boot
tmpfs            25M     0   25M   0% /run/user/1000

Changes I made

I increased the size to 10G in qemu-img resize raspbian-lite.qcow2 +10G \, but the newly built image has the same size as the 2G version.

raspbian.   10g                 8b2e42cc8522        4 minutes ago       8.14GB
hannseman/raspbian    latest              afb4152be6c6        8 weeks ago         8.14GB

Is there any other changes I need to make?

[Lunarequest]

+1 for this. you can't even run apt update.

[aboisvert]

You guys were on the right path but there's a few more things to do after allocating more space on the (virtual) physical disk.

As you noted, by default the allocation size for /dev/sda2 (the root fs) is small ... just 1.5G.

root@raspberrypi:~# fdisk -l | grep /dev/sda2
/dev/sda2       532480 3612671 3080192  1.5G 83 Linux

What needs to be done, is 1) resize/expand the root partition and 2) resize/expand the root file system.

Expand the root partition

1. Run parted /dev/sda
2. Execute the resizepart on the /dev/sda device - resizepart 2
3. For the end of the partition, enter -1 to use all remaining unallocated space.

root@raspberrypi:~# parted /dev/sda
GNU Parted 3.2
Using /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p                                                                
Model: QEMU QEMU HARDDISK (scsi)
Disk /dev/sda: 3997MB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system  Flags
 1      4194kB  273MB   268MB   primary  fat32        lba
 2      273MB   1850MB  1577MB  primary  ext4

(parted) resizepart 2                                                     
End?  [1850MB]? -1                                                        
(parted) p                                                                
Model: QEMU QEMU HARDDISK (scsi)
Disk /dev/sda: 3997MB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system  Flags
 1      4194kB  273MB   268MB   primary  fat32        lba
 2      273MB   3996MB  3724MB  primary  ext4


(parted) q                                                                
Information: You may need to update /etc/fstab.

Expand the root filesystem

Execute resize2fs /dev/sda2 and it will automatically expand to the newly expanded partition size.

root@raspberrypi:~# resize2fs /dev/sda2                                  
resize2fs 1.44.5 (15-Dec-2018)
Filesystem at /dev/sda2 is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
The filesystem on /dev/sda2 is now 909068 (4k) blocks long.

Check the final available filesystem size

root@raspberrypi:~# fdisk -l | grep /dev/sda2
/dev/sda2       532480 7805023 7272544  3.5G 83 Linux

As you can see, by default the docker image allows allocating up to 3.5G which seems sufficient for many uses. You can tweak the physical size as you noted above, by changing this line in the Dockerfile:

qemu-img resize raspbian-lite.qcow2 +2G \

to, e.g.

qemu-img resize raspbian-lite.qcow2 +4G \

to get an extra 2G allocated (for a new total of 5.5G).

[mbouadeus]

Thank you so much for the detailed explanation!