After installing the latest stable version of docker-ce (5:18.09.0~3-0~raspbian-stretch as of the time of writing), Docker would take ages to start after a reboot. Commands would even time out waiting for it.

/var/log/daemon.log shows a gap of almost 4 minutes between the attempt to start the Docker Application Container Engine and the first log line from dockerd.

Jul  5 10:10:37 RPi systemd[1]: Starting Docker Application Container Engine...
Jul  5 10:14:07 RPi dockerd[683]: time="2019-07-05T10:14:07.808215720+02:00" level=info msg="parsed scheme: \"unix\"" module=grpc

After installing a later version of docker-ce from the test branch in attempt to remedy this, I got an interesting message while the issue persisted:

Jul  5 10:42:18 RPi systemd[1]: Starting Docker Application Container Engine...
Jul  5 10:43:30 RPi dockerd[720]: crypto/rand: blocked for 60 seconds waiting to read random data from the kernel
Jul  5 10:47:27 RPi dockerd[720]: time="2019-07-05T10:47:27.245479521+02:00" level=info msg="Starting up"

Turns out it doesn’t have enough random entropy to start. We can help the Pi generate this by running haveged. A quick apt-get install haveged and a reboot later, the logs look much better, and Docker starts immediately.

# apt-get install haveged
...
# reboot

The result, after downgrading to the stable version of Docker again:

Jul  5 11:08:02 RPi systemd[1]: Starting Docker Application Container Engine...
Jul  5 11:08:06 RPi dockerd[707]: time="2019-07-05T11:08:06.793516408+02:00" level=info msg="parsed scheme: \"unix\"" module=grpc

From 4 minutes to 4 seconds is a rather significant improvement, I think 🙂

Tasked with recovering files you don’t have access to through the web interface, you can always find these through the file system if you’re the operator. You could, of course, give yourself access, but let’s save that for another time. Right now we want the files our users removed and/or can’t find.

We start by looking for them in Owncloud’s data directory.

# find /mnt/data/owncloud/ -name "AWOL Excel file.xlsm*"
/mnt/data/owncloud/files/user/files_versions/Important/Stuff/AWOL Excel file.xlsm.v1542980717
/mnt/data/owncloud/files/user/files_versions/Important/Stuff/AWOL Excel file.xlsm.v1542029758
/mnt/data/owncloud/files/user/files_versions/Important/Stuff/AWOL Excel file.xlsm.v1542303810
/mnt/data/owncloud/files/user/files_versions/Important/Stuff/AWOL Excel file.xlsm.v1542631862
/mnt/data/owncloud/files/user/files_versions/Important/Stuff/AWOL Excel file.xlsm.v1541686827
/mnt/data/owncloud/files/user/files_versions/Important/Stuff/AWOL Excel file.xlsm.v1543226434
/mnt/data/owncloud/files/user/files_versions/Important/Stuff/AWOL Excel file.xlsm.v1542889051
/mnt/data/owncloud/files/user/files_versions/Important/Stuff/AWOL Excel file.xlsm.v1541775363
/mnt/data/owncloud/files/user/files_versions/Important/Stuff/AWOL Excel file.xlsm.v1542722172
/mnt/data/owncloud/files/user/files_versions/Important/Stuff/AWOL Excel file.xlsm.v1541922874

Oh hey, there they are!

So, now we could simply copy them and ship them to our user, but let’s be a bit more fancy, since we can.

# FILE_SUFFIX=".xlsm"
# find /mnt/data/owncloud/ -name "AWOL Excel file.xlsm*" |
>   grep -E "\.v[0-9]+(\.d[0-9]+)?$" |
>   while read -r file; do
>       ts="${file##*.v}"; ts="${ts%.*}";
>       date=$(date --date="@${ts}" +"%Y%m%dT%H%M%S")
>       base="$(basename "${file%.v*}")"
>       name="${base%${FILE_SUFFIX:-}}"
>       echo "${name}-${date}${FILE_SUFFIX:-}"
>   done
AWOL Excel file-20181123T134517.xlsm
AWOL Excel file-20181112T133558.xlsm
AWOL Excel file-20181115T174330.xlsm
AWOL Excel file-20181119T125102.xlsm
AWOL Excel file-20181108T142027.xlsm
AWOL Excel file-20181126T100034.xlsm
AWOL Excel file-20181122T121731.xlsm
AWOL Excel file-20181109T145603.xlsm
AWOL Excel file-20181120T135612.xlsm
AWOL Excel file-20181111T075434.xlsm

So that’s the list of our files, with all the names neatly timestamped (translated from the UNIX timestamp at the end of Owncloud’s file names).
Not setting the $FILE_SUFFIX variable will work fine too, but you will end up with names such as “AWOL Excel file.xlsm-20181126T100034”

Now, let’s copy the files to their new names in our current directory.

# FILE_SUFFIX=".xlsm"
# find /mnt/data/owncloud/ -name "AWOL Excel file.xlsm*" |
>   grep -E "\.v[0-9]+(\.d[0-9]+)?$" |
>   while read -r file; do
>       ts="${file##*.v}"; ts="${ts%.*}";
>       date=$(date --date="@${ts}" +"%Y%m%dT%H%M%S")
>       base="$(basename "${file%.v*}")"
>       name="${base%${FILE_SUFFIX:-}}"
>       cp -v "$file" "${name}-${date}${FILE_SUFFIX:-}"
>   done
'/mnt/data/owncloud/files/user/files_versions/Important/Stuff/AWOL Excel file.xlsm.v1542980717' -> 'AWOL Excel file-20181123T134517.xlsm'
'/mnt/data/owncloud/files/user/files_versions/Important/Stuff/AWOL Excel file.xlsm.v1542029758' -> 'AWOL Excel file-20181112T133558.xlsm'
[... and so on ... ]

Cool.

Here it is as a one-liner, which your browser might add a line break to anyway, in case you’re interested:

FILE_SUFFIX=".xlsm"; find /mnt/data/owncloud/ -name "AWOL Excel file.xlsm*" | grep -E "\.v[0-9]+(\.d[0-9]+)?$" | while read -r file; do ts="${file##*.v}"; ts="${ts%.*}"; date=$(date --date="@${ts}" +"%Y%m%dT%H%M%S"); base="$(basename "${file%.v*}")"; name="${base%${FILE_SUFFIX:-}}"; cp -v "$file" "${name}-${date}${FILE_SUFFIX:-}"; done