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The python implemention of MagickWand, aptly named Wand, requires ImageMagick and MagickWand installed. While building docker images using the python:alpine base images, these dependencies can be installed through:

ENV MAGICK_HOME=/usr
RUN apk add --no-cache imagemagick && \
apk add --no-cache imagemagick-dev

The first one is required for Wand to find the installed MagickWand libraries, while the second installs the imagickmagick development dependencies (and thus, the magickwand shared library).

After digging through this issue for _at least_ four hours today, I’ve revisited an issue that crept up 1,5 years ago. This time I found out that it actually happened to most 32-bit programs launched under cmd. Since the Android SDK’s utilities are compiled in 32-bit mode by default, this time I had to actually find out what was causing the issue.

Turns out it was ansicon.exe. After starting the 32-bit cmd.exe from windows\SysWOW64 and stuff worked – I discovered I got an error about ansicon.exe not being able to load. Removing ansicon.exe completely solved the problem. I’m .. stunned.

After stumbling over a question on stackoverflow about how you’d use python-gearman for checking the current status of a running background task, I decided to dig a bit deeper into python-gearman and .. well, answer how you’d do just that.

It turns out it wasn’t as straight forward as it should have been, but at least I managed to solve it by using the current API. First of all you’ll have to keep track of which Gearman server gets your task, and what handle it has assigned to the task. These two values identify a current running task, and since the identifiers (handle) isn’t globally unique, you’ll also have to keep track of the current server (so you know where to ask).

To request the current status of a long running task you’ll have to create appropriate instances of the GearmanJob and GearmanJobRequest yourself.

Here’s a small example of how you can do this:

import gearman
    
client = gearman.GearmanClient(['localhost'])
result = client.submit_job('reverse', 'this is a string', background=True);

The connection information is available through result.job.connection (.gearman_host and .gearman_port), while the handle is available through result.job.handle.

To check the status of a currently running job you create a GearmanClient, but only supply the server you want to query for the current state:

client = gearman.GearmanClient(['localhost'])

# configure the job to request status for - the last four is not needed for Status requests.
j = gearman.job.GearmanJob(client.connection_list[0], result.job.handle, None, None, None, None)

# create a job request 
jr = gearman.job.GearmanJobRequest(j)
jr.state = 'CREATED'

# request the state from gearmand
res = client.get_job_status(jr)

# the res structure should now be filled with the status information about the task
print(str(res.status.numerator) + " / " + str(res.status.denominator))

That should at least solve the problem until python-gearman gets an easier API to do these kinds of requests.

Update: I’ve also added a convenience function to my python-gearman fork at github.

While attempting to add torrents to a closed tracker I needed the info_hash structure for a given torrent file, as this is what the tracker uses to identify a given torrent file. I tried searching the regular sources but came up empty (I later discovered that btshowmetainfo from the original python bittorrent client package also shows the calculated info_hash for a torrent file), so I wrote a simple python script for all your shell scripting or command line needs.

#!/usr/bin/python
import bencode, BTL, hashlib, sys

if (len(sys.argv) < 2):
    sys.stderr.write("Usage: " + sys.argv[0] + " \n")
    sys.exit()

try:
    with open(sys.argv[1], "rb") as torrent_file:
        try:
            bstruct = bencode.bdecode(torrent_file.read())

            if 'info' in bstruct:
                print(hashlib.sha1(bencode.bencode(bstruct['info'])).hexdigest())
            else:
                sys.stderr.write("Did not find an info element in the torrent file.\n")
                sys.exit()
        except BTL.BTFailure:
          sys.stderr.write("Torrent file did not contain a valid bencoded structure.\n")
          sys.exit()
except IOError as e:
    sys.stderr.write("Could not open file: " + str(e) + "\n")
    sys.exit()

This depends on the bencode.py and BTL.py from the bencode python package (their .eggs are borked, so you’ll have to copy the two .py files yourself after downloading the source file).