This commit removes the complex pipeline leveraging output from
/dev/urandom and simply uses $RANDOM variable. For the purpose
of generating an available container name, it will works well.
Suggested-by: Matt McCormick <matt.mccormick@kitware.com>
As explained in [1], when using dockcross from python subprocess, the
interactive mode is disabled and output of "cat /dev/urandom" is block
buffered instead of being line buffered.
Workaround to this problem is to simply read a fixed amount of characters
from urandom.
The following two snippets illustrates the problem and the
the implemented solution:
Works
```python
import subprocess as sp
sp.check_call("var=$(head -c 500 /dev/urandom | base64 | tr -dc 'a-zA-Z0-9' | fold -w 7 | head -n 1); echo $var", shell=True)
```
=> output random string
Fail:
```python
import subprocess as sp
sp.check_call("var=$(cat /dev/urandom | base64 | tr -dc 'a-zA-Z0-9' | fold -w 7 | head -n 1); echo $var", shell=True)
```
=> Hang
[1] http://stackoverflow.com/questions/16805827/unable-to-read-stdout-from-a-running-process#16806506
where RAND is a 7 characters long randomly generated alphanumeric string.
Note that container name can NOT start with "_",
only [a-zA-Z0-9][a-zA-Z0-9_.-] are allowed
See #50
