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From Wido den Hollander <w...@widodh.nl>
Subject Re: kvm: /var/log/cloudstack/agent/agent.log is a binary file
Date Thu, 05 Sep 2019 06:08:14 GMT


On 9/3/19 2:55 PM, Daan Hoogland wrote:
> On Tue, Sep 3, 2019 at 2:22 PM Wido den Hollander <wido@widodh.nl> wrote:
> 
>>
>>
>> On 9/3/19 9:57 AM, Daan Hoogland wrote:
>>> Can you find/look at the line before in the log. It is probably the one
>>> containing the hindering data. Or otherwise it *might* be a clue where in
>>> the flow it happens.
>>>
>>
>> Do you have any idea what the easiest way might be?
>>
> In short, no, but.. in totally skewed order of alleged quickness
> 1: I'm afraid it is a line by line analysis. If you are lucky the line
> start with date and class name is not obscured and there is a newline
> entered in the log. That would give you the exact location. when in bad
> luck the binary data contains control chars that erase to beginning of line
> or so and the best you can find is the previous and next lines.
> 3: code analysis; My first thought is that some binary data is read from a
> file or a socket and logged as is. but starting this with code analysis is
> not the quickest way to get to the culprit I imagine.
> 2: Other than line by line log analysis and if you can reproduce the issue,
> you could try zooming in by playing around with log levels for different
> classes.
> 

I checked, but on all hypervisors I checked the "agent.log" contains
binary data, but all the rotated (.gz) files do not.

The binary data is at the beginning of the file(s). So it seems like it
is logrotate and maybe a combination of log4j causing this?

I'm not sure yet, but that seems to be the case.

Wido

> 
>>
>> I checked agent.log.1.gz and after I decompress is that file is not
>> binary, text only.
>>
> so much for reproducibilty. Hope it was not a buffer overflow hack attempt.
> 
> 
>>
>> The binary data only seems to be present in the current file.
>>
>> Wido
>>
>>> On Tue, Sep 3, 2019 at 8:22 AM Wido den Hollander <wido@widodh.nl>
>> wrote:
>>>
>>>>
>>>>
>>>> On 9/2/19 10:18 PM, Wei ZHOU wrote:
>>>>> Hi Wido,
>>>>>
>>>>> I had similar issue (not agent.log). It is probably caused by one or
>>>> few> lines with special characters.
>>>>
>>>> And I'm trying to figure out what causes it :-)
>>>>
>>>>> "grep -a" should work.
>>>>
>>>> I know, but other tools which analyze the logfile might also have
>>>> trouble reading the file due to binary characters.
>>>>
>>>> Wido
>>>>
>>>>>
>>>>> -Wei
>>>>>
>>>>> On Mon, 2 Sep 2019 at 19:35, Wido den Hollander <wido@widodh.nl>
>> wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> I've seen this on multiple occasions with Ubuntu 18.04 (and maybe
>>>>>> 16.04?) hypervisors where according to 'grep' the agent.log is a
>> binary
>>>>>> file:
>>>>>>
>>>>>> root@n06:~# grep security_group /var/log/cloudstack/agent/agent.log
>>>>>> Binary file /var/log/cloudstack/agent/agent.log matches
>>>>>> root@n06:~#
>>>>>>
>>>>>> If I open the file with 'less' I indeed see binary data.
>>>>>>
>>>>>> Tailing the file works just fine.
>>>>>>
>>>>>> Does anybody know where this is coming from? What in the CloudStack
>>>>>> agent causes it to write binary data to the logfile?
>>>>>>
>>>>>> Wido
>>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>
> 
> 

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