Hi,
We are having parallel mail chains so i will paste David's input here and share my inputs. Rainer's mail added in "" 1) "Your contribution is happily accepted at https://github.com/rsyslog/rsyslog-doc -" [[LAK]]: I will take time and share my inputs for this. You guys are doing so much, i really appreciate that. 2) "I would really like to understand why you think global constants (there are NOT variable, right?) would make sense. Maybe we are overlooking something... " [[LAK]]: I called them variables because that is what they were called in David's document. https://www.usenix.org/publications/login/october-2013-volume-38-number-5/log-filtering-rsyslog We can call them as constants as they are not run-time modifiable. 3) Regarding the backticks option. [[Lak]]: Does it support pipes and awk. Say i have rsyslogserver_config_file with content as IPADDRESS1=10.40.60.50 IPADDRESS2=10.50.70.60 `grep IPADDRESS1 rsyslogserver_config_file| awk -F= '{print $2}'` -- Does this work? 4) "I would really like to understand why you think global constants (there are NOT variable, right?) would make sense. Maybe we are overlooking something..." [[LAK]]: I felt that global constants could be part of one of the config files loaded when rsyslogd starts or restarted. that way they are still part of rsyslogd. May be an example of how and where global constants must be used can enlighten me and others like me. David's mail enclosed below and my responses are inline: 1) When you are already editing the config file and restarting syslog to implement your change, why should we suffer the cost of making this a variable? [[Lak]]: We can merge bullet-3 and bullet-4 above. Backticks provides an alternate way. Current document opens up lot of questions as to what all one can do with that. Is the current support extended to everything that can be done using backticks. Note, i could write whole bunch of script and run it using backticks. It could have ';' and is that acceptable. It's not just the cost of a variable lookup, it's the cost of maintaining a table of connectons, expiring them, figuring out how to re-use connections, etc. We do this with filenames using the dynafile mechanism, and it's a significant enough overhead that it has to be explicitly opted in to each time it's used (and misuse of this feature and it's settings is a very common cause of horrifically bad performance) [[LAK]]: Recommended usage in the document and references to tickets which caused bad performance due to bad usage can help users understand it better and not repeat the mistakes. sending to a wide variety of destinations is just not that common a use case, and when people are doing it (high volume systems distributing load), they don't want to pay the overhead. And even there, it's very unusual for there to be more than a handful of destinations, so simple if-then-else nested outputs handle the job. [[LAK]]: But configuring the remote syslog server, changing the severity of the logs to be streamed should be and is configurable. Since we have scripting option, I could use the following mechanism. set $.configuredSeverity = "6"; ($syslogseverity <= $.configuredSeverity) There can be multiple configuration files each filter certain set of logs based on their properties (Severity, process-name, msg content, etc). With separate configuration files I could achieve modularity by separating application processes from platform processes. Allowing the user to have different severity for each of them. One common variable among all the configuration files is the target IP and port. So instead of setting it in each config file, i thought of using GLOBAL variable. I will explore the Backticks option today. ________________________________ From: Rainer Gerhards <[email protected]> Sent: Tuesday, April 24, 2018 12:01 PM To: putcha narayana Cc: rsyslog-users; David Lang Subject: Re: [rsyslog] Urgent, need help with correct usage of local variables in an action 2018-04-24 13:38 GMT+02:00 putcha narayana <[email protected]<mailto:[email protected]>>: 😊 wasn't me. so that makes 2 of us asking for same lol. i think, using global variable would have kept the export and backtick options out of the rsyslogd. But i am sure the support was provided after careful consideration and requests from others. Actually, I still don't understand why this is helpful. After all, that means you need to *edit* the rsyslog configuration. That's actually what your script does when it modifies the local variables. So you need to mess up with the config in any case. With the backticks approach, all is done outside of the actual config, and actually this was the design goal - keep the config read only, so you can ship a standard config for your application and have an external file that just adds the special bits. I would really like to understand why you think global constants (there are NOT variable, right?) would make sense. Maybe we are overlooking something... the link https://www.rsyslog.com/doc/master/rainerscript/constant_strings.html is missing info on when to us them. https://github.com/rsyslog/rsyslog-docker/tree/master/appliance/alpine provides one example. may be having references from action and other places where it can be used could help. or a short explanation in the constant_strings section about usage and examples will help too. i felt that gap that each section is missing that short list of examples. i bet not all scenarios can be covered with examples but a short list of plausible alternatives can help to a great extent. Your contribution is happily accepted at https://github.com/rsyslog/rsyslog-doc - really, not kidding. There is so much to do, we depend on contributions (especially on the doc, as e.g. from my perspective I really don't come up with the questions new users might have)... Rainer ________________________________ From: Rainer Gerhards <[email protected]<mailto:[email protected]>> Sent: Tuesday, April 24, 2018 11:11 AM To: putcha narayana Cc: rsyslog-users; David Lang Subject: Re: [rsyslog] Urgent, need help with correct usage of local variables in an action You can also have a look here - came in co-incidentely (or was it you? ;-)): https://unix.stackexchange.com/questions/439286/how-to-set-and-use-constants-in-rsyslog-rainerscript/ [https://cdn.sstatic.net/Sites/unix/img/[email protected]?v=32fb07f7ce26]<https://unix.stackexchange.com/questions/439286/how-to-set-and-use-constants-in-rsyslog-rainerscript/> How to set and use constants in rsyslog (RainerScript)?<https://unix.stackexchange.com/questions/439286/how-to-set-and-use-constants-in-rsyslog-rainerscript/> unix.stackexchange.com<http://unix.stackexchange.com> I'm writing an application which includes an rsyslog configuration which gets placed in /etc/rsyslog.d/. Certain logmessages should be redirected to a named pipe, like so: template (name="my_fmt"... Rainer 2018-04-24 12:56 GMT+02:00 Rainer Gerhards <[email protected]<mailto:[email protected]>>: > Looking at your script, I wonder why you make it so complicated. You > replace the local variable via sed anyway. Why not simply replacing > the name inside the action target? > > Rainer > > 2018-04-24 10:47 GMT+02:00 putcha narayana > <[email protected]<mailto:[email protected]>>: >> Hello Rainer, >> >> >> I shared an example of the mechanism i planned to employ. I understand that >> my mechanism cannot be achieved with the current rsyslogd. There is no hard >> and fast rule to only use the mechanism i shared. >> >> >> I will be happy to employ an alternate working mechanism. Now that my end >> goal is clear, please share some example for the alternate methods, i will >> employ them. >> >> >> Appreciate your help. >> >> >> Thanks and Regards >> >> Lak. >> >> >> ________________________________ >> From: Rainer Gerhards >> <[email protected]<mailto:[email protected]>> >> Sent: Tuesday, April 24, 2018 8:43 AM >> To: putcha narayana >> Cc: rsyslog-users; David Lang >> >> Subject: Re: [rsyslog] Urgent, need help with correct usage of local >> variables in an action >> >> Well, there are ways to do this, just not like you want ;-) >> >> Environment variables and files is the way to go. >> >> Rainer >> >> Sent from phone, thus brief. >> >> putcha narayana <[email protected]<mailto:[email protected]>> >> schrieb am Di., 24. Apr. 2018, >> 10:32: >> >> I believe it will be a good useful feature to allow users to define >> local/global variables so that update in individual conf file or one place >> update of global variables will enable configuring the external server IP >> and Port. >> >> >> I plan to use a static IP in the .66-MgmtMsgsLogging.conf. >> >> When IP and Port are updated then using the script i will replace them. >> >> When enable option is given then the comment in front of action will be >> removed. >> >> To disable add the # back. >> >> >> #action(type="omfwd" Target="10.10.10.10" Port="0" Protocol="udp" >> Template="ForwardFormat") >> #action(type="omfwd" Target="11.11.11.11" Port="0" Protocol="udp" >> Template="ForwardFormat") >> >> >> Thanks and Regards >> >> Lak. >> >> >> >> >> >> ________________________________ >> From: Rainer Gerhards >> <[email protected]<mailto:[email protected]>> >> Sent: Tuesday, April 24, 2018 8:23 AM >> To: rsyslog-users >> Cc: David Lang; putcha narayana >> Subject: Re: [rsyslog] Urgent, need help with correct usage of local >> variables in an action >> >> Of you insist on using local variables, the answer is: no, this does not >> work. >> >> Rainer >> >> Sent from phone, thus brief. >> >> putcha narayana via rsyslog >> <[email protected]<mailto:[email protected]>> schrieb am >> Di., 24. >> Apr. 2018, 10:08: >> >> Hi, >> >> >> I am not requesting for script to update the config file. I have already >> implemented that. I have attached the shell script and a sample config file. >> >> >> I am seeking help w.r.t the config file with a provision to use local >> variables so that they can be updated/configurable by user. >> >> >> Thanks and Regards >> >> Lak. >> >> >> ________________________________ >> From: David Lang <[email protected]<mailto:[email protected]>> >> Sent: Tuesday, April 24, 2018 6:59 AM >> To: putcha narayana >> Cc: David Lang; putcha narayana via rsyslog >> Subject: Re: [rsyslog] Urgent, need help with correct usage of local >> variables in an action >> >> This cannot be done inside rsyslog, you would need to use some external >> software >> (puppet, chef, salt, ansible, or even just sed) to change the config file >> and >> then start/restart rsyslog >> >> On Tue, 24 Apr 2018, putcha narayana wrote: >> >>> Date: Tue, 24 Apr 2018 06:47:03 +0000 >>> From: putcha narayana >>> <[email protected]<mailto:[email protected]>> >>> To: David Lang <[email protected]<mailto:[email protected]>>, >>> putcha narayana via rsyslog >>> <[email protected]<mailto:[email protected]>> >>> Subject: Re: [rsyslog] Urgent, >>> need help with correct usage of local variables in an action >>> >>> Hi, >>> >>> >>> In our design we have a GUI where operator can configure the IP and Port >>> of the remote syslog server. Operator can enable or disable streaming to the >>> configured IP and Port using a flag. >>> >>> >>> In the backend we will consume the configuration made by the operator and >>> prepare the required configuration file to stream logs to the configured >>> remote syslog server (Identified by IP and Port). >>> >>> >>> 1) In the design i chose, I plan to have initial config files prefixed >>> with '.' so that those config files will not be read by rsyslogd. >>> >>> Example config file is enclosed below. >>> >>> 2) When operator configures the IP, Port, then a script will be invoked in >>> the background which will update the initial set of lines that define the >>> local variables. Say set $.IPADDRESS1 = ""; will be updated as set >>> $.IPADDRESS1 = "10.10.100.200"; >>> >>> 3) Config file updated will be saved without the '.' prefix. restarting >>> rsyslod will/should apply the configuration (i.e., stream logs to remote >>> syslog server 10.10.100.200. >>> >>> >>> Example config file with 2 remote syslog servers for illustration purpose: >>> >>> set $.IPADDRESS1 = ""; >>> set $.IPADDRESS2 = ""; >>> set $.PORTNUMBER1 = ""; >>> set $.PORTNUMBER2 = ""; >>> >>> if ($syslogseverity-text == 'info') >>> then >>> { >>> action(type="omfwd" Target="$.IPADDRESS1" Port="$.PORTNUMBER1" >>> Protocol="udp" Template="ForwardFormat") >>> action(type="omfwd" Target="$.IPADDRESS2" Port="$.PORTNUMBER2" >>> Protocol="udp" Template="ForwardFormat") >>> stop >>> } >>> >>> >>> Please guide me if the same can be achieved using alternate mechanisms. >>> >>> >>> thanks and regards >>> >>> Lak. >>> >>> >>> >>> ________________________________ >>> From: David Lang <[email protected]<mailto:[email protected]>> >>> Sent: Tuesday, April 24, 2018 5:36 AM >>> To: putcha narayana via rsyslog >>> Cc: Rainer Gerhards; putcha narayana >>> Subject: Re: [rsyslog] Urgent, need help with correct usage of local >>> variables in an action >>> >>> target and port cannot be variables, variables can only be used where they >>> are >>> explicitly allowed (almost entirely in templates) >>> >>> let's back up a bit and ask what you are trying to do rather than why this >>> specific approach doesn't work. >>> >> _______________________________________________ >> rsyslog mailing list >> http://lists.adiscon.net/mailman/listinfo/rsyslog >> http://www.rsyslog.com/professional-services/ >> What's up with rsyslog? Follow https://twitter.com/rgerhards >> NOTE WELL: This is a PUBLIC mailing list, posts are ARCHIVED by a myriad of >> sites beyond our control. PLEASE UNSUBSCRIBE and DO NOT POST if you DON'T >> LIKE THAT. _______________________________________________ rsyslog mailing list http://lists.adiscon.net/mailman/listinfo/rsyslog http://www.rsyslog.com/professional-services/ What's up with rsyslog? Follow https://twitter.com/rgerhards NOTE WELL: This is a PUBLIC mailing list, posts are ARCHIVED by a myriad of sites beyond our control. PLEASE UNSUBSCRIBE and DO NOT POST if you DON'T LIKE THAT.
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