Logrotation throu CATALINA_OUT_CMD in Tomcat9

[Peter Rader <p....@gmx.net.INVALID>]

Hi,

my catalina.out is getting bigger and bigger.

In order to have smaller catalina.out I noticed this environment-variable: CATALINA_OUT_CMD

Inside the catalina.sh is documented:

# CATALINA_OUT_CMD (Optional) Command which will be executed and receive
#                   as its stdin the stdout and stderr from the Tomcat java
#                   process. If CATALINA_OUT_CMD is set, the value of
#                   CATALINA_OUT will be used as a named pipe.
#                   No default.
#                   Example (all one line)
#                   CATALINA_OUT_CMD="/usr/bin/rotatelogs -f $CATALINA_BASE/logs/catalina.out.%Y-%m-%d.log 86400"

I try to use that example and export this variable before start of tomcat:

   export CATALINA_OUT_CMD="/usr/bin/rotatelogs -f /home/tomcat/apache-tomcat-9.0.75/logs/catalina.out.%Y-%m-%d.log 86400" 

Unfortunately the tomcat does not work anymore, instead this message appear:

    /home/tomcat/apache-tomcat-9.0.75/logs/catalina.out exists and is not a named pipe. Start aborted.
 
Any Ideas?
 
Kind regards

Peter Rader

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Aw: Re: Logrotation throu CATALINA_OUT_CMD in Tomcat9

[Peter Rader <p....@gmx.net.INVALID>]

> You need to do what the instructions state: create a FIFO and specify its name in the CATALINA_OUT variable. For example, do

Ah, yes,

    mkfifo catalina.out

fixed it for me. I had no idea what a fifo is, now I knew.

Kind regards

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Re: Logrotation throu CATALINA_OUT_CMD in Tomcat9

[Chuck Caldarale <n8...@gmail.com>]

> On May 15, 2024, at 12:43, Peter Rader <p....@gmx.net.INVALID> wrote:
> 
> my catalina.out is getting bigger and bigger.


(I should Insert a philosophical discussion on not using stdout for application logging here, but I’ll leave that for some other time.)


> In order to have smaller catalina.out I noticed this environment-variable: CATALINA_OUT_CMD
> 
> Inside the catalina.sh is documented:
> 
> # CATALINA_OUT_CMD (Optional) Command which will be executed and receive
> #                   as its stdin the stdout and stderr from the Tomcat java
> #                   process. If CATALINA_OUT_CMD is set, the value of
> #                   CATALINA_OUT will be used as a named pipe.
> #                   No default.
> #                   Example (all one line)
> #                   CATALINA_OUT_CMD="/usr/bin/rotatelogs -f $CATALINA_BASE/logs/catalina.out.%Y-%m-%d.log 86400"
> 
> I try to use that example and export this variable before start of tomcat:
> 
>   export CATALINA_OUT_CMD="/usr/bin/rotatelogs -f /home/tomcat/apache-tomcat-9.0.75/logs/catalina.out.%Y-%m-%d.log 86400" 
> 
> Unfortunately the tomcat does not work anymore, instead this message appear:
> 
>    /home/tomcat/apache-tomcat-9.0.75/logs/catalina.out exists and is not a named pipe. Start aborted.


You need to do what the instructions state: create a FIFO and specify its name in the CATALINA_OUT variable. For example, do

mkfifo logs/catalina_out.pipe

one time, before starting Tomcat, then add the following to bin/setenv.sh:

export CATALINA_OUT="$CATALINA_HOME/logs/catalina_out.pipe"
export CATALINA_OUT_CMD=“rotatelogs -f $CATALINA_HOME/logs/catalina.out.%Y-%m-%d.log 86400"

This causes Tomcat to use the named pipe rather than logs/catalina.out for stdout and stderr messages, and then invoke rotatelogs to process the entries. As an alternative to setting CATALINA_OUT, you could just delete the existing logs/catalina.out file and recreate it as a FIFO, but I wouldn’t recommend it due to potential confusion.

  - Chuck