Supervisor series: 5. Log

supervisor series ：5、 journal

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List of articles

• ​ ​supervisor series ：5、 journal ​​

• ​ ​1. Activity log ​​

• ​ ​1.1 Example of activity log output ​​
• ​ ​1.2 Activity log level ​​
• ​ ​1.3 Activity log rotation ​​

• ​ ​2. Child process log ​​

• ​ ​2.1 Capture mode ​​

supervisord One of the main tasks performed is logging .

supervisord An activity log will be recorded , Describe in detail what it does at runtime . It also sub processes stdout and stderr Output records to other files ( If configured to do so ).

1. Activity log

Activity log is supervisord Record your health 、 Sub process status changes 、 Any messages generated by the event, as well as debugging and information messages . The path of the activity log is through the configuration file ​​[supervisord]​​​ In section ​​logfile​​​ Parameter configuration , The default is ​​$CWD/supervisord.log​​​. If the value of this option is a special string ​​syslog​​, Then the activity log will be routed to syslog service , Instead of writing to a file . An example of activity log traffic is shown below . In order to better adapt to the screen , Some lines are broken .

1.1 Example of activity log output

Log in and copy

      
      

       
       2007-09-08 14:43:22,886 DEBG 127.0.0.1:Medusa (V1.11) started at Sat Sep  8 14:43:22 2007
       
       
        Hostname: kingfish
       
       
        Port:9001
       
       
2007-09-08 14:43:22,961 INFO RPC interface 'supervisor' initialized
       
       
2007-09-08 14:43:22,961 CRIT Running without any HTTP authentication checking
       
       
2007-09-08 14:43:22,962 INFO supervisord started with pid 27347
       
       
2007-09-08 14:43:23,965 INFO spawned: 'listener_00' with pid 27349
       
       
2007-09-08 14:43:23,970 INFO spawned: 'eventgen' with pid 27350
       
       
2007-09-08 14:43:23,990 INFO spawned: 'grower' with pid 27351
       
       
2007-09-08 14:43:24,059 DEBG 'listener_00' stderr output:
       
       
 /Users/chrism/projects/supervisor/supervisor2/dev-sandbox/bin/python:
       
       
 can't open file '/Users/chrism/projects/supervisor/supervisor2/src/supervisor/scripts/osx_eventgen_listener.py':
       
       
 [Errno 2] No such file or directory
       
       
2007-09-08 14:43:24,060 DEBG fd 7 closed, stopped monitoring <PEventListenerDispatcher at 19910168 for
       
       
 <Subprocess at 18892960 with name listener_00 in state STARTING> (stdout)>
       
       
2007-09-08 14:43:24,060 INFO exited: listener_00 (exit status 2; not expected)
       
       
2007-09-08 14:43:24,061 DEBG received SIGCHLD indicating a child quit
      
      
      
      

       
       
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Activity log “level” In the configuration file ​​[supervisord]​​​ini In the document section ​​loglevel​​​ Parameter configuration . Set up ​​loglevel​​​ after , Messages with a specified priority and messages with a higher priority will be recorded in the activity log . for example , If ​​loglevel​​​ by ​​error​​​, Will record ​​error​​​ and ​​critical​​​ Priority messages . however , If ​​loglevel​​​ by ​​warn​​​, Will record ​​warn​​​、​​error​​​ and ​​critical​​ news .

1.2 Activity log level

The following table describes log levels in more detail , Sort from the highest priority to the lowest priority .“ Profile values ” Is in the configuration file ​​[supervisord]​​​ Partially provided to ​​loglevel​​ String for parameter ,“ Output code ” Is the code displayed in the output line of the activity log .

Profile values	Output encoding	describe
critical	CRIT	Indicates the conditions that require the user's immediate attention 、 Message of administrator status change or administrator's own error .
error	ERRO	A message indicating a potentially negligible error condition ( for example , Unable to clear the log directory ).
warn	WARN	Indicates an abnormal condition ( It's not a mistake ) The news of .
info	INFO	Normal information output . If the log level is not explicitly configured , Then this is the default log level .
debug	DEBG	For trying to debug process configuration and communication behavior ( Process output 、 Listener state changes 、 Event notification ) Useful messages for users .
trace	TRAC	Useful messages for developers trying to debug management plug-ins , And about the HTTP and RPC Request and response information .
blather	BLAT	Yes, try debugging supervisor Useful news for its own developers .

1.3 Activity log rotation

According to the configuration file ​​[supervisord]​​​ In section ​​logfile_maxbytes​​​ and ​​logfile_backups​​ Combination of parameters ,supervisord The activity log will be rotated . When the activity log reaches ​​logfile_maxbytes​​​ Byte time , The current log file will be moved to the backup file , And create a new activity log file . When this happens , If the number of existing backup files is greater than or equal to ​​logfile_backups​​​, Delete the oldest backup file , And rename the backup file accordingly . If the file name being written is ​​supervisord.log​​​, When it exceeds ​​logfile_maxbytes​​​ when , It will be closed and renamed ​​supervisord.log.1​​​, If the file ​​supervisord.log.1​​​, ​​supervisord.log.2​​​ And so on already exist , Then rename it to ​​supervisord.log.2​​​, ​​supervisord.log.3​​​ etc. . If ​​logfile_maxbytes​​​ by 0, Log files will never be converted ( So never back up ). If ​​logfile_backups​​ by 0, Do not keep any backups .

2. Child process log

By default , Will catch supervisor The standard output of the generated subprocess , So that it can be redisplayed to ​​supervisorctl​​​ And other client users . If the ​​[program:x]​​​,​​[fcgi-program:x]​​​, or ​​[eventlistener:x]​​ Some do not implement specific configurations related to log files , Then for true:

• supervisord The... Of the child process will be captured stdout and stderr Output to temporary file . Each stream is captured in a separate file . That's what's called ​​AUTO​​ Logging mode .
• ​​AUTO​​​ Log files are automatically named , And put it in the ​​[supervisord]​​​ Part of the ​​childlogdir​​ Under the table of contents .
• Every ​​AUTO​​​ The size of the log file is determined by the ​​{streamname}_logfile_maxbytes​​​ Value limit ( among {streamname} yes " stdout “ or ” stderr "). When it reaches this number , It will be based on ​​{streamname}_logfile_backups​​ Rotation ( Just like the activity log ).

Affect child process login ​​[program:x]​​​ and ​​[fcgi-program:x]​​ The configuration keywords of section are as follows :

​​redirect_stderr​​​, ​​stdout_logfile​​​, ​​stdout_logfile_maxbytes​​​, ​​stdout_logfile_backups​​​, ​​stdout_capture_maxbytes​​​, ​​stdout_syslog​​​, ​​stderr_logfile​​​, ​​stderr_logfile_maxbytes​​​, ​​stderr_logfile_backups​​​, ​​stderr_capture_maxbytes​​​, and ​​stderr_syslog​​.

​​[eventlistener:x]​​​ Segments may not specify ​​redirect_stderr​​​、​​stdout_capture_maxbytes​​​ or ​​stderr_capture_maxbytes​​, But otherwise they accept the same value .

stay ​​[supervisord]​​​ The configuration keywords that affect the logging of child processes in the configuration file section are :​​childlogdir​​​ and ​​nocleanup​​.

2.1 Capture mode

The capture mode is Supervisor An advanced feature of . You don't need to understand capture patterns , Unless you want to take action based on the data parsed from the child process output .

If the ​​[program:x]​​​ Section defines a nonzero ​​stdout_capture_maxbytes​​​ or ​​stderr_capture_maxbytes​​​ Parameters , from program Each process represented in part can be represented in its stdout or stderr flow ( , respectively, ) Send a special token on , This will effectively lead to supervisor issue ​​PROCESS_COMMUNICATION​​​ event ( Description of the event , see also ​ ​Events​​).

The process communication protocol relies on two tags , A command supervisor Enter capture mode , Another command exits . When the process flow enters capture mode , The data sent to the stream will be sent to a separate buffer in memory , Capture buffer , The buffer is allowed to contain the largest ​​capture_maxbytes​​​ byte . In capture mode , When the length of the buffer exceeds ​​capture_maxbytes​​​ Byte time , The oldest data in the buffer will be discarded , To make room for new data . When a process flow exits capture mode , One ​​PROCESS_COMMUNICATION​​ The event subtype will be supervisor Trigger , It may be intercepted by event listeners .

Start in the process flow “ Capture mode ” The sign of is ​​<!--XSUPERVISOR:BEGIN-->​​​. The flag to exit capture mode is ​​<!--XSUPERVISOR:END-->​​​. The data between these tags can be arbitrary , And constitute ​​PROCESS_COMMUNICATION​​​ Payload of events . for example , If a program ​​stdout_capture_maxbytes​​ Set to “1MB”, It is in its stdout Send the following content on the stream :

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       <!--XSUPERVISOR:BEGIN-->Hello!<!--XSUPERVISOR:END-->
      
      
      
      

       
       
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under these circumstances ,supervisord Will send out a ​​PROCESS_COMMUNICATIONS_STDOUT​​ event , It contains the payload “Hello!” Data in .

One ( use Python Compiling ) An example script that emits process communication events is located at supervisor Bag ​​scripts​​​ Directory , be known as ​​sample_comment.py​​.

Designated as “ Event listener ”(​​[eventlistener:x]​​ section ) The output of the process will not be processed in this way . The output of these processes cannot enter capture mode .