s6-overlay logging configuration

README.md

Logging

The log will be written to both /var/log/some-service as well as standard output.

The key is that s6-log reads in a whole "logging script" on the command line, and you can have multiple actions - here's the link to the manual.

S6_LOGGING_SCRIPT="T 1 n20 s1000000 T"

• s6-log -bp - call s6-log in blocking, protected mode (same as logutil-service does)

• T 1 -- this is my first action directive

  • take all lines of input (because I don't have any line selection directives)
  • prepend with an ISO 8601 timestamp (done with T)
  • forward to stdout (done with the 1)

• n20 s1000000 T /var/log/some-service -- this is second first action directive, and it's the default mode for logutil-service

  • take all lines of input (again, no selection directives)
  • keep up to 20 files (n20)
  • each file is max 1000000 bytes (s1000000)
  • prepend with an ISO 8601 timestamp (T)
  • save to logdir /var/log/some-service

Ref: just-containers/s6-overlay#252

myapp-log-prepare/up

Simple

if { mkdir -p /var/log/myapp }
if { chown nobody:nogroup /var/log/myapp }
chmod 02755 /var/log/myapp

Custom

envfile /etc/myapp-env
importas myapp_version MYAPP_VERSION

foreground {
    if { mkdir -p /var/log/myapp/$myapp_version }
    if { chown nobody:nogroup /var/log/myapp/$myapp_version }
    chmod 02755 /var/log/myapp/$myapp_version
}

# This line will be executed regardless of the exit status in the if above
echo "[INFO] myapp-log-prepare: The log files are stored in /var/log/myapp/$myapp_version"