wait-for-compose-log.sh

#!/bin/bash
# This script monitors an ENV specified log file for the provided TRIGGER_STRING,
# at which point, the final command is executed.
# TODO: USAGE:

TRIGGER_STRING=$1
FINAL_CMD=$2

# Where the host compose log file will be mounted within the container asynchronously waiting
CONTAINER_COMPOSE_LOG="$CONTAINER_LOG_DIR/$COMPOSE_LOG_FILE"

# Log monitoring command
TAIL_CMD="tail -f $CONTAINER_COMPOSE_LOG"

# Prevent logging the TRIGGER string in order to hold final command execution until the real signal is received
LOGGABLE_TRIGGER_STRING="${TRIGGER_STRING:0:1}:${TRIGGER_STRING:1}"
LOGGABLE_FINAL_CMD="${FINAL_CMD/$TRIGGER_STRING/$LOGGABLE_TRIGGER_STRING}"
echo "Waiting for \"$TAIL_CMD\" to log \"$LOGGABLE_TRIGGER_STRING\" in $CONTAINER_COMPOSE_LOG before executing \"$LOGGABLE_FINAL_CMD\""

$TAIL_CMD | while read LOGLINE
do
    if [[ "$LOGLINE" == *$TRIGGER_STRING* ]]; then
      $FINAL_CMD
      kill -SIGPIPE $$  # ugly -- doesn't return proper exit codes but prevents log delay with break/exit
      exit
    fi
done