scripts/watch-containers.sh

#!/usr/bin/env bash


    ## ## ## ## ## ## ## ## ## ## ## ## ## ##
   ##                                       ##
  ##           watch-containers.sh           ##
 ##                                           ##
 ##   Watch running containers and report     ##
  ##      any changes to Healthchecks        ##
   ##                                       ##
    ## ## ## ## ## ## ## ## ## ## ## ## ## ##


##
## Information
## (don't touch unless you are me)
##

NAME="watch-containers.sh"
DESCRIPTION="Watch running containers and report any changes to Healthchecks"
VERSION="0.2.0"
AUTHOR="david@socialnerds.org"
LICENSE="MIT"
WEBSITE="https://git.socialnerds.org/david/scripts"
CHANGELOG=("[2023-10-30][v0.2.0] Complete rewrite based on the new template.sh"
           "[2022-01-22][v0.1.0] Initial version")


##
## Configuration
##

EXECUTABLE="$(basename $0)"
LIBRARIES="lib.sh"
DEPENDENCIES="basename dirname readlink cat jq docker"
REQUIRE_ROOT=1
#TODO: make the cache file configurable with an option flag
CACHE_FILE="/var/cache/watch-containers.json"


##
## Functions
##

# Print help information
function print_help() {
  printf "%s\n\n%s\n%b\n\n%s\n  %-15s %s\n  %-15s %s\n  %-15s %s\n  %-15s %s\n  %-15s %s\n" \
         "$DESCRIPTION" "Usage:" "$LIB_BOLD$EXECUTABLE <options> [healthchecks-url]$LIB_CLEAR" "Options:" \
         "-s, --state" "Save current state to file and exit" \
         "-h, --help" "Print help screen and exit" \
         "-i, --info" "Print script information and exit" \
         "-v, --verbose" "More verbose output" \
         "-q, --quiet" "No output except errors (overrides -v)"
}


##
## Preflight
##

# Load BASH libraries
SCRIPT_PATH=$(readlink -f "$0")
SCRIPT_DIR=$(dirname "$SCRIPT_PATH")
for LIBRARY in $LIBRARIES; do
  if [[ -r "$SCRIPT_DIR/$LIBRARY" ]]; then
    #echo "Loading library file [$SCRIPT_DIR/$LIBRARY]"
    source "$SCRIPT_DIR/$LIBRARY"
  else
    echo "Error: Cannot load library file [$SCRIPT_DIR/$LIBRARY]"
    exit 1
  fi
done

# Check for root privileges
if ! lib_amiroot && [[ $REQUIRE_ROOT -eq 1 ]]; then
  lib_print "!You need to have root privileges"
  exit 1
fi

# Check for dependencies
MISSING_COMMANDS=$(lib_missing_commands $DEPENDENCIES)
if [[ -n "$MISSING_COMMANDS" ]]; then
  lib_print "!One or more commands missing [$MISSING_COMMANDS]"
  lib_print "Try installing them with your package manager"
  exit 1
fi


##
## Liftoff
##

while [[ "$1" =~ ^- && ! "$1" == "--" ]]; do
  case $1 in
    -s|--state)
      S=1
      ;;
    -h|--help)
      H=1
      ;;
    -i|--info)
      I=1
      ;;
    -v|--verbose)
      V=1
      ;;
    -q|--quiet)
      Q=1
      ;;
    *)
      lib_print "!Unknown option [$1]"
      lib_print "Try --help or -h for available options"
      exit 1
      ;;
  esac
  shift
done

if [[ "$1" == '--' ]]; then
  shift
fi

if [[ $I -eq 1 ]]; then
  lib_print_info
  exit 0
elif [[ $H -eq 1 ]]; then
  print_help
  exit 0
elif [[ $S -eq 1 ]]; then
  docker ps --no-trunc --format json > $CACHE_FILE
  lib_print "Saving current state to cache file [$CACHE_FILE]"
  exit 0
fi

# Get containers from cache file
if [[ -r "$CACHE_FILE" ]]; then
  lib_print "?Reading cache from file [$CACHE_FILE]"
  CACHE=($(cat $CACHE_FILE | jq -r .Names))
else
  lib_print "!No cache file found [$CACHE_FILE]"
  exit 1
fi

# Get currently running containers
CURRENT=($(docker ps --no-trunc --format json | jq -r .Names))

# Iterate through the $CACHE array and check if each element is in the $CURRENT array
for I in "${CACHE[@]}"; do
  if [[ " ${CURRENT[*]} " != *" $I "* ]]; then
    ONLY_IN_CACHE+=("$I")
  fi
done

# Iterate through the $CURRENT array and check if each element is in the CACHE array
for I in "${CURRENT[@]}"; do
  if [[ " ${CACHE[*]} " != *" $I "* ]]; then
    ONLY_IN_CURRENT+=("$I")
  fi
done

# Construct result
if [[ -n "${ONLY_IN_CACHE[@]}" ]] && [[ -n "${ONLY_IN_CURRENT[@]}" ]]; then
  RESULT=$(printf "Missing container(s): %s\nNew container(s): %s\n" "${ONLY_IN_CACHE[@]}" "${ONLY_IN_CURRENT[@]}")
elif [[ -n "${ONLY_IN_CACHE[@]}" ]]; then
  RESULT=$(printf "Missing container(s): %s\n" "${ONLY_IN_CACHE[@]}")
elif [[ -n "${ONLY_IN_CURRENT[@]}" ]]; then
  RESULT=$(printf "New container(s): %s\n" "${ONLY_IN_CURRENT[@]}")
else
  RESULT=$(printf "No changes detected")
fi

# Post result to Healthchecks
if [[ -n "$1" ]] && lib_is_url "$1"; then
  if [[ "$RESULT" == "No changes detected" ]]; then
    lib_healthchecks "$1" "$RESULT"
  else
    lib_healthchecks "${1%/}/fail" "$RESULT"
  fi
fi

# Print result to screen
lib_print "$RESULT"

##
## Here be dragons
##

exit 0