Merge pull request #2 from seatgeek/colinodell-improved-logging

Improved logging

buildkit-prestop.sh

@@ -29,36 +29,49 @@
 # Because this is a somewhat naive approach that only looks at individual points in time,
 # we will check multiple times just to be sure that we're not missing any builds.
 
-# Variables
+# Variables (change these as needed)
 CHECK_FREQUENCY_MS=500                      # How often we should for running build processes (in milliseconds)
 WAIT_UNTIL_NO_BUILDS_SEEN_FOR_X_SECONDS=10  # If no build processes are seen for this many seconds, we assume that all builds have stopped
 BUILDKITD_PORT=1234                         # Port on which buildkitd is listening for buildx clients
+LOG_FORMAT="json"                           # Log format to use (either "json" or "text")
+LOG_PREFIX="[PreStop Hook]"                 # Optional prefix to add to log messages
 
 # Calculate the number of checks required based on the wait time and sleep period
 REQUIRED_CHECK_COUNT=$((WAIT_UNTIL_NO_BUILDS_SEEN_FOR_X_SECONDS * 1000 / CHECK_FREQUENCY_MS))
 
-# How many consecutive times we've seen no running builds
-times=0
-
 # Print logs both locally as in pod logs
 print_logs() {
-    # If we're running in a Kubernetes pod, write logs to stdout of the container
+    message=$1
+    level=${2:-"info"}
+
+    if [ -n "$LOG_PREFIX" ]; then
+        message="$LOG_PREFIX $message"
+    fi
+
+    if [ "$LOG_FORMAT" = "json" ]; then
+        message="{\"message\": \"$message\", \"timestamp\": \"$(date -u +"%Y-%m-%dT%H:%M:%SZ")\", \"level\": \"$level\"}"
+    fi
+
+    # If we're running in a Kubernetes pod, write logs to stderr of the container
     if [ -n "$KUBERNETES_SERVICE_HOST" ]; then
-        echo "PreStop Hook: $1" >> /proc/1/fd/1
+        echo "$message" >> /proc/1/fd/2
     else
-        echo "$1"
+        echo "$message" >&2
     fi
 }
 
 # Function to print a message conditionally based on DEBUG environment variable
 print_debug() {
     if [ -n "$DEBUG" ]; then
-        print_logs "$1"
+        print_logs "$1" "debug"
     fi
 }
 
 print_logs "Waiting for build processes to finish..."
 
+# How many consecutive times we've seen no running builds
+times=0
+
 # Loop until we see zero active connections REQUIRED_CHECK_COUNT consecutive times
 while true; do
     ACTIVE_CONNECTIONS=$(netstat -tnp | grep buildkitd | grep ":${BUILDKITD_PORT}" | grep -c ESTABLISHED)