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skynet-webportal/scripts/purge-nginx-blocklist.sh

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Bash

#!/bin/bash
# TODO:
#
# 1. the purging should batch the skylinks to purge in a single command
#
# python example:
#
# cached_files_command = (
# "find /data/nginx/cache/ -type f | xargs -r grep -Els '^Skynet-Skylink: ("
# + "|".join(skylinks[i : i + batch_size])
# + ")'"
# )
#
# cached_files_count += int(
# exec(
# 'docker exec nginx bash -c "'
# + cached_files_command
# + ' | xargs -r rm -v | wc -l"'
# )
# )
# This script reads skylinks from a file and purges them from the Nginx cache.
# It uses the atomic mkdir operation to create a lock on the file, under which
# it copies the file and truncates it.
set -e # exit on first error
# The following variables define the paths to the file containing the skylinks
# that need to be purged, the file in which we store the queued skylinks and the
# lock directory that ensures the blocker API and the crontab don't manipulate
# the same files concurrently.
NGINX_PURGE_SKYLINKS_FILE="/home/user/skynet-webportal/docker/data/nginx/blocker/skylinks.txt"
NGINX_PURGE_SKYLINKS_QUEUED="/home/user/skynet-webportal/docker/data/nginx/blocker/queued.txt"
NGINX_PURGE_SKYLINKS_LOCK="/home/user/skynet-webportal/docker/data/nginx/blocker/lock"
NGINX_CACHE_DIR="/home/user/skynet-webportal/docker/data/nginx/cache/"
purge_skylinks () {
# read all skylinks from the queued skylinks file
skylinks=()
line_number=1
while IFS="" read -r line || [ -n "$line" ];
do
if [[ $line =~ (^[a-zA-Z0-9_-]{46}$) ]]; then
skylinks+=("$line")
else
echo "Incorrect skylink at line ${line_number}: $line"
fi
let line_number+=1
done < $NGINX_PURGE_SKYLINKS_QUEUED;
for skylink in "${skylinks[@]}";
do
echo ".. ⌁ Purging skylink ${skylink}"
cached_files_command="find ${NGINX_CACHE_DIR} -type f | xargs -r grep -Els '^Skynet-Skylink: ${skylink}'"
echo $cached_files_command
docker exec -it nginx bash -c "${cached_files_command} | xargs -r rm"
echo ".. ⌁ Skylink ${skylink} purged"
echo "--------------------------------------------"
done
# remove the queue file
rm $NGINX_PURGE_SKYLINKS_QUEUED
}
acquire_lock () {
attempts=0
locked=false
until [ "$attempts" -ge 10 ]
do
if ! mkdir $NGINX_PURGE_SKYLINKS_LOCK 2>/dev/null
then
echo "skylinks file is locked, waiting..."
((attempts++))
sleep 1;
else
locked=true
break
fi
done
if ! $locked
then
echo "failed to acquire lock, warrants investigation"
exit 1
fi
}
release_lock () {
rmdir $NGINX_PURGE_SKYLINKS_LOCK
}
# if there is a queue file - purge all skylinks in that file from nginx cache
if [ -f "$NGINX_PURGE_SKYLINKS_QUEUED" ]
then
echo "found queue file, purging skylinks from file"
purge_skylinks
echo "✓ Done"
exit 1
fi
# if there is no skylinks file - escape early
if [ ! -f "$NGINX_PURGE_SKYLINKS_FILE" ]
then
echo "no skylinks found"
echo "✓ Done"
exit 1
fi
# move the skylinks file to the queue under lock
acquire_lock
mv $NGINX_PURGE_SKYLINKS_FILE $NGINX_PURGE_SKYLINKS_QUEUED
release_lock
# purge the skylinks from the queue file
purge_skylinks
echo "✓ Done"
exit 1