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Lock file create and remove improvements (#2183)

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* changed the locking function to better support multiple servers running at once and sharing the same config

* helper function testing now runs inside of container

Co-authored-by: Brennan Kinney <5098581+polarathene@users.noreply.github.com>
This commit is contained in:
Nathan Pierce 2021-09-13 04:09:01 -04:00 • committed by GitHub
parent f8a621dadb
commit be35d9bef1
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GPG key ID: 4AEE18F83AFDEB23
11 changed files with 172 additions and 37 deletions
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9
target/scripts/check-for-changes.sh
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@ -6,8 +6,6 @@
LOG_DATE=$(date +"%Y-%m-%d %H:%M:%S ")
_notify 'task' "${LOG_DATE} Start check-for-changes script."
SCRIPT_NAME="$(basename "$0")"
# ? ––––––––––––––––––––––––––––––––––––––––––––– Checks
cd /tmp/docker-mailserver || exit 1
@ -40,9 +38,6 @@ while true
do
LOG_DATE=$(date +"%Y-%m-%d %H:%M:%S ")
# Lock configuration while working
create_lock "${SCRIPT_NAME}"
# get chksum and check it, no need to lock config yet
_monitored_files_checksums >"${CHKSUM_FILE}.new"
cmp --silent -- "${CHKSUM_FILE}" "${CHKSUM_FILE}.new"
@ -53,6 +48,7 @@ do
if [ $? -eq 1 ]
then
_notify 'inf' "${LOG_DATE} Change detected"
create_lock # Shared config safety lock
CHANGED=$(grep -Fxvf "${CHKSUM_FILE}" "${CHKSUM_FILE}.new" | sed 's/^[^ ]\+ //')
# Bug alert! This overwrites the alias set by start-mailserver.sh
@ -227,11 +223,12 @@ s/$/ regexp:\/etc\/postfix\/regexp/
# prevent restart of dovecot when smtp_only=1
[[ ${SMTP_ONLY} -ne 1 ]] && supervisorctl restart dovecot
remove_lock
fi
# mark changes as applied
mv "${CHKSUM_FILE}.new" "${CHKSUM_FILE}"
remove_lock "${SCRIPT_NAME}"
sleep 1
done

32
target/scripts/helper-functions.sh
View file

@ -1,6 +1,8 @@
#! /bin/bash
DMS_DEBUG="${DMS_DEBUG:=0}"
SCRIPT_NAME="$(basename "$0")" # This becomes the sourcing script name (Example: check-for-changes.sh)
LOCK_ID="$(uuid)" # Used inside of lock files to identify them and prevent removal by other instances of docker-mailserver
# ? --------------------------------------------- BIN HELPER
@ -17,17 +19,33 @@ function escape
function create_lock
{
SCRIPT_NAME="$1"
LOCK_FILE="/tmp/docker-mailserver/${SCRIPT_NAME}.lock"
[[ -e "${LOCK_FILE}" ]] && errex "Lock file ${LOCK_FILE} exists. Another $1 execution is happening. Try again later."
trap remove_lock EXIT # This won't work if the script is, for example, check-for-changes.sh which uses a while loop to stay running; you'll need to include a remove_lock call at the end of your logic
touch "${LOCK_FILE}"
LOCK_FILE="/tmp/docker-mailserver/${SCRIPT_NAME}.lock"
while [[ -e "${LOCK_FILE}" ]]
do
_notify 'warn' "Lock file ${LOCK_FILE} exists. Another ${SCRIPT_NAME} execution is happening. Trying again shortly..."
# Handle stale lock files left behind on crashes
# or premature/non-graceful exits of containers while they're making changes
if [[ -n "$(find "${LOCK_FILE}" -mmin +1 2>/dev/null)" ]]
then
_notify 'warn' "Lock file older than 1 minute. Removing stale lock file."
rm -f "${LOCK_FILE}"
_notify 'inf' "Removed stale lock ${LOCK_FILE}."
fi
sleep 5
done
trap remove_lock EXIT
echo "${LOCK_ID}" > "${LOCK_FILE}"
}
function remove_lock
{
SCRIPT_NAME=${SCRIPT_NAME:-$1}
rm -f "/tmp/docker-mailserver/${SCRIPT_NAME}.lock"
LOCK_FILE="${LOCK_FILE:-"/tmp/docker-mailserver/${SCRIPT_NAME}.lock"}"
[[ -z "${LOCK_ID}" ]] && errex "Cannot remove ${LOCK_FILE} as there is no LOCK_ID set"
if [[ -e "${LOCK_FILE}" && $(grep -c "${LOCK_ID}" "${LOCK_FILE}") -gt 0 ]] # Ensure we don't delete a lock that's not ours
then
rm -f "${LOCK_FILE}"
_notify 'inf' "Removed lock ${LOCK_FILE}."
fi
}
# ? ––––––––––––––––––––––––––––––––––––––––––––– IP & CIDR