#!/bin/bash
#
# Script Evobackup client
# See https://gitea.evolix.org/evolix/evobackup
#
# Authors: Evolix <info@evolix.fr>,
#          Gregory Colpart <reg@evolix.fr>,
#          Romain Dessort <rdessort@evolix.fr>,
#          Benoit Série <bserie@evolix.fr>,
#          Tristan Pilat <tpilat@evolix.fr>,
#          Victor Laborie <vlaborie@evolix.fr>,
#          Jérémy Lecour <jlecour@evolix.fr>
#          and others.
#
# Licence: AGPLv3
#
# /!\ DON'T FORGET TO SET "MAIL" and "SERVERS" VARIABLES

##### Configuration ###################################################

VERSION="22.12"

# email adress for notifications
MAIL=jdoe@example.com

# list of hosts (hostname or IP) and SSH port for Rsync
SERVERS="node0.backup.example.com:2XXX node1.backup.example.com:2XXX"

# explicit PATH
PATH=/sbin:/usr/sbin:/bin:/usr/bin:/usr/local/sbin:/usr/local/bin

# Should we fallback on other servers when the first one is unreachable?
SERVERS_FALLBACK=${SERVERS_FALLBACK:-1}

# timeout (in seconds) for SSH connections
SSH_CONNECT_TIMEOUT=${SSH_CONNECT_TIMEOUT:-90}

# We use /home/backup : feel free to use your own dir
LOCAL_BACKUP_DIR="/home/backup"

# You can set "linux" or "bsd" manually or let it choose automatically
SYSTEM=$(uname | tr '[:upper:]' '[:lower:]')

# Store pid in a file named after this program's name
PROGNAME=$(basename "$0")
PIDFILE="/var/run/${PROGNAME}.pid"

# Customize the log path if you have multiple scripts and with separate logs
LOGFILE="/var/log/evobackup.log"

# Full Rsync log file, reset each time
RSYNC_LOGFILE="/var/log/${PROGNAME}.rsync.log"

HOSTNAME=$(hostname)

DATE_FORMAT="%Y-%m-%d %H:%M:%S"

# Enable/disable local tasks (default: enabled)
: "${LOCAL_TASKS:=1}"
# Enable/disable sync tasks (default: enabled)
: "${SYNC_TASKS:=1}"

CANARY_FILE="/zzz_evobackup_canary"

# Source paths can be customized
# Empty lines, and lines containing # or ; are ignored
RSYNC_INCLUDES="
/etc
/root
/var
/home
"

# Excluded paths can be customized
# Empty lines, and lines beginning with # or ; are ignored
RSYNC_EXCLUDES="
/dev
/proc
/run
/sys
/tmp
/usr/doc
/usr/obj
/usr/share/doc
/usr/src
/var/apt
/var/cache
/var/db/munin/*.tmp
/var/lib/amavis/amavisd.sock
/var/lib/amavis/tmp
/var/lib/clamav/*.tmp
/var/lib/elasticsearch
/var/lib/metche
/var/lib/mongodb
/var/lib/munin/*tmp*
/var/lib/mysql
/var/lib/php/sessions
/var/lib/php5
/var/lib/postgres
/var/lib/postgresql
/var/lib/sympa
/var/lock
/var/run
/var/spool/postfix
/var/spool/smtpd
/var/spool/squid
/var/state
/var/tmp
lost+found
.nfs.*
lxc/*/rootfs/tmp
lxc/*/rootfs/usr/doc
lxc/*/rootfs/usr/obj
lxc/*/rootfs/usr/share/doc
lxc/*/rootfs/usr/src
lxc/*/rootfs/var/apt
lxc/*/rootfs/var/cache
lxc/*/rootfs/var/lib/php5
lxc/*/rootfs/var/lib/php/sessions
lxc/*/rootfs/var/lock
lxc/*/rootfs/var/run
lxc/*/rootfs/var/state
lxc/*/rootfs/var/tmp
/home/mysqltmp
"


##### FUNCTIONS #######################################################

mysql_list_databases() {
    port=${1:-"3306"}

    mysql --defaults-extra-file=/etc/mysql/debian.cnf -P ${port} -e 'show databases' -s --skip-column-names | grep --extended-regexp --invert-match "^(Database|information_schema|performance_schema|sys)"
}
# shellcheck disable=SC2317
dump_ldap() {
    ## OpenLDAP : example with slapcat
    dump_dir="${LOCAL_BACKUP_DIR}/ldap/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"

    slapcat -n 0 -l "${dump_dir}/config.bak"
    slapcat -n 1 -l "${dump_dir}/data.bak"
    slapcat      -l "${dump_dir}/ldap.bak"
}
# shellcheck disable=SC2317
dump_mysql_global() {
    dump_dir="${LOCAL_BACKUP_DIR}/mysql-global/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"

    mysqldump --defaults-extra-file=/etc/mysql/debian.cnf -P 3306 --opt --all-databases --force --events --hex-blob 2> "${dump_dir}/mysql.bak.err" | gzip --best > "${dump_dir}/mysql.bak.gz"

    last_rc=$?
    if [ ${last_rc} -ne 0 ]; then
        error "mysqldump (global compressed) returned an error ${last_rc}, check ${dump_dir}/mysql.bak.err"
        rc=101
    else
        rm -f "${dump_dir}/mysql.bak.err"
    fi
}
# shellcheck disable=SC2317
dump_mysql_per_base() {
    dump_dir="${LOCAL_BACKUP_DIR}/mysql-per-base/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"

    for i in $(mysql_list_databases 3306); do
        mysqldump --defaults-extra-file=/etc/mysql/debian.cnf --force -P 3306 --events --hex-blob $i 2> "${dump_dir}/${i}.err" | gzip --best > "${dump_dir}/${i}.sql.gz"

        last_rc=$?
        if [ ${last_rc} -ne 0 ]; then
            error "mysqldump (${i} compressed) returned an error ${last_rc}, check ${dump_dir}/${i}.err"
            rc=102
        else
            rm -f "${dump_dir}/${i}.err"
        fi
    done
}
# shellcheck disable=SC2317
dump_mysql_meta() {
    dump_dir="${LOCAL_BACKUP_DIR}/mysql-meta/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"

    ## Dump all grants (requires 'percona-toolkit' package)
    pt-show-grants --flush --no-header 2> "${dump_dir}/all_grants.err" > "${dump_dir}/all_grants.sql"

    last_rc=$?
    if [ ${last_rc} -ne 0 ]; then
        error "pt-show-grants returned an error ${last_rc}, check ${dump_dir}/all_grants.err"
        rc=103
    else
        rm -f "${dump_dir}/all_grants.err"
    fi

    ## Dump all variables
    mysql -A -e"SHOW GLOBAL VARIABLES;" 2> "${dump_dir}/variables.err" > "${dump_dir}/variables.txt"

    last_rc=$?
    if [ ${last_rc} -ne 0 ]; then
        error "mysql (variables) returned an error ${last_rc}, check ${dump_dir}/variables.err"
        rc=104
    else
        rm -f "${dump_dir}/variables.err"
    fi

    ## Schema only (no data) for each databases
    for i in $(mysql_list_databases 3306); do
        mysqldump --defaults-extra-file=/etc/mysql/debian.cnf --force -P 3306 --no-data --databases $i 2> "${dump_dir}/${i}.schema.err" > "${dump_dir}/${i}.schema.sql"

        last_rc=$?
        if [ ${last_rc} -ne 0 ]; then
            error "mysqldump (${i} schema) returned an error ${last_rc}, check ${dump_dir}/${i}.schema.err"
            rc=105
        else
            rm -f "${dump_dir}/${i}.schema.err"
        fi
    done
}
# shellcheck disable=SC2317
dump_mysql_tabs() {
    for i in $(mysql_list_databases 3306); do
        dump_dir="${LOCAL_BACKUP_DIR}/mysql-tabs/$i"
        rm -rf "${dump_dir}"
        mkdir -p -m 700 "${dump_dir}"
        chown -RL mysql "${dump_dir}"

        mysqldump --defaults-extra-file=/etc/mysql/debian.cnf --force -P 3306 -Q --opt --events --hex-blob --skip-comments --fields-enclosed-by='\"' --fields-terminated-by=',' -T "${dump_dir}" $i 2> "${dump_dir}.err"
 
        last_rc=$?
        if [ ${last_rc} -ne 0 ]; then
            error "mysqldump (${i} files) returned an error ${last_rc}, check ${dump_dir}.err"
            rc=107
        else
            rm -f "${dump_dir}.err"
        fi
    done
}
# shellcheck disable=SC2317
dump_mysql_hotcopy() {
    dump_dir="${LOCAL_BACKUP_DIR}/mysql-hotcopy/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"

    mysqlhotcopy MYBASE "${dump_dir}/" 2> "${dump_dir}/MYBASE.err"

    last_rc=$?
    if [ ${last_rc} -ne 0 ]; then
        error "mysqlhotcopy returned an error ${last_rc}, check ${dump_dir}/MYBASE.err"
        rc=108
    else
        rm -f "${dump_dir}/MYBASE.err"
    fi
}
# shellcheck disable=SC2317
dump_mysql_instances() {
    dump_dir="${LOCAL_BACKUP_DIR}/mysql-instances/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"

    mysqladminpasswd=$(grep -m1 'password = .*' /root/.my.cnf|cut -d" " -f3)

    grep --extended-regexp "^port\s*=\s*\d*" /etc/mysql/my.cnf | while read instance; do
        instance=$(echo "$instance"|awk '{ print $3 }')
        if [ "$instance" != "3306" ]; then
            mysqldump -P ${instance} --opt --all-databases --hex-blob -u mysqladmin -p${mysqladminpasswd} 2> "${dump_dir}/${instance}.err" | gzip --best > "${dump_dir}/${instance}.bak.gz"

            last_rc=$?
            if [ ${last_rc} -ne 0 ]; then
                error "mysqldump (instance ${instance}) returned an error ${last_rc}, check ${dump_dir}/${instance}.err"
                rc=107
            else
                rm -f "${dump_dir}/${instance}.err"
            fi
        fi
    done
}
# shellcheck disable=SC2317
dump_postgresql_global() {
    dump_dir="${LOCAL_BACKUP_DIR}/postgresql-global/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"

    ## example with pg_dumpall
    # WARNING: you need space in ~postgres
    su - postgres -c "pg_dumpall > ~/pg.dump.bak"
    mv ~postgres/pg.dump.bak "${dump_dir}/"

    ## another method with gzip directly piped
    # (
    #    cd /var/lib/postgresql;
    #    sudo -u postgres pg_dumpall | gzip > ${dump_dir}/pg.dump.bak.gz
    # )

}
# shellcheck disable=SC2317
dump_postgresql_per_base() {
    dump_dir="${LOCAL_BACKUP_DIR}/postgresql-per-base/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"

    (
       cd /var/lib/postgresql
       databases=$(sudo -u postgres psql -U postgres -lt | awk -F\| '{print $1}' | grep -v template*)
       for database in ${databases} ; do
          sudo -u postgres /usr/bin/pg_dump --create -s -U postgres -d ${database} | gzip --best -c > ${dump_dir}/$databases.sql.gz
       done
    )
}
# shellcheck disable=SC2317
dump_postgresql_filtered() {
    dump_dir="${LOCAL_BACKUP_DIR}/postgresql-filtered/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"

    ## example with all tables from MYBASE excepts TABLE1 and TABLE2
    # pg_dump -p 5432 -h 127.0.0.1 -U USER --clean -F t --inserts -f "${dump_dir}/pg-backup.tar" -t 'TABLE1' -t 'TABLE2' MYBASE

    ## example with only TABLE1 and TABLE2 from MYBASE
    # pg_dump -p 5432 -h 127.0.0.1 -U USER --clean -F t --inserts -f "${dump_dir}/pg-backup.tar" -T 'TABLE1' -T 'TABLE2' MYBASE
}
# shellcheck disable=SC2317
dump_redis() {
    for instance in $(find /var/lib/ -mindepth 1 -maxdepth 1 -type d -name 'redis*'); do
        name=$(basename "${instance}")
        dump_dir="${LOCAL_BACKUP_DIR}/${name}/"
        rm -rf "${dump_dir}"

        if [ -f "${instance}/dump.rdb" ]; then
            mkdir -p -m 700 "${dump_dir}"
            cp -a "${instance}/dump.rdb" "${dump_dir}/"
        fi
    done
}
# shellcheck disable=SC2317
dump_mongodb() {
    ## don't forget to create use with read-only access
    ## > use admin
    ## > db.createUser( { user: "mongobackup", pwd: "PASS", roles: [ "backup", ] } )

    dump_dir="${LOCAL_BACKUP_DIR}/mongodump/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"
    mongo_user=""
    mongo_password=""

    mongodump --quiet -u ${mongo_user} -p${mongo_password} -o "${dump_dir}/"

    if [ $? -ne 0 ]; then
      echo "Error with mongodump!"
    fi
}
# shellcheck disable=SC2317
dump_megacli_config() {
    megacli -CfgSave -f "${LOCAL_BACKUP_DIR}/megacli_conf.dump" -a0 >/dev/null
}
# shellcheck disable=SC2317
dump_traceroute() {
    dump_dir="${LOCAL_BACKUP_DIR}/traceroute/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"

    network_targets="8.8.8.8 www.evolix.fr travaux.evolix.net"

    mtr_bin=$(command -v mtr)
    if [ -n "${network_targets}" ] && [ -n "${mtr_bin}" ]; then
        for addr in ${network_targets}; do
            ${mtr_bin} -r "${addr}" > "${dump_dir}/mtr-${addr}"
        done
    fi

    traceroute_bin=$(command -v traceroute)
    if [ -n "${network_targets}" ] && [ -n "${traceroute_bin}" ]; then
        for addr in ${network_targets}; do
            ${traceroute_bin} -n "${addr}" > "${dump_dir}/traceroute-${addr}" 2>&1
        done
    fi
}
# shellcheck disable=SC2317
dump_server_state() {
    dump_dir="${LOCAL_BACKUP_DIR}/server-state"
    rm -rf "${dump_dir}"
    # Do not create the directory
    # mkdir -p -m 700 "${dump_dir}"

    dump_server_state_bin=$(command -v dump-server-state)
    if [ -z "${dump_server_state_bin}" ]; then
        error "dump-server-state is missing"
        rc=1
    else
        if [ "${SYSTEM}" = "linux" ]; then
            ${dump_server_state_bin} --all --dump-dir "${dump_dir}"
            last_rc=$?
            if [ ${last_rc} -ne 0 ]; then
                error "dump-server-state returned an error ${last_rc}, check ${dump_dir}"
                rc=1
            fi
        else
            ${dump_server_state_bin} --all --dump-dir "${dump_dir}"
            last_rc=$?
            if [ ${last_rc} -ne 0 ]; then
                error "dump-server-state returned an error ${last_rc}, check ${dump_dir}"
                rc=1
            fi
        fi
    fi
}
# shellcheck disable=SC2317
dump_rabbitmq() {
    dump_dir="${LOCAL_BACKUP_DIR}/rabbitmq/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"

    rabbitmqadmin export "${dump_dir}/config" >> "${LOGFILE}"
}
# shellcheck disable=SC2317
dump_facl() {
    dump_dir="${LOCAL_BACKUP_DIR}/facl/"
    rm -rf "${dump_dir}"
    mkdir -p -m 700 "${dump_dir}"

    getfacl -R /etc  > "${dump_dir}/etc.txt"
    getfacl -R /home > "${dump_dir}/home.txt"
    getfacl -R /usr  > "${dump_dir}/usr.txt"
    getfacl -R /var  > "${dump_dir}/var.txt"
}
# shellcheck disable=SC2317
dump_elasticsearch_snapshot() {
    ## Take a snapshot as a backup.
    ## Warning: You need to have a path.repo configured.
    ## See: https://wiki.evolix.org/HowtoElasticsearch#snapshots-et-sauvegardes

    curl -s -XDELETE "localhost:9200/_snapshot/snaprepo/snapshot.daily" >> "${LOGFILE}"
    curl -s -XPUT "localhost:9200/_snapshot/snaprepo/snapshot.daily?wait_for_completion=true" >> "${LOGFILE}"

    # Clustered version here
    # It basically the same thing except that you need to check that NFS is mounted
    # if ss | grep ':nfs' | grep -q 'ip\.add\.res\.s1' && ss | grep ':nfs' | grep -q 'ip\.add\.res\.s2'
    # then
    #     curl -s -XDELETE "localhost:9200/_snapshot/snaprepo/snapshot.daily" >> "${LOGFILE}"
    #     curl -s -XPUT "localhost:9200/_snapshot/snaprepo/snapshot.daily?wait_for_completion=true" >> "${LOGFILE}"
    # else
    #     echo 'Cannot make a snapshot of elasticsearch, at least one node is not mounting the repository.'
    # fi

    ## If you need to keep older snapshot, for example the last 10 daily snapshots, replace the XDELETE and XPUT lines by :
    # for snapshot in $(curl -s -XGET "localhost:9200/_snapshot/snaprepo/_all?pretty=true" | grep -Eo 'snapshot_[0-9]{4}-[0-9]{2}-[0-9]{2}' | head -n -10); do
    #     curl -s -XDELETE "localhost:9200/_snapshot/snaprepo/${snapshot}" | grep -v -Fx '{"acknowledged":true}'
    # done
    # date=$(/bin/date +%F)
    # curl -s -XPUT "localhost:9200/_snapshot/snaprepo/snapshot_${date}?wait_for_completion=true" >> "${LOGFILE}"
}

local_tasks() {
    log "START LOCAL_TASKS"

    # Remove previous error files
    find "${LOCAL_BACKUP_DIR}/" -type f -name '*.err' -delete

    # You can comment or uncomment sections below to customize the backup

    ## OpenLDAP
    # dump_ldap

    ## MySQL

    ### example with global and compressed mysqldump
    # dump_mysql_global
    ### example with compressed SQL dump (with data) for each databases
    # dump_mysql_per_base
    ### meta-data (grants, variables, schema…)
    # dump_mysql_meta
    ### example with two dumps for each table (.sql/.txt) for all databases
    # dump_mysql_tabs
    ### example with mysqlhotcopy
    # dump_mysql_hotcopy
    ### example for multiples MySQL instances
    # dump_mysql_instances

    ## PostgreSQL

    ### example with global dump
    # dump_postgresql_global
    ### example with filtered tables ("only" or "except")
    # dump_postgresql_filtered
    ### example with compressed PostgreSQL dump for each databases
    # dump_postgresql_per_base

    ## MongoDB
    # dump_mongodb

    ## Redis
    # dump_redis

    ## ElasticSearch
    # dump_elasticsearch_snapshot

    ## RabbitMQ config
    # dump_rabbitmq

    ## MegaCli config
    # dump_megacli_config

    ## Dump network routes with mtr and traceroute (warning: could be long with aggressive firewalls)
    dump_traceroute

    ## Dump various information about server state
    dump_server_state

    ## Dump file access control lists
    # dump_facl

    log "STOP LOCAL_TASKS"
}
build_rsync_main_cmd() {
    ###################################################################
    # /!\ WARNING /!\ WARNING /!\ WARNING /!\ WARNING /!\ WARNING /!\ #
    ###################################################################
    # DO NOT USE COMMENTS in rsync lines                              #
    # DO NOT ADD WHITESPACES AFTER \ in rsync lines                   #
    # It breaks the command and destroys data                         #
    # You should not modify this, unless you are really REALLY sure   #
    ###################################################################

    # Create a temp file for excludes and includes
    includes_file="$(mktemp "${PROGNAME}.includes.XXXXXX")"
    excludes_file="$(mktemp "${PROGNAME}.excludes.XXXXXX")"
    # … and add them to the list of files to delete at exit
    temp_files="${temp_files} ${includes_file} ${excludes_file}"

    # Store includes/excludes in files
    # without blank lines of comments (# or ;)
    echo "${RSYNC_INCLUDES}" | sed -e 's/\s*\(#\|;\).*//; /^\s*$/d' > "${includes_file}"
    echo "${RSYNC_EXCLUDES}" | sed -e 's/\s*\(#\|;\).*//; /^\s*$/d' > "${excludes_file}"

    # Rsync command
    cmd="$(command -v rsync)"

    # Rsync main options
    cmd="${cmd} --archive"
    cmd="${cmd} --itemize-changes"
    cmd="${cmd} --quiet"
    cmd="${cmd} --stats"
    cmd="${cmd} --human-readable"
    cmd="${cmd} --relative"
    cmd="${cmd} --partial"
    cmd="${cmd} --delete"
    cmd="${cmd} --delete-excluded"
    cmd="${cmd} --force"
    cmd="${cmd} --ignore-errors"
    cmd="${cmd} --log-file=${RSYNC_LOGFILE}"
    cmd="${cmd} --rsh='ssh -p ${SSH_PORT} -o \"ConnectTimeout ${SSH_CONNECT_TIMEOUT}\"'"

    # Rsync excludes
    while read line ; do
        cmd="${cmd} --exclude ${line}"
    done < "${excludes_file}"

    # Rsync local sources
    cmd="${cmd} ${default_includes}"
    while read line ; do
        cmd="${cmd} ${line}"
    done < "${includes_file}"

    # Rsync remote destination
    cmd="${cmd} root@${SSH_SERVER}:/var/backup/"

    # output final command
    echo "${cmd}"
}
build_rsync_canary_cmd() {
    # Rsync command
    cmd="$(command -v rsync)"
    # Rsync options
    cmd="${cmd} --rsh='ssh -p ${SSH_PORT} -o \"ConnectTimeout ${SSH_CONNECT_TIMEOUT}\"'"
    # Rsync local source
    cmd="${cmd} ${CANARY_FILE}"
    # Rsync remote destination
    cmd="${cmd} root@${SSH_SERVER}:/var/backup/"

    # output final command
    echo "${cmd}"
}
sync_tasks() {
    n=0
    server=""
    if [ "${SERVERS_FALLBACK}" = "1" ]; then
        # We try to find a suitable server
        while :; do
            server=$(pick_server "${n}")
            test $? = 0 || exit 2

            if test_server "${server}"; then
                break
            else
                server=""
                n=$(( n + 1 ))
            fi
        done
    else
        # we force the server
        server=$(pick_server "${n}")
    fi

    SSH_SERVER=$(echo "${server}" | cut -d':' -f1)
    SSH_PORT=$(echo "${server}" | cut -d':' -f2)

    log "START SYNC_TASKS - server=${server}"

    # default paths, depending on system
    if [ "${SYSTEM}" = "linux" ]; then
        default_includes="/bin /boot /lib /opt /sbin /usr"
    else
        default_includes="/bsd /bin /sbin /usr"
    fi

    # reset Rsync log file
    if [ -n "$(command -v truncate)" ]; then 
        truncate -s 0 "${RSYNC_LOGFILE}"
    else
        printf "" > "${RSYNC_LOGFILE}"
    fi

    # Build the final Rsync command
    rsync_main_cmd=$(build_rsync_main_cmd)

    # … log it
    log "SYNC_TASKS - Rsync main command : ${rsync_main_cmd}"

    # … execute it
    eval "${rsync_main_cmd}"

    rsync_main_rc=$?

    # Copy last lines of rsync log to the main log
    tail -n 30 "${RSYNC_LOGFILE}" >> "${LOGFILE}"

    if [ ${rsync_main_rc} -ne 0 ]; then
        error "rsync returned an error ${rsync_main_rc}, check ${LOGFILE}"
        rc=201
    else
        # Build the canary Rsync command
        rsync_canary_cmd=$(build_rsync_canary_cmd)

        # … log it
        log "SYNC_TASKS - Rsync canary command : ${rsync_canary_cmd}"

        # … execute it
        eval "${rsync_canary_cmd}"
    fi

    log "STOP SYNC_TASKS - server=${server}"
}

# Call test_server with "HOST:PORT" string
# It will return with 0 if the server is reachable.
# It will return with 1 and a message on stderr if not.
test_server() {
    item=$1
    # split HOST and PORT from the input string
    host=$(echo "${item}" | cut -d':' -f1)
    port=$(echo "${item}" | cut -d':' -f2)

    # Test if the server is accepting connections
    ssh -q -o "ConnectTimeout ${SSH_CONNECT_TIMEOUT}" "${host}" -p "${port}" -t "exit"
    # shellcheck disable=SC2181
    if [ $? = 0 ]; then
        # SSH connection is OK
        return 0
    else
        # SSH connection failed
        new_error=$(printf "Failed to connect to \`%s' within %s seconds" "${item}" "${SSH_CONNECT_TIMEOUT}")
        log "${new_error}"
        SERVERS_SSH_ERRORS=$(printf "%s\\n%s" "${SERVERS_SSH_ERRORS}" "${new_error}" | sed -e '/^$/d')

        return 1
    fi
}
# Call pick_server with an optional positive integer to get the nth server in the list.
pick_server() {
    increment=${1:-0}
    list_length=$(echo "${SERVERS}" | wc -w)

    if [ "${increment}" -ge "${list_length}" ]; then
        # We've reached the end of the list
        new_error="No more server available"
        log "${new_error}"
        SERVERS_SSH_ERRORS=$(printf "%s\\n%s" "${SERVERS_SSH_ERRORS}" "${new_error}" | sed -e '/^$/d')

        # Log errors to stderr
        printf "%s\\n" "${SERVERS_SSH_ERRORS}" >&2
        return 1
    fi

    # Extract the day of month, without leading 0 (which would give an octal based number)
    today=$(/bin/date +%e)
    # A salt is useful to randomize the starting point in the list
    # but stay identical each time it's called for a server (based on hostname).
    salt=$(hostname | cksum | cut -d' ' -f1)
    # Pick an integer between 0 and the length of the SERVERS list
    # It changes each day
    item=$(( (today + salt + increment) % list_length ))
    # cut starts counting fields at 1, not 0.
    field=$(( item + 1 ))

    echo "${SERVERS}" | cut -d' ' -f${field}
}
log() {
    msg="${1:-$(cat /dev/stdin)}"
    pid=$$
    printf "[%s] %s[%s]: %s\\n" \
        "$(/bin/date +"${DATE_FORMAT}")" "${PROGNAME}" "${pid}" "${msg}" \
        >> "${LOGFILE}"
}
error() {
    msg="${1:-$(cat /dev/stdin)}"
    pid=$$
    printf "[%s] %s[%s]: %s\\n" \
        "$(/bin/date +"${DATE_FORMAT}")" "${PROGNAME}" "${pid}" "${msg}" \
        >&2
}

main() {
    START_EPOCH=$(/bin/date +%s)
    log "START GLOBAL - VERSION=${VERSION} LOCAL_TASKS=${LOCAL_TASKS} SYNC_TASKS=${SYNC_TASKS}"

    # shellcheck disable=SC2174
    mkdir -p -m 700 ${LOCAL_BACKUP_DIR}

    ## Force umask
    umask 077

    ## Initialize variable to store SSH connection errors
    SERVERS_SSH_ERRORS=""

    ## Verify other evobackup process and kill if needed
    if [ -e "${PIDFILE}" ]; then
        pid=$(cat "${PIDFILE}")
        # Does process still exist ?
        if kill -0 "${pid}" 2> /dev/null; then
            # Killing the childs of evobackup.
            for ppid in $(pgrep -P "${pid}"); do
                kill -9 "${ppid}";
            done
            # Then kill the main PID.
            kill -9 "${pid}"
            printf "%s is still running (PID %s). Process has been killed" "$0" "${pid}\\n" >&2
        else
            rm -f "${PIDFILE}"
        fi
    fi
    echo "$$" > "${PIDFILE}"

    # Initialize a list of files to delete at exit
    # Any file added to the list will also be deleted at exit
    temp_files="${PIDFILE}"

    # shellcheck disable=SC2064
    trap "rm -f ${temp_files}" EXIT

    # Update canary to keep track of each run
    update-evobackup-canary --who "${PROGNAME}" --file "${CANARY_FILE}"

    if [ "${LOCAL_TASKS}" = "1" ]; then
        local_tasks
    fi

    if [ "${SYNC_TASKS}" = "1" ]; then
        sync_tasks
    fi

    STOP_EPOCH=$(/bin/date +%s)

    if [ "${SYSTEM}" = "openbsd" ]; then
        start_time=$(/bin/date -f "%s" -j "${START_EPOCH}" +"${DATE_FORMAT}")
        stop_time=$(/bin/date -f "%s" -j "${STOP_EPOCH}" +"${DATE_FORMAT}")
    else
        start_time=$(/bin/date --date="@${START_EPOCH}" +"${DATE_FORMAT}")
        stop_time=$(/bin/date --date="@${STOP_EPOCH}" +"${DATE_FORMAT}")
    fi
    duration=$(( STOP_EPOCH - START_EPOCH ))

    log "STOP GLOBAL - start='${start_time}' stop='${stop_time}' duration=${duration}s"

    tail -20 "${LOGFILE}" | mail -s "[info] EvoBackup - Client ${HOSTNAME}" ${MAIL}
}

# set all programs to C language (english)
export LC_ALL=C

# If expansion is attempted on an unset variable or parameter, the shell prints an
# error message, and, if not interactive, exits with a non-zero status.
set -u
# The pipeline's return status is the value of the last (rightmost) command
# to exit with a non-zero status, or zero if all commands exit successfully.
set -o pipefail

# Default return-code (0 == succes)
rc=0

# execute main funciton
main

exit ${rc}