discourse_ynh/scripts/_common.sh

#!/bin/bash
#
# Common variables
#

pkg_dependencies="libjemalloc1 libjemalloc-dev zlib1g-dev libreadline-dev libpq-dev libssl-dev libyaml-dev libcurl4-openssl-dev libapr1-dev libxslt1-dev checkinstall libxml2-dev vim imagemagick postgresql postgresql-server-dev-all postgresql-contrib optipng jhead jpegoptim gifsicle"
RUBY_VERSION="2.6.0"

# Execute a command as another user with login
# (hence in user home dir, with prior loading of .profile, etc.)
# usage: exec_login_as USER COMMAND [ARG ...]
exec_login_as() {
  local user=$1
  shift 1
  exec_as $user --login "$@"
}
# Execute a command as another user
# usage: exec_as USER COMMAND [ARG ...]
exec_as() {
  local user=$1
  shift 1

  if [[ $user = $(whoami) ]]; then
    eval "$@"
  else
    sudo -u "$user" "$@"
  fi
}

# Returns true if a swap partition is enabled, false otherwise
# usage: is_swap_present
is_swap_present() {
  [ $(awk '/^SwapTotal:/{print $2}' /proc/meminfo)  -gt 0 ]
}

# Returns true if swappiness higher than 50
# usage: is_swappiness_sufficient
is_swappiness_sufficient() {
  [ $(cat /proc/sys/vm/swappiness)  -gt 50 ]
}

# Returns true if specified free memory is available (RAM + swap)
# usage: is_memory_available MEMORY (in bytes)
is_memory_available() {
  local needed_memory=$1
  local freemem="$(awk '/^MemAvailable:/{print $2}' /proc/meminfo)"
  local freeswap="$(awk '/^SwapFree:/{print $2}' /proc/meminfo)"
  [ $(($freemem+$freeswap)) -gt $needed_memory ]
}

# Checks discourse install memory requirements
# terminates installation if requirements not met
check_memory_requirements() {
  if ! is_swap_present ; then
    ynh_die "You must have a swap partition in order to install and use this application"
  elif ! is_swappiness_sufficient ; then
    ynh_die "Your swappiness must be higher than 50; please see https://en.wikipedia.org/wiki/Swappiness"
  elif ! is_memory_available 1000000 ; then
    ynh_die "You must have a minimum of 1Gb available memory (RAM+swap) for the installation"
  fi
}
# Checks discourse upgrade memory requirements
# Less requirements as the software is already installed and running
# terminates upgrade if requirements not met
check_memory_requirements_upgrade() {
  if ! is_memory_available 400000 ; then
    ynh_die "You must have a minimum of 400Mb available memory (RAM+swap) for the upgrade"
  fi
}
#=================================================
# POSTGRES HELPERS
#=================================================

# Create a master password and set up global settings
# Please always call this script in install and restore scripts
#
# usage: ynh_psql_test_if_first_run

ynh_psql_test_if_first_run() {
	if [ -f /etc/yunohost/psql ];
	then
		echo "PostgreSQL is already installed, no need to create master password"
	else
		pgsql=$(ynh_string_random)
		pg_hba=""
		echo "$pgsql" >> /etc/yunohost/psql

		if [ -e /etc/postgresql/9.4/ ]
		then
			pg_hba=/etc/postgresql/9.4/main/pg_hba.conf
		elif [ -e /etc/postgresql/9.6/ ]
		then
			pg_hba=/etc/postgresql/9.6/main/pg_hba.conf
		else
			ynh_die "postgresql shoud be 9.4 or 9.6"
		fi

		systemctl start postgresql
		sudo --login --user=postgres psql -c"ALTER user postgres WITH PASSWORD '$pgsql'" postgres

		# force all user to connect to local database using passwords
		# https://www.postgresql.org/docs/current/static/auth-pg-hba-conf.html#EXAMPLE-PG-HBA.CONF
		# Note: we can't use peer since YunoHost create users with nologin
		#  See: https://github.com/YunoHost/yunohost/blob/unstable/data/helpers.d/user
		sed -i '/local\s*all\s*all\s*peer/i \
		local all all password' "$pg_hba"
		systemctl enable postgresql
		systemctl reload postgresql
	fi
}

# Open a connection as a user
#
# example: ynh_psql_connect_as 'user' 'pass' <<< "UPDATE ...;"
# example: ynh_psql_connect_as 'user' 'pass' < /path/to/file.sql
#
# usage: ynh_psql_connect_as user pwd [db]
# | arg: user - the user name to connect as
# | arg: pwd - the user password
# | arg: db - the database to connect to
ynh_psql_connect_as() {
	user="$1"
	pwd="$2"
	db="$3"
	sudo --login --user=postgres PGUSER="$user" PGPASSWORD="$pwd" psql "$db"
}

# # Execute a command as root user
#
# usage: ynh_psql_execute_as_root sql [db]
# | arg: sql - the SQL command to execute
# | arg: db - the database to connect to
ynh_psql_execute_as_root () {
	sql="$1"
	sudo --login --user=postgres psql <<< "$sql"
}

# Execute a command from a file as root user
#
# usage: ynh_psql_execute_file_as_root file [db]
# | arg: file - the file containing SQL commands
# | arg: db - the database to connect to
ynh_psql_execute_file_as_root() {
	file="$1"
	db="$2"
	sudo --login --user=postgres psql "$db" < "$file"
}

# Create a database, an user and its password. Then store the password in the app's config
#
# After executing this helper, the password of the created database will be available in $db_pwd
# It will also be stored as "psqlpwd" into the app settings.
#
# usage: ynh_psql_setup_db user name [pwd]
# | arg: user - Owner of the database
# | arg: name - Name of the database
# | arg: pwd - Password of the database. If not given, a password will be generated
ynh_psql_setup_db () {
	db_user="$1"
	db_name="$2"
	new_db_pwd=$(ynh_string_random)	# Generate a random password
	# If $3 is not given, use new_db_pwd instead for db_pwd.
	db_pwd="${3:-$new_db_pwd}"
	ynh_psql_create_db "$db_name" "$db_user" "$db_pwd"	# Create the database
	ynh_app_setting_set "$app" psqlpwd "$db_pwd"	# Store the password in the app's config
}

# Create a database and grant privilegies to a user
#
# usage: ynh_psql_create_db db [user [pwd]]
# | arg: db - the database name to create
# | arg: user - the user to grant privilegies
# | arg: pwd  - the user password
ynh_psql_create_db() {
	db="$1"
	user="$2"
	pwd="$3"
	ynh_psql_create_user "$user" "$pwd"
	sudo --login --user=postgres createdb --owner="$user" "$db"
}

# Drop a database
#
# usage: ynh_psql_drop_db db
# | arg: db - the database name to drop
# | arg: user - the user to drop
ynh_psql_remove_db() {
	db="$1"
	user="$2"
	sudo --login --user=postgres dropdb "$db"
	ynh_psql_drop_user "$user"
}

# Dump a database
#
# example: ynh_psql_dump_db 'roundcube' > ./dump.sql
#
# usage: ynh_psql_dump_db db
# | arg: db - the database name to dump
# | ret: the psqldump output
ynh_psql_dump_db() {
	db="$1"
	sudo --login --user=postgres pg_dump "$db"
}


# Create a user
#
# usage: ynh_psql_create_user user pwd [host]
# | arg: user - the user name to create
ynh_psql_create_user() {
	user="$1"
	pwd="$2"
        sudo --login --user=postgres psql -c"CREATE USER $user WITH PASSWORD '$pwd'" postgres
}

# Drop a user
#
# usage: ynh_psql_drop_user user
# | arg: user - the user name to drop
ynh_psql_drop_user() {
	user="$1"
	sudo --login --user=postgres dropuser "$user"
}

# ============= MODIFIED EXISTING YUNOHOST HELPERS =============

# Create a system user
#
# usage: ynh_system_user_create user_name [home_dir] [use_shell]
# | arg: user_name - Name of the system user that will be create
# | arg: home_dir - Path of the home dir for the user. Usually the final path of the app. If this argument is omitted, the user will be created without home
# | arg: use_shell - Create a user using the default shell if present. If this argument is omitted, the user will be created with /usr/sbin/nologin shell
ynh_system_user_create () {
	if ! ynh_system_user_exists "$1"	# Check if the user exists on the system
	then	# If the user doesn't exist
		if [ $# -ge 2 ]; then	# If a home dir is mentioned
			local user_home_dir="-d $2"
		else
			local user_home_dir="--no-create-home"
		fi
    if [ $# -ge 3 ]; then	# If we want a shell for the user
      local shell="" # Use default shell
		else
			local shell="--shell /usr/sbin/nologin"
		fi
		useradd $user_home_dir --system --user-group $1 $shell || ynh_die "Unable to create $1 system account"
	fi
}

# ============= FUTURE YUNOHOST HELPERS =============

# Create a dedicated fail2ban config (jail and filter conf files)
#
# usage: ynh_add_fail2ban_config log_file filter [max_retry [ports]]
# | arg: log_file - Log file to be checked by fail2ban
# | arg: failregex - Failregex to be looked for by fail2ban
# | arg: max_retry - Maximum number of retries allowed before banning IP address - default: 3
# | arg: ports - Ports blocked for a banned IP address - default: http,https
ynh_add_fail2ban_config () {
   # Process parameters
   logpath=$1
   failregex=$2
   max_retry=${3:-3}
   ports=${4:-http,https}

  test -n "$logpath" || ynh_die "ynh_add_fail2ban_config expects a logfile path as first argument and received nothing."
  test -n "$failregex" || ynh_die "ynh_add_fail2ban_config expects a failure regex as second argument and received nothing."

	finalfail2banjailconf="/etc/fail2ban/jail.d/$app.conf"
	finalfail2banfilterconf="/etc/fail2ban/filter.d/$app.conf"
	ynh_backup_if_checksum_is_different "$finalfail2banjailconf" 1
	ynh_backup_if_checksum_is_different "$finalfail2banfilterconf" 1

  cat > $finalfail2banjailconf <<EOF
[$app]
enabled = true
port = $ports
filter = $app
logpath = $logpath
maxretry = $max_retry
EOF

  cat > $finalfail2banfilterconf <<EOF
[INCLUDES]
before = common.conf
[Definition]
failregex = $failregex
ignoreregex =
EOF

	ynh_store_file_checksum "$finalfail2banjailconf"
	ynh_store_file_checksum "$finalfail2banfilterconf"

  systemctl restart fail2ban
  local fail2ban_error="$(journalctl -u fail2ban | tail -n50 | grep "WARNING.*$app.*")"
  if [ -n "$fail2ban_error" ]
  then
    echo "[ERR] Fail2ban failed to load the jail for $app" >&2
    echo "WARNING${fail2ban_error#*WARNING}" >&2
  fi
}

# Remove the dedicated fail2ban config (jail and filter conf files)
#
# usage: ynh_remove_fail2ban_config
ynh_remove_fail2ban_config () {
	ynh_secure_remove "/etc/fail2ban/jail.d/$app.conf"
  ynh_secure_remove "/etc/fail2ban/filter.d/$app.conf"
	systemctl restart fail2ban
}

# Delete a file checksum from the app settings
#
# $app should be defined when calling this helper
#
# usage: ynh_remove_file_checksum file
# | arg: file - The file for which the checksum will be deleted
ynh_delete_file_checksum () {
	local checksum_setting_name=checksum_${1//[\/ ]/_}	# Replace all '/' and ' ' by '_'
	ynh_app_setting_delete $app $checksum_setting_name
}

rbenv_install_dir="/opt/rbenv"
# RBENV_ROOT is the directory of rbenv, it needs to be loaded as a environment variable.
export RBENV_ROOT="$rbenv_install_dir"

# Install ruby version management
#
# [internal]
#
# usage: ynh_install_rbenv
ynh_install_rbenv () {
	echo "Installation of rbenv - ruby version management" >&2
	# Build an app.src for rbenv
	mkdir -p "../conf"
	echo "SOURCE_URL=https://github.com/rbenv/rbenv/archive/v1.1.1.tar.gz
SOURCE_SUM=41f1a60714c55eceb21d692a469aee1ec4f46bba351d0dfcb0c660ff9cf1a1c9" > "../conf/rbenv.src"
	# Download and extract rbenv
	ynh_setup_source "$rbenv_install_dir" rbenv

  (cd $rbenv_install_dir
  ./src/configure && make -C src)

# Create shims directory if needed
if [ ! -d $rbenv_install_dir/shims ] ; then
  mkdir $rbenv_install_dir/shims
fi
}

# Install a specific version of ruby
#
# ynh_install_ruby will install the version of ruby provided as argument by using rbenv.
#
# rbenv (ruby version management) stores the target ruby version in a .ruby_version file created in the target folder (using rbenv local <version>)
# It then uses that information for every ruby user that uses rbenv provided ruby command
#
# This helper creates a /etc/profile.d/rbenv.sh that configures PATH environment for rbenv
# for every LOGIN user, hence your user must have a defined shell (as opposed to /usr/sbin/nologin)
#
# Don't forget to execute ruby-dependent command in a login environment
# (e.g. sudo --login option)
# When not possible (e.g. in systemd service definition), please use direct path
# to rbenv shims (e.g. $RBENV_ROOT/shims/bundle)
#
# usage: ynh_install_ruby ruby_version user
# | arg: ruby_version - Version of ruby to install.
#        If possible, prefer to use major version number (e.g. 8 instead of 8.10.0).
#        The crontab will handle the update of minor versions when needed.
ynh_install_ruby () {
	# Use rbenv, https://github.com/rbenv/rbenv to manage the ruby versions
	local ruby_version="$1"

	# Create $rbenv_install_dir
	mkdir -p "$rbenv_install_dir/plugins/ruby-build"

	# Load rbenv path in PATH
	CLEAR_PATH="$rbenv_install_dir/bin:$PATH"

	# Remove /usr/local/bin in PATH in case of ruby prior installation
	PATH=$(echo $CLEAR_PATH | sed 's@/usr/local/bin:@@')

	# Move an existing ruby binary, to avoid to block rbenv
	test -x /usr/bin/ruby && mv /usr/bin/ruby /usr/bin/ruby_rbenv

	# If rbenv is not previously setup, install it
	if ! type rbenv > /dev/null 2>&1
	then
		ynh_install_rbenv
	fi

  # Download ruby-build (replace if already exists)
  if [ -d $rbenv_install_dir/plugins/ruby-build ]; then
    rm -Rf $rbenv_install_dir/plugins/ruby-build
  fi
  # Build an app.src for ruby-build
  mkdir -p "../conf"
  echo "SOURCE_URL=https://github.com/rbenv/ruby-build/archive/v20181225.tar.gz
SOURCE_SUM=5ace4787ace47384dc419b20f5eb5a59f1174e00bfabcfed74a175033cd0b18a" > "../conf/ruby-build.src"
  # Download and extract ruby-build
  ynh_setup_source "$rbenv_install_dir/plugins/ruby-build" ruby-build
	# Restore /usr/local/bin in PATH (if needed)
	PATH=$CLEAR_PATH

	# And replace the old ruby binary
	test -x /usr/bin/ruby_rbenv && mv /usr/bin/ruby_rbenv /usr/bin/ruby

	# Install the requested version of ruby
	CONFIGURE_OPTS="--disable-install-doc --with-jemalloc" MAKE_OPTS="-j2" rbenv install --skip-existing $ruby_version

	# Store the ID of this app and the version of ruby requested for it
	echo "$YNH_APP_ID:$ruby_version" | tee --append "$rbenv_install_dir/ynh_app_version"

	# Store ruby_version into the config of this app
	ynh_app_setting_set $app ruby_version $ruby_version

  # Set environment for ruby users
  echo  "#rbenv
export RBENV_ROOT=$rbenv_install_dir
export PATH=\"$rbenv_install_dir/bin:$PATH\"
eval \"\$(rbenv init -)\"
#rbenv" > /etc/profile.d/rbenv.sh

  # Load the right environment for the Installation
  eval "$(rbenv init -)"

  (cd $final_path
  rbenv local $ruby_version)
}

# Remove the version of ruby used by the app.
#
# This helper will check if another app uses the same version of ruby,
# if not, this version of ruby will be removed.
# If no other app uses ruby, rbenv will be also removed.
#
# usage: ynh_remove_ruby
ynh_remove_ruby () {
	ruby_version=$(ynh_app_setting_get $app ruby_version)

	# Remove the line for this app
	sed --in-place "/$YNH_APP_ID:$ruby_version/d" "$rbenv_install_dir/ynh_app_version"

	# If no other app uses this version of ruby, remove it.
	if ! grep --quiet "$ruby_version" "$rbenv_install_dir/ynh_app_version"
	then
		$rbenv_install_dir/bin/rbenv uninstall --force $ruby_version
	fi

  # Remove rbenv environment configuration
  rm /etc/profile.d/rbenv.sh

	# If no other app uses rbenv, remove rbenv and dedicated group
	if [ ! -s "$rbenv_install_dir/ynh_app_version" ]
	then
		ynh_secure_remove "$rbenv_install_dir"
	fi
}

# ============= EXPERIMENTAL HELPERS =============

# Returns true if upstream version is up to date
#
# This helper should be used to avoid an upgrade of the upstream version
# when it's not needed (but yet allowing to upgrade other parts of the
# YunoHost application (e.g. nginx conf)
#
# usage: ynh_is_upstream_up_to_date (returns a boolean)
ynh_is_upstream_up_to_date () {
	local version=$(ynh_read_manifest "/etc/yunohost/apps/$YNH_APP_INSTANCE_NAME/manifest.json" "version" || echo 1.0)
  version="${version/~ynh*/}"
	local last_version=$(ynh_read_manifest "../manifest.json" "version" || echo 1.0)
  last_version="${last_version/~ynh*/}"
  [ "$version" = "$last_version" ]
}

# Read the value of a key in a ynh manifest file
#
# usage: ynh_read_manifest manifest key
# | arg: manifest - Path of the manifest to read
# | arg: key - Name of the key to find
ynh_read_manifest () {
	manifest="$1"
	key="$2"
	python3 -c "import sys, json;print(json.load(open('$manifest', encoding='utf-8'))['$key'])"
}

# Read the upstream version from the manifest
# The version number in the manifest is defined by <upstreamversion>~ynh<packageversion>
# For example : 4.3-2~ynh3
# This include the number before ~ynh
# In the last example it return 4.3-2
#
# usage: ynh_app_upstream_version
ynh_app_upstream_version () {
    manifest_path="../manifest.json"
    if [ ! -e "$manifest_path" ]; then
        manifest_path="../settings/manifest.json"	# Into the restore script, the manifest is not at the same place
    fi
    version_key=$(ynh_read_manifest "$manifest_path" "version")
    echo "${version_key/~ynh*/}"
}

# Read package version from the manifest
# The version number in the manifest is defined by <upstreamversion>~ynh<packageversion>
# For example : 4.3-2~ynh3
# This include the number after ~ynh
# In the last example it return 3
#
# usage: ynh_app_package_version
ynh_app_package_version () {
    manifest_path="../manifest.json"
    if [ ! -e "$manifest_path" ]; then
        manifest_path="../settings/manifest.json"	# Into the restore script, the manifest is not at the same place
    fi
    version_key=$(ynh_read_manifest "$manifest_path" "version")
    echo "${version_key/*~ynh/}"
}

# Start or restart a service and follow its booting
#
# usage: ynh_check_starting "Line to match" [Log file] [Timeout] [Service name]
#
# | arg: Line to match - The line to find in the log to attest the service have finished to boot.
# | arg: Log file - The log file to watch; specify "systemd" to read systemd journal for specified service
#    /var/log/$app/$app.log will be used if no other log is defined.
# | arg: Timeout - The maximum time to wait before ending the watching. Defaut 300 seconds.
# | arg: Service name
ynh_check_starting () {
	local line_to_match="$1"
	local service_name="${4:-$app}"
	local app_log="${2:-/var/log/$service_name/$service_name.log}"
	local timeout=${3:-300}

	echo "Starting of $service_name" >&2
	systemctl stop $service_name
	local templog="$(mktemp)"
	# Following the starting of the app in its log
	if [ "$app_log" == "systemd" ] ; then
		# Read the systemd journal
		journalctl -u $service_name -f --since=-45 > "$templog" &
	else
		# Read the specified log file
		tail -F -n0 "$app_log" > "$templog" &
	fi
	# Get the PID of the last command
	local pid_tail=$!
	systemctl start $service_name

	local i=0
	for i in `seq 1 $timeout`
	do
		# Read the log until the sentence is found, which means the app finished starting. Or run until the timeout.
		if grep --quiet "$line_to_match" "$templog"
		then
			echo "The service $service_name has correctly started." >&2
			break
		fi
		echo -n "." >&2
		sleep 1
	done
	if [ $i -eq $timeout ]
	then
		echo "The service $service_name didn't fully start before the timeout." >&2
	fi

	echo ""
	ynh_clean_check_starting
}
# Clean temporary process and file used by ynh_check_starting
# (usually used in ynh_clean_setup scripts)
#
# usage: ynh_clean_check_starting

ynh_clean_check_starting () {
	# Stop the execution of tail.
	kill -s 15 $pid_tail 2>&1
	ynh_secure_remove "$templog" 2>&1
}

ynh_maintenance_mode_ON () {
	# Load value of $path_url and $domain from the config if their not set
	if [ -z $path_url ]; then
		path_url=$(ynh_app_setting_get $app path)
	fi
	if [ -z $domain ]; then
		domain=$(ynh_app_setting_get $app domain)
	fi

	# Create an html to serve as maintenance notice
	echo "<!DOCTYPE html>
<html>
<head>
<meta http-equiv="refresh" content="3">
<title>Your app $app is currently under maintenance!</title>
<style>
	body {
		width: 70em;
		margin: 0 auto;
	}
</style>
</head>
<body>
<h1>Your app $app is currently under maintenance!</h1>
<p>This app has been put under maintenance by your administrator at $(date)</p>
<p>Please wait until the maintenance operation is done. This page will be reloaded as soon as your app will be back.</p>

</body>
</html>" > "/var/www/html/maintenance.$app.html"

	# Create a new nginx config file to redirect all access to the app to the maintenance notice instead.
	echo "# All request to the app will be redirected to ${path_url}_maintenance and fall on the maintenance notice
rewrite ^${path_url}/(.*)$ ${path_url}_maintenance/? redirect;
# Use another location, to not be in conflict with the original config file
location ${path_url}_maintenance/ {
alias /var/www/html/ ;

try_files maintenance.$app.html =503;

# Include SSOWAT user panel.
include conf.d/yunohost_panel.conf.inc;
}" > "/etc/nginx/conf.d/$domain.d/maintenance.$app.conf"

	# The current config file will redirect all requests to the root of the app.
	# To keep the full path, we can use the following rewrite rule:
	# 	rewrite ^${path_url}/(.*)$ ${path_url}_maintenance/\$1? redirect;
	# The difference will be in the $1 at the end, which keep the following queries.
	# But, if it works perfectly for a html request, there's an issue with any php files.
	# This files are treated as simple files, and will be downloaded by the browser.
	# Would be really be nice to be able to fix that issue. So that, when the page is reloaded after the maintenance, the user will be redirected to the real page he was.

	systemctl reload nginx
}

ynh_maintenance_mode_OFF () {
	# Load value of $path_url and $domain from the config if their not set
	if [ -z $path_url ]; then
		path_url=$(ynh_app_setting_get $app path)
	fi
	if [ -z $domain ]; then
		domain=$(ynh_app_setting_get $app domain)
	fi

	# Rewrite the nginx config file to redirect from ${path_url}_maintenance to the real url of the app.
	echo "rewrite ^${path_url}_maintenance/(.*)$ ${path_url}/\$1 redirect;" > "/etc/nginx/conf.d/$domain.d/maintenance.$app.conf"
	systemctl reload nginx

	# Sleep 4 seconds to let the browser reload the pages and redirect the user to the app.
	sleep 4

	# Then remove the temporary files used for the maintenance.
	rm "/var/www/html/maintenance.$app.html"
	rm "/etc/nginx/conf.d/$domain.d/maintenance.$app.conf"

	systemctl reload nginx
}

#=================================================
# REDIS HELPERS
#=================================================

# get the first available redis database
#
# usage: ynh_redis_get_free_db
# | returns: the database number to use
ynh_redis_get_free_db() {
	local result max db
	result="$(redis-cli INFO keyspace)"

	# get the num
	max=$(cat /etc/redis/redis.conf | grep ^databases | grep -Eow "[0-9]+")

	db=0
	# default Debian setting is 15 databases
	for i in $(seq 0 "$max")
	do
	 	if ! echo "$result" | grep -q "db$i"
	 	then
			db=$i
	 		break 1
 		fi
 		db=-1
	done

	test "$db" -eq -1 && ynh_die "No available Redis databases..."

	echo "$db"
}

# Create a master password and set up global settings
# Please always call this script in install and restore scripts
#
# usage: ynh_redis_remove_db database
# | arg: database - the database to erase
ynh_redis_remove_db() {
	local db=$1
	redis-cli -n "$db" flushall
}