diff --git a/data/helpers.d/apt b/data/helpers.d/apt
index 7859d44c5..bcce02dcb 100644
--- a/data/helpers.d/apt
+++ b/data/helpers.d/apt
@@ -189,7 +189,16 @@ ynh_package_install_from_equivs () {
     # If install fails we use "apt-get check" to try to debug and diagnose possible unmet dependencies
     # Note the use of { } which allows to group commands without starting a subshell (otherwise the ynh_die wouldn't exit the current shell). 
     # Be careful with the syntax : the semicolon + space at the end is important!
-    ynh_package_install -f || { apt-get check 2>&1; ynh_die --message="Unable to install dependencies"; }
+
+    ynh_package_install -f || \
+        { # If the installation failed
+        # Get the list of dependencies from the deb
+        local dependencies="$(dpkg --info "$TMPDIR/${pkgname}_${pkgversion}_all.deb" | grep Depends | \
+             sed 's/^ Depends: //' | sed 's/,//g')"
+        # Fake an install of those dependencies to see the errors
+        # The sed command here is, Print only from '--fix-broken' to the end.
+        ynh_package_install $dependencies --dry-run | sed -n '/--fix-broken/,$p' >&2
+        ynh_die --message="Unable to install dependencies"; }
     [[ -n "$TMPDIR" ]] && rm -rf $TMPDIR	# Remove the temp dir.
 
     # check if the package is actually installed
@@ -208,7 +217,8 @@ ynh_package_install_from_equivs () {
 # Requires YunoHost version 2.6.4 or higher.
 ynh_install_app_dependencies () {
     local dependencies=$@
-    local dependencies=${dependencies// /, }
+    # Add a comma for each space between packages. But not add a comma if the space separate a version specification. (See  below)
+    dependencies="$(echo "$dependencies" | sed 's/\([^\<=\>]\)\ \([^(]\)/\1, \2/g')"
     local dependencies=${dependencies//|/ | }
     local manifest_path="../manifest.json"
     if [ ! -e "$manifest_path" ]; then
@@ -221,6 +231,20 @@ ynh_install_app_dependencies () {
     fi
     local dep_app=${app//_/-}	# Replace all '_' by '-'
 
+    # Handle specific versions
+    if [[ "$dependencies" =~ [\<=\>] ]]
+    then
+        # Replace version specifications by relationships syntax
+        # https://www.debian.org/doc/debian-policy/ch-relationships.html
+        # Sed clarification
+        # [^(\<=\>] ignore if it begins by ( or < = >. To not apply twice.
+        # [\<=\>] matches < = or >
+        # \+ matches one or more occurence of the previous characters, for >= or >>.
+        # [^,]\+ matches all characters except ','
+        # Ex: 'package>=1.0' will be replaced by 'package (>= 1.0)'
+        dependencies="$(echo "$dependencies" | sed 's/\([^(\<=\>]\)\([\<=\>]\+\)\([^,]\+\)/\1 (\2 \3)/g')"
+    fi
+
     #
     # Epic ugly hack to fix the goddamn dependency nightmare of sury
     # Sponsored by the "Djeezusse Fokin Kraiste Why Do Adminsys Has To Be So Fucking Complicated I Should Go Grow Potatoes Instead Of This Shit" collective
@@ -236,8 +260,11 @@ ynh_install_app_dependencies () {
             if ! grep -nrq "sury" /etc/apt/sources.list*
             then
                 # Re-add sury
-                echo "deb https://packages.sury.org/php/ $(lsb_release -sc) main" > /etc/apt/sources.list.d/sury.list
-                wget -O /etc/apt/trusted.gpg.d/sury.gpg https://packages.sury.org/php/apt.gpg    
+                ynh_install_extra_repo --repo="https://packages.sury.org/php/ $(lsb_release -sc) main" --key="https://packages.sury.org/php/apt.gpg" --name=extra_php_version
+
+                # Pin this sury repository to prevent sury of doing shit
+                ynh_pin_repo --package="*" --pin="origin \"packages.sury.org\"" --priority=200 --name=extra_php_version
+                ynh_pin_repo --package="php${$YNH_DEFAULT_PHP_VERSION}*" --pin="origin \"packages.sury.org\"" --priority=600 --name=extra_php_version --append
             fi
         fi
     fi
@@ -258,6 +285,38 @@ EOF
     ynh_app_setting_set --app=$app --key=apt_dependencies --value="$dependencies"
 }
 
+# Add dependencies to install with ynh_install_app_dependencies
+#
+# [internal]
+#
+# usage: ynh_add_app_dependencies --package=phpversion [--replace]
+# | arg: -p, --package - Packages to add as dependencies for the app.
+# | arg: -r, --replace - Replace dependencies instead of adding to existing ones.
+ynh_add_app_dependencies () {
+	# Declare an array to define the options of this helper.
+	local legacy_args=pr
+	declare -Ar args_array=( [p]=package= [r]=replace)
+	local package
+	local replace
+	# Manage arguments with getopts
+	ynh_handle_getopts_args "$@"
+	replace=${replace:-0}
+
+	local current_dependencies=""
+	if [ $replace -eq 0 ]
+	then
+		local dep_app=${app//_/-}	# Replace all '_' by '-'
+		if ynh_package_is_installed --package="${dep_app}-ynh-deps"
+		then
+			current_dependencies="$(dpkg-query --show --showformat='${Depends}' ${dep_app}-ynh-deps) "
+		fi
+
+		current_dependencies=${current_dependencies// | /|}
+	fi
+
+	ynh_install_app_dependencies "${current_dependencies}${package}"
+}
+
 # Remove fake package and its dependencies
 #
 # Dependencies will removed only if no other package need them.
@@ -269,3 +328,223 @@ ynh_remove_app_dependencies () {
     local dep_app=${app//_/-}	# Replace all '_' by '-'
     ynh_package_autopurge ${dep_app}-ynh-deps	# Remove the fake package and its dependencies if they not still used.
 }
+
+#=================================================
+
+# Install packages from an extra repository properly.
+#
+# usage: ynh_install_extra_app_dependencies --repo="repo" --package="dep1 dep2" [--key=key_url] [--name=name]
+# | arg: -r, --repo - Complete url of the extra repository.
+# | arg: -p, --package - The packages to install from this extra repository
+# | arg: -k, --key - url to get the public key.
+# | arg: -n, --name - Name for the files for this repo, $app as default value.
+ynh_install_extra_app_dependencies () {
+	# Declare an array to define the options of this helper.
+	local legacy_args=rpkn
+	declare -Ar args_array=( [r]=repo= [p]=package= [k]=key= [n]=name= )
+	local repo
+	local package
+	local key
+	local name
+	# Manage arguments with getopts
+	ynh_handle_getopts_args "$@"
+	name="${name:-$app}"
+	key=${key:-}
+
+	# Set a key only if asked
+	if [ -n "$key" ]
+	then
+		key="--key=$key"
+	fi
+	# Add an extra repository for those packages
+	ynh_install_extra_repo --repo="$repo" $key --priority=995 --name=$name
+
+	# Install requested dependencies from this extra repository.
+	ynh_add_app_dependencies --package="$package"
+
+	# Remove this extra repository after packages are installed
+	ynh_remove_extra_repo --name=$app
+}
+
+# Add an extra repository correctly, pin it and get the key.
+#
+# [internal]
+#
+# usage: ynh_install_extra_repo --repo="repo" [--key=key_url] [--priority=priority_value] [--name=name] [--append]
+# | arg: -r, --repo - Complete url of the extra repository.
+# | arg: -k, --key - url to get the public key.
+# | arg: -p, --priority - Priority for the pin
+# | arg: -n, --name - Name for the files for this repo, $app as default value.
+# | arg: -a, --append - Do not overwrite existing files.
+ynh_install_extra_repo () {
+	# Declare an array to define the options of this helper.
+	local legacy_args=rkpna
+	declare -Ar args_array=( [r]=repo= [k]=key= [p]=priority= [n]=name= [a]=append )
+	local repo
+	local key
+	local priority
+	local name
+	local append
+	# Manage arguments with getopts
+	ynh_handle_getopts_args "$@"
+	name="${name:-$app}"
+	append=${append:-0}
+	key=${key:-}
+	priority=${priority:-}
+
+	if [ $append -eq 1 ]
+	then
+		append="--append"
+		wget_append="tee -a"
+	else
+		append=""
+		wget_append="tee"
+	fi
+
+	# Split the repository into uri, suite and components.
+	# Remove "deb " at the beginning of the repo.
+	repo="${repo#deb }"
+
+	# Get the uri
+	local uri="$(echo "$repo" | awk '{ print $1 }')"
+
+	# Get the suite
+	local suite="$(echo "$repo" | awk '{ print $2 }')"
+
+	# Get the components
+	local component="${repo##$uri $suite }"
+
+	# Add the repository into sources.list.d
+	ynh_add_repo --uri="$uri" --suite="$suite" --component="$component" --name="$name" $append
+
+	# Pin the new repo with the default priority, so it won't be used for upgrades.
+	# Build $pin from the uri without http and any sub path
+	local pin="${uri#*://}"
+	pin="${pin%%/*}"
+	# Set a priority only if asked
+	if [ -n "$priority" ]
+	then
+		priority="--priority=$priority"
+	fi
+	ynh_pin_repo --package="*" --pin="origin \"$pin\"" $priority --name="$name" $append
+
+	# Get the public key for the repo
+	if [ -n "$key" ]
+	then
+		mkdir -p "/etc/apt/trusted.gpg.d"
+		wget -q "$key" -O - | gpg --dearmor | $wget_append /etc/apt/trusted.gpg.d/$name.gpg > /dev/null
+	fi
+
+	# Update the list of package with the new repo
+	ynh_package_update
+}
+
+# Remove an extra repository and the assiociated configuration.
+#
+# [internal]
+#
+# usage: ynh_remove_extra_repo [--name=name]
+# | arg: -n, --name - Name for the files for this repo, $app as default value.
+ynh_remove_extra_repo () {
+	# Declare an array to define the options of this helper.
+	local legacy_args=n
+	declare -Ar args_array=( [n]=name= )
+	local name
+	# Manage arguments with getopts
+	ynh_handle_getopts_args "$@"
+	name="${name:-$app}"
+
+	ynh_secure_remove "/etc/apt/sources.list.d/$name.list"
+	ynh_secure_remove "/etc/apt/preferences.d/$name"
+	ynh_secure_remove "/etc/apt/trusted.gpg.d/$name.gpg"
+	ynh_secure_remove "/etc/apt/trusted.gpg.d/$name.asc"
+
+	# Update the list of package to exclude the old repo
+	ynh_package_update
+}
+
+# Add a repository.
+#
+# [internal]
+#
+# usage: ynh_add_repo --uri=uri --suite=suite --component=component [--name=name] [--append]
+# | arg: -u, --uri - Uri of the repository.
+# | arg: -s, --suite - Suite of the repository.
+# | arg: -c, --component - Component of the repository.
+# | arg: -n, --name - Name for the files for this repo, $app as default value.
+# | arg: -a, --append - Do not overwrite existing files.
+#
+# Example for a repo like deb http://forge.yunohost.org/debian/ stretch stable
+#                             uri                               suite   component
+# ynh_add_repo --uri=http://forge.yunohost.org/debian/ --suite=stretch --component=stable
+#
+ynh_add_repo () {
+	# Declare an array to define the options of this helper.
+	local legacy_args=uscna
+	declare -Ar args_array=( [u]=uri= [s]=suite= [c]=component= [n]=name= [a]=append )
+	local uri
+	local suite
+	local component
+	local name
+	local append
+	# Manage arguments with getopts
+	ynh_handle_getopts_args "$@"
+	name="${name:-$app}"
+	append=${append:-0}
+
+	if [ $append -eq 1 ]
+	then
+		append="tee -a"
+	else
+		append="tee"
+	fi
+
+	mkdir -p "/etc/apt/sources.list.d"
+	# Add the new repo in sources.list.d
+	echo "deb $uri $suite $component" \
+		| $append "/etc/apt/sources.list.d/$name.list"
+}
+
+# Pin a repository.
+#
+# [internal]
+#
+# usage: ynh_pin_repo --package=packages --pin=pin_filter [--priority=priority_value] [--name=name] [--append]
+# | arg: -p, --package - Packages concerned by the pin. Or all, *.
+# | arg: -i, --pin - Filter for the pin.
+# | arg: -p, --priority - Priority for the pin
+# | arg: -n, --name - Name for the files for this repo, $app as default value.
+# | arg: -a, --append - Do not overwrite existing files.
+#
+# See https://manpages.debian.org/stretch/apt/apt_preferences.5.en.html#How_APT_Interprets_Priorities for information about pinning.
+#
+ynh_pin_repo () {
+	# Declare an array to define the options of this helper.
+	local legacy_args=pirna
+	declare -Ar args_array=( [p]=package= [i]=pin= [r]=priority= [n]=name= [a]=append )
+	local package
+	local pin
+	local priority
+	local name
+	local append
+	# Manage arguments with getopts
+	ynh_handle_getopts_args "$@"
+	package="${package:-*}"
+	priority=${priority:-50}
+	name="${name:-$app}"
+	append=${append:-0}
+
+	if [ $append -eq 1 ]
+	then
+		append="tee -a"
+	else
+		append="tee"
+	fi
+
+	mkdir -p "/etc/apt/preferences.d"
+	echo "Package: $package
+Pin: $pin
+Pin-Priority: $priority
+" \
+	| $append "/etc/apt/preferences.d/$name"
+}
diff --git a/data/helpers.d/hardware b/data/helpers.d/hardware
new file mode 100644
index 000000000..46e27caf4
--- /dev/null
+++ b/data/helpers.d/hardware
@@ -0,0 +1,102 @@
+#!/bin/bash
+
+# Get the total or free amount of RAM+swap on the system
+#
+# usage: ynh_get_ram [--free|--total] [--ignore_swap|--only_swap]
+# | arg: -f, --free  - Count free RAM+swap
+# | arg: -t, --total - Count total RAM+swap
+# | arg: -s, --ignore_swap - Ignore swap, consider only real RAM
+# | arg: -o, --only_swap - Ignore real RAM, consider only swap
+ynh_get_ram () {
+	# Declare an array to define the options of this helper.
+	local legacy_args=ftso
+	declare -Ar args_array=( [f]=free [t]=total [s]=ignore_swap [o]=only_swap )
+	local free
+	local total
+	local ignore_swap
+	local only_swap
+	# Manage arguments with getopts
+	ynh_handle_getopts_args "$@"
+	ignore_swap=${ignore_swap:-0}
+	only_swap=${only_swap:-0}
+	free=${free:-0}
+	total=${total:-0}
+
+	local total_ram=$(vmstat --stats --unit M | grep "total memory" | awk '{print $1}')
+	local total_swap=$(vmstat --stats --unit M | grep "total swap" | awk '{print $1}')
+	local total_ram_swap=$(( total_ram + total_swap ))
+
+	local free_ram=$(vmstat --stats --unit M | grep "free memory" | awk '{print $1}')
+	local free_swap=$(vmstat --stats --unit M | grep "free swap" | awk '{print $1}')
+	local free_ram_swap=$(( free_ram + free_swap ))
+
+	# Use the total amount of ram
+	if [ $free -eq 1 ]
+	then
+		# Use the total amount of free ram
+		local ram=$free_ram_swap
+		if [ $ignore_swap -eq 1 ]
+		then
+			# Use only the amount of free ram
+			ram=$free_ram
+		elif [ $only_swap -eq 1 ]
+		then
+			# Use only the amount of free swap
+			ram=$free_swap
+		fi
+	elif [ $total -eq 1 ]
+	then
+		local ram=$total_ram_swap
+		if [ $ignore_swap -eq 1 ]
+		then
+			# Use only the amount of free ram
+			ram=$total_ram
+		elif [ $only_swap -eq 1 ]
+		then
+			# Use only the amount of free swap
+			ram=$total_swap
+		fi
+	else
+		ynh_print_warn --message="You have to choose --free or --total when using ynh_get_ram"
+		ram=0
+	fi
+
+    echo $ram
+}
+
+# Return 0 or 1 depending if the system has a given amount of RAM+swap free or total
+#
+# usage: ynh_require_ram --required=RAM required in Mb [--free|--total] [--ignore_swap|--only_swap]
+# | arg: -r, --required - The amount to require, in Mb
+# | arg: -f, --free  - Count free RAM+swap
+# | arg: -t, --total - Count total RAM+swap
+# | arg: -s, --ignore_swap - Ignore swap, consider only real RAM
+# | arg: -o, --only_swap - Ignore real RAM, consider only swap
+ynh_require_ram () {
+    # Declare an array to define the options of this helper.
+    local legacy_args=rftso
+    declare -Ar args_array=( [r]=required= [f]=free [t]=total [s]=ignore_swap [o]=only_swap )
+    local required
+    local free
+    local total
+    local ignore_swap
+    local only_swap
+    # Manage arguments with getopts
+    ynh_handle_getopts_args "$@"
+    # Dunno if that's the right way to do, but that's some black magic to be able to
+    # forward the bool args to ynh_get_ram easily?
+    # If the variable $free is not empty, set it to '--free'
+    free=${free:+--free}
+    total=${total:+--total}
+    ignore_swap=${ignore_swap:+--ignore_swap}
+    only_swap=${only_swap:+--only_swap}
+
+    local ram=$(ynh_get_ram $free $total $ignore_swap $only_swap)
+
+    if [ $ram -lt $required ]
+    then
+        return 1
+    else
+        return 0
+    fi
+}
diff --git a/data/helpers.d/php b/data/helpers.d/php
index e70302912..118477a0b 100644
--- a/data/helpers.d/php
+++ b/data/helpers.d/php
@@ -7,21 +7,94 @@ YNH_PHP_VERSION=${YNH_PHP_VERSION:-$YNH_DEFAULT_PHP_VERSION}
 
 # Create a dedicated php-fpm config
 #
-# usage: ynh_add_fpm_config [--phpversion=7.X]
+# usage 1: ynh_add_fpm_config [--phpversion=7.X] [--use_template] [--package=packages]
 # | arg: -v, --phpversion - Version of php to use.
+# | arg: -t, --use_template - Use this helper in template mode.
+# | arg: -p, --package - Additionnal php packages to install
+#
+# -----------------------------------------------------------------------------
+#
+# usage 2: ynh_add_fpm_config [--phpversion=7.X] --usage=usage --footprint=footprint [--package=packages]
+# | arg: -v, --phpversion - Version of php to use.
+# | arg: -f, --footprint      - Memory footprint of the service (low/medium/high).
+# low    - Less than 20Mb of ram by pool.
+# medium - Between 20Mb and 40Mb of ram by pool.
+# high   - More than 40Mb of ram by pool.
+# Or specify exactly the footprint, the load of the service as Mb by pool instead of having a standard value.
+# To have this value, use the following command and stress the service.
+# watch -n0.5 ps -o user,cmd,%cpu,rss -u APP
+#
+# | arg: -u, --usage     - Expected usage of the service (low/medium/high).
+# low    - Personal usage, behind the sso.
+# medium - Low usage, few people or/and publicly accessible.
+# high   - High usage, frequently visited website.
+#
+# | arg: -p, --package - Additionnal php packages to install for a specific version of php
+#
+#
+# The footprint of the service will be used to defined the maximum footprint we can allow, which is half the maximum RAM.
+# So it will be used to defined 'pm.max_children'
+# A lower value for the footprint will allow more children for 'pm.max_children'. And so for
+#    'pm.start_servers', 'pm.min_spare_servers' and 'pm.max_spare_servers' which are defined from the
+#    value of 'pm.max_children'
+# NOTE: 'pm.max_children' can't exceed 4 times the number of processor's cores.
+#
+# The usage value will defined the way php will handle the children for the pool.
+# A value set as 'low' will set the process manager to 'ondemand'. Children will start only if the
+#   service is used, otherwise no child will stay alive. This config gives the lower footprint when the
+#   service is idle. But will use more proc since it has to start a child as soon it's used.
+# Set as 'medium', the process manager will be at dynamic. If the service is idle, a number of children
+#   equal to pm.min_spare_servers will stay alive. So the service can be quick to answer to any request.
+#   The number of children can grow if needed. The footprint can stay low if the service is idle, but
+#   not null. The impact on the proc is a little bit less than 'ondemand' as there's always a few
+#   children already available.
+# Set as 'high', the process manager will be set at 'static'. There will be always as many children as
+#   'pm.max_children', the footprint is important (but will be set as maximum a quarter of the maximum
+#   RAM) but the impact on the proc is lower. The service will be quick to answer as there's always many
+#   children ready to answer.
 #
 # Requires YunoHost version 2.7.2 or higher.
 ynh_add_fpm_config () {
 	# Declare an array to define the options of this helper.
-	local legacy_args=v
-	declare -Ar args_array=( [v]=phpversion= )
+	local legacy_args=vtufp
+	declare -Ar args_array=( [v]=phpversion= [t]=use_template [u]=usage= [f]=footprint= [p]=package= )
 	local phpversion
+	local use_template
+	local usage
+	local footprint
+	local package
 	# Manage arguments with getopts
 	ynh_handle_getopts_args "$@"
+	package=${package:-}
+
+	# The default behaviour is to use the template.
+	use_template="${use_template:-1}"
+	usage="${usage:-}"
+	footprint="${footprint:-}"
+	if [ -n "$usage" ] || [ -n "$footprint" ]; then
+		use_template=0
+	fi
 
 	# Set the default PHP-FPM version by default
 	phpversion="${phpversion:-$YNH_PHP_VERSION}"
 
+	# If the requested php version is not the default version for YunoHost
+	if [ "$phpversion" != "$YNH_DEFAULT_PHP_VERSION" ]
+	then
+		# If the argument --package is used, add the packages to ynh_install_php to install them from sury
+		if [ -n "$package" ]; then
+			local additionnal_packages="--package=$package"
+		else
+			local additionnal_packages=""
+		fi
+		# Install this specific version of php.
+		ynh_install_php --phpversion=$phpversion "$additionnal_packages"
+	elif [ -n "$package" ]
+	then
+		# Install the additionnal packages from the default repository
+		ynh_add_app_dependencies --package="$package"
+	fi
+
 	local fpm_config_dir="/etc/php/$phpversion/fpm"
 	local fpm_service="php${phpversion}-fpm"
 	# Configure PHP-FPM 5 on Debian Jessie
@@ -34,23 +107,82 @@ ynh_add_fpm_config () {
 	ynh_app_setting_set --app=$app --key=phpversion --value=$phpversion
 	finalphpconf="$fpm_config_dir/pool.d/$app.conf"
 	ynh_backup_if_checksum_is_different --file="$finalphpconf"
-	cp ../conf/php-fpm.conf "$finalphpconf"
-	ynh_replace_string --match_string="__NAMETOCHANGE__" --replace_string="$app" --target_file="$finalphpconf"
-	ynh_replace_string --match_string="__FINALPATH__" --replace_string="$final_path" --target_file="$finalphpconf"
-	ynh_replace_string --match_string="__USER__" --replace_string="$app" --target_file="$finalphpconf"
-	ynh_replace_string --match_string="__PHPVERSION__" --replace_string="$phpversion" --target_file="$finalphpconf"
+
+	if [ $use_template -eq 1 ]
+	then
+                # Usage 1, use the template in ../conf/php-fpm.conf
+                cp ../conf/php-fpm.conf "$finalphpconf"
+                ynh_replace_string --match_string="__NAMETOCHANGE__" --replace_string="$app" --target_file="$finalphpconf"
+                ynh_replace_string --match_string="__FINALPATH__" --replace_string="$final_path" --target_file="$finalphpconf"
+                ynh_replace_string --match_string="__USER__" --replace_string="$app" --target_file="$finalphpconf"
+                ynh_replace_string --match_string="__PHPVERSION__" --replace_string="$phpversion" --target_file="$finalphpconf"
+
+	else
+                # Usage 2, generate a php-fpm config file with ynh_get_scalable_phpfpm
+
+                # Store settings
+                ynh_app_setting_set --app=$app --key=fpm_footprint --value=$footprint
+                ynh_app_setting_set --app=$app --key=fpm_usage --value=$usage
+
+                # Define the values to use for the configuration of php.
+                ynh_get_scalable_phpfpm --usage=$usage --footprint=$footprint
+
+                # Copy the default file
+                cp "$fpm_config_dir/pool.d/www.conf" "$finalphpconf"
+
+                # Replace standard variables into the default file
+                ynh_replace_string --match_string="^\[www\]" --replace_string="[$app]" --target_file="$finalphpconf"
+                ynh_replace_string --match_string=".*listen = .*" --replace_string="listen = /var/run/php/php$phpversion-fpm-$app.sock" --target_file="$finalphpconf"
+                ynh_replace_string --match_string="^user = .*" --replace_string="user = $app" --target_file="$finalphpconf"
+                ynh_replace_string --match_string="^group = .*" --replace_string="group = $app" --target_file="$finalphpconf"
+                ynh_replace_string --match_string=".*chdir = .*" --replace_string="chdir = $final_path" --target_file="$finalphpconf"
+
+                # Configure fpm children
+                ynh_replace_string --match_string=".*pm = .*" --replace_string="pm = $php_pm" --target_file="$finalphpconf"
+                ynh_replace_string --match_string=".*pm.max_children = .*" --replace_string="pm.max_children = $php_max_children" --target_file="$finalphpconf"
+                ynh_replace_string --match_string=".*pm.max_requests = .*" --replace_string="pm.max_requests = 500" --target_file="$finalphpconf"
+                ynh_replace_string --match_string=".*request_terminate_timeout = .*" --replace_string="request_terminate_timeout = 1d" --target_file="$finalphpconf"
+                if [ "$php_pm" = "dynamic" ]
+                then
+			ynh_replace_string --match_string=".*pm.start_servers = .*" --replace_string="pm.start_servers = $php_start_servers" --target_file="$finalphpconf"
+			ynh_replace_string --match_string=".*pm.min_spare_servers = .*" --replace_string="pm.min_spare_servers = $php_min_spare_servers" --target_file="$finalphpconf"
+			ynh_replace_string --match_string=".*pm.max_spare_servers = .*" --replace_string="pm.max_spare_servers = $php_max_spare_servers" --target_file="$finalphpconf"
+		elif [ "$php_pm" = "ondemand" ]
+		then
+			ynh_replace_string --match_string=".*pm.process_idle_timeout = .*" --replace_string="pm.process_idle_timeout = 10s" --target_file="$finalphpconf"
+		fi
+
+		# Comment unused parameters
+		if [ "$php_pm" != "dynamic" ]
+		then
+			ynh_replace_string --match_string=".*\(pm.start_servers = .*\)" --replace_string=";\1" --target_file="$finalphpconf"
+			ynh_replace_string --match_string=".*\(pm.min_spare_servers = .*\)" --replace_string=";\1" --target_file="$finalphpconf"
+			ynh_replace_string --match_string=".*\(pm.max_spare_servers = .*\)" --replace_string=";\1" --target_file="$finalphpconf"
+		fi
+		if [ "$php_pm" != "ondemand" ]
+		then
+			ynh_replace_string --match_string=".*\(pm.process_idle_timeout = .*\)" --replace_string=";\1" --target_file="$finalphpconf"
+		fi
+
+		# Concatene the extra config.
+		if [ -e ../conf/extra_php-fpm.conf ]; then
+			cat ../conf/extra_php-fpm.conf >> "$finalphpconf"
+		fi
+	fi
+
 	chown root: "$finalphpconf"
 	ynh_store_file_checksum --file="$finalphpconf"
 
 	if [ -e "../conf/php-fpm.ini" ]
 	then
-		echo "Packagers ! Please do not use a separate php ini file, merge your directives in the pool file instead." >&2
+		ynh_print_warn -message="Packagers ! Please do not use a separate php ini file, merge your directives in the pool file instead."
 		finalphpini="$fpm_config_dir/conf.d/20-$app.ini"
 		ynh_backup_if_checksum_is_different "$finalphpini"
 		cp ../conf/php-fpm.ini "$finalphpini"
 		chown root: "$finalphpini"
 		ynh_store_file_checksum "$finalphpini"
 	fi
+
 	ynh_systemd_action --service_name=$fpm_service --action=reload
 }
 
@@ -62,12 +194,251 @@ ynh_add_fpm_config () {
 ynh_remove_fpm_config () {
 	local fpm_config_dir=$(ynh_app_setting_get --app=$app --key=fpm_config_dir)
 	local fpm_service=$(ynh_app_setting_get --app=$app --key=fpm_service)
-	# Assume default php version if not set
+	# Get the version of php used by this app
+	local phpversion=$(ynh_app_setting_get $app phpversion)
+
+	# Assume default PHP-FPM version by default
+	phpversion="${phpversion:-$YNH_DEFAULT_PHP_VERSION}"
+
+	# Assume default php files if not set
 	if [ -z "$fpm_config_dir" ]; then
 		fpm_config_dir="/etc/php/$YNH_DEFAULT_PHP_VERSION/fpm"
 		fpm_service="php$YNH_DEFAULT_PHP_VERSION-fpm"
 	fi
 	ynh_secure_remove --file="$fpm_config_dir/pool.d/$app.conf"
 	ynh_secure_remove --file="$fpm_config_dir/conf.d/20-$app.ini" 2>&1
-	ynh_systemd_action --service_name=$fpm_service --action=reload
+
+	if ynh_package_is_installed --package="php${phpversion}-fpm"; then
+		ynh_systemd_action --service_name=$fpm_service --action=reload
+	fi
+
+	# If the php version used is not the default version for YunoHost
+	if [ "$phpversion" != "$YNH_DEFAULT_PHP_VERSION" ]
+	then
+		# Remove this specific version of php
+		ynh_remove_php
+	fi
+}
+
+# Install another version of php.
+#
+# [internal]
+#
+# usage: ynh_install_php --phpversion=phpversion [--package=packages]
+# | arg: -v, --phpversion - Version of php to install.
+# | arg: -p, --package - Additionnal php packages to install
+ynh_install_php () {
+	# Declare an array to define the options of this helper.
+	local legacy_args=vp
+	declare -Ar args_array=( [v]=phpversion= [p]=package= )
+	local phpversion
+	local package
+	# Manage arguments with getopts
+	ynh_handle_getopts_args "$@"
+	package=${package:-}
+
+	# Store phpversion into the config of this app
+	ynh_app_setting_set $app phpversion $phpversion
+
+	if [ "$phpversion" == "$YNH_DEFAULT_PHP_VERSION" ]
+	then
+		ynh_die "Do not use ynh_install_php to install php$YNH_DEFAULT_PHP_VERSION"
+	fi
+
+	# Create the file if doesn't exist already
+	touch /etc/php/ynh_app_version
+
+	# Do not add twice the same line
+	if ! grep --quiet "$YNH_APP_INSTANCE_NAME:" "/etc/php/ynh_app_version"
+	then
+		# Store the ID of this app and the version of php requested for it
+		echo "$YNH_APP_INSTANCE_NAME:$phpversion" | tee --append "/etc/php/ynh_app_version"
+	fi
+
+	# Add an extra repository for those packages
+	ynh_install_extra_repo --repo="https://packages.sury.org/php/ $(lsb_release -sc) main" --key="https://packages.sury.org/php/apt.gpg" --priority=995 --name=extra_php_version
+
+	# Install requested dependencies from this extra repository.
+	# Install php-fpm first, otherwise php will install apache as a dependency.
+	ynh_add_app_dependencies --package="php${phpversion}-fpm"
+	ynh_add_app_dependencies --package="php$phpversion php${phpversion}-common $package"
+
+	# Set the default php version back as the default version for php-cli.
+	update-alternatives --set php /usr/bin/php$YNH_DEFAULT_PHP_VERSION
+
+	# Pin this extra repository after packages are installed to prevent sury of doing shit
+	ynh_pin_repo --package="*" --pin="origin \"packages.sury.org\"" --priority=200 --name=extra_php_version
+	ynh_pin_repo --package="php${YNH_DEFAULT_PHP_VERSION}*" --pin="origin \"packages.sury.org\"" --priority=600 --name=extra_php_version --append
+
+	# Advertise service in admin panel
+	yunohost service add php${phpversion}-fpm --log "/var/log/php${phpversion}-fpm.log"
+}
+
+# Remove the specific version of php used by the app.
+#
+# [internal]
+#
+# usage: ynh_install_php
+ynh_remove_php () {
+	# Get the version of php used by this app
+	local phpversion=$(ynh_app_setting_get $app phpversion)
+
+	if [ "$phpversion" == "$YNH_DEFAULT_PHP_VERSION" ] || [ -z "$phpversion" ]
+	then
+		if [ "$phpversion" == "$YNH_DEFAULT_PHP_VERSION" ]
+		then
+			ynh_print_err "Do not use ynh_remove_php to remove php$YNH_DEFAULT_PHP_VERSION !"
+		fi
+		return 0
+	fi
+
+	# Create the file if doesn't exist already
+	touch /etc/php/ynh_app_version
+
+	# Remove the line for this app
+	sed --in-place "/$YNH_APP_INSTANCE_NAME:$phpversion/d" "/etc/php/ynh_app_version"
+
+	# If no other app uses this version of php, remove it.
+	if ! grep --quiet "$phpversion" "/etc/php/ynh_app_version"
+	then
+		# Remove the service from the admin panel
+		if ynh_package_is_installed --package="php${phpversion}-fpm"; then
+			yunohost service remove php${phpversion}-fpm
+		fi
+
+		# Purge php dependencies for this version.
+		ynh_package_autopurge "php$phpversion php${phpversion}-fpm php${phpversion}-common"
+	fi
+}
+
+# Define the values to configure php-fpm
+#
+# [internal]
+#
+# usage: ynh_get_scalable_phpfpm --usage=usage --footprint=footprint [--print]
+# | arg: -f, --footprint      - Memory footprint of the service (low/medium/high).
+# low    - Less than 20Mb of ram by pool.
+# medium - Between 20Mb and 40Mb of ram by pool.
+# high   - More than 40Mb of ram by pool.
+# Or specify exactly the footprint, the load of the service as Mb by pool instead of having a standard value.
+# To have this value, use the following command and stress the service.
+# watch -n0.5 ps -o user,cmd,%cpu,rss -u APP
+#
+# | arg: -u, --usage     - Expected usage of the service (low/medium/high).
+# low    - Personal usage, behind the sso.
+# medium - Low usage, few people or/and publicly accessible.
+# high   - High usage, frequently visited website.
+#
+# | arg: -p, --print - Print the result (intended for debug purpose only when packaging the app)
+ynh_get_scalable_phpfpm () {
+    local legacy_args=ufp
+    # Declare an array to define the options of this helper.
+    declare -Ar args_array=( [u]=usage= [f]=footprint= [p]=print )
+    local usage
+    local footprint
+    local print
+    # Manage arguments with getopts
+    ynh_handle_getopts_args "$@"
+    # Set all characters as lowercase
+    footprint=${footprint,,}
+    usage=${usage,,}
+    print=${print:-0}
+
+    if [ "$footprint" = "low" ]
+    then
+        footprint=20
+    elif [ "$footprint" = "medium" ]
+    then
+        footprint=35
+    elif [ "$footprint" = "high" ]
+    then
+        footprint=50
+    fi
+
+    # Define the way the process manager handle child processes.
+    if [ "$usage" = "low" ]
+    then
+        php_pm=ondemand
+    elif [ "$usage" = "medium" ]
+    then
+        php_pm=dynamic
+    elif [ "$usage" = "high" ]
+    then
+        php_pm=static
+    else
+        ynh_die --message="Does not recognize '$usage' as an usage value."
+    fi
+
+    # Get the total of RAM available, except swap.
+    local max_ram=$(ynh_get_ram --total --ignore_swap)
+
+    at_least_one() {
+        # Do not allow value below 1
+        if [ $1 -le 0 ]
+        then
+            echo 1
+        else
+            echo $1
+        fi
+    }
+
+    # Define pm.max_children
+    # The value of pm.max_children is the total amount of ram divide by 2 and divide again by the footprint of a pool for this app.
+    # So if php-fpm start the maximum of children, it won't exceed half of the ram.
+    php_max_children=$(( $max_ram / 2 / $footprint ))
+    # If process manager is set as static, use half less children.
+    # Used as static, there's always as many children as the value of pm.max_children
+    if [ "$php_pm" = "static" ]
+    then
+        php_max_children=$(( $php_max_children / 2 ))
+    fi
+    php_max_children=$(at_least_one $php_max_children)
+
+    # To not overload the proc, limit the number of children to 4 times the number of cores.
+    local core_number=$(nproc)
+    local max_proc=$(( $core_number * 4 ))
+    if [ $php_max_children -gt $max_proc ]
+    then
+        php_max_children=$max_proc
+    fi
+
+    if [ "$php_pm" = "dynamic" ]
+    then
+        # Define pm.start_servers, pm.min_spare_servers and pm.max_spare_servers for a dynamic process manager
+        php_min_spare_servers=$(( $php_max_children / 8 ))
+        php_min_spare_servers=$(at_least_one $php_min_spare_servers)
+
+        php_max_spare_servers=$(( $php_max_children / 2 ))
+        php_max_spare_servers=$(at_least_one $php_max_spare_servers)
+
+        php_start_servers=$(( $php_min_spare_servers + ( $php_max_spare_servers - $php_min_spare_servers ) /2 ))
+        php_start_servers=$(at_least_one $php_start_servers)
+    else
+        php_min_spare_servers=0
+        php_max_spare_servers=0
+        php_start_servers=0
+    fi
+
+    if [ $print -eq 1 ]
+    then
+        ynh_debug --message="Footprint=${footprint}Mb by pool."
+        ynh_debug --message="Process manager=$php_pm"
+        ynh_debug --message="Max RAM=${max_ram}Mb"
+        if [ "$php_pm" != "static" ]; then
+            ynh_debug --message="\nMax estimated footprint=$(( $php_max_children * $footprint ))"
+            ynh_debug --message="Min estimated footprint=$(( $php_min_spare_servers * $footprint ))"
+        fi
+        if [ "$php_pm" = "dynamic" ]; then
+            ynh_debug --message="Estimated average footprint=$(( $php_max_spare_servers * $footprint ))"
+        elif [ "$php_pm" = "static" ]; then
+            ynh_debug --message="Estimated footprint=$(( $php_max_children * $footprint ))"
+        fi
+        ynh_debug --message="\nRaw php-fpm values:"
+        ynh_debug --message="pm.max_children = $php_max_children"
+        if [ "$php_pm" = "dynamic" ]; then
+            ynh_debug --message="pm.start_servers = $php_start_servers"
+            ynh_debug --message="pm.min_spare_servers = $php_min_spare_servers"
+            ynh_debug --message="pm.max_spare_servers = $php_max_spare_servers"
+        fi
+    fi
 }