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Add swap helpers. This provides yunohost 2 things:
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* Remove duplication and centralize code and bugfixes for easier maintainance
* The day the core supports swap files or we want to change the logic, these helpers will be empty shells
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Salamandar committed May 31, 2024
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114 changes: 114 additions & 0 deletions helpers/helpers.v1.d/hardware
Original file line number Diff line number Diff line change
Expand Up @@ -103,3 +103,117 @@ ynh_require_ram() {
return 0
fi
}


# Ask the creation of a swap file for the application.
# The helper might or might not create the swap file, considering the machine's configuration.
#
# [packagingv1]
#
# usage: ynh_add_swap --size=SWAP in Mb
# | arg: -s, --size= - Amount of SWAP to add in Mb.
ynh_add_swap () {
# Declare an array to define the options of this helper.
local -A args_array=( [s]=size= )
local size
# Manage arguments with getopts
ynh_handle_getopts_args "$@"

# Could be moved to an argument
swapfile_dir="$(realpath /)"
swapfile_path="$(realpath $swapfile_dir/swap_$app)"

# Early warning exit: Can't swap inside LXD
if [[ "$(systemd-detect-virt)" == "lxc" ]]; then
ynh_print_warn --message="You are inside a LXC container, swap will not be added."
ynh_print_warn --message="That can cause troubles for $app. Please make sure you have more than $((size/1024))G of RAM/swap available."
return
fi

# Early warning exit: Preserve SD cards and do not swap on them
if ynh_is_on_sd_card --dir="$swapfile_dir" && [[ "${SD_CARD_CAN_SWAP:-0}" == "0" ]]; then
ynh_print_warn --message="Swap files on an SD card is not recommended, swap will not be added."
ynh_print_warn --message="That can cause troubles for $app. Please make sure you have more than $((size/1024))G of RAM/swap available."
ynh_print_warn --message="If you still want activate the swap, you can relaunch the command preceded by 'SD_CARD_CAN_SWAP=1'"
return
fi

# Early warning exit: swapfile already exists
if [ -f "$swapfile_path" ]; then
ynh_print_warn --message="Swap file $swapfile_path already exists!"
return
fi

local swap_max_size_kb=$(( size * 1024 ))

local free_space_kb
free_space_kb=$(df --block-size=K --output=avail "$swapfile_dir" | sed 1d | sed -e 's/K$//')
# Because we don't want to fill the disk with a swap file, divide by 2 the available space.
local usable_space_kb=$(( free_space_kb / 2 ))

# Compare the available space with the size of the swap.
# And set a acceptable size from the request
size_space_ratio=$(( swap_max_size_kb / usable_space_kb + 1 ))
if (( size_space_ratio > 4)); then
ynh_print_warn --message="Not enough space for a swap file at $swapfile_path."
return
fi
swap_size_kb=$(( swap_max_size_kb / size_space_ratio ))

# Workaround for some copy-on-write filesystems like btrfs.
# Create the file
truncate -s 0 "$swapfile_path"
# Set the No_COW attribute on the swapfile with chattr
chattr +C "$swapfile_path" || true
# Set the final file size
dd if=/dev/zero of="$swapfile_path" bs=1024 count="$swap_size_kb"
chmod 0600 "$swapfile_path"

# Create the swap
mkswap "$swapfile_path"
# And activate it
swapon "$swapfile_path"
# Then add an entry in fstab to load this swap at each boot.
echo -e "$swapfile_path swap swap defaults 0 0 #Swap added by $app" >> /etc/fstab
}

ynh_del_swap () {
# Could be moved to an argument
swapfile_dir="$(realpath /)"
swapfile_path="$(realpath $swapfile_dir/swap_$app)"

if [ ! -f "$swapfile_path" ]; then
return
fi

# Clean the fstab...
sed -i "/#Swap added by $app/d" /etc/fstab
# Desactive the swap file...
swapoff "$swapfile_path"
# And remove it.
rm "$swapfile_path"
}

# Check if the device of the provided directory is an SD card
#
# [internal]
#
# usage: ynh_is_on_sd_card --dir=/
# | arg: -d, --dir= - Directory to check
ynh_is_on_sd_card () {
# Declare an array to define the options of this helper.
local -A args_array=( [d]=dir= )
local dir
# Manage arguments with getopts
ynh_handle_getopts_args "$@"

device_dev=$(findmnt --nofsroot --uniq --output source --noheadings --first-only --target "$dir")
device_pkname=$(lsblk --output PKNAME --noheadings "$device_dev")
device_rotational=$(lsblk --output ROTA --noheadings "$device_dev")

if [[ "$device_pkname" == *"mmc"* ]] && [[ "$device_rotational" == "0" ]]; then
return 0
else
return 1
fi
}

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