[bug] Monitor break when disk resource is mapped with nfs share

[rysiulg]

Describe the bug
After install no data is sent to openWISP -in logread on Openwrt v.24 response error status 400 and error parsing nil values

Steps To Reproduce
Mount nfs share -or usb share?

Expected behavior
Add control of parsed value to check if is vallid

Screenshots
If applicable, add screenshots to help explain your problem.

System Informatioon:

• OpenWrt 24 on Banana PI 8GB

After change on installatioon file /usr/lib/lua/openwisp-monitoring/resources.lua (added checkoing for nil -monitor starts sending data):
Original funkcjiion:

function resources.parse_disk_usage_org()
  local disk_usage_info = {}
  local disk_usage_file = io.popen('df')
  local disk_usage = disk_usage_file:read("*a")
  disk_usage_file:close()
  for _, line in ipairs(utils.split(disk_usage, "\n")) do
    if line:sub(1, 10) ~= 'Filesystem' then
      local filesystem, size, used, available, percent, location = line:match(
        '(%S+)%s+(%S+)%s+(%S+)%s+(%S+)%s+(%S+)%s+(%S+)')
      if filesystem ~= 'tmpfs' and not string.match(filesystem, 'overlayfs') then
        percent = percent:gsub('%W', '')
        -- available, size and used are in KiB
        table.insert(disk_usage_info, {
          filesystem = filesystem,
          available_bytes = tonumber(available) * 1024,
          size_bytes = tonumber(size) * 1024,
          used_bytes = tonumber(used) * 1024,
          used_percent = tonumber(percent),
          mount_point = location
        })
      end
    end
  end
  return disk_usage_info
end

Modified funkction:

function resources.parse_disk_usage()
  local disk_usage_info = {}
  local disk_usage_file = io.popen('df')
  local disk_usage = disk_usage_file:read("*a")
  disk_usage_file:close()

  for _, line in ipairs(utils.split(disk_usage, "\n")) do
    if line:sub(1, 10) ~= 'Filesystem' then
      local filesystem, size, used, available, percent, location = line:match(
        '(%S+)%s+(%S+)%s+(%S+)%s+(%S+)%s+(%S+)%s+(%S+)')

      -- ....... Zabezpieczenie przed nil:
      if filesystem and size and used and available and percent and location then
        if filesystem ~= 'tmpfs' and not string.match(filesystem, 'overlayfs') then
          percent = percent:gsub('%W', '')
          table.insert(disk_usage_info, {
            filesystem = filesystem,
            available_bytes = tonumber(available) * 1024,
            size_bytes = tonumber(size) * 1024,
            used_bytes = tonumber(used) * 1024,
            used_percent = tonumber(percent),
            mount_point = location
          })
        end
      else
        -- (opcjonalnie) logowanie b....dnej linii:
        -- print("Unable to parse line: " .. line)
      end
    end
  end

  return disk_usage_info
end

[pandafy]

@rysiulg you issue seems to be related to the OpenWrt package. If you confirm, I will move this issue to https://github.com/openwisp/openwrt-openwisp-monitoring repository.