Bin-packing a large object into smaller enumerated objects with max size in jsonnet.

configmap-binpack.libsonnet

local cm = {
  binPack(data, maxSize, nameTemplate)::
    self.innerBinPack(data, maxSize, nameTemplate, std.objectFields(data), maxSize, 0),
  innerBinPack(data, maxSize, nameTemplate, items, remainingSize, count)::
    if std.length(items) == 0 then
      {}
    else
      local curName = items[0];
      local cur = { [curName]: data[curName] };
      // Size is the sum of the length of the key + length of the content plus
      // the yaml divider ": " of `key: value`. This is likely not 100% correct
      // as objects may be converted to different formats in the process thus
      // their actual size may differ.
      local curSize = std.length(curName) + std.length(cur) + 2;

      if (remainingSize - curSize) < 0 then
        self.innerBinPack(data, maxSize, nameTemplate, items, maxSize, count + 1) tailstrict
      else
        { [nameTemplate + count]+: cur } + self.innerBinPack(data, maxSize, nameTemplate, items[1:], remainingSize - curSize, count) tailstrict,
};

local data = {
  '1': 'a',
  '2': 'a',
  '3': 'a',
  '4': 'a',
  '5': 'a',
  '6': 'a',
  '7': 'a',
  '8': 'a',
  '9': 'a',
  '10': 'a',
  '11': 'a',
  '12': 'a',
  '13': 'a',
};

cm.binPack(data, 10, 'configmap')