Checkmk Werk 15662: Bug fixes for <tt>cmk.gui.plugins.metrics.utils.indexed_color</tt>

ID: 15662 Title: Bug fixes for <tt>cmk.gui.plugins.metrics.utils.indexed_color</tt> Component: metrics Level: 1 Class: Bug fix Version: 2.3.0b1 This werk is mainly relevant to users who deploy or develop custom Checkmk plugins. For all other users, the werk might result in some changes regarding the colors of certain metrics in graphs. The above mentioned function, also available via <tt>cmk.gui.plugins.metrics.indexed_color</tt>, computes colors for graphs. It was buggy in multiple ways: LI: There was no validation of the input arguments <tt>idx</tt> and <tt>total</tt>. We now ensure that <tt>0 <= idx <= total</tt> and <tt>total > 0</tt>. If these requirements are violated, an error is raised. LI: <tt>indexed_color</tt> crashed for certain (valid) parameter combinations. For small values of <tt>idx</tt>, <tt>indexed_color</tt> returns values from a fixed set of pre-defined colors. Once this set was exhausted, the function crashed if <tt>idx</tt> was close to <tt>total</tt>. LI: Depending on the value of <tt>total</tt>, <tt>indexed_color</tt> produced very dark colors after exhausting the pre-defined set. Instead, we now always start with the same brightness and then then become successively darker.