This is a work in progress.

Introduction

Nodeclass is a reimplementation of the extended version of Reclass (insert link to extended and original). The extended version added inventory queries, nested references, escaping the reference token (the dollar-curly-brace). The reimplementation brings significant performance gains for inventory queries and a slight performance gain overall.

The goal was to improve readability and maintainability of the code base.

High level overview (for developers)

The interpolator (for a node):

• starts by merging together all the exports
• then all of the parameters;
• then it figures out what the inventory queries are;
• it evaluates all the inventory queries;
• it works out all of the nodes references and then
• it evaluates all the exports
• returns the data

Glossary

• Interpolate: Merge down all the data for the node and classes and resolving all the references and inventory queries.
• Inventory query: marked by dollar-square-bracket, takes data from other nodes' exports
• Reference: data taken from another parameter path using dollar-curly-brace notation
• Path:
• Context: thread-local storage of configuration settings that control behaviour at low level
• Klass loader: takes care of loading classes from some (set of) URI(s) and presenting it to the interpolator in a standard way
• Node loader: same for the node files
• Hierarchy: top-level dictionary like parameters or exports

centos7

pygit2 - No rpm for python3.6 for centos7 in epel, so install via pip. But the latest versions available via pip will not install. First install dependences via yum: yum install python3-devel libgit2-devel Second install version 0.28.2 via pip: pip3.6 install pygit2==0.28.2