Rudder

We want to make the policy generation node by node, so that:

• a faulty node does not block the policy generation for other nodes,
• in case of very long generation (>30 min), we don't have to wait the whole time to have node starting to get new policy generation,
• errors are reported on a node by node basis
• we can have a meaningfull progress bar for the generation ("7 nodes out of 25"...)

This, of course, lead a number of questions, for example:

• how do we manage dependencies (typically between a node and its policy server, if hostname change)? What happen if only one the the two updates breaks?
• how do we make errors understandable and discoverable? Imagine if 7000 nodes are in error.

(and certainly a number of others).

Moreover, the parallelism of the policy generation can be more fine-grained controlled, along with the JS timeout, dynamic group computation at start of generation, and change computation with API:

# for max parallelism, either use '1x' to mean "1 time the number of CPU / 2" or '3' to mean '3 threads'
curl -k -H "X-API-Token: xxx"  -X POST 'https://.../rudder/api/latest/settings/rudder_generation_max_parallelism' -d "value=1x" 
# value is in seconds
curl -k -H "X-API-Token: xxx"  -X POST 'https://.../rudder/api/latest/settings/rudder_generation_js_timeout' -d "value=10" 
# use 'false' or 'true' 
curl -k -H "X-API-Token: xxx"  -X POST 'https://.../rudder/api/latest/settings/rudder_generation_compute_dyngroups' -d "value=false" 
curl -k -H "X-API-Token: xxx"  -X POST 'https://.../rudder/api/latest/settings/rudder_compute_changes' -d "value=false"