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Original source (github.com)
Tags: golang go concurrency github.com
Clipped on: 2017-12-18

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    cr is a job executor concerned with achieving the highest parallel execution possible.

    Given a definition of jobs and their dependencies, it builds a graph that outlines the execution plan of these jobs.

    For instance, consider the following plan:

      - Id: 'SayFoo'
        Run: 'echo foo'
      - Id: 'SayBaz'
        Run: 'echo baz'
        DependsOn: [ 'SayFoo' ]
      - Id: 'SayCaz'
        Run: 'echo caz'
        DependsOn: [ 'SayFoo' ]

    This plan states that we have 3 jobs to be executed: SayFoo, SayBaz and SayCaz but the last two jobs must only be executed after the first one and in case it succeeds.

    To visualize the execution plan we can run it with --graph, which validates the plan and prints out a dot digraph.

    # Execute CR telling it where the execution
    # plan is (execution.yaml) and that it should
    # just print the graph and exit.
    cr --file ./execution.yaml  --graph
    digraph {
    	compound = "true"
    	newrank = "true"
    	subgraph "root" {
    		"[root] SayFoo" -> "[root] SayBaz"
    		"[root] SayFoo" -> "[root] SayCaz"
    		"[root] _root" -> "[root] SayFoo"
    # If we pipe this to `dot` and than take the output
    # of `dot` we can see the visual representation of the 
    # digraph.
    cr --file ./examples/hello-world.yaml --graph \
            | dot -Tpng > ./assets/hello-world.graph.png

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