github.com/Ilhicas/nomad@v1.0.4-0.20210304152020-e86851182bc3/website/content/docs/autoscaling/internals/checks.mdx (about)

     1  ---
     2  layout: docs
     3  page_title: Checks
     4  sidebar_title: Checks
     5  description: Learn about how the Autoscaler deals with policy checks.
     6  ---
     7  
     8  # Nomad Autoscaler Check Calculations
     9  
    10  A scaling policy can include several checks all of which produce a scaling
    11  suggesting. The checks are executed at the same time during a policy evaluation
    12  and the results can conflict with each other. In a scenario like this, the
    13  autoscaler iterates the results the chooses the safest result which results in
    14  retaining the most capacity of the resource.
    15  
    16  In a scenario where two checks return different desired directions, the following
    17  logic is applied.
    18  
    19  - `ScaleOut and ScaleIn => ScaleOut`
    20  - `ScaleOut and ScaleNone => ScaleOut`
    21  - `ScaleIn and ScaleNone => ScaleNone`
    22  
    23  In situations where the two same actions are suggested, but with different counts the
    24  following logic is applied, where the count is the absolute desired value.
    25  
    26  - `ScaleOut(10) and ScaleOut(9) => ScaleOut(10)`
    27  - `ScaleIn(3) and ScaleIn(4) => ScaleIn(4)`