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Sebastiaan van Stijn df43eb931e Fix cpu/memory limits and reservations being reset on service update

Before this change:
----------------------------------------------------

Create a service with reservations and limits for memory and cpu:

    docker service create --name test \
      --limit-memory=100M --limit-cpu=1 \
      --reserve-memory=100M --reserve-cpu=1 \
      nginx:alpine

Verify the configuration

    docker service inspect --format '{{json .Spec.TaskTemplate.Resources}}' test
    {
      "Limits": {
        "NanoCPUs": 1000000000,
        "MemoryBytes": 104857600
      },
      "Reservations": {
        "NanoCPUs": 1000000000,
        "MemoryBytes": 104857600
      }
    }

Update just CPU limit and reservation:

    docker service update --limit-cpu=2 --reserve-cpu=2 test

Notice that the memory limit and reservation is not preserved:

    docker service inspect --format '{{json .Spec.TaskTemplate.Resources}}' test
    {
      "Limits": {
        "NanoCPUs": 2000000000
      },
      "Reservations": {
        "NanoCPUs": 2000000000
      }
    }

Update just Memory limit and reservation:

    docker service update --limit-memory=200M --reserve-memory=200M test

Notice that the CPU limit and reservation is not preserved:

    docker service inspect --format '{{json .Spec.TaskTemplate.Resources}}' test
    {
      "Limits": {
        "MemoryBytes": 209715200
      },
      "Reservations": {
        "MemoryBytes": 209715200
      }
    }

After this change:
----------------------------------------------------

Create a service with reservations and limits for memory and cpu:

    docker service create --name test \
      --limit-memory=100M --limit-cpu=1 \
      --reserve-memory=100M --reserve-cpu=1 \
      nginx:alpine

Verify the configuration

    docker service inspect --format '{{json .Spec.TaskTemplate.Resources}}' test
    {
      "Limits": {
        "NanoCPUs": 1000000000,
        "MemoryBytes": 104857600
      },
      "Reservations": {
        "NanoCPUs": 1000000000,
        "MemoryBytes": 104857600
      }
    }

Update just CPU limit and reservation:

    docker service update --limit-cpu=2 --reserve-cpu=2 test

Confirm that the CPU limits/reservations are updated, but memory limit and reservation are preserved:

    docker service inspect --format '{{json .Spec.TaskTemplate.Resources}}' test
    {
      "Limits": {
        "NanoCPUs": 2000000000,
        "MemoryBytes": 104857600
      },
      "Reservations": {
        "NanoCPUs": 2000000000,
        "MemoryBytes": 104857600
      }
    }

Update just Memory limit and reservation:

    docker service update --limit-memory=200M --reserve-memory=200M test

Confirm that the Mempry limits/reservations are updated, but CPU limit and reservation are preserved:

    docker service inspect --format '{{json .Spec.TaskTemplate.Resources}}' test
    {
      "Limits": {
        "NanoCPUs": 2000000000,
        "MemoryBytes": 209715200
      },
      "Reservations": {
        "NanoCPUs": 2000000000,
        "MemoryBytes": 209715200
      }
    }

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

2018-05-24 01:30:00 +02:00