65f6bcb927
On AWS, we should not reuse device names as long as possible, see https://aws.amazon.com/premiumsupport/knowledge-center/ebs-stuck-attaching/ "If you specify a device name that is not in use by EC2, but is being used by the block device driver within the EC2 instance, the attachment of the EBS volume does not succeed and the EBS volume is stuck in the attaching state." This patch adds a device name allocator that tries to find a name that's next to the last used device name instead of using the first available one. This way we will loop through all device names ("xvdba" .. "xvdzz") before a device name is reused.
104 lines
2.4 KiB
Go
104 lines
2.4 KiB
Go
/*
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Copyright 2016 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package aws
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import "testing"
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func TestDeviceAllocator(t *testing.T) {
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tests := []struct {
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name string
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existingDevices ExistingDevices
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length int
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firstDevice mountDevice
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lastAllocated mountDevice
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expectedOutput mountDevice
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}{
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{
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"empty device list",
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ExistingDevices{},
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2,
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"aa",
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"aa",
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"ab",
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},
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{
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"empty device list with wrap",
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ExistingDevices{},
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2,
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"ba",
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"zz",
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"ba", // next to 'zz' is the first one, 'ba'
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},
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{
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"device list",
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ExistingDevices{"aa": "used", "ab": "used", "ac": "used"},
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2,
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"aa",
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"aa",
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"ad", // all up to "ac" are used
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},
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{
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"device list with wrap",
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ExistingDevices{"zy": "used", "zz": "used", "ba": "used"},
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2,
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"ba",
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"zx",
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"bb", // "zy", "zz" and "ba" are used
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},
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{
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"three characters with wrap",
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ExistingDevices{"zzy": "used", "zzz": "used", "baa": "used"},
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3,
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"baa",
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"zzx",
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"bab",
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},
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}
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for _, test := range tests {
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allocator := NewDeviceAllocator(test.length, test.firstDevice).(*deviceAllocator)
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allocator.lastAssignedDevice = test.lastAllocated
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got, err := allocator.GetNext(test.existingDevices)
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if err != nil {
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t.Errorf("text %q: unexpected error: %v", test.name, err)
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}
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if got != test.expectedOutput {
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t.Errorf("text %q: expected %q, got %q", test.name, test.expectedOutput, got)
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}
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}
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}
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func TestDeviceAllocatorError(t *testing.T) {
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allocator := NewDeviceAllocator(2, "ba").(*deviceAllocator)
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existingDevices := ExistingDevices{}
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// make all devices used
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var first, second byte
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for first = 'b'; first <= 'z'; first++ {
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for second = 'a'; second <= 'z'; second++ {
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device := [2]byte{first, second}
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existingDevices[mountDevice(device[:])] = "used"
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}
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}
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device, err := allocator.GetNext(existingDevices)
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if err == nil {
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t.Errorf("expected error, got device %q", device)
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}
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}
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