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devmapper: add snapshotter config
Signed-off-by: Maksym Pavlenko <[email protected]>
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‎snapshots/devmapper/config.go‎

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/*
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Copyright The containerd 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 devmapper
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import (
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"fmt"
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"os"
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"github.com/BurntSushi/toml"
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"github.com/containerd/containerd/snapshots/devmapper/dmsetup"
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"github.com/docker/go-units"
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"github.com/hashicorp/go-multierror"
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"github.com/pkg/errors"
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)
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const (
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// See https://www.kernel.org/doc/Documentation/device-mapper/thin-provisioning.txt for details
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dataBlockMinSize = 128
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dataBlockMaxSize = 2097152
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)
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var (
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errInvalidBlockSize = errors.Errorf("block size should be between %d and %d", dataBlockMinSize, dataBlockMaxSize)
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errInvalidBlockAlignment = errors.Errorf("block size should be multiple of %d sectors", dataBlockMinSize)
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)
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// Config represents device mapper configuration loaded from file.
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// Size units can be specified in human-readable string format (like "32KIB", "32GB", "32Tb")
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type Config struct {
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// Device snapshotter root directory for metadata
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RootPath string `toml:"root_path"`
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// Name for 'thin-pool' device to be used by snapshotter (without /dev/mapper/ prefix)
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PoolName string `toml:"pool_name"`
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// Path to data volume to be used by thin-pool
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DataDevice string `toml:"data_device"`
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// Path to metadata volume to be used by thin-pool
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MetadataDevice string `toml:"meta_device"`
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// The size of allocation chunks in data file.
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// Must be between 128 sectors (64KB) and 2097152 sectors (1GB) and a multiple of 128 sectors (64KB)
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// Block size can't be changed after pool created.
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// See https://www.kernel.org/doc/Documentation/device-mapper/thin-provisioning.txt
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DataBlockSize string `toml:"data_block_size"`
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DataBlockSizeSectors uint32 `toml:"-"`
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// Defines how much space to allocate when creating base image for container
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BaseImageSize string `toml:"base_image_size"`
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BaseImageSizeBytes uint64 `toml:"-"`
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}
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// LoadConfig reads devmapper configuration file JSON format from disk
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func LoadConfig(path string) (*Config, error) {
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if _, err := os.Stat(path); err != nil {
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if os.IsNotExist(err) {
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return nil, os.ErrNotExist
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}
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return nil, err
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}
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config := Config{}
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if _, err := toml.DecodeFile(path, &config); err != nil {
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return nil, errors.Wrapf(err, "failed to unmarshal data at '%s'", path)
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}
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if err := config.parse(); err != nil {
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return nil, err
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}
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if err := config.Validate(); err != nil {
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return nil, err
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}
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return &config, nil
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}
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func (c *Config) parse() error {
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var result *multierror.Error
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if c.DataBlockSize != "" {
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if blockSize, err := units.RAMInBytes(c.DataBlockSize); err != nil {
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result = multierror.Append(result, errors.Wrapf(err, "failed to parse data block size: %q", c.DataBlockSize))
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} else {
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c.DataBlockSizeSectors = uint32(blockSize / dmsetup.SectorSize)
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}
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}
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if baseImageSize, err := units.RAMInBytes(c.BaseImageSize); err != nil {
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result = multierror.Append(result, errors.Wrapf(err, "failed to parse base image size: %q", c.BaseImageSize))
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} else {
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c.BaseImageSizeBytes = uint64(baseImageSize)
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}
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return result.ErrorOrNil()
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}
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// Validate makes sure configuration fields are valid
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func (c *Config) Validate() error {
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var result *multierror.Error
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if c.PoolName == "" {
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result = multierror.Append(result, fmt.Errorf("pool_name is required"))
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}
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if c.RootPath == "" {
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result = multierror.Append(result, fmt.Errorf("root_path is required"))
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}
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if c.BaseImageSize == "" {
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result = multierror.Append(result, fmt.Errorf("base_image_size is required"))
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}
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// The following fields are required only if we want to create or reload pool.
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// Otherwise existing pool with 'PoolName' (prepared in advance) can be used by snapshotter.
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if c.DataDevice != "" || c.MetadataDevice != "" || c.DataBlockSize != "" || c.DataBlockSizeSectors != 0 {
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strChecks := []struct {
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field string
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name string
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}{
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{c.DataDevice, "data_device"},
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{c.MetadataDevice, "meta_device"},
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{c.DataBlockSize, "data_block_size"},
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}
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for _, check := range strChecks {
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if check.field == "" {
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result = multierror.Append(result, errors.Errorf("%s is empty", check.name))
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}
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}
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if c.DataBlockSizeSectors < dataBlockMinSize || c.DataBlockSizeSectors > dataBlockMaxSize {
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result = multierror.Append(result, errInvalidBlockSize)
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}
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if c.DataBlockSizeSectors%dataBlockMinSize != 0 {
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result = multierror.Append(result, errInvalidBlockAlignment)
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}
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}
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return result.ErrorOrNil()
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}

‎snapshots/devmapper/config_test.go‎

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/*
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Copyright The containerd 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 devmapper
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import (
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"io/ioutil"
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"os"
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"strings"
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"testing"
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"github.com/BurntSushi/toml"
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"github.com/hashicorp/go-multierror"
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"gotest.tools/assert"
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is "gotest.tools/assert/cmp"
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)
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func TestLoadConfig(t *testing.T) {
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expected := Config{
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RootPath: "/tmp",
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PoolName: "test",
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DataDevice: "/dev/loop0",
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MetadataDevice: "/dev/loop1",
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DataBlockSize: "1mb",
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BaseImageSize: "128Mb",
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}
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file, err := ioutil.TempFile("", "devmapper-config-")
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assert.NilError(t, err)
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encoder := toml.NewEncoder(file)
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err = encoder.Encode(&expected)
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assert.NilError(t, err)
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defer func() {
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err := file.Close()
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assert.NilError(t, err)
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err = os.Remove(file.Name())
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assert.NilError(t, err)
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}()
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loaded, err := LoadConfig(file.Name())
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assert.NilError(t, err)
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assert.Equal(t, loaded.RootPath, expected.RootPath)
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assert.Equal(t, loaded.PoolName, expected.PoolName)
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assert.Equal(t, loaded.DataDevice, expected.DataDevice)
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assert.Equal(t, loaded.MetadataDevice, expected.MetadataDevice)
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assert.Equal(t, loaded.DataBlockSize, expected.DataBlockSize)
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assert.Equal(t, loaded.BaseImageSize, expected.BaseImageSize)
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assert.Assert(t, loaded.DataBlockSizeSectors == 1*1024*1024/512)
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assert.Assert(t, loaded.BaseImageSizeBytes == 128*1024*1024)
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}
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func TestLoadConfigInvalidPath(t *testing.T) {
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_, err := LoadConfig("")
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assert.Equal(t, os.ErrNotExist, err)
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_, err = LoadConfig("/dev/null")
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assert.Assert(t, err != nil)
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}
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func TestParseInvalidData(t *testing.T) {
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config := Config{
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DataBlockSize: "x",
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BaseImageSize: "y",
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}
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err := config.parse()
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assert.Assert(t, err != nil)
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multErr := (err).(*multierror.Error)
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assert.Assert(t, is.Len(multErr.Errors, 2))
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assert.Assert(t, strings.Contains(multErr.Errors[0].Error(), "failed to parse data block size: \"x\""))
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assert.Assert(t, strings.Contains(multErr.Errors[1].Error(), "failed to parse base image size: \"y\""))
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}
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func TestFieldValidation(t *testing.T) {
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config := &Config{DataBlockSizeSectors: 1}
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err := config.Validate()
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assert.Assert(t, err != nil)
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multErr := (err).(*multierror.Error)
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assert.Assert(t, is.Len(multErr.Errors, 8))
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assert.Assert(t, multErr.Errors[0] != nil, "pool_name is empty")
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assert.Assert(t, multErr.Errors[1] != nil, "root_path is empty")
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assert.Assert(t, multErr.Errors[2] != nil, "base_image_size is empty")
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assert.Assert(t, multErr.Errors[3] != nil, "data_device is empty")
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assert.Assert(t, multErr.Errors[4] != nil, "meta_device is empty")
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assert.Assert(t, multErr.Errors[5] != nil, "data_block_size is empty")
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assert.Equal(t, multErr.Errors[6], errInvalidBlockSize)
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assert.Equal(t, multErr.Errors[7], errInvalidBlockAlignment)
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}
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func TestExistingPoolFieldValidation(t *testing.T) {
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config := &Config{
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PoolName: "test",
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RootPath: "test",
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BaseImageSize: "10mb",
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}
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err := config.Validate()
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assert.NilError(t, err)
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}

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