storage

package
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 Go to latest Published: Jan 8, 2019 License: Apache-2.0 Imports: 19 Imported by: 0

Documentation

Overview

Package storage provides abstractions for interacting with storage locations, both management and access. There are two primary type of storage handled by this package at this time: a. VMDKs on a vSphere datastore b. NFS shares

We have more than two sub-packages however as we use distinct packages to provide different lifecycle and usage semantics for types of data using those mechanisms. Examples include: * application logic (images) * application transient data (image read/write layer) * application persistent data (volumes)

As such there are a set of concepts, with all but `store` captured as interfaces: * store * resolver * exporter * importer * data source * data sink

The odd one out for these concepts is the `store`. This is because we did not want to be prescriptive about what a store supports, but it may well distill into an interface at a later date. Currently the various store implementations consist of a composition of `resolver`, `importer`, and `exporter` interfaces.

The `data source` and `data sink` interfaces are present to allow abstracted read and write access respectively to a specific storage mechanism. The data source and data sink instances should be considered single use and not reused for multiple access. This semantic was chosen as it's the least prescriptive on storage availability and connectivity - the precise means used to read or write from storage may change, for example, based on whether the storage is in use (has an owner). The `resolver` interface is present to translate a potentially store specific ID into an unambiguous URI, and to allow discovery of which virtual machines, if any, currently claim that ID. This returns virtual machines instead of a further abstracted interface because it's not clear at time of writing what that abstraction should or would be. The `importer` and `exporter` interfaces are the factories used to acquire `data source` and `data sink` instances. They also provide convenience methods for directly creating and consuming the source/sink in one operation.

It is not required that all storage elements implement both Importer and Exporter mechanisms - having write only or read only storage is viable.

The data source and sink interfaces also specify a basic accessor method for the underlying mechanism. This was added to allow for some future-proofing, with the primary extension expected to be a generic FileWalker interface so that directory walk and listings can be done without needing to care about the access mechanism (e.g. common between a local filesystem mount, an XDR NFS client, or a VM toolbox client).

The general structure of a specific storage implementation is as follows and is imposed so that it is easier to locate a specific functional path for a given usage/storage type combination. As of this writing there are two additional folders in this structure, nfs and vsphere. These contain implementation specific logic used across store types and must be at this level to avoid cyclic package dependencies: ``` storage/ - this package ├── [type]/ - the high level type of use, implies semantics (i.e., container, image, volume) │ ├── [type].go - the common store implementation aspects across implementations │ ├── errors.go - [type] specific error types │ ├── cache - a `store` compliant cache implementation, if needed, with appropriate semantics for the type of use │ │ └── cache.go │ └── [implementation]/ - a specific implementation type (e.g., vsphere) │ ├── bind.go - modifies a portlayer handle to configure active use of a specific `joined` storage │ ├── export.go - implements the `read` side of the interfaces (Exporter and DataSource) │ ├── import.go - a specific implementation type │ ├── join.go - modifies a portlayer handle to configure basic access to a specific instance of the storage type │ └── store.go - constructor and implementation for specific store type and implementation ├── storage.go - interface definitions, portlayer lifecycle management functions, and the registration/lookup | mechanisms for store instances. └── [purpose].go - common functions used by the various type/implementation combinations ```

This structure is not completely consistent at the time of writing. Most notable is that the bind.go functions have all been rolled into the Join calls (the portlayer uses the following common verbs across components, again with some inconsistencies at this time: Join, Bind, Inspect, Unbind, Remove, Wait). In the case of the `container` store type there is only one implementation at this time (vsphere VMDKs) and the `implementation` subdirectory has been omitted.

This file implements lookup of store implementations via the `RegisterImporter` and `RegisterExporter` functions. This is provided to allow a common pattern for implementing, finding, and accessing store implementations without the caller requiring specific knowledge about the type of a specific store. All that's required is knowledge of the set of `store` interfaces and the identifier with which a given store was implemented.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func Finalize added in v1.5.0 

func Finalize(ctx context.Context) error

TODO: figure out why the Init calls are wrapped in once.Do - implies it can be called multiple times, but once Finalize is called things will not be functional.

func GetExporters 

func GetExporters() []string

GetExporters returns the set of known importers.

func GetImporters 

func GetImporters() []string

GetImporters returns the set of known importers.

func Init 

func Init(ctx context.Context, session *session.Session, pool *object.ResourcePool, source extraconfig.DataSource, _ extraconfig.DataSink) error

Init performs basic initialization, including population of storage.Config

func RegisterExporter 

func RegisterExporter(op trace.Operation, store string, e Exporter)

RegisterExporter registers the specified exporter against the provided store for later retrieval.

func RegisterImporter 

func RegisterImporter(op trace.Operation, store string, i Importer)

RegisterImporter registers the specified importer against the provided store for later retrieval.

Types

type Configuration 

type Configuration struct {
	// Turn on debug logging
	DebugLevel int `vic:"0.1" scope:"read-only" key:"init/diagnostics/debug"`

	// Port Layer - storage
	config.Storage `vic:"0.1" scope:"read-only" key:"storage"`

	// ContainerView
	// https://pubs.vmware.com/vsphere-6-0/index.jsp#com.vmware.wssdk.apiref.doc/vim.view.ContainerView.html
	ContainerView *view.ContainerView

	// Disk Manager for local VM
	DiskManager *disk.Manager
}

Configuration is a slice of the VCH config that is relevant to the storage part of the port layer 

var Config Configuration

type DataSink 

type DataSink interface {
	// Close releases all resources associated with this sink. Shared resources should be reference counted.
	io.Closer

	// Import performs an import of the tar stream to the source held by this DataSink.  This is single use; once
	// the export has completed it should not be assumed that the sink remains functional.
	//
	// spec: specifies which files will be included/excluded in the import and allows for path rebasing/stripping
	// tarStream: the tar stream to from which to import data
	Import(op trace.Operation, spec *archive.FilterSpec, tarStream io.ReadCloser) error

	// Sink returns the mechanism by which the data sink is accessed
	// Examples:
	//     vmdk mounted locally: *os.File
	//     nfs volume:  		 XDR-client
	//     via guesttools:  	 toolbox client
	Sink() interface{}
}

DataSink defines the methods for importing data to a specific storage element from a tar stream

type DataSource 

type DataSource interface {
	// Close releases all resources associated with this source. Shared resources should be reference counted.
	io.Closer

	// Export performs an export of the specified files, returning the data as a tar stream. This is single use; once
	// the export has completed it should not be assumed that the source remains functional.
	//
	// spec: specifies which files will be included/excluded in the export and allows for path rebasing/stripping
	// data: if true the actual file data is included, if false only the file headers are present
	Export(op trace.Operation, spec *archive.FilterSpec, data bool) (io.ReadCloser, error)

	// Source returns the mechanism by which the data source is accessed
	// Examples:
	//     vmdk mounted locally: *os.File
	//     nfs volume:  		 XDR-client
	//     via guesttools:  	 toolbox client
	Source() interface{}

	// Stat stats the filesystem target indicated by the last entry in the given Filterspecs inclusion map
	Stat(op trace.Operation, spec *archive.FilterSpec) (*FileStat, error)
}

DataSource defines the methods for exporting data from a specific storage element as a tar stream

type Exporter 

type Exporter interface {
	// Export allows direct construction and invocation of a data source for the specified ID.
	Export(op trace.Operation, id, ancestor string, spec *archive.FilterSpec, data bool) (io.ReadCloser, error)

	// NewDataSource constructs a data source for the specified ID within the context of the Exporter. This is a single
	// use source which may hold resources until Closed.
	NewDataSource(op trace.Operation, id string) (DataSource, error)
}

Exporter defines the methods needed to read data from a storage element, optionally diff with an ancestor. This shoiuld be implemented by the various store types.

func GetExporter 

func GetExporter(store string) (Exporter, bool)

GetExporter retrieves an exporter registered with the provided store. Will return nil, false if the store is not found.

type FileStat 

type FileStat struct {
	LinkTarget string
	Mode       uint32
	Name       string
	Size       int64
	ModTime    time.Time
}

type Importer 

type Importer interface {
	// Import allows direct construction and invocation of a data sink for the specified ID.
	Import(op trace.Operation, id string, spec *archive.FilterSpec, tarStream io.ReadCloser) error

	// NewDataSink constructs a data sink for the specified ID within the context of the Importer. This is a single
	// use sink which may hold resources until Closed.
	NewDataSink(op trace.Operation, id string) (DataSink, error)
}

Importer defines the methods needed to write data into a storage element. This should be implemented by the various store types.

func GetImporter 

func GetImporter(store string) (Importer, bool)

GetImporter retrieves an importer registered with the provided store. Will return nil, false if the store is not found.

type MountDataSink 

type MountDataSink struct {
	Path  *os.File
	Clean func()
	// contains filtered or unexported fields
}

MountDataSink implements the DataSink interface for mounted devices This is a single use mechanism and will be tidied up on exit from MountDataSink.Import

func NewMountDataSink 

func NewMountDataSink(op trace.Operation, path *os.File, cleanup func()) *MountDataSink

NewMountDataSink creates a new data sink associated with a specific mount, with the mount point being the path argument. The cleanup function is invoked once the import is complete.

func (*MountDataSink) Close 

func (m *MountDataSink) Close() error

Close handles conditional cleanup of the underlying file path and calls any cleanup function associated with the datasink during it's creation.

func (*MountDataSink) Import 

func (m *MountDataSink) Import(op trace.Operation, spec *archive.FilterSpec, data io.ReadCloser) error

Import writes `data` to the data source associated with this DataSource This will call MountDataSink.Close on exit, irrespective of success or error

func (*MountDataSink) Sink 

func (m *MountDataSink) Sink() interface{}

Sink returns the data source associated with the DataSink

type MountDataSource 

type MountDataSource struct {
	Path  *os.File
	Clean func()
	// contains filtered or unexported fields
}

MountDataSource implements the DataSource interface for mounted devices

func NewMountDataSource 

func NewMountDataSource(op trace.Operation, path *os.File, cleanup func()) *MountDataSource

NewMountDataSource creates a new data source associated with a specific mount, with the mount point being the path argument. The cleanup function is invoked with the Close of the ReadCloser from Export, or explicitly

func (*MountDataSource) Close 

func (m *MountDataSource) Close() error

func (*MountDataSource) Export 

func (m *MountDataSource) Export(op trace.Operation, spec *archive.FilterSpec, data bool) (io.ReadCloser, error)

Export reads data from the associated data source and returns it as a tar archive

func (*MountDataSource) Source 

func (m *MountDataSource) Source() interface{}

Source returns the data source associated with the DataSource

func (*MountDataSource) Stat 

func (m *MountDataSource) Stat(op trace.Operation, spec *archive.FilterSpec) (*FileStat, error)

Stat stats the filesystem target indicated by the last entry in the given Filterspecs inclusion map

type ProxyReadCloser 

type ProxyReadCloser struct {
	io.ReadCloser
	Closer func() error
}

ProxyReadCloser is a read closer that provides for wrapping the Close with a custom Close call. The original ReadCloser.Close function will be invoked after the custom call. Errors from the custom call with be ignored.

func (*ProxyReadCloser) Close 

func (p *ProxyReadCloser) Close() error

type Resolver 

type Resolver interface {
	// URL returns a url to the data source representing `id`
	// For historic reasons this is not the same URL that other parts of the storage component use, but an actual
	// URL suited for locating the storage element without having additional precursor knowledge.
	URL(op trace.Operation, id string) (*url.URL, error)

	// Owners returns a list of VMs that are using the resource specified by `url`
	Owners(op trace.Operation, url *url.URL, filter func(vm *mo.VirtualMachine) bool) ([]*vm.VirtualMachine, error)
}

Resolver defines methods for mapping ids to URLS, and urls to owners of that device

Source Files

View all Source files

Directories

Path Synopsis
cache
mock
vsphere
cache
mock
nfs
vsphere

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