Ensure that clients can use the blob descriptor cache provider without needing
the redis package.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
This PR refactors the blob service API to be oriented around blob descriptors.
Identified by digests, blobs become an abstract entity that can be read and
written using a descriptor as a handle. This allows blobs to take many forms,
such as a ReadSeekCloser or a simple byte buffer, allowing blob oriented
operations to better integrate with blob agnostic APIs (such as the `io`
package). The error definitions are now better organized to reflect conditions
that can only be seen when interacting with the blob API.
The main benefit of this is to separate the much smaller metadata from large
file storage. Many benefits also follow from this. Reading and writing has
been separated into discrete services. Backend implementation is also
simplified, by reducing the amount of metadata that needs to be picked up to
simply serve a read. This also improves cacheability.
"Opening" a blob simply consists of an access check (Stat) and a path
calculation. Caching is greatly simplified and we've made the mapping of
provisional to canonical hashes a first-class concept. BlobDescriptorService
and BlobProvider can be combined in different ways to achieve varying effects.
Recommend Review Approach
-------------------------
This is a very large patch. While apologies are in order, we are getting a
considerable amount of refactoring. Most changes follow from the changes to
the root package (distribution), so start there. From there, the main changes
are in storage. Looking at (*repository).Blobs will help to understand the how
the linkedBlobStore is wired. One can explore the internals within and also
branch out into understanding the changes to the caching layer. Following the
descriptions below will also help to guide you.
To reduce the chances for regressions, it was critical that major changes to
unit tests were avoided. Where possible, they are left untouched and where
not, the spirit is hopefully captured. Pay particular attention to where
behavior may have changed.
Storage
-------
The primary changes to the `storage` package, other than the interface
updates, were to merge the layerstore and blobstore. Blob access is now
layered even further. The first layer, blobStore, exposes a global
`BlobStatter` and `BlobProvider`. Operations here provide a fast path for most
read operations that don't take access control into account. The
`linkedBlobStore` layers on top of the `blobStore`, providing repository-
scoped blob link management in the backend. The `linkedBlobStore` implements
the full `BlobStore` suite, providing access-controlled, repository-local blob
writers. The abstraction between the two is slightly broken in that
`linkedBlobStore` is the only channel under which one can write into the global
blob store. The `linkedBlobStore` also provides flexibility in that it can act
over different link sets depending on configuration. This allows us to use the
same code for signature links, manifest links and blob links. Eventually, we
will fully consolidate this storage.
The improved cache flow comes from the `linkedBlobStatter` component
of `linkedBlobStore`. Using a `cachedBlobStatter`, these combine together to
provide a simple cache hierarchy that should streamline access checks on read
and write operations, or at least provide a single path to optimize. The
metrics have been changed in a slightly incompatible way since the former
operations, Fetch and Exists, are no longer relevant.
The fileWriter and fileReader have been slightly modified to support the rest
of the changes. The most interesting is the removal of the `Stat` call from
`newFileReader`. This was the source of unnecessary round trips that were only
present to look up the size of the resulting reader. Now, one must simply pass
in the size, requiring the caller to decide whether or not the `Stat` call is
appropriate. In several cases, it turned out the caller already had the size
already. The `WriterAt` implementation has been removed from `fileWriter`,
since it is no longer required for `BlobWriter`, reducing the number of paths
which writes may take.
Cache
-----
Unfortunately, the `cache` package required a near full rewrite. It was pretty
mechanical in that the cache is oriented around the `BlobDescriptorService`
slightly modified to include the ability to set the values for individual
digests. While the implementation is oriented towards caching, it can act as a
primary store. Provisions are in place to have repository local metadata, in
addition to global metadata. Fallback is implemented as a part of the storage
package to maintain this flexibility.
One unfortunate side-effect is that caching is now repository-scoped, rather
than global. This should have little effect on performance but may increase
memory usage.
Handlers
--------
The `handlers` package has been updated to leverage the new API. For the most
part, the changes are superficial or mechanical based on the API changes. This
did expose a bug in the handling of provisional vs canonical digests that was
fixed in the unit tests.
Configuration
-------------
One user-facing change has been made to the configuration and is updated in
the associated documentation. The `layerinfo` cache parameter has been
deprecated by the `blobdescriptor` cache parameter. Both are equivalent and
configuration files should be backward compatible.
Notifications
-------------
Changes the `notification` package are simply to support the interface
changes.
Context
-------
A small change has been made to the tracing log-level. Traces have been moved
from "info" to "debug" level to reduce output when not needed.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
- Change driver interface to take a context as its first argument
- Make newFileReader take a context as its first argument
- Make newFileWriter take a context as its first argument
- Make blobstore exists and delete take a context as a first argument
- Pass the layerreader's context to the storage layer
- Pass the app's context to purgeuploads
- Store the app's context into the blobstore (was previously null)
- Pass the trace'd context to the storage drivers
Signed-off-by: Richard Scothern <richard.scothern@gmail.com>
When the registry starts a background timer will periodically
scan the upload directories on the file system every 24 hours
and delete any files older than 1 week. An initial jitter
intends to avoid contention on the filesystem where multiple
registries with the same storage driver are started
simultaneously.
Ensure that the status is logged in the context by instantiating before the
request is routed to handlers. While this requires some level of hacking to
acheive, the result is that the context value of "http.request.status" is as
accurate as possible for each request.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
Registry is intended to be used as a repository service than an abstract collection of repositories. Namespace better describes a collection of repositories retrievable by name.
The registry service serves any repository in the global scope.
Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
This moves the instance id out of the app so that it is associated with an
instantiation of the runtime. The instance id is stored on the background
context. This allows allow contexts using the main background context to
include an instance id for log messages. It also simplifies the application
slightly.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
For consistency with other systems, the redis and caching monitoring data has
been moved under the "registry" section in expvar. This ensures the entire
registry state is kept to a single section.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
This allows one to better control the usage of the cache and turn it off
completely. The storage configuration module was modified to allow parameters
to be passed to just the storage implementation, rather than to the driver.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
This changeset integrates the layer info cache with the registry webapp and
storage backend. The main benefit is to cache immutable layer meta data,
reducing backend roundtrips. The cache can be configured to use either redis or
an inmemory cache.
This provides massive performance benefits for HEAD http checks on layer blobs
and manifest verification.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
Redis has been integrated with the web application for use with various
services. The configuraiton exposes connection details, timeouts and pool
parameters. Documentation has been updated accordingly.
A few convenience methods have been added to the context package to get loggers
with certain fields, exposing some missing functionality from logrus.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
Convert middleware in the config to be a map of type->[]Middleware
Add support for registry & repository middleware.
Some naming updates as well.
Signed-off-by: Andy Goldstein <agoldste@redhat.com>
middleware concept.
This also breaks the dependency the storage package had on goamz
Signed-off-by: David Lawrence <david.lawrence@docker.com> (github: endophage)
This changeset implements immutable manifest references via the HTTP API. Most
of the changes follow from modifications to ManifestService. Once updates were
made across the repo to implement these changes, the http handlers were change
accordingly. The new methods on ManifestService will be broken out into a
tagging service in a later PR.
Unfortunately, due to complexities around managing the manifest tag index in an
eventually consistent manner, direct deletes of manifests have been disabled.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
The method (Registry).Repository may now return an error. This is too allow
certain implementationt to validate the name or opt to not return a repository
under certain conditions.
In conjunction with this change, error declarations have been moved into a
single file in the distribution package. Several error declarations that had
remained in the storage package have been moved into distribution, as well. The
declarations for Layer and LayerUpload have also been moved into the main
registry file, as a result.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
Since the notifications package is now decoupled from storage, we are moving it
to the root package.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
After consideration, it has been decided that the interfaces defined in the
storage package provide a good base for interacting with various registry
instances. Whether interacting with a remote API or a local, on-disk registry,
these types have proved flexible. By moving them here, they can become the
central components of interacting with distribution components.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
This change is slightly more complex than previous package maves in that the
package name changed. To address this, we simply always reference the package
driver as storagedriver to avoid compatbility issues with existing code. While
unfortunate, this can be cleaned up over time.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
The goal is to free up the distribution/registry package to include common
registry types. This moves the webapp definitions out of the way to allow for
this change in the future.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
