Filesystem storage driver

An implementation of the storagedriver.StorageDriver interface which uses the local filesystem.

Parameters

rootdirectory: (optional) The absolute path to a root directory tree in which to store all registry files. The registry stores all its data here so make sure there is adequate space available. Defaults to /var/lib/registry. If the directory does not exist, it will be created honoring umask bits. If umask bits are not set, the resulting permission will be 0777.
maxthreads: (optional) The maximum number of simultaneous blocking filesystem operations permitted within the registry. Each operation spawns a new thread and may cause thread exhaustion issues if many are done in parallel. Defaults to 100, and cannot be lower than 25.
writebuffersize: (optional) The size, in bytes, of the buffer the driver uses when writing files. Defaults to 4096, and cannot be lower than 4096. See Write buffer size.

Write buffer size

The driver collects data written to a file in a buffer and passes it to the filesystem whenever the buffer is full, and once more when the file is committed or closed. A write that is larger than an empty buffer skips the buffer and is passed to the filesystem directly. The registry writes blob uploads in chunks of up to 32KiB, so with the default buffer of 4096 bytes uploads reach the filesystem as writes of up to 32KiB. A writebuffersize larger than 32KiB combines these chunks into fewer, larger writes, which can improve throughput on filesystems that perform poorly with many small writes, such as some network filesystems. A value between 4096 and 32KiB has little effect on blob uploads.

Each in-progress write, including every in-progress blob upload, allocates its own buffer. The memory used for buffers is therefore about writebuffersize multiplied by the number of concurrent uploads.

For example, to write blob uploads in chunks of 1MiB:

storage:
  filesystem:
    rootdirectory: /var/lib/registry
    writebuffersize: 1048576

You can also set it with the REGISTRY_STORAGE_FILESYSTEM_WRITEBUFFERSIZE environment variable.