oracular (1) nbdkit-gcs-plugin.1.gz

NAME

       nbdkit-gcs-plugin - expose data in Google Cloud Storage (GCS) buckets as block device

SYNOPSIS

        nbdkit gcs [json-credentials=FILE]
                   [size=NN object-size=NN]
                   bucket=BUCKET key=STRING

DESCRIPTION

       "nbdkit-gcs-plugin" is a plugin for nbdkit(1) which lets you open objects stored in Google Cloud Storage
       (GCS) as disk images.

       This plugin uses the Python Google Cloud Storage client library (google-cloud-storage).  It requires
       Python ≥ 3.7.

EXAMPLES

        nbdkit gcs json-credentials=/path/to-my-json-credentials.json \
                   bucket=MY-BUCKET key=disk.img

       Provides a read only block device holding the data contained in the disk.img object.

        nbdkit gcs json-credentials=/path/to-my-json-credentials.json \
                   size=50G object-size=128k \
                   bucket=MY-BUCKET key=disk

       Provides a read-write block device with size 50G, whose contents are stored across multiple in objects of
       size 128k, prefixed with disk/

PARAMETERS

       json-credentials=FILE
           Path to a JSON file with Google Service account keys. Application Default Credentials will be used if
           "json-credentials" is not specified (see "CREDENTIALS" below).

       bucket=BUCKET
           The bucket containing the object(s).  This parameter is required.

       key=STRING
           The object name (if "size" is not specified) or object prefix (if "size" is specified) to use within
           the bucket.  This parameter is required.

       size=SIZE
       object-size=SIZE
           These two parameters must always be specified together. If set, data will be split into blocks of
           "object-size" and stored as separate objects. The block device will report a total size of "size" and
           be writeable and trim-able.

           Object names will have the form key/%16x, where %16x is the 16-digit hexadecimal block number. If
           there are existing objects under the prefix that do not have the expected size, the plugin will
           crash.

PERFORMANCE CONSIDERATIONS

       It is highly recommended that clients do their utmost to issue requests that exactly match the object
       size: Smaller write requests will incur a performance penalty due to the need for read-modify-write
       cycles (thus also incurring latency from two network round-trips). Larger read and write requests will
       incur a performance penalty because of sequential execution.

       The nbdkit-blocksize-filter(1) can be used to alleviate the impact of requests larger than the object
       size, but does not help if the client issues requests smaller than the block size.

       The nbdkit-stats-filter(1) can be used to investigate what block sizes and alignments are used by the
       client.

       When connecting through the Linux kernel's NBD module, consider setting
       "/sys/block/nbd<X>/queue/max_sectors_kb" to match the object size.

CREDENTIALS

       Refer to the following web pages:

       Google Service account keys
           https://developers.google.com/workspace/guides/create-credentials#service-account

       Application Default Credentials
           https://cloud.google.com/docs/authentication/application-default-credentials

FILES

       $plugindir/nbdkit-gcs-plugin
           The plugin.

           Use "nbdkit --dump-config" to find the location of $plugindir.

       $HOME/.config/gcloud/application_default_credentials.json
           Application Default Credentials.

ENVIRONMENT VARIABLES

       "GOOGLE_APPLICATION_CREDENTIALS"
           You can use the "GOOGLE_APPLICATION_CREDENTIALS" environment variable to provide the location of a
           credential JSON file.

COMPARISON TO S3 PLUGIN

       You can use the "S3" plugin to access Google Cloud Storage in interoperability mode.  "read" and "write"
       work perfectly fine, while "trim" and "zero" operations don't work in the general case: trimmed or
       zeroed-out blocks cannot be deleted from the storage using the "S3" plugin.

VERSION

       "nbdkit-gcs-plugin" first appeared in nbdkit 1.38.

SEE ALSO

       nbdkit(1), nbdkit-plugin(3), nbdkit-python-plugin(3), nbdkit-S3-plugin(3),
       https://pypi.org/project/google-cloud-storage/,
       https://developers.google.com/workspace/guides/create-credentials#service-account,
       https://cloud.google.com/docs/authentication/application-default-credentials.

AUTHORS

       Mykola Ivanets

COPYRIGHT

       Copyright Infrascale Inc.

LICENSE

       Redistribution and use in source and binary forms, with or without modification, are permitted provided
       that the following conditions are met:

       •   Redistributions of source code must retain the above copyright notice, this list of conditions and
           the following disclaimer.

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           the following disclaimer in the documentation and/or other materials provided with the distribution.

       •   Neither the name of Red Hat nor the names of its contributors may be used to endorse or promote
           products derived from this software without specific prior written permission.

       THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
       INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
       PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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