The aws s3
transfer commands, which include the cp
, sync
, mv
,
and rm
commands, have additional configuration values you can use to
control S3 transfers. This topic guide discusses these parameters as well as
best practices and guidelines for setting these values.
Before discussing the specifics of these values, note that these values are
entirely optional. You should be able to use the aws s3
transfer commands
without having to configure any of these values. These configuration values
are provided in the case where you need to modify one of these values, either
for performance reasons or to account for the specific environment where these
aws s3
commands are being run.
These are the configuration values you can set specifically for the aws s3
command set:
max_concurrent_requests
- The maximum number of concurrent requests.
max_queue_size
- The maximum number of tasks in the task queue.
multipart_threshold
- The size threshold the CLI uses for multipart
transfers of individual files.
multipart_chunksize
- When using multipart transfers, this is the chunk
size that the CLI uses for multipart transfers of individual files.
max_bandwidth
- The maximum bandwidth that will be consumed for uploading
and downloading data to and from Amazon S3.
For experimental s3
configuration values, see the the
Experimental Configuration Values
section.
These are the configuration values that can be set for both aws s3
and aws s3api
:
use_accelerate_endpoint
- Use the Amazon S3 Accelerate endpoint for
all s3
and s3api
commands. You must first enable S3 Accelerate
on your bucket before attempting to use the endpoint. This is mutually
exclusive with the use_dualstack_endpoint
option.
use_dualstack_endpoint
- Use the Amazon S3 dual IPv4 / IPv6 endpoint for
all s3
and s3api
commands. This is mutually exclusive with the
use_accelerate_endpoint
option.
addressing_style
- Specifies which addressing style to use. This controls
if the bucket name is in the hostname or part of the URL. Value values are:
path
, virtual
, and auto
. The default value is auto
.
payload_signing_enabled
- Refers to whether or not to SHA256 sign sigv4
payloads. By default, this is disabled for streaming uploads (UploadPart
and PutObject) when using https.
These values must be set under the top level s3
key in the AWS Config File,
which has a default location of ~/.aws/config
. Below is an example
configuration:
[profile development]
aws_access_key_id=foo
aws_secret_access_key=bar
s3 =
max_concurrent_requests = 20
max_queue_size = 10000
multipart_threshold = 64MB
multipart_chunksize = 16MB
max_bandwidth = 50MB/s
use_accelerate_endpoint = true
addressing_style = path
Note that all the S3 configuration values are indented and nested under the top
level s3
key.
You can also set these values programmatically using the aws configure set
command. For example, to set the above values for the default profile, you
could instead run these commands:
$ aws configure set default.s3.max_concurrent_requests 20
$ aws configure set default.s3.max_queue_size 10000
$ aws configure set default.s3.multipart_threshold 64MB
$ aws configure set default.s3.multipart_chunksize 16MB
$ aws configure set default.s3.max_bandwidth 50MB/s
$ aws configure set default.s3.use_accelerate_endpoint true
$ aws configure set default.s3.addressing_style path
To programmatically set these values for a profile other than the default
profile the --profile
flag can be provided. For example, to set
configuration for a profile named test-profile
you could run a command like
this one:
$ aws configure set s3.max_concurrent_requests 20 --profile test-profile
Default - 10
The aws s3
transfer commands are multithreaded. At any given time,
multiple requests to Amazon S3 are in flight. For example, if you are
uploading a directory via aws s3 cp localdir s3://bucket/ --recursive
, the
AWS CLI could be uploading the local files localdir/file1
,
localdir/file2
, and localdir/file3
in parallel. The
max_concurrent_requests
specifies the maximum number of transfer commands
that are allowed at any given time.
You may need to change this value for a few reasons:
Decreasing this value - On some environments, the default of 10 concurrent
requests can overwhelm a system. This may cause connection timeouts or
slow the responsiveness of the system. Lowering this value will make the
S3 transfer commands less resource intensive. The tradeoff is that
S3 transfers may take longer to complete. Lowering this value may be
necessary if using a tool such as trickle
to limit bandwidth.
Increasing this value - In some scenarios, you may want the S3 transfers to complete as quickly as possible, using as much network bandwidth as necessary. In this scenario, the default number of concurrent requests may not be sufficient to utilize all the network bandwidth available. Increasing this value may improve the time it takes to complete an S3 transfer.
Default - 1000
The AWS CLI internally uses a producer consumer model, where we queue up S3
tasks that are then executed by consumers, which in this case utilize a bound
thread pool, controlled by max_concurrent_requests
. A task generally maps
to a single S3 operation. For example, as task could be a PutObjectTask
,
or a GetObjectTask
, or an UploadPartTask
. The enqueuing rate can be
much faster than the rate at which consumers are executing tasks. To avoid
unbounded growth, the task queue size is capped to a specific size. This
configuration value changes the value of that maximum number.
You generally will not need to change this value. This value also corresponds
to the number of tasks we are aware of that need to be executed. This means
that by default we can only see 1000 tasks ahead. Until the S3 command knows
the total number of tasks executed, the progress line will show a total of
...
. Increasing this value means that we will be able to more quickly know
the total number of tasks needed, assuming that the enqueuing rate is quicker
than the rate of task consumption. The tradeoff is that a larger max queue
size will require more memory.
Default - 8MB
When uploading, downloading, or copying a file, the S3 commands
will switch to multipart operations if the file reaches a given
size threshold. The multipart_threshold
controls this value.
You can specify this value in one of two ways:
The file size in bytes. For example, 1048576
.
The file size with a size suffix. You can use KB
, MB
, GB
,
TB
. For example: 10MB
, 1GB
. Note that S3 imposes
constraints on valid values that can be used for multipart
operations.
Default - 8MB
Minimum For Uploads - 5MB
Once the S3 commands have decided to use multipart operations, the
file is divided into chunks. This configuration option specifies what
the chunk size (also referred to as the part size) should be. This
value can specified using the same semantics as multipart_threshold
,
that is either as the number of bytes as an integer, or using a size
suffix.
Default - None
This controls the maximum bandwidth that the S3 commands will utilize when streaming content data to and from S3. Thus, this value only applies for uploads and downloads. It does not apply to copies nor deletes because those data transfers take place server side. The value can be specified as:
An integer in terms of bytes per second. For example, 1048576
would
set the maximum bandwidth usage to 1 MB per second.
A rate suffix. This can be expressed in terms of either bytes per second
(B/s
) or bits per second (b/s
). You can specify rate suffixes
using: KB/s
, MB/s
, GB/s
, Kb/s
, Mb/s
, Gb/s
etc.
For example: 300KB/s
, 10MB/s
, 300Kb/s
, 10Mb/s
.
In general, it is recommended to first use max_concurrent_requests
to lower
transfers to the desired bandwidth consumption. The max_bandwidth
setting
should then be used to further limit bandwidth consumption if setting
max_concurrent_requests
is unable to lower bandwidth consumption to the
desired rate. This is recommended because max_concurrent_requests
controls
how many threads are currently running. So if a high max_concurrent_requests
value is set and a low max_bandwidth
value is set, it may result in
threads having to wait unnecessarily which can lead to excess resource
consumption and connection timeouts.
Default - false
If set to true
, will direct all Amazon S3 requests to the S3 Accelerate
endpoint: s3-accelerate.amazonaws.com
. To use this endpoint, your bucket
must be enabled to use S3 Accelerate. All request will be sent using the
virtual style of bucket addressing: my-bucket.s3-accelerate.amazonaws.com
.
Any ListBuckets
, CreateBucket
, and DeleteBucket
requests will not
be sent to the Accelerate endpoint as the endpoint does not support those
operations. This behavior can also be set if --endpoint-url
parameter
is set to https://s3-accelerate.amazonaws.com
or
http://s3-accelerate.amazonaws.com
for any s3
or s3api
command. This
option is mutually exclusive with the use_dualstack_endpoint
option.
Default - false
If set to true
, will direct all Amazon S3 requests to the dual IPv4 / IPv6
endpoint for the configured region. This option is mutually exclusive with
the use_accelerate_endpoint
option.
Default - auto
There’s two styles of constructing an S3 endpoint. The first is with
the bucket included as part of the hostname. This corresponds to the
addressing style of virtual
. The second is with the bucket included
as part of the path of the URI, corresponding to the addressing style
of path
. The default value in the CLI is to use auto
, which
will attempt to use virtual
where possible, but will fall back to
path
style if necessary. For example, if your bucket name is not
DNS compatible, the bucket name cannot be part of the hostname and
must be in the path. With auto
, the CLI will detect this condition
and automatically switch to path
style for you. If you set the
addressing style to path
, you must ensure that the AWS region you
configured in the AWS CLI matches the same region of your bucket.
If set to true
, s3 payloads will receive additional content validation in
the form of a SHA256 checksum which will be calculated for you and included in
the request signature. If set to false
, the checksum will not be calculated.
Disabling this can be useful to save the performance overhead that the
checksum calculation would otherwise cause.
By default, this is disabled for streaming uploads (UploadPart and PutObject), but only if a ContentMD5 is present (it is generated by default) and the endpoint uses HTTPS.
Warning
All configuration values listed in this section are considered experimental and are not recommended for use in production. Furthermore, backwards compatibility or even existence of each configuration value is not guaranteed between versions of the AWS CLI.
Default - default
Determines the underlying Amazon S3 transfer client to use for transferring files to and from S3. Valid choices are:
default
- Use the builtin, Python-based transfer client that supports
all s3
commands, parameters, and non-experimental configuration values.
crt
- Use the AWS Common Runtime (CRT) transfer client when
possible. It is a C-based S3 transfer client that can improve transfer
throughput. Currently, the CRT transfer client does not support all of the
functionality available in the default
transfer client. The list below
details what functionality is not supported by the crt
transfer client
option and the corresponding behavior of the AWS CLI if it is configured to
prefer the crt
transfer client:
S3 to S3 copies - Falls back to using the default
transfer client
Streaming uploads from standard input and downloads to standard output -
Falls back to using default
transfer client.
Region redirects - Transfers fail for requests sent to a region that does not match the region of the targeted S3 bucket.
max_concurrent_requests
, max_queue_size
, multipart_threshold
,
and max_bandwidth
configuration values - Ignores these configuration
values.
Note
This experimental configuration option is only supported when
preferred_transfer_client
is set to crt
. The default
transfer
client does not support it.
Default - 5Gb/s
Controls the target bandwidth that the transfer client will try to reach for S3 uploads and downloads. The value can be specified as:
An integer in terms of bytes per second. For example,
1073741824
would set the target bandwidth to 1 GB per second.
A rate suffix. This can be expressed in terms of either bytes per second
(B/s
) or bits per second (b/s
). You can specify rate suffixes
using: KB/s
, MB/s
, GB/s
, Kb/s
, Mb/s
, Gb/s
etc.
For example: 200MB/s
, 10GB/s
, 200Mb/s
, 10Gb/s
.
This difference between target_bandwidth
and the max_bandwidth
is that
max_bandwidth
is purely for rate limiting and makes no adjustments to
increase throughput. The target_bandwidth
configuration may make
adjustments mid-transfer command in order to increase throughput and reach the
requested bandwidth.