s3du is a tool which lets you know how much space your [AWS S3] buckets are
using according to either [AWS CloudWatch] or AWS S3.
The CloudWatch mode is the cheapest, but least accurate option for getting the bucket sizes. It is less accurate because there is up to a 24 hour delay on the real bucket size vs. the size in CloudWatch as CloudWatch is only updated with S3 bucket sizes [once per day].
The S3 mode is the most accurate but more expensive mode of operation. In this mode all of the objects in each discovered bucket are listed and their sizes summed.
s3du can be installed by running cargo install s3du.
s3du uses the default [AWS credentials] chain. As long as your AWS
credentials are available in some fashion, and your IAM user/role has the
correct permissions simply running s3du should return some results.
For example, if you manage your credentials with [aws-vault], you might run
s3du as follows:
shell
aws-vault exec s3du-role -- s3du
By default, s3du will operate in the us-east-1 region. This can be
overridden either by the AWS_REGION environment variable, or the --region
CLI argument.
```shell
env AWS_REGION=eu-west-1 s3du
s3du --region=eu-central-1
s3du --mode=s3
s3du --mode=s3 --object-versions=non-current my-bucket ```
More information on running s3du can be found in the man page or via
s3du --help.
The crate has two features, which are both enabled by default.
| Feature | Purpose |
|--------------|------------------------------|
| cloudwatch | Enable use of CloudWatch API |
| s3 | Enable use of S3 API |
s3du requires at least one of these features be enabled, attempting to
compile the crate with both features disabled will result in compilation
errors.
The CloudWatch and S3 modes will report sizes slightly differently. The CloudWatch mode will always show the total bucket size, that is, it will show the size of all current objects versions + non-current object versions. It is not possible to change this behaviour.
The S3 mode will, by default, only show the bucket size for current object versions. Command line flags (or environment variables) can be used to change how the S3 mode operates. With these you can change the S3 mode to operate in one of 3 ways:
These can be selected via the --object-versions CLI flag if s3du was
compiled with the s3 feature.
In order to enable use of s3du, your IAM user or role will need one or both
of the following IAM policies attached, depending on which s3du modes you
wish to use.
Full examples of these policies are provided as:
Under the aws directory of the source repository.
This policy will enforce HTTPS use and will allow s3du access to the AWS
CloudWatch APIs that it requires.
json
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "s3du-cloudwatch",
"Effect": "Allow",
"Action": [
"cloudwatch:GetMetricStatistics",
"cloudwatch:ListMetrics"
],
"Resource": [
"*"
],
"Condition": {
"Bool": {
"aws:SecureTransport": true
}
}
}
]
}
This policy will enforce HTTPS use and will allow s3du access to the AWS S3
APIs that it requires.
json
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "s3du-s3",
"Effect": "Allow",
"Action": [
"s3:GetBucketLocation",
"s3:ListAllMyBuckets",
"s3:ListBucket",
"s3:ListBucketMultipartUploads",
"s3:ListMultipartUploadParts"
],
"Resource": [
"*"
],
"Condition": {
"Bool": {
"aws:SecureTransport": true
}
}
}
]
}
Each of the methods for obtaining bucket sizes have different costs within AWS as they will make differing numbers of API calls, and each API has its own pricing model which may also vary by region.
AWS CloudWatch is the cheapest method of running s3du, at the cost of some
accuracy.
The CloudWatch mode of s3du will use at least 1 API call to perform the
ListMetrics call and at least 1 API call per S3 bucket for the
GetMetricStatistics call.
The reason these are listed as "at least 1" is because the API call results
could be paginated if the results lists are sufficiently long. ListMetrics
will paginate after 500 results while GetMetricStatistics will paginate after
1,440 statistics.
As a basic example, getting bucket sizes for an AWS account with 4 S3 buckets
in it should use 5 API calls total. 1 ListMetrics call to discover the
buckets and 4 GetMetricStatistics calls (one for each bucket).
AWS S3 is a more expensive, but more accurate, method of listing bucket sizes.
The S3 mode of s3du will use 1 API call to perform the ListBuckets API
call, 1 API call per listed bucket to GetBucketLocation to discover its
region, 1 API call per listed bucket to HeadBucket to make sure we have
access to list the objects, and:
ListMultipartUploads, at least 1 call to
ListObjectVersions, and at least 1 call to ListParts if in-progress
multipart uploads are found in the All object modeListObjectsV2 per-bucket in the Current object
(default) modeListObjectVersions per bucket in the NonCurrent
object modeListMultipartUploads per-bucket in the Multipart
mode with at least 1 call to ListParts if any in-progress multipart
uploads are foundEach of the API calls listed above will return 1,000 objects maximum, if your bucket has more objects than this, pagination will be required.
For example, let's say we're running in S3 mode getting the sizes of current
object versions and our AWS account has 2 buckets.
bucket-a (no versioning enabled) has 10,000 objects and bucket-b
(versioning enabled) has 32,768 object versions of which 13,720 are current
versions and 19,048 are non-current versions. There is also an in-progress
multipart upload with 2 parts uploaded in bucket-a. This would mean:
ListBuckets for bucket discoveryGetBucketLocation for region discovery, 1 for each bucketHeadBucket to check we have access, 1 for each bucketListObjectsV2 for bucket-aListObjectsV2 for bucket-bfor a total of 29 API calls.
If we were to run s3du against the same account a second time, but ask for
the sum of all object versions, we'd get the following:
ListBuckets for bucket discoveryGetBucketLocation for region discovery, 1 for each bucketHeadBucket to check we have access, 1 for each bucketListObjectVersions for bucket-aListObjectVersions for bucket-bListMultipartUploads for bucket-aListMultipartUploads for bucket-bListParts for bucket-afor a total of 51 API calls.
A third run of s3du against the same account but asking for the sum of
non-current object versions would result in the following:
ListBuckets for bucket discoveryGetBucketLocation for region discovery, 1 for each bucketHeadBucket to check we have access, 1 for each bucketListObjectVersions for bucket-aListObjectVersions for bucket-bfor a total of 39 API calls.
You will notice that the number of API calls to ListObjectVersions for
bucket-b are the same across both the all and non-current object versions
requests, this is because any filtering for current vs. non-current objects in
these scenarios must be done by s3du. The ListObjectVersions API does not
let us specify which object versions we'd like to retrieve.
s3du allows a custom endpoint to be specified while running in S3 mode. This
allows use on S3 compatible storage such as [MinIO].
This use case is currently only tested against MinIO and is very basic.
shell
env AWS_ACCESS_KEY_ID=minio \
AWS_SECRET_ACCESS_KEY=miniosecret \
s3du --mode=s3 --endpoint=https://minio.example.org/