Configuration: Output

Here is a sample configuration and available parameters for fluentd v1 or later. See also Configuration: credentials for common comprehensive parameters.

<match pattern>
  @type s3

  aws_key_id YOUR_AWS_KEY_ID
  aws_sec_key YOUR_AWS_SECRET_KEY
  s3_bucket YOUR_S3_BUCKET_NAME
  s3_region ap-northeast-1

  path logs/${tag}/%Y/%m/%d/
  s3_object_key_format %{path}%{time_slice}_%{index}.%{file_extension}

  # if you want to use ${tag} or %Y/%m/%d/ like syntax in path / s3_object_key_format,
  # need to specify tag for ${tag} and time for %Y/%m/%d in <buffer> argument.
  <buffer tag,time>
    @type file
    path /var/log/fluent/s3
    timekey 3600 # 1 hour partition
    timekey_wait 10m
    timekey_use_utc true # use utc
  </buffer>
  <format>
    @type json
  </format>
</match>

For <buffer>, you can use any record field in path / s3_object_key_format.

path logs/${tag}/${foo}
<buffer tag,foo>
  # parameters...
</buffer>

See official article for available parameters and usage of placeholder in detail: Config: Buffer Section

Note that this configuration doesn't work with fluentd v0.12. See v0.12 for v0.12 style.

aws_iam_retries

This parameter is deprecated. Use instance_profile_credentials instead.

The number of attempts to make (with exponential backoff) when loading instance profile credentials from the EC2 metadata service using an IAM role. Defaults to 5 retries.

s3_bucket (required)

S3 bucket name.

s3_region

s3 region name. For example, US West (Oregon) Region is "us-west-2". The full list of regions are available here. > http://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region. We recommend using s3_region instead of s3_endpoint.

s3_endpoint

endpoint for S3 compatible services. For example, Riak CS based storage or something. This option is deprecated for AWS S3, use s3_region instead.

See also AWS article: Working with Regions.

enable_transfer_acceleration

Enable S3 Transfer Acceleration for uploads. IMPORTANT: For this to work, you must first enable this feature on your destination S3 bucket.

enable_dual_stack

Enable Amazon S3 Dual-Stack Endpoints for uploads. Will make it possible to use either IPv4 or IPv6 when connecting to S3.

use_bundled_cert

For cases where the default SSL certificate is unavailable (e.g. Windows), you can set this option to true in order to use the AWS SDK bundled certificate. Default is false.

This fixes the following error often seen in Windows:

SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed (Seahorse::Client::NetworkingError)

ssl_ca_bundle

Full path to the SSL certificate authority bundle file that should be used when verifying peer certificates. If you do not pass ssl_ca_bundle or ssl_ca_directory the the system default will be used if available.

ssl_ca_directory

Full path of the directory that contains the unbundled SSL certificate authority files for verifying peer certificates. If you do not pass ssl_ca_bundle or ssl_ca_directory the the system default will be used if available.

ssl_verify_peer

Verify SSL certificate of the endpoint. Default is true. Set false when you want to ignore the endpoint SSL certificate.

s3_object_key_format

The format of S3 object keys. You can use several built-in variables:

%{path}
%{time_slice}
%{index}
%{file_extension}
%{hex_random}
%{uuid_flush}
%{hostname}

to decide keys dynamically.

%{path} is exactly the value of path configured in the configuration file. E.g., "logs/" in the example configuration above.
%{time_slice} is the time-slice in text that are formatted with time_slice_format.
%{index} is the sequential number starts from 0, increments when multiple files are uploaded to S3 in the same time slice.
%{file_extension} depends on store_as parameter.
%{uuid_flush} a uuid that is replaced everytime the buffer will be flushed.
%{hostname} is replaced with Socket.gethostname result.
%{hex_random} a random hex string that is replaced for each buffer chunk, not assured to be unique. This is used to follow a way of performance tuning, Add a Hex Hash Prefix to Key Name, written in Request Rate and Performance Considerations - Amazon Simple Storage Service. You can configure the length of string with a hex_random_length parameter (Default: 4).

The default format is %{path}%{time_slice}_%{index}.%{file_extension}. In addition, you can use buffer placeholders in this parameter, so you can embed tag, time and record value like below:

s3_object_key_format %{path}/events/%Y%m%d/${tag}_%{index}.%{file_extension}
<buffer tag,time>
  # buffer parameters...
</buffer>

For instance, using the example configuration above, actual object keys on S3 will be something like:

"logs/20130111-22_0.gz"
"logs/20130111-23_0.gz"
"logs/20130111-23_1.gz"
"logs/20130112-00_0.gz"

With the configuration:

s3_object_key_format %{path}/events/ts=%{time_slice}/events_%{index}.%{file_extension}
path log
time_slice_format %Y%m%d-%H

You get:

"log/events/ts=20130111-22/events_0.gz"
"log/events/ts=20130111-23/events_0.gz"
"log/events/ts=20130111-23/events_1.gz"
"log/events/ts=20130112-00/events_0.gz"

NOTE: ${hostname} placeholder is deprecated since v0.8. You can get same result by using configuration's embedded ruby code feature.

s3_object_key_format %{path}%{time_slice}_%{hostname}%{index}.%{file_extension}
s3_object_key_format "%{path}%{time_slice}_#{Socket.gethostname}%{index}.%{file_extension}"

Above two configurations are same. The important point is wrapping "" is needed for #{Socket.gethostname}.

NOTE: If check_object is set to false, Ensure the value of s3_object_key_format must be unique in each write, If not, existing file will be overwritten.

force_path_style

:force_path_style (Boolean) — default: false — When set to true, the bucket name is always left in the request URI and never moved to the host as a sub-domain. See Plugins::S3BucketDns for more details.

This parameter is deprecated. See AWS announcement: https://aws.amazon.com/blogs/aws/amazon-s3-path-deprecation-plan-the-rest-of-the-story/

store_as

archive format on S3. You can use several format:

gzip (default)
json
text
lzo (Need lzop command)
lzma2 (Need xz command)
gzip_command (Need gzip command)
- This compressor uses an external gzip command, hence would result in utilizing CPU cores well compared with gzip
parquet (Need columnify command)
- This compressor uses an external columnify command.
- Use <compress> section to configure columnify command behavior.

See Use your compression algorithm section for adding another format.

<compress> (for parquet compressor only) section

parquet_compression_codec

parquet compression codec.

uncompressed
snappy (default)
gzip
lzo (unsupported by columnify)
brotli (unsupported by columnify)
lz4 (unsupported by columnify)
zstd

parquet_page_size

parquet file page size. default: 8192 bytes

parquet_row_group_size

parquet file row group size. default: 128 MB

record_type

record data format type.

avro
csv
jsonl
msgpack
tsv
msgpack (default)
json

schema_type

schema type.

avro (default)
bigquery

schema_file (required)

path to schema file.

<format> section

Change one line format in the S3 object. Supported formats are "out_file", "json", "ltsv", "single_value" and other formatter plugins. See also official Formatter article.

out_file (default).

  time\ttag\t{..json1..}
  time\ttag\t{..json2..}
  ...

json
```
  {..json1..}
  {..json2..}
  ...
```

At this format, "time" and "tag" are omitted. But you can set these information to the record by setting <inject> option. If you set following configuration in S3 output:

<format>
  @type json
</format>
<inject>
  time_key log_time
</inject>

then the record has log_time field.

{"log_time":"time string",...}

ltsv

  key1:value1\tkey2:value2
  key1:value1\tkey2:value2
  ...

single_value

Use specified value instead of entire recode. If you get '{"message":"my log"}', then contents are

my log1
my log2
...

You can change key name by "message_key" option.

auto_create_bucket

Create S3 bucket if it does not exists. Default is true.

check_bucket

Check mentioned bucket if it exists in AWS or not. Default is true.

When it is false, fluentd will not check aws s3 for the existence of the mentioned bucket. This is the case where bucket will be pre-created before running fluentd.

check_object

Check object before creation if it exists or not. Default is true.

When it is false, s3_object_key_format will be %{path}%{time_slice}_%{hms_slice}.%{file_extension} by default where, hms_slice will be time-slice in hhmmss format, so that each object will be unique. Example object name, assuming it is created on 2016/16/11 3:30:54 PM 20161611_153054.txt (extension can be anything as per user's choice)

check_apikey_on_start

Check AWS key on start. Default is true.

proxy_uri

uri of proxy environment.

path

path prefix of the files on S3. Default is "" (no prefix). buffer placeholder is supported, so you can embed tag, time and record value like below.

path logs/%Y%m%d/${tag}/
<buffer tag,time>
  # buffer parameters...
</buffer>

utc

Use UTC instead of local time.

storage_class

Set storage class. Possible values are STANDARD, REDUCED_REDUNDANCY, STANDARD_IA from Ruby SDK.

Note that reduced redundancy is not reccomended.

reduced_redundancy

Use S3 reduced redundancy storage for 33% cheaper pricing. Default is false.

This is deprecated. Use storage_class REDUCED_REDUNDANCY instead.

acl

Permission for the object in S3. This is useful for cross-account access using IAM roles. Valid values are:

private (default)
public-read
public-read-write (not recommended - see Canned ACL)
authenticated-read
bucket-owner-read
bucket-owner-full-control

To use cross-account access, you will need to create a bucket policy granting the specific access required. Refer to the AWS documentation for examples.

grant_full_control

Allows grantee READ, READ_ACP, and WRITE_ACP permissions on the object. This is useful for cross-account access using IAM roles.

Valid values are id="Grantee-CanonicalUserID". Please specify the grantee's canonical user ID.

e.g. id="79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2be"

Note that a canonical user ID is different from an AWS account ID. Please refer to AWS documentation for more details.

grant_read

Allows grantee to read the object data and its metadata. Valid values are id="Grantee-CanonicalUserID". Please specify the grantee's canonical user ID.

e.g. id="79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2be"

grant_read_acp

Allows grantee to read the object ACL. Valid values are id="Grantee-CanonicalUserID". Please specify the grantee's canonical user ID.

e.g. id="79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2be"

grant_write_acp

Allows grantee to write the ACL for the applicable object. Valid values are id="Grantee-CanonicalUserID". Please specify the grantee's canonical user ID.

e.g. id="79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2be"

hex_random_length

The length of %{hex_random} placeholder. Default is 4 as written in Request Rate and Performance Considerations - Amazon Simple Storage Service. The maximum length is 16.

index_format

%{index} is formatted by sprintf using this format_string. Default is '%d'. Zero padding is supported e.g. %04d to ensure minimum length four digits. %{index} can be in lowercase or uppercase hex using '%x' or '%X'

overwrite

Overwrite already existing path. Default is false, which raises an error if a s3 object of the same path already exists, or increment the %{index} placeholder until finding an absent path.

use_server_side_encryption

The Server-side encryption algorithm used when storing this object in S3 (e.g., AES256, aws:kms)

ssekms_key_id

Specifies the AWS KMS key ID to use for object encryption. You have to set "aws:kms" to use_server_side_encryption to use the KMS encryption.

sse_customer_algorithm

Specifies the algorithm to use to when encrypting the object (e.g., AES256).

sse_customer_key

Specifies the AWS KMS key ID to use for object encryption.

sse_customer_key_md5

Specifies the 128-bit MD5 digest of the encryption key according to RFC 1321.

compute_checksums

AWS SDK uses MD5 for API request/response by default. On FIPS enabled environment, OpenSSL returns an error because MD5 is disabled. If you want to use this plugin on FIPS enabled environment, set compute_checksums false.

signature_version

Signature version for API request. s3 means signature version 2 and v4 means signature version 4. Default is nil (Following SDK's default). It would be useful when you use S3 compatible storage that accepts only signature version 2.

warn_for_delay

Given a threshold to treat events as delay, output warning logs if delayed events were put into s3.

tagging

The S3 tag-set for the object. The tag-set must be encoded as URL Query parameters. (For example, "Key1=Value1").

<bucket_lifecycle_rule> section

Specify one or more lifecycle rules for the bucket

<bucket_lifecycle_rule>
  id UNIQUE_ID_FOR_THE_RULE
  prefix OPTIONAL_PREFIX # Objects whose keys begin with this prefix will be affected by the rule. If not specified all objects of the bucket will be affected
  expiration_days NUMBER_OF_DAYS # The number of days before the object will expire
</bucket_lifecycle_rule>

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Configuration: Output

aws_iam_retries

s3_bucket (required)

s3_region

s3_endpoint

enable_transfer_acceleration

enable_dual_stack

use_bundled_cert

ssl_ca_bundle

ssl_ca_directory

ssl_verify_peer

s3_object_key_format

force_path_style

store_as

<compress> (for parquet compressor only) section

parquet_compression_codec

parquet_page_size

parquet_row_group_size

record_type

schema_type

schema_file (required)

<format> section

auto_create_bucket

check_bucket

check_object

check_apikey_on_start

proxy_uri

path

utc

storage_class

reduced_redundancy

acl

grant_full_control

grant_read

grant_read_acp

grant_write_acp

hex_random_length

index_format

overwrite

use_server_side_encryption

ssekms_key_id

sse_customer_algorithm

sse_customer_key

sse_customer_key_md5

compute_checksums

signature_version

warn_for_delay

tagging

<bucket_lifecycle_rule> section