This is documentation for the next version of Loki. For the latest stable release, go to the latest version.

Storage

Open source

Manage storage

You can read a high level overview of Loki storage here

Grafana Loki needs to store two different types of data: chunks and indexes.

Loki receives logs in separate streams, where each stream is uniquely identified by its tenant ID and its set of labels. As log entries from a stream arrive, they are compressed as “chunks” and saved in the chunks store. See chunk format for how chunks are stored internally.

The index stores each stream’s label set and links them to the individual chunks.

Refer to Loki’s configuration for details on how to configure the storage and the index.

For more information:

Supported Stores

The following are supported for the index:

TSDB index store which stores TSDB index files in the object store. This is the recommended index store for Loki 2.8 and newer.
Single Store (boltdb-shipper) index store which stores boltdb index files in the object store.
Amazon DynamoDB
Google Bigtable
Apache Cassandra
BoltDB (doesn’t work when clustering Loki)

The following are deprecated for the index and will be removed in a future release:

Amazon DynamoDB. Support for this is deprecated and will be removed in a future release.
Google Bigtable. Support for this is deprecated and will be removed in a future release.
Apache Cassandra. Support for this is deprecated and will be removed in a future release.

The following are supported and recommended for the chunks:

Amazon S3
Google Cloud Storage
Filesystem (please read more about the filesystem to understand the pros/cons before using with production data)
Baidu Object Storage
IBM Cloud Object Storage

The following are supported for the chunks, but not typically recommended for production use:

Filesystem (please read more about the filesystem to understand the pros/cons before using with production data)

The following are deprecated for the chunks and will be removed in a future release:

Amazon DynamoDB. Support for this is deprecated and will be removed in a future release.
Google Bigtable. Support for this is deprecated and will be removed in a future release.
Apache Cassandra. Support for this is deprecated and will be removed in a future release.

Cloud Storage Permissions

S3

When using S3 as object storage, the following permissions are needed:

s3:ListBucket
s3:PutObject
s3:GetObject
s3:DeleteObject (if running the Single Store (boltdb-shipper) compactor)

Resources: arn:aws:s3:::<bucket_name>, arn:aws:s3:::<bucket_name>/*

See the AWS deployment section on the storage page for a detailed setup guide.

DynamoDB

Note: DynamoDB support is deprecated and will be removed in a future release.

When using DynamoDB for the index, the following permissions are needed:

dynamodb:BatchGetItem
dynamodb:BatchWriteItem
dynamodb:DeleteItem
dynamodb:DescribeTable
dynamodb:GetItem
dynamodb:ListTagsOfResource
dynamodb:PutItem
dynamodb:Query
dynamodb:TagResource
dynamodb:UntagResource
dynamodb:UpdateItem
dynamodb:UpdateTable
dynamodb:CreateTable
dynamodb:DeleteTable (if table_manager.retention_period is more than 0s)

Resources: arn:aws:dynamodb:<aws_region>:<aws_account_id>:table/<prefix>*

dynamodb:ListTables

Resources: *

AutoScaling

If you enable autoscaling from table manager, the following permissions are needed:

Application Autoscaling

application-autoscaling:DescribeScalableTargets
application-autoscaling:DescribeScalingPolicies
application-autoscaling:RegisterScalableTarget
application-autoscaling:DeregisterScalableTarget
application-autoscaling:PutScalingPolicy
application-autoscaling:DeleteScalingPolicy

Resources: *

IAM

iam:GetRole
iam:PassRole

Resources: arn:aws:iam::<aws_account_id>:role/<role_name>

IBM Cloud Object Storage

When using IBM Cloud Object Storage (COS) as object storage, IAM Writer role is needed.

See the IBM Cloud Object Storage section on the storage page for a detailed setup guide.

Chunk Format

  -------------------------------------------------------------------
  |                               |                                 |
  |        MagicNumber(4b)        |           version(1b)           |
  |                               |                                 |
  -------------------------------------------------------------------
  |         block-1 bytes         |          checksum (4b)          |
  -------------------------------------------------------------------
  |         block-2 bytes         |          checksum (4b)          |
  -------------------------------------------------------------------
  |         block-n bytes         |          checksum (4b)          |
  -------------------------------------------------------------------
  |                        #blocks (uvarint)                        |
  -------------------------------------------------------------------
  | #entries(uvarint) | mint, maxt (varint) | offset, len (uvarint) |
  -------------------------------------------------------------------
  | #entries(uvarint) | mint, maxt (varint) | offset, len (uvarint) |
  -------------------------------------------------------------------
  | #entries(uvarint) | mint, maxt (varint) | offset, len (uvarint) |
  -------------------------------------------------------------------
  | #entries(uvarint) | mint, maxt (varint) | offset, len (uvarint) |
  -------------------------------------------------------------------
  |                      checksum(from #blocks)                     |
  -------------------------------------------------------------------
  |           metasOffset - offset to the point with #blocks        |
  -------------------------------------------------------------------