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

Grafana Loki documentation Operations Grafana Loki Storage

Grafana Loki Storage

High level storage overview 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:

1. Table Manager
2. Retention
3. Logs Deletion

Supported Stores

The following are supported for the index:

• Single Store (boltdb-shipper) - Recommended for 2.0 and newer 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 supported for the chunks:

• Amazon DynamoDB
• Google Bigtable
• Apache Cassandra
• 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

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

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        |
  -------------------------------------------------------------------