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Thanos Object Storage Client

objstore is a Go module providing unified interface and efficient clients to work with various object storage providers.

Features:

  • Ability to perform common operations with clear contract against most popular object storages.
  • High focus on efficiency and reliability required for distributed databases on object storages.
  • Optional built-in YAML based configuration definition for consistent configuration.
  • Optional Prometheus metric instrumentation for bucket operations.

This moduile is battle-tested and used on high scale production by projects like Thanos, Loki, Cortex, Mimir, Tempo, Parca and more.

Contributing

Contributions are very welcome! See our CONTRIBUTING.md for more information.

Community

Thanos is an open source project and we value and welcome new contributors and members of the community. Here are ways to get in touch with the community:

Adopters

See [Adopters List](https://github.com/thanos-io/thanos/blob/main/website/data/adopters.yml.

Background

This library was initially developed as a Thanos objstore package. Thanos uses object storage as primary storage for metrics and metadata related to them. This package ended up being used by other projects like Cortex, Loki, Mimir, Tempo, Parca and more.

Given reusability, Thanos community promoted this package to standalone Go module with smaller amount of dependencies.

Maintainers

See MAINTAINERS.md

How to use objstore

The core this module is the Bucket interface:

type Bucket interface {
	io.Closer
	BucketReader

	// Upload the contents of the reader as an object into the bucket.
	// Upload should be idempotent.
	Upload(ctx context.Context, name string, r io.Reader) error

	// Delete removes the object with the given name.
	// If object does not exists in the moment of deletion, Delete should throw error.
	Delete(ctx context.Context, name string) error

	// Name returns the bucket name for the provider.
	Name() string

All provider implementations have to implement Bucket interface that allows common read and write operations that all supported by all object providers. If you want to limit the code that will do bucket operation to only read access (smart idea, allowing to limit access permissions), you can use the BucketReader interface:

type BucketReader interface {
	// Iter calls f for each entry in the given directory (not recursive.). The argument to f is the full
	// object name including the prefix of the inspected directory.
	// Entries are passed to function in sorted order.
	Iter(ctx context.Context, dir string, f func(string) error, options ...IterOption) error

	// Get returns a reader for the given object name.
	Get(ctx context.Context, name string) (io.ReadCloser, error)

	// GetRange returns a new range reader for the given object name and range.
	GetRange(ctx context.Context, name string, off, length int64) (io.ReadCloser, error)

	// Exists checks if the given object exists in the bucket.
	Exists(ctx context.Context, name string) (bool, error)

	// IsObjNotFoundErr returns true if error means that object is not found. Relevant to Get operations.
	IsObjNotFoundErr(err error) bool

	// Attributes returns information about the specified object.
	Attributes(ctx context.Context, name string) (ObjectAttributes, error)
}

Those interfaces represent the object storage operations your code can use from objstore clients.

Factory

Generally, you have two ways of using objstore module:

First is to import the provider you want e.g. github.com/thanos-io/objstore/providers/s3 and instantiate it with available constructor (e.g. NewBucket).

The second option is to use the factory NewBucket(logger log.Logger, confContentYaml []byte, reg prometheus.Registerer, component string) that will instantiate the object storage client based on YAML file provided. The YAML file has generally the format like this:

type: <PROVIDER_TYPE>
config:
  <PROVIDER_TYPE specific options>

The exact option depends on provider and are in sections below.

NOTE: All code snippets are auto-generated from code and up-to-date.

Check out the Thanos documentation to see how Thanos uses this module.

Supported Providers (Clients)

Current object storage client implementations:

Provider Maturity Aimed For Auto-tested on CI Maintainers
Google Cloud Storage Stable Production Usage yes @bwplotka
AWS/S3 (and all S3-compatible storages e.g disk-based Minio) Stable Production Usage yes @bwplotka
Azure Storage Account Stable Production Usage no @vglafirov
OpenStack Swift Beta (working PoC) Production Usage yes @FUSAKLA
Tencent COS Beta Production Usage no @jojohappy,@hanjm
AliYun OSS Beta Production Usage no @shaulboozhiao,@wujinhu
Baidu BOS Beta Production Usage no ??
Local Filesystem Stable Testing and Demo only yes @bwplotka

Missing support to some object storage? Check out how to add your client section

NOTE: Currently Thanos requires strong consistency (write-read) for object store implementation for singleton Compaction purposes.

S3

Thanos uses the minio client library to upload Prometheus data into AWS S3.

NOTE: S3 client was designed for AWS S3, but it can be configured against other S3-compatible object storages e.g Ceph

The S# object storage yaml configuration definition:

type: S3
config:
  bucket: ""
  endpoint: ""
  region: ""
  aws_sdk_auth: false
  access_key: ""
  insecure: false
  signature_version2: false
  secret_key: ""
  put_user_metadata: {}
  http_config:
    idle_conn_timeout: 1m30s
    response_header_timeout: 2m
    insecure_skip_verify: false
    tls_handshake_timeout: 10s
    expect_continue_timeout: 1s
    max_idle_conns: 100
    max_idle_conns_per_host: 100
    max_conns_per_host: 0
    tls_config:
      ca_file: ""
      cert_file: ""
      key_file: ""
      server_name: ""
      insecure_skip_verify: false
    disable_compression: false
  trace:
    enable: false
  list_objects_version: ""
  bucket_lookup_type: auto
  part_size: 67108864
  sse_config:
    type: ""
    kms_key_id: ""
    kms_encryption_context: {}
    encryption_key: ""
  sts_endpoint: ""
prefix: ""

At a minimum, you will need to provide a value for the bucket, endpoint, access_key, and secret_key keys. The rest of the keys are optional.

However if you set aws_sdk_auth: true Thanos will use the default authentication methods of the AWS SDK for go based on known environment variables (AWS_PROFILE, AWS_WEB_IDENTITY_TOKEN_FILE … etc) and known AWS config files (~/.aws/config). If you turn this on, then the bucket and endpoint are the required config keys.

The field prefix can be used to transparently use prefixes in your S3 bucket. This allows you to separate blocks coming from different sources into paths with different prefixes, making it easier to understand what’s going on (i.e. you don’t have to use Thanos tooling to know from where which blocks came).

The AWS region to endpoint mapping can be found in this link.

Make sure you use a correct signature version. Currently AWS requires signature v4, so it needs signature_version2: false. If you don’t specify it, you will get an Access Denied error. On the other hand, several S3 compatible APIs use signature_version2: true.

You can configure the timeout settings for the HTTP client by setting the http_config.idle_conn_timeout and http_config.response_header_timeout keys. As a rule of thumb, if you are seeing errors like timeout awaiting response headers in your logs, you may want to increase the value of http_config.response_header_timeout.

Please refer to the documentation of the Transport type in the net/http package for detailed information on what each option does.

part_size is specified in bytes and refers to the minimum file size used for multipart uploads, as some custom S3 implementations may have different requirements. A value of 0 means to use a default 128 MiB size.

Set list_objects_version: "v1" for S3 compatible APIs that don’t support ListObjectsV2 (e.g. some versions of Ceph). Default value ("") is equivalent to "v2".

http_config.tls_config allows configuring TLS connections. Please refer to the document of tls_config for detailed information on what each option does.

bucket_lookup_type can be auto, virtual-hosted or path. Read more about it here.

For debug and testing purposes you can set

  • insecure: true to switch to plain insecure HTTP instead of HTTPS

  • http_config.insecure_skip_verify: true to disable TLS certificate verification (if your S3 based storage is using a self-signed certificate, for example)

  • trace.enable: true to enable the minio client’s verbose logging. Each request and response will be logged into the debug logger, so debug level logging must be enabled for this functionality.

S3 Server-Side Encryption

SSE can be configued using the sse_config. SSE-S3, SSE-KMS, and SSE-C are supported.

  • If type is set to SSE-S3 you do not need to configure other options.

  • If type is set to SSE-KMS you must set kms_key_id. The kms_encryption_context is optional, as AWS provides a default encryption context.

  • If type is set to SSE-C you must provide a path to the encryption key using encryption_key.

If the SSE Config block is set but the type is not one of SSE-S3, SSE-KMS, or SSE-C, an error is raised.

You will also need to apply the following AWS IAM policy for the user to access the KMS key:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "KMSAccess",
            "Effect": "Allow",
            "Action": [
                "kms:GenerateDataKey",
                "kms:Encrypt",
                "kms:Decrypt"
            ],
            "Resource": "arn:aws:kms:<region>:<account>:key/<KMS key id>"
        }
    ]
}
Credentials

By default Thanos will try to retrieve credentials from the following sources:

  1. From config file if BOTH access_key and secret_key are present.
  2. From the standard AWS environment variable – AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY
  3. From ~/.aws/credentials
  4. IAM credentials retrieved from an instance profile.

NOTE: Getting access key from config file and secret key from other method (and vice versa) is not supported.

AWS Policies

Example working AWS IAM policy for user:

  • For deployment (policy for Thanos services):

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "Statement",
            "Effect": "Allow",
            "Action": [
                "s3:ListBucket",
                "s3:GetObject",
                "s3:DeleteObject",
                "s3:PutObject"
            ],
            "Resource": [
                "arn:aws:s3:::<bucket>/*",
                "arn:aws:s3:::<bucket>"
            ]
        }
    ]
}

(No bucket policy)

To test the policy, set env vars for S3 access for empty, not used bucket as well as:

THANOS_TEST_OBJSTORE_SKIP=GCS,AZURE,SWIFT,COS,ALIYUNOSS
THANOS_ALLOW_EXISTING_BUCKET_USE=true

And run: GOCACHE=off go test -v -run TestObjStore_AcceptanceTest_e2e ./pkg/...

  • For testing (policy to run e2e tests):

We need access to CreateBucket and DeleteBucket and access to all buckets:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "Statement",
            "Effect": "Allow",
            "Action": [
                "s3:ListBucket",
                "s3:GetObject",
                "s3:DeleteObject",
                "s3:PutObject",
                "s3:CreateBucket",
                "s3:DeleteBucket"
            ],
            "Resource": [
                "arn:aws:s3:::<bucket>/*",
                "arn:aws:s3:::<bucket>"
            ]
        }
    ]
}

With this policy you should be able to run set THANOS_TEST_OBJSTORE_SKIP=GCS,AZURE,SWIFT,COS,ALIYUNOSS and unset S3_BUCKET and run all tests using make test.

Details about AWS policies: https://docs.aws.amazon.com/AmazonS3/latest/dev/using-with-s3-actions.html

STS Endpoint

If you want to use IAM credential retrieved from an instance profile, Thanos needs to authenticate through AWS STS. For this purposes you can specify your own STS Endpoint.

By default Thanos will use endpoint: https://sts.amazonaws.com and AWS region corresponding endpoints.

GCS

To configure Google Cloud Storage bucket as an object store you need to set bucket with GCS bucket name and configure Google Application credentials.

For example:

type: GCS
config:
  bucket: ""
  service_account: ""
prefix: ""
Using GOOGLE_APPLICATION_CREDENTIALS

Application credentials are configured via JSON file and only the bucket needs to be specified, the client looks for:

  1. A JSON file whose path is specified by the GOOGLE_APPLICATION_CREDENTIALS environment variable.
  2. A JSON file in a location known to the gcloud command-line tool. On Windows, this is %APPDATA%/gcloud/application_default_credentials.json. On other systems, $HOME/.config/gcloud/application_default_credentials.json.
  3. On Google App Engine it uses the appengine.AccessToken function.
  4. On Google Compute Engine and Google App Engine Managed VMs, it fetches credentials from the metadata server. (In this final case any provided scopes are ignored.)

You can read more on how to get application credential json file in https://cloud.google.com/docs/authentication/production

Using inline a Service Account

Another possibility is to inline the ServiceAccount into the Thanos configuration and only maintain one file. This feature was added, so that the Prometheus Operator only needs to take care of one secret file.

type: GCS
config:
  bucket: "thanos"
  service_account: |-
    {
      "type": "service_account",
      "project_id": "project",
      "private_key_id": "abcdefghijklmnopqrstuvwxyz12345678906666",
      "private_key": "-----BEGIN PRIVATE KEY-----\...\n-----END PRIVATE KEY-----\n",
      "client_email": "[email protected]",
      "client_id": "123456789012345678901",
      "auth_uri": "https://accounts.google.com/o/oauth2/auth",
      "token_uri": "https://oauth2.googleapis.com/token",
      "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
      "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/thanos%40gitpods.iam.gserviceaccount.com"
    }
GCS Policies

Note: GCS Policies should be applied at the project level, not at the bucket level

For deployment:

Storage Object Creator and Storage Object Viewer

For testing:

Storage Object Admin for ability to create and delete temporary buckets.

To test the policy is working as expected, exec into the sidecar container, eg:

kubectl exec -it -n <namespace> <prometheus with sidecar pod name> -c <sidecar container name> -- /bin/sh

Then test that you can at least list objects in the bucket, eg:

thanos tools bucket ls --objstore.config="${OBJSTORE_CONFIG}"
Azure

To use Azure Storage as Thanos object store, you need to precreate storage account from Azure portal or using Azure CLI. Follow the instructions from Azure Storage Documentation: https://docs.microsoft.com/en-us/azure/storage/common/storage-quickstart-create-account

Config file format is the following:

type: AZURE
config:
  storage_account: ""
  storage_account_key: ""
  container: ""
  endpoint: ""
  max_retries: 0
  msi_resource: ""
  user_assigned_id: ""
  pipeline_config:
    max_tries: 0
    try_timeout: 0s
    retry_delay: 0s
    max_retry_delay: 0s
  reader_config:
    max_retry_requests: 0
  http_config:
    idle_conn_timeout: 0s
    response_header_timeout: 0s
    insecure_skip_verify: false
    tls_handshake_timeout: 0s
    expect_continue_timeout: 0s
    max_idle_conns: 0
    max_idle_conns_per_host: 0
    max_conns_per_host: 0
    tls_config:
      ca_file: ""
      cert_file: ""
      key_file: ""
      server_name: ""
      insecure_skip_verify: false
    disable_compression: false
prefix: ""

If msi_resource is used, authentication is done via system-assigned managed identity. The value for Azure should be https://<storage-account-name>.blob.core.windows.net.

If user_assigned_id is used, authentication is done via user-assigned managed identity. When using user_assigned_id the msi_resource defaults to https://<storage_account>.<endpoint>

The generic max_retries will be used as value for the pipeline_config‘s max_tries and reader_config‘s max_retry_requests. For more control, max_retries could be ignored (0) and one could set specific retry values.

OpenStack Swift

Thanos uses ncw/swift client to upload Prometheus data into OpenStack Swift.

Below is an example configuration file for thanos to use OpenStack swift container as an object store. Note that if the name of a user, project or tenant is used one must also specify its domain by ID or name. Various examples for OpenStack authentication can be found in the official documentation.

By default, OpenStack Swift has a limit for maximum file size of 5 GiB. Thanos index files are often larger than that. To resolve this issue, Thanos uses Static Large Objects (SLO) which are uploaded as segments. These are by default put into the segments directory of the same container. The default limit for using SLO is 1 GiB which is also the maximum size of the segment. If you don’t want to use the same container for the segments (best practise is to use <container_name>_segments to avoid polluting listing of the container objects) you can use the large_file_segments_container_name option to override the default and put the segments to other container. In rare cases you can switch to Dynamic Large Objects (DLO) by setting the use_dynamic_large_objects to true, but use it with caution since it even more relies on eventual consistency.

type: SWIFT
config:
  auth_version: 0
  auth_url: ""
  username: ""
  user_domain_name: ""
  user_domain_id: ""
  user_id: ""
  password: ""
  domain_id: ""
  domain_name: ""
  project_id: ""
  project_name: ""
  project_domain_id: ""
  project_domain_name: ""
  region_name: ""
  container_name: ""
  large_object_chunk_size: 1073741824
  large_object_segments_container_name: ""
  retries: 3
  connect_timeout: 10s
  timeout: 5m
  use_dynamic_large_objects: false
prefix: ""
Tencent COS

To use Tencent COS as storage store, you should apply a Tencent Account to create an object storage bucket at first. Note that detailed from Tencent Cloud Documents: https://cloud.tencent.com/document/product/436

To configure Tencent Account to use COS as storage store you need to set these parameters in yaml format stored in a file:

type: COS
config:
  bucket: ""
  region: ""
  app_id: ""
  endpoint: ""
  secret_key: ""
  secret_id: ""
  http_config:
    idle_conn_timeout: 1m30s
    response_header_timeout: 2m
    insecure_skip_verify: false
    tls_handshake_timeout: 10s
    expect_continue_timeout: 1s
    max_idle_conns: 100
    max_idle_conns_per_host: 100
    max_conns_per_host: 0
    tls_config:
      ca_file: ""
      cert_file: ""
      key_file: ""
      server_name: ""
      insecure_skip_verify: false
    disable_compression: false
prefix: ""

The secret_key and secret_id field is required. The http_config field is optional for optimize HTTP transport settings. There are two ways to configure the required bucket information:

  1. Provide the values of bucket, region and app_id keys.
  2. Provide the values of endpoint key with url format when you want to specify vpc internal endpoint. Please refer to the document of endpoint for more detail.
AliYun OSS

In order to use AliYun OSS object storage, you should first create a bucket with proper Storage Class , ACLs and get the access key on the AliYun cloud. Go to https://www.alibabacloud.com/product/oss for more detail.

The AliYun OSS object storage yaml configuration definition:

type: ALIYUNOSS
config:
  endpoint: ""
  bucket: ""
  access_key_id: ""
  access_key_secret: ""
prefix: ""
Baidu BOS

In order to use Baidu BOS object storage, you should apply for a Baidu Account and create an object storage bucket first. Refer to Baidu Cloud Documents for more details. The Baidu BOS object storage yaml configuration definition:

type: BOS
config:
  bucket: ""
  endpoint: ""
  access_key: ""
  secret_key: ""
prefix: ""
Filesystem

This storage type is used when user wants to store and access the bucket in the local filesystem. We treat filesystem the same way we would treat object storage, so all optimization for remote bucket applies even though, we might have the files locally.

NOTE: This storage type is experimental and might be inefficient. It is NOT advised to use it as the main storage for metrics in production environment. Particularly there is no planned support for distributed filesystems like NFS. This is mainly useful for testing and demos.

Filesystem “object storage” yaml configuration definition:

type: FILESYSTEM
config:
  directory: ""
prefix: ""

How to add a new client to Thanos?

Following checklist allows adding new Go code client to supported providers:

  1. Create new directory under ./providers/<provider>
  2. Implement objstore.Bucket interface
  3. Add NewTestBucket constructor for testing purposes, that creates and deletes temporary bucket.
  4. Use created NewTestBucket in ForeachStore method to ensure we can run tests against new provider. (In PR)
  5. RUN the TestObjStoreAcceptanceTest against your provider to ensure it fits. Fix any found error until test passes. (In PR)
  6. Add client implementation to the factory in factory code. (Using as small amount of flags as possible in every command)
  7. Add client struct config to cfggen; to allow config auto generation.

At that point, anyone can use your provider by spec.

GitHub

View Github