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Migrate the Mimir Helm chart from version 2.x to 3.0

There are breaking changes between the Grafana Mimir Helm chart versions 2.x and 3.0. Several parameters that were available in versions 2.x of the mimir-distributed Helm chart have changed.

To migrate from Helm chart 2.x to 3.0:

  1. Understand the improvements that we made to the Mimir configuration in the Helm chart:

    • The Mimir configuration is now stored in a Kubernetes ConfigMap by default, instead of a Kubernetes Secret.
    • You can override individual properties without copying the entire mimir.config block. Specify properties you want to override under the mimir.structuredConfig.
    • You can move secrets outside the Mimir configuration via external secrets and environment variables. Environment variables can be used to externalize secrets from the configuration file.

  2. Decide whether or not you need to update the Mimir configuration:

    • If you are using external configuration (useExternalConfig: true), then you must set configStorageType: Secret.

      Note: It is now possible to use a ConfigMap to manage your external configuration instead. If your external configuration contains secrets, then you can externalize them and use a ConfigMap. See Externalize secrets.

    • If you are not using external configuration (useExternalConfig: false), and your Mimir configuration contains secrets, chose one of two options:

      • Keep the previous location as-is by setting configStorageType: Secret.

      • Externalize secrets:

        1. Move secrets from the Mimir configuration to a Kubernetes Secret.

        2. Mount the Kubernetes Secret via global.extraEnvFrom:

          YAML 
          global:
  extraEnvFrom:
    - secretRef:
        name: mysecret

          For more information, see Secrets - Use case: As container environment variables.

        3. Replace the values in the Mimir configuration with environment variables.

          For example:

          YAML 
          mimir:
  structuredConfig:
    blocks_storage:
      s3:
        secret_access_key: ${AWS_SECRET_ACCESS_KEY}

    • If you are not using an external configuration (useExternalConfig: false), and your Mimir configuration does not contain secrets, then the storage location is automatically changed by Helm and you do not need to do anything.

    See Example migrated values file.

  3. Update your memcached configuration via your customized Helm chart values, if needed:

    The mimir-distributed Helm chart supports multiple cache types. If you have not enabled any memcached caches, and you are not overriding the values of memcached, memcached-queries, memcached-metadata, or memcached-results sections, then you do not need to update the memcached configuration.

    Otherwise, check to see if you need to change any of the following configuration parameters:

    • The memcached section was repurposed, and chunks-cache was added.
    • The contents of the memcached section now contain the following common values that are shared across all memcached instances: image, podSecurityContext, and containerSecurityContext.
    • The following sections were renamed:
      • memcached-queries is now index-cache
      • memcached-metadata is now metadata-cache
      • memcached-results is now results-cache
    • The memcached*.replicaCount values were renamed:
      • memcached.replicaCount is now chunks-cache.replicas
      • memcached-queries.replicaCount is now index-cache.replicas
      • memcached-metadata.replicaCount is now metadata-cache.replicas
      • memcached-results.replicaCount is now results-cache.replicas
    • The memcached*.architecture values were removed.
    • The memcached*.arguments values were removed.
    • The default arguments are now encoded in the Helm chart templates; the values *-cache.allocatedMemory, *-cache.maxItemMemory and *-cache.port control the arguments -m, -I and -u. To provide additional arguments, use *-cache.extraArgs.
    • The memcached*.metrics values were consolidated under memcachedExporter.

    See also an example of migration of customized memcached values between versions 2.x and 3.0.

  4. Update your memcached-related Mimir configuration via your customized Helm chart value that is named mimir.config, if needed:

    The configuration parameters for memcached addresses and max_item_size have changed in the default mimir.config value. If you previously copied the value of mimir.config into your values file, then take the latest version of the memcached configuration in the mimir.config from the values.yaml file in the Helm chart.

  5. (Conditional) If you have enabled serviceMonitor, or you are overriding the value of anything under the serviceMonitor section, or both, then move the serviceMonitor section under metaMonitoring.

  6. Update the rbac section, based on the following changes:

    • If you are not overriding the value of anything under the rbac section, then skip this step.
    • The rbac.pspEnabled value was removed.
    • To continue using Pod Security Policy (PSP), set rbac.create to true and rbac.type to psp.
    • To start using Security Context Constraints (SCC) instead of PSP, set rbac.create to true and rbac.type to scc.

  7. Update the mimir.config value, based on the following information:

    • Compare your overridden value of mimir.config with the one in the values.yaml file in the chart. If you are not overriding the value of mimir.config, then skip this step.

  8. Decide whether or not to update the nginx configuration:

    • Unless you have overridden the value of nginx.nginxConfig.file, and you are using the default mimir.config, then skip this step.

    • Otherwise, compare the overridden nginx.nginxConfig.file value to the one in the values.yaml file in the Helm chart, and incorporate the differences. Pay attention to the sections that contain x_scope_orgid. The value in the values.yaml file contains Nginx configuration that adds the X-Scope-OrgId header to incoming requests that do not already set it.

      Note: This change allows Mimir clients to keep sending requests without needing to specify a tenant ID, even though multi-tenancy is now enabled by default.

Example of migrated values

The example values file is compatible with any 2.x version of the mimir-distributed Helm chart, and demonstrates a few things:

  • All memcached caches are enabled.
  • The default pod security policy is disabled.
  • ServiceMonitors are enabled.
  • Object storage credentials for block storage are specified directly in the mimir.config value.

    Note

    The unmodified parts of the default mimir.config are omitted for brevity, even though in a valid 2.x values file they need to be included.

YAML 
rbac:
  pspEnabled: false

memcached:
  enabled: true
  replicaCount: 1

memcached-queries:
  enabled: true
  replicaCount: 1

memcached-metadata:
  enabled: true
  replicaCount: 1

memcached-results:
  enabled: true
  replicaCount: 1

serviceMonitor:
  enabled: true

mimir:
  config: |-
    #######
    # default contents omitted for brevity
    #######

    blocks_storage:
      backend: s3
      s3:
        endpoint: s3.amazonaws.com
        bucket_name: my-blocks-bucket
        access_key_id: FAKEACCESSKEY
        secret_access_key: FAKESECRETKEY

    #######
    # default contents omitted for brevity
    #######

After applying the migration steps listed in this guide, you now have a Kubernetes Secret that contains the S3 credentials, and a values file for version 3.0. The values file is does not have any omissions. The parts that were omitted in the 2.x version are automatically included by the Helm chart in version 3.0.

Kubernetes Secret:

YAML 
apiVersion: v1
kind: Secret
metadata:
  name: mimir-bucket-secret
data:
  AWS_ACCESS_KEY_ID: FAKEACCESSKEY
  AWS_SECRET_ACCESS_KEY: FAKESECRETKEY

Values file:

YAML 
rbac:
  create: false

chunks-cache:
  enabled: true
  replicas: 1

index-cache:
  enabled: true
  replicas: 1

metadata-cache:
  enabled: true
  replicas: 1

results-cache:
  enabled: true
  replicas: 1

metaMonitoring:
  serviceMonitor:
    enabled: true

mimir:
  structuredConfig:
    blocks_storage:
      backend: s3
      s3:
        access_key_id: ${AWS_ACCESS_KEY_ID}
        bucket_name: my-blocks-bucket
        endpoint: s3.amazonaws.com
        secret_access_key: ${AWS_SECRET_ACCESS_KEY}

global:
  extraEnvFrom:
    - secretRef:
        name: mimir-bucket-secret

Example of migration of customized memcached values between versions 2.x and 3.0

Version 2.1:

YAML 
memcached:
  replicaCount: 12
  arguments:
    - -m 2048
    - -I 128m
    - -u 12345
  image:
    repository: memcached
    tag: 1.6.9-alpine

memcached-queries:
  replicaCount: 3
  architecture: modern
  image:
    repository: memcached
    tag: 1.6.9-alpine

Version 3.0:

YAML 
memcached:
  image:
    repository: memcached
    tag: 1.6.9-alpine

chunks-cache:
  allocatedMemory: 2048
  maxItemMemory: 128
  port: 12345
  replicas: 12

index-cache:
  replicas: 3