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premhashmap/cain

By premhashmap

•Updated over 7 years ago

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premhashmap/cain repository overview

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⁠Cain

Cain is a backup and restore tool for Cassandra on Kubernetes. It is named after the DC Comics superhero Cassandra Cain⁠.

Cain supports the following cloud storage services:

  • AWS S3
  • Minio S3
  • Azure Blob Storage
  • Google Cloud Storage

Cain is now an official part of the Helm incubator/cassandra⁠ chart!

⁠Install

⁠Prerequisites
  1. git
  2. dep⁠
⁠From a release

Download the latest release from the Releases page⁠ or use it with a Docker image⁠

⁠From source
mkdir -p $GOPATH/src/github.com/maorfr && cd $_
git clone https://github.com/maorfr/cain.git && cd cain
make

⁠Commands

⁠Backup Cassandra cluster to cloud storage

Cain performs a backup in the following way:

  1. Backup the keyspace schema (using cqlsh).
  2. Get backup data using nodetool snapshot - it creates a snapshot of the keyspace in all Cassandra pods in the given namespace (according to selector).
  3. Copy the files in parallel to cloud storage using Skbn⁠ - it copies the files to the specified dst, under namespace/<cassandrClusterName>/keyspace/<keyspaceSchemaHash>/tag/.
  4. Clear all snapshots.
⁠Usage
$ cain backup --help
backup cassandra cluster to cloud storage

Usage:
  cain backup [flags]

Flags:
  -b, --buffer-size float           in memory buffer size (MB) to use for files copy (buffer per file). Overrides $CAIN_BUFFER_SIZE (default 6.75)
      --cassandra-data-dir string   cassandra data directory. Overrides $CAIN_CASSANDRA_DATA_DIR (default "/var/lib/cassandra/data")
  -c, --container string            container name to act on. Overrides $CAIN_CONTAINER (default "cassandra")
      --dst string                  destination to backup to. Example: s3://bucket/cassandra. Overrides $CAIN_DST
  -k, --keyspace string             keyspace to act on. Overrides $CAIN_KEYSPACE
  -n, --namespace string            namespace to find cassandra cluster. Overrides $CAIN_NAMESPACE (default "default")
  -p, --parallel int                number of files to copy in parallel. set this flag to 0 for full parallelism. Overrides $CAIN_PARALLEL (default 1)
  -l, --selector string             selector to filter on. Overrides $CAIN_SELECTOR (default "app=cassandra")
⁠Examples

Backup to AWS S3

cain backup \
    -n default \
    -l release=cassandra \
    -k keyspace \
    --dst s3://db-backup/cassandra

Backup to Azure Blob Storage

cain backup \
    -n default \
    -l release=cassandra \
    -k keyspace \
    --dst abs://my-account/db-backup-container/cassandra

Backup to Google Cloud Storage

cain backup \
    -n default \
    -l release=cassandra \
    -k keyspace \
    --dst gcs://db-backup/cassandra
⁠Restore Cassandra backup from cloud storage

Cain performs a restore in the following way:

  1. Restore schema if schema is specified.
  2. Truncate all tables in keyspace.
  3. Copy files from the specified src (under keyspace/<keyspaceSchemaHash>/tag/) - restore is only possible for the same keyspace schema.
  4. Load new data using nodetool refresh.
⁠Usage
$ cain restore --help
restore cassandra cluster from cloud storage

Usage:
  cain restore [flags]

Flags:
  -b, --buffer-size float           in memory buffer size (MB) to use for files copy (buffer per file). Overrides $CAIN_BUFFER_SIZE (default 6.75)
      --cassandra-data-dir string   cassandra data directory. Overrides $CAIN_CASSANDRA_DATA_DIR (default "/var/lib/cassandra/data")
  -c, --container string            container name to act on. Overrides $CAIN_CONTAINER (default "cassandra")
  -k, --keyspace string             keyspace to act on. Overrides $CAIN_KEYSPACE
  -n, --namespace string            namespace to find cassandra cluster. Overrides $CAIN_NAMESPACE (default "default")
  -p, --parallel int                number of files to copy in parallel. set this flag to 0 for full parallelism. Overrides $CAIN_PARALLEL (default 1)
  -s, --schema string               schema version to restore (optional). Overrides $CAIN_SCHEMA
  -l, --selector string             selector to filter on. Overrides $CAIN_SELECTOR (default "app=cassandra")
      --src string                  source to restore from. Example: s3://bucket/cassandra/namespace/cluster-name. Overrides $CAIN_SRC
  -t, --tag string                  tag to restore. Overrides $CAIN_TAG
      --user-group string           user and group who should own restored files. Overrides $CAIN_USER_GROUP (default "cassandra:cassandra")
⁠Examples

Restore from S3

cain restore \
    --src s3://db-backup/cassandra/default/ring01
    -n default \
    -k keyspace \
    -l release=cassandra \
    -t 20180903091624

Restore from Azure Blob Storage

cain restore \
    --src s3://my-account/db-backup-container/cassandra/default/ring01
    -n default \
    -k keyspace \
    -l release=cassandra \
    -t 20180903091624

Restore from Google Cloud Storage

cain restore \
    --src gcs://db-backup/cassandra/default/ring01
    -n default \
    -k keyspace \
    -l release=cassandra \
    -t 20180903091624
⁠Describe keyspace schema

Cain describes the keyspace schema using cqlsh. It can return the schema itself, or a checksum of the schema file (used by backup and restore).

⁠Usage
$ cain schema --help
get schema of cassandra cluster

Usage:
  cain schema [flags]

Flags:
  -c, --container string   container name to act on. Overrides $CAIN_CONTAINER (default "cassandra")
  -k, --keyspace string    keyspace to act on. Overrides $CAIN_KEYSPACE
  -n, --namespace string   namespace to find cassandra cluster. Overrides $CAIN_NAMESPACE (default "default")
  -l, --selector string    selector to filter on. Overrides $CAIN_SELECTOR (default "app=cassandra")
      --sum                print only checksum. Overrides $CAIN_SUM
⁠Examples
cain schema \
    -n default \
    -l release=cassandra \
    -k keyspace

cain schema \
    -n default \
    -l release=cassandra \
    -k keyspace \
    --sum

⁠Environment variables support

Cain commands support the usage of environment variables instead of flags. For example: The backup command can be executed as mentioned in the example:

cain backup \
    -n default \
    -l release=cassandra \
    -k keyspace \
    --dst s3://db-backup/cassandra

You can also set the appropriate envrionment variables (CAIN_FLAG, _ instead of -):

export CAIN_NAMESPACE=default
export CAIN_SELECTOR=release=cassandra
export CAIN_KEYSPACE=keyspace
export CAIN_DST=s3://db-backup/cassandra

cain backup

⁠Support for additional storage services

Since Cain uses Skbn⁠, adding support for additional storage services is simple. Read this post⁠ for more information.

⁠Skbn compatibility matrix

Cain versionSkbn version
0.6.00.5.0
0.5.10.4.2
0.5.00.4.1
0.4.20.4.1
0.4.10.4.1
0.4.00.4.0
0.3.00.3.0
0.2.00.2.0
0.1.00.1.1

⁠Credentials

⁠Kubernetes

Cain tries to get credentials in the following order:

  1. if KUBECONFIG environment variable is set - cain will use the current context from that config file
  2. if ~/.kube/config exists - cain will use the current context from that config file with an out-of-cluster client configuration⁠
  3. if ~/.kube/config does not exist - cain will assume it is working from inside a pod and will use an in-cluster client configuration⁠
⁠AWS

Cain uses the default AWS credentials chain⁠.

⁠Azure Blob Storage

Cain uses AZURE_STORAGE_ACCOUNT and AZURE_STORAGE_ACCESS_KEY environment variables for authentication.

⁠Google Cloud Storage

Cain uses Google Application Default Credentials⁠. Basically, it will first look for the GOOGLE_APPLICATION_CREDENTIALS environment variable. If it is not defined, it will look for the default service account, or throw an error if none is configured.

⁠Examples

  1. Helm example⁠
  2. Code example⁠

Tag summary

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Image

Digest

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19.1 MB

Last updated

over 7 years ago

docker pull premhashmap/cain