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nuvo/cain

By nuvo

•Updated over 2 years ago

Backup and restore tool for Cassandra on Kubernetes

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nuvo/cain repository overview

ReleaseTravis branch

⁠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

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/nuvo && cd $_
git clone https://github.com/nuvo/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:
  -a, --authentication                     use authentication for nodetool and clqsh. Overrides $CAIN_AUTHENTICATION
  -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")
  -u, --cassandra-username string          cassandra username. Overrides $CAIN_CASSANDRA_USERNAME (default "cain")
  -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
  -h, --help                               help for backup
  -k, --keyspace string                    keyspace to act on. Overrides $CAIN_KEYSPACE
  -n, --namespace string                   namespace to find cassandra cluster. Overrides $CAIN_NAMESPACE (default "default")
      --nodetool-credentials-file string   path to nodetool credentials file. Overrides $CAIN_NODETOOL_CREDENTIALS_FILE (default "/home/cassandra/.nodetool/credentials")
  -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
⁠Examples

Backup to AWS S3

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

Backup to AWS S3 with Cassandra authentication enabled

cain backup \
    -n default \
    -l release=cassandra \
    -k keyspace \
    --dst s3://db-backup/cassandra
    -a
    -u cain
    --nodetool-credentials-file /home/cassandra/.nodetool/credentials

Backup to Azure Blob Storage

cain backup \
    -n default \
    -l release=cassandra \
    -k keyspace \
    --dst abs://my-account/db-backup-container/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:
  -a, --authentication                     use authentication for nodetool and clqsh. Overrides $CAIN_AUTHENTICATION
  -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")
  -u, --cassandra-username string          cassandra username. Overrides $CAIN_CASSANDRA_USERNAME (default "cain")
  -c, --container string                   container name to act on. Overrides $CAIN_CONTAINER (default "cassandra")
  -h, --help                               help for restore
  -k, --keyspace string                    keyspace to act on. Overrides $CAIN_KEYSPACE
  -n, --namespace string                   namespace to find cassandra cluster. Overrides $CAIN_NAMESPACE (default "default")
  -f, --nodetool-credentials-file string   path to nodetool credentials file. Overrides $CAIN_NODETOOL_CREDENTIALS_FILE (default "/home/cassandra/.nodetool/credentials")
  -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
⁠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
0.5.20.4.2
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 - skbn will use the current context from that config file
  2. if ~/.kube/config exists - skbn will use the current context from that config file with an out-of-cluster client configuration⁠
  3. if ~/.kube/config does not exist - skbn will assume it is working from inside a pod and will use an in-cluster client configuration⁠
⁠AWS

Skbn uses the default AWS credentials chain⁠.

⁠Azure Blob Storage

Skbn uses AZURE_STORAGE_ACCOUNT and AZURE_STORAGE_ACCESS_KEY environment variables for authentication.

⁠Cassandra Credentials

When Authentication is enabled Cain will look for default credentials
for cqlsh in /home/cassandra/.cassandra/credentials
if you use authentication please make sure the cassandra
container has this file and the username and password are correct.

For nodetool authentications default credentials are in:
/home/cassandra/.nodetool/credentials can be overridden by
setting the --nodetool-credentials-file flag.
When this flag is used, the username for the nodetool
authentication must be provided as well .

⁠Examples

  1. Helm example⁠
  2. Code example⁠

Tag summary

Content type

Image

Digest

Size

17.2 MB

Last updated

almost 6 years ago

docker pull nuvo/cain