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Attaché

A sidecar that allows for effortless scaling of Redis Clusters using Hashicorp Nomad and Consul.

Features

  • Create a new cluster when no cluster is present
  • Add new primary node and perform a shard slot rebalance
  • Add new replica node to the primary node with the least replicas
  • Full support for Redis mTLS and ACL Auth
  • Full support for Consul mTLS and ACL Tokens

To Do

  • Redis ACL
  • Redis Password
  • Redis mTLS
  • Drain, failover, and FORGET an existing primary node
  • Remove and FORGET an existing replica node

attache-check

A sidecar that servers an HTTP API that allows Consul to track the health of Redis Cluster Nodes, route new nodes to the Await (introduction) Consul Service for their Redis Cluster, then migrate them to the Destination Consul Service once they've joined a cluster.

Usage

$ attache-check -help
Usage of attache-check:
  -check-serv-addr string
    	address this utility should listen on (e.g. 127.0.0.1:8080)
  -redis-auth-password-file string
    	redis-server password file path, (required)
  -redis-auth-username string
    	redis-server username, (required)
  -redis-node-addr string
    	redis-server listening address, (required)
  -redis-tls-ca-cert string
    	Redis client CA certificate file, (required)
  -redis-tls-cert-file string
    	Redis client certificate file, (required)
  -redis-tls-key-file string
    	Redis client key file, (required)
  -shutdown-grace duration
    	duration to wait before shutting down (e.g. '1s') (default 5s)

attache-control

An ephemeral sidecar that acts as an agent for each Redis node when it's started. If a node's node info reflects that of a new node, this agent will attempt to introduce it to an existing Redis Cluster, if it exists, else it will attempt to orchestrate the create a new Redis Cluster if there are enough new Redis nodes (in the Await Consul Service) to do so.

Usage

$ ./attache-control -help
Usage of ./attache-control:
  -attempt-interval duration
    	Duration to wait between attempts to join or create a cluster (e.g. '1s') (default 3s)
  -await-service-name string
    	Consul Service for newly created Redis Cluster Nodes, (required)
  -consul-acl-token string
    	Consul client ACL token
  -consul-addr string
    	Consul client address (default "127.0.0.1:8501")
  -consul-dc string
    	Consul client datacenter (default "dev-general")
  -consul-tls-ca-cert string, (required)
    	Consul client CA certificate file
  -consul-tls-cert string, (required)
    	Consul client certificate file
  -consul-tls-key string, (required)
    	Consul client key file
  -dest-service-name string
    	Consul Service for healthy Redis Cluster Nodes, (required)
  -lock-kv-path string
    	Consul KV path to use as a leader lock for Redis Cluster operations (default "service/attache/leader")
  -log-level string
    	Set the log level (default "info")
  -redis-auth-password-file string
    	Redis password file path, (required)
  -redis-auth-username string
    	Redis username, (required)
  -redis-node-addr string
    	redis-server listening address, (required)
  -redis-tls-ca-cert string
    	Redis client CA certificate file, (required)
  -redis-tls-cert-file string
    	Redis client certificate file, (required)
  -redis-tls-key-file string
    	Redis client key file, (required)

Running the Example Nomad Job

Note: these steps assume that you have the nomad, consul, and terraform binaries installed on your machine and that they exist in your PATH.

Build the attache-control and attache-check binaries:

$ go build -o attache-check ./cmd/attache-check/main.go && go build -o attache-control ./cmd/attache-control/main.go ./cmd/attache-control/config.go

In another shell, start the Consul server in dev mode:

$ consul agent -dev -config-format=hcl -config-file consul.conf.hcl

In another shell, start the Nomad server in dev mode:

$ sudo nomad agent -dev -config nomad.conf.hcl

Start a Nomad job deployment using Terraform:

cd example
terraform init
terraform plan
terraform apply

Open the Nomad UI: http://localhost:4646/ui to view information about the Redis Cluster deployment

Open the Consul UI: http://localhost:8501/ui to view health check information for the Redis Cluster

Useful Commands

Purge Nomad Job

This is useful for stopping and garbage collecting a job in Nomad immediately.

nomad job stop -purge "<jobname>"

Count Primary Redis Nodes

redis-cli -p <tls-port> --tls --cert ./example/tls/redis/cert.pem --key ./example/tls/redis/key.pem --cacert ./example/tls/ca-cert.pem --user replication-user --pass <redis-password> cluster nodes | grep master | wc -l

Count Replica Redis Nodes

redis-cli -p <tls-port> --tls --cert ./example/tls/redis/cert.pem --key ./example/tls/redis/key.pem --cacert ./example/tls/ca-cert.pem --user replication-user --pass <redis-password> cluster nodes | grep slave | wc -l

Create New Consul CA-Cert and Key

consul tls ca create

Create and Sign New Consul Server Cert and Key

In the same directory as the CA Cert:

consul tls cert create -client -dc "dev-general"

Create and Sign New Consul Client Cert and Key

In the same directory as the CA Cert:

consul tls cert create -server -dc "dev-general"