compose-anything/src/etcd

etcd

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This service deploys etcd, a distributed, reliable key-value store for the most critical data of a distributed system.

Services

• etcd: The etcd key-value store service.

Environment Variables

Variable Name	Description	Default Value
ETCD_VERSION	etcd image version	v3.6.0
ETCD_CLIENT_PORT_OVERRIDE	Host port mapping for client connections (2379)	2379
ETCD_PEER_PORT_OVERRIDE	Host port mapping for peer connections (2380)	2380
ETCD_NAME	Human-readable name for this etcd member	etcd-node
ETCD_INITIAL_CLUSTER	Initial cluster configuration	etcd-node=http://localhost:2380
ETCD_INITIAL_CLUSTER_STATE	Initial cluster state ('new' or 'existing')	new
ETCD_INITIAL_CLUSTER_TOKEN	Initial cluster token for bootstrap	etcd-cluster
ETCD_AUTO_COMPACTION_RETENTION	Auto compaction retention in hours	1
ETCD_QUOTA_BACKEND_BYTES	Storage size limit in bytes	2147483648 (2GB)
ETCD_HEARTBEAT_INTERVAL	Heartbeat interval in milliseconds	100
ETCD_ELECTION_TIMEOUT	Election timeout in milliseconds	1000
ETCD_ENABLE_V2	Enable etcd v2 API	false

Please modify the .env file as needed for your use case.

Volumes

• etcd_data: A volume for storing etcd data persistently.

Network Ports

• 2379: Client communication port
• 2380: Peer communication port (for clustering)

Single Node Setup

The default configuration runs etcd as a single node, suitable for development and testing.

Cluster Setup

To set up a multi-node etcd cluster, you need to:

1. Define multiple etcd services in your compose file
2. Configure the ETCD_INITIAL_CLUSTER variable properly
3. Set unique names for each node

Example for a 3-node cluster:

services:
  etcd1:
    # ... base config
    environment:
      - ETCD_NAME=etcd1
      - ETCD_INITIAL_CLUSTER=etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380
      - ETCD_ADVERTISE_CLIENT_URLS=http://etcd1:2379
      - ETCD_INITIAL_ADVERTISE_PEER_URLS=http://etcd1:2380

  etcd2:
    # ... base config
    environment:
      - ETCD_NAME=etcd2
      - ETCD_INITIAL_CLUSTER=etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380
      - ETCD_ADVERTISE_CLIENT_URLS=http://etcd2:2379
      - ETCD_INITIAL_ADVERTISE_PEER_URLS=http://etcd2:2380

  etcd3:
    # ... base config
    environment:
      - ETCD_NAME=etcd3
      - ETCD_INITIAL_CLUSTER=etcd1=http://etcd1:2380,etcd2=http://etcd2:2380,etcd3=http://etcd3:2380
      - ETCD_ADVERTISE_CLIENT_URLS=http://etcd3:2379
      - ETCD_INITIAL_ADVERTISE_PEER_URLS=http://etcd3:2380

Client Access

Using etcdctl

Connect to etcd using the etcdctl client:

# Set endpoint
export ETCDCTL_ENDPOINTS=http://localhost:2379

# Put a key-value pair
etcdctl put mykey myvalue

# Get a value
etcdctl get mykey

# List all keys
etcdctl get --prefix ""

Using HTTP API

etcd provides a RESTful HTTP API:

# Put a key-value pair
curl -X PUT http://localhost:2379/v3/kv/put \
  -H 'Content-Type: application/json' \
  -d '{"key":"bXlrZXk=","value":"bXl2YWx1ZQ=="}'

# Get a value
curl -X POST http://localhost:2379/v3/kv/range \
  -H 'Content-Type: application/json' \
  -d '{"key":"bXlrZXk="}'

Performance Tuning

• Adjust ETCD_QUOTA_BACKEND_BYTES based on your storage needs
• Tune ETCD_HEARTBEAT_INTERVAL and ETCD_ELECTION_TIMEOUT for your network latency
• Configure ETCD_AUTO_COMPACTION_RETENTION to manage data size

Security Notes

• The default configuration is for development/testing only
• For production, enable TLS encryption and authentication
• Consider network security and firewall rules
• Regular backups are recommended

Monitoring

etcd exposes metrics at http://localhost:2379/metrics in Prometheus format.

License

etcd is licensed under the Apache 2.0 license.