Configuration flags

etcd is configurable through a configuration file, various command-line flags, and environment variables.

A reusable configuration file is a YAML file made with name and value of one or more command-line flags described below. In order to use this file, specify the file path as a value to the --config-file flag or ETCD_CONFIG_FILE environment variable. The sample configuration file can be used as a starting point to create a new configuration file as needed.

Options set on the command line take precedence over those from the environment. If a configuration file is provided, other command line flags and environment variables will be ignored.
For example, etcd --config-file etcd.conf.yml.sample --data-dir /tmp will ignore the --data-dir flag.

The format of environment variable for flag --my-flag is ETCD_MY_FLAG. It applies to all flags.

The official etcd ports are 2379 for client requests and 2380 for peer communication. The etcd ports can be set to accept TLS traffic, non-TLS traffic, or both TLS and non-TLS traffic.

To start etcd automatically using custom settings at startup in Linux, using a systemd unit is highly recommended.

Member flags

--name

Human-readable name for this member.
default: "default"
env variable: ETCD_NAME
This value is referenced as this node's own entries listed in the --initial-cluster flag (e.g., default=http://localhost:2380). This needs to match the key used in the flag if using static bootstrapping. When using discovery, each member must have a unique name. Hostname or machine-id can be a good choice.

--data-dir

Path to the data directory.
default: "${name}.etcd"
env variable: ETCD_DATA_DIR

--wal-dir

Path to the dedicated wal directory. If this flag is set, etcd will write the WAL files to the walDir rather than the dataDir. This allows a dedicated disk to be used, and helps avoid io competition between logging and other IO operations.
default: ""
env variable: ETCD_WAL_DIR

--snapshot-count

Number of committed transactions to trigger a snapshot to disk.
default: "100000"
env variable: ETCD_SNAPSHOT_COUNT

--heartbeat-interval

Time (in milliseconds) of a heartbeat interval.
default: "100"
env variable: ETCD_HEARTBEAT_INTERVAL

--election-timeout

Time (in milliseconds) for an election to timeout. See Documentation/tuning.md for details.
default: "1000"
env variable: ETCD_ELECTION_TIMEOUT

--listen-peer-urls

List of URLs to listen on for peer traffic. This flag tells the etcd to accept incoming requests from its peers on the specified scheme://IP:port combinations. Scheme can be http or https. Alternatively, use unix://<file-path> or unixs://<file-path> for unix sockets. If 0.0.0.0 is specified as the IP, etcd listens to the given port on all interfaces. If an IP address is given as well as a port, etcd will listen on the given port and interface. Multiple URLs may be used to specify a number of addresses and ports to listen on. The etcd will respond to requests from any of the listed addresses and ports.
default: "http://localhost:2380"
env variable: ETCD_LISTEN_PEER_URLS
example: "http://10.0.0.1:2380"
invalid example: "http://example.com:2380" (domain name is invalid for binding)

--listen-client-urls

List of URLs to listen on for client traffic. This flag tells the etcd to accept incoming requests from the clients on the specified scheme://IP:port combinations. Scheme can be either http or https. Alternatively, use unix://<file-path> or unixs://<file-path> for unix sockets. If 0.0.0.0 is specified as the IP, etcd listens to the given port on all interfaces. If an IP address is given as well as a port, etcd will listen on the given port and interface. Multiple URLs may be used to specify a number of addresses and ports to listen on. The etcd will respond to requests from any of the listed addresses and ports.
default: "http://localhost:2379"
env variable: ETCD_LISTEN_CLIENT_URLS
example: "http://10.0.0.1:2379"
invalid example: "http://example.com:2379" (domain name is invalid for binding)

--max-snapshots

Maximum number of snapshot files to retain (0 is unlimited)
default: 5
env variable: ETCD_MAX_SNAPSHOTS
The default for users on Windows is unlimited, and manual purging down to 5 (or some preference for safety) is recommended.

--max-wals

Maximum number of wal files to retain (0 is unlimited)
default: 5
env variable: ETCD_MAX_WALS
The default for users on Windows is unlimited, and manual purging down to 5 (or some preference for safety) is recommended.

--cors

Comma-separated white list of origins for CORS (cross-origin resource sharing).
default: ""
env variable: ETCD_CORS

--quota-backend-bytes

Raise alarms when backend size exceeds the given quota (0 defaults to low space quota).
default: 0
env variable: ETCD_QUOTA_BACKEND_BYTES

--backend-batch-limit

BackendBatchLimit is the maximum operations before commit the backend transaction.
default: 0
env variable: ETCD_BACKEND_BATCH_LIMIT

--backend-batch-interval

BackendBatchInterval is the maximum time before commit the backend transaction.
default: 0
env variable: ETCD_BACKEND_BATCH_INTERVAL

--max-txn-ops

Maximum number of operations permitted in a transaction.
default: 128
env variable: ETCD_MAX_TXN_OPS

--max-request-bytes

Maximum client request size in bytes the server will accept.
default: 1572864
env variable: ETCD_MAX_REQUEST_BYTES

--grpc-keepalive-min-time

Minimum duration interval that a client should wait before pinging server.
default: 5s
env variable: ETCD_GRPC_KEEPALIVE_MIN_TIME

--grpc-keepalive-interval

Frequency duration of server-to-client ping to check if a connection is alive (0 to disable).
default: 2h
env variable: ETCD_GRPC_KEEPALIVE_INTERVAL

--grpc-keepalive-timeout

Additional duration of wait before closing a non-responsive connection (0 to disable).
default: 20s
env variable: ETCD_GRPC_KEEPALIVE_TIMEOUT

Clustering flags

--initial-advertise-peer-urls, --initial-cluster, --initial-cluster-state, and --initial-cluster-token flags are used in bootstrapping (static bootstrap, discovery-service bootstrap or runtime reconfiguration) a new member, and ignored when restarting an existing member.

--discovery prefix flags need to be set when using discovery service.

--initial-advertise-peer-urls

List of this member's peer URLs to advertise to the rest of the cluster. These addresses are used for communicating etcd data around the cluster. At least one must be routable to all cluster members. These URLs can contain domain names.
default: "http://localhost:2380"
env variable: ETCD_INITIAL_ADVERTISE_PEER_URLS
example: "http://example.com:2380, http://10.0.0.1:2380"

--initial-cluster

Initial cluster configuration for bootstrapping.
default: "default=http://localhost:2380"
env variable: ETCD_INITIAL_CLUSTER
The key is the value of the --name flag for each node provided. The default uses default for the key because this is the default for the --name flag.

--initial-cluster-state

Initial cluster state ("new" or "existing"). Set to new for all members present during initial static or DNS bootstrapping. If this option is set to existing, etcd will attempt to join the existing cluster. If the wrong value is set, etcd will attempt to start but fail safely.
default: "new"
env variable: ETCD_INITIAL_CLUSTER_STATE

--initial-cluster-token

Initial cluster token for the etcd cluster during bootstrap.
default: "etcd-cluster"
env variable: ETCD_INITIAL_CLUSTER_TOKEN

--advertise-client-urls

List of this member's client URLs to advertise to the rest of the cluster. These URLs can contain domain names.
default: "http://localhost:2379"
env variable: ETCD_ADVERTISE_CLIENT_URLS
example: "http://example.com:2379, http://10.0.0.1:2379"
Be careful if advertising URLs such as http://localhost:2379 from a cluster member and are using the proxy feature of etcd. This will cause loops, because the proxy will be forwarding requests to itself until its resources (memory, file descriptors) are eventually depleted.

--discovery

Discovery URL used to bootstrap the cluster.
default: ""
env variable: ETCD_DISCOVERY

--discovery-srv

DNS srv domain used to bootstrap the cluster.
default: ""
env variable: ETCD_DISCOVERY_SRV

--discovery-srv-name

Suffix to the DNS srv name queried when bootstrapping using DNS.
default: ""
env variable: ETCD_DISCOVERY_SRV_NAME

--discovery-fallback

Expected behavior ("exit" or "proxy") when discovery services fails. "proxy" supports v2 API only.
default: "proxy"
env variable: ETCD_DISCOVERY_FALLBACK

--discovery-proxy

HTTP proxy to use for traffic to discovery service.
default: ""
env variable: ETCD_DISCOVERY_PROXY

--strict-reconfig-check

Reject reconfiguration requests that would cause quorum loss.
default: true
env variable: ETCD_STRICT_RECONFIG_CHECK

--auto-compaction-retention

Auto compaction retention for mvcc key value store in hour. 0 means disable auto compaction.
default: 0
env variable: ETCD_AUTO_COMPACTION_RETENTION

--auto-compaction-mode

Interpret 'auto-compaction-retention' one of: 'periodic', 'revision'. 'periodic' for duration based retention, defaulting to hours if no time unit is provided (e.g. '5m'). 'revision' for revision number based retention.
default: periodic
env variable: ETCD_AUTO_COMPACTION_MODE

--enable-v2

Accept etcd V2 client requests
default: false
env variable: ETCD_ENABLE_V2

Proxy flags

--proxy prefix flags configures etcd to run in proxy mode. "proxy" supports v2 API only.

--proxy

Proxy mode setting ("off", "readonly" or "on").
default: "off"
env variable: ETCD_PROXY

--proxy-failure-wait

Time (in milliseconds) an endpoint will be held in a failed state before being reconsidered for proxied requests.
default: 5000
env variable: ETCD_PROXY_FAILURE_WAIT

--proxy-refresh-interval

Time (in milliseconds) of the endpoints refresh interval.
default: 30000
env variable: ETCD_PROXY_REFRESH_INTERVAL

--proxy-dial-timeout

Time (in milliseconds) for a dial to timeout or 0 to disable the timeout
default: 1000
env variable: ETCD_PROXY_DIAL_TIMEOUT

--proxy-write-timeout

Time (in milliseconds) for a write to timeout or 0 to disable the timeout.
default: 5000
env variable: ETCD_PROXY_WRITE_TIMEOUT

--proxy-read-timeout

Time (in milliseconds) for a read to timeout or 0 to disable the timeout.
Don't change this value if using watches because use long polling requests.
default: 0
env variable: ETCD_PROXY_READ_TIMEOUT

Security flags

The security flags help to build a secure etcd cluster.

--ca-file

DEPRECATED

Path to the client server TLS CA file. --ca-file ca.crt could be replaced by --trusted-ca-file ca.crt --client-cert-auth and etcd will perform the same.
default: ""
env variable: ETCD_CA_FILE

--cert-file

Path to the client server TLS cert file.
default: ""
env variable: ETCD_CERT_FILE

--key-file

Path to the client server TLS key file.
default: ""
env variable: ETCD_KEY_FILE

--client-cert-auth

Enable client cert authentication.
default: false
env variable: ETCD_CLIENT_CERT_AUTH
CN authentication is not supported by gRPC-gateway.

--client-crl-file

Path to the client certificate revocation list file.
default: ""
env variable: ETCD_CLIENT_CRL_FILE

--client-cert-allowed-hostname

Allowed Allowed TLS name for client cert authentication.
default: ""
env variable: ETCD_CLIENT_CERT_ALLOWED_HOSTNAME

--trusted-ca-file

Path to the client server TLS trusted CA cert file.
default: ""
env variable: ETCD_TRUSTED_CA_FILE

--auto-tls

Client TLS using generated certificates
default: false
env variable: ETCD_AUTO_TLS

--peer-ca-file

DEPRECATED

Path to the peer server TLS CA file. --peer-ca-file ca.crt could be replaced by --peer-trusted-ca-file ca.crt --peer-client-cert-auth and etcd will perform the same.
default: ""
env variable: ETCD_PEER_CA_FILE

--peer-cert-file

Path to the peer server TLS cert file. This is the cert for peer-to-peer traffic, used both for server and client.
default: ""
env variable: ETCD_PEER_CERT_FILE

--peer-key-file

Path to the peer server TLS key file. This is the key for peer-to-peer traffic, used both for server and client.
default: ""
env variable: ETCD_PEER_KEY_FILE

--peer-client-cert-auth

Enable peer client cert authentication.
default: false
env variable: ETCD_PEER_CLIENT_CERT_AUTH

--peer-crl-file

Path to the peer certificate revocation list file.
default: ""
env variable: ETCD_PEER_CRL_FILE

--peer-trusted-ca-file

Path to the peer server TLS trusted CA file.
default: ""
env variable: ETCD_PEER_TRUSTED_CA_FILE

--peer-auto-tls

Peer TLS using generated certificates
default: false
env variable: ETCD_PEER_AUTO_TLS

--peer-cert-allowed-cn

Allowed CommonName for inter peer authentication.
default: ""
env variable: ETCD_PEER_CERT_ALLOWED_CN

--peer-cert-allowed-hostname

Allowed TLS certificate name for inter peer authentication.
default: ""
env variable: ETCD_PEER_CERT_ALLOWED_HOSTNAME

--cipher-suites

Comma-separated list of supported TLS cipher suites between server/client and peers.
default: ""
env variable: ETCD_CIPHER_SUITES

Logging flags

--logger

Available from v3.4.
WARNING: --logger=capnslog to be deprecated in v3.5.

Specify 'zap' for structured logging or 'capnslog'.
default: capnslog
env variable: ETCD_LOGGER

--log-outputs

Specify 'stdout' or 'stderr' to skip journald logging even when running under systemd, or list of comma separated output targets.
default: default
env variable: ETCD_LOG_OUTPUTS
'default' use 'stderr' config for v3.4 during zap logger migraion

--log-level

Available from v3.4.

Configures log level. Only supports debug, info, warn, error, panic, or fatal.
default: info
env variable: ETCD_LOG_LEVEL
'default' use 'info'.

--debug

WARNING: to be deprecated in v3.5.

Drop the default log level to DEBUG for all subpackages.
default: false (INFO for all packages)
env variable: ETCD_DEBUG

--log-package-levels