mirror of https://github.com/hashicorp/consul
208 lines
10 KiB
Markdown
208 lines
10 KiB
Markdown
---
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layout: "docs"
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page_title: "Configuration"
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sidebar_current: "docs-agent-config"
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---
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# Configuration
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The agent has various configuration options that can be specified via
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the command-line or via configuration files. All of the configuration
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options are completely optional and their defaults will be specified
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with their descriptions.
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When loading configuration, Consul loads the configuration from files
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and directories in the order specified. Configuration specified later
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will be merged into configuration specified earlier. In most cases,
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"merge" means that the later version will override the earlier. But in
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some cases, such as event handlers, merging just appends the handlers.
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The exact merging behavior will be specified.
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Consul also supports reloading of configuration when it receives the
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SIGHUP signal. Not all changes are respected, but those that are
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are documented below.
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## Command-line Options
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The options below are all specified on the command-line.
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* `-serf-bind` - The address that the underlying Serf library will bind to.
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This is an IP address that should be reachable by all other nodes in the cluster.
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By default this is "0.0.0.0", meaning Consul will use the first available private
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IP address. Consul uses both TCP and UDP and use the same port for both, so if you
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have any firewalls be sure to allow both protocols.
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* `-server-addr` - The address that the agent will bind to for handling RPC calls
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if running in server mode. This does not affect clients running in client mode.
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By default this is "0.0.0.0:8300". This port is used for TCP communications so any
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firewalls must be configured to allow this.
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* `-advertise` - The advertise flag is used to change the address that we
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advertise to other nodes in the cluster. By default, the `-serf-bind` address is
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advertised. However, in some cases (specifically NAT traversal), there may
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be a routable address that cannot be bound to. This flag enables gossiping
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a different address to support this. If this address is not routable, the node
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will be in a constant flapping state, as other nodes will treat the non-routability
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as a failure.
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* `-config-file` - A configuration file to load. For more information on
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the format of this file, read the "Configuration Files" section below.
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This option can be specified multiple times to load multiple configuration
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files. If it is specified multiple times, configuration files loaded later
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will merge with configuration files loaded earlier, with the later values
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overriding the earlier values.
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* `-config-dir` - A directory of configuration files to load. Consul will
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load all files in this directory ending in ".json" as configuration files
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in alphabetical order. For more information on the format of the configuration
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files, see the "Configuration Files" section below.
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* `-encrypt` - Specifies the secret key to use for encryption of Consul
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network traffic. This key must be 16-bytes that are base64 encoded. The
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easiest way to create an encryption key is to use `consul keygen`. All
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nodes within a cluster must share the same encryption key to communicate.
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* `-log-level` - The level of logging to show after the Consul agent has
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started. This defaults to "info". The available log levels are "trace",
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"debug", "info", "warn", "err". This is the log level that will be shown
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for the agent output, but note you can always connect via `consul monitor`
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to an agent at any log level. The log level can be changed during a
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config reload.
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* `-node` - The name of this node in the cluster. This must be unique within
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the cluster. By default this is the hostname of the machine.
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* `-rpc-addr` - The address that Consul will bind to for the agent's RPC server.
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By default this is "127.0.0.1:8400", allowing only loopback connections.
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The RPC address is used by other Consul commands, such as `consul members`,
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in order to query a running Consul agent. It is also used by other applications
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to control Consul using it's [RPC protocol](/docs/agent/rpc.html).
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* `-data-dir` - This flag provides a data directory for the agent to store state.
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This is required for all agents. The directory should be durable across reboots.
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This is especially critical for agents that are running in server mode, as they
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must be able to persist the cluster state.
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* `-dc` - This flag controls the datacenter the agent is running in. If not provided
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it defaults to "dc1". Consul has first class support for multiple data centers but
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it relies on proper configuration. Nodes in the same datacenter should be on a single
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LAN.
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* `-recursor` - This flag provides an address of an upstream DNS server that is used to
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recursively resolve queries if they are not inside the service domain for consul. For example,
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a node can use Consul directly as a DNS server, and if the record is outside of the "consul." domain,
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the query will be resolved upstream using this server.
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* `-http-addr` - This flag controls the address the agent listens on for HTTP requests.
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By default it is bound to "127.0.0.1:8500". This port must allow for TCP traffic.
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* `-dns-addr` - This flag controls the address the agent listens on for DNS requests.
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By default it is bound to "127.0.0.1:8600". This port must allow for UDP and TCP traffic.
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* `-server` - This flag is used to control if an agent is in server or client mode. When provided,
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an agent will act as a Consul server. Each Consul cluster must have at least one server, and ideally
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no more than 5 *per* datacenter. All servers participate in the Raft consensus algorithm, to ensure that
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transactions occur in a consistent, linearlizable manner. Transactions modify cluster state, which
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is maintained on all server nodes to ensure availability in the case of node failure. Server nodes also
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participate in a WAN gossip pool with server nodes in other datacenters. Servers act as gateways
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to other datacenters and forward traffic as appropriate.
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* `-bootstrap` - This flag is used to control if a server is in "bootstrap" mode. It is important that
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no more than one server *per* datacenter be running in this mode. The initial server **must** be in bootstrap
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mode. Technically, a server in boostrap mode is allowed to self-elect as the Raft leader. It is important
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that only a single node is in this mode, because otherwise consistency cannot be guarenteed if multiple
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nodes are able to self-elect. Once there are multiple servers in a datacenter, it is generally a good idea
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to disable bootstrap mode on all of them.
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* `-statsite` - This flag provides the address of a statsite instance. If provided Consul will stream
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various telemetry information to that instance for aggregation. This can be used to capture various
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runtime information.
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* `-protocol` - The Consul protocol version to use. This defaults to the latest
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version. This should be set only when [upgrading](/docs/upgrading.html).
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You can view the protocol versions supported by Consul by running `serf -v`.
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## Configuration Files
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In addition to the command-line options, configuration can be put into
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files. This may be easier in certain situations, for example when Consul is
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being configured using a configuration management system.
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The configuration files are JSON formatted, making them easily readable
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and editable by both humans and computers. The configuration is formatted
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at a single JSON object with configuration within it.
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Configuration files are used for more than just setting up the agent,
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they are also used to provide check and service definitions. These are used
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to announce the availability of system servers to the rest of the cluster.
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They are documented seperately under [check configuration](/docs/agent/checks.html) and
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[service configuration](/docs/agent/services.html) respectively. The service and check
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definitions support being updated during a reload.
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#### Example Configuration File
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<pre class="prettyprint lang-json">
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{
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"datacenter": "east-aws",
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"data_dir": "/opt/consul",
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"log_level": "INFO",
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"node_name": "foobar",
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"server": true
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}
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</pre>
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#### Configuration Key Reference
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* `bootstrap` - Equivalent to the `-bootstrap` command-line flag.
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* `datacenter` - Equivalent to the `-dc` command-line flag.
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* `data_dir` - Equivalent to the `-data-dir` command-line flag.
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* `dns_addr` - Equivalent to the `-dns-addr` command-line flag.
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* `recursor` - Equivalent to the `-recursor` command-line flag.
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* `domain` - By default, Consul responds to DNS queries in the "consul." domain.
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This flag can be used to change that domain. All queries in this domain are assumed
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to be handled by Consul, and will not be recursively resolved.
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* `encrypt` - Equivalent to the `-encrypt` command-line flag.
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* `http_addr` - Equivalent to the `-http-addr` command-line flag.
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* `log_level` - Equivalent to the `-log-level` command-line flag.
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* `node_name` - Equivalent to the `-node` command-line flag.
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* `rpc_addr` - Equivalent to the `-rpc-addr` command-line flag.
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* `serf_bind_addr` - Equivalent to the `-serf-bind` command-line flag.
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* `serf_lan_port` - This configures which port Serf listens on to communicate
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with nodes on the local LAN. By default this is 8301. All nodes in the datacenter
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should be able to reach this port over TCP and UDP.
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* `serf_wan_port` - This configures which port Serf listens on to communicate
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with nodes on the remote WAN. By default this is 8302. All nodes in the WAN gossip
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pool should be able to reach this port over TCP and UDP. This only applies to
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agents running in server mode.
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* `server_addr` - Equivalent to the `-server-addr` command-line flag.
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* `advertise_addr` - Equivalent to the `-advertise` command-line flag.
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* `server` - Equivalent to the `-server` command-line flag.
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* `leave_on_terminate` - If enabled, when the agent receives a TERM signal,
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it will send a Leave message to the rest of the cluster and gracefully
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leave. Defaults to false.
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* `skip_leave_on_interrupt` - This is the similar to`leave_on_terminate` but
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only affects interrupt handling. By default, an interrupt causes Consul to
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gracefully leave, but setting this to true disables that. Defaults to false.
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Interrupts are usually from a Control-C from a shell.
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* `statsite_addr` - Equivalent to the `-statsite` command-line flag.
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