74 lines
3.1 KiB
Markdown
74 lines
3.1 KiB
Markdown
---
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layout: "docs"
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page_title: "Commands: Exec"
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sidebar_current: "docs-commands-exec"
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description: |-
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The exec command provides a mechanism for remote execution. For example, this can be used to run the `uptime` command across all machines providing the `web` service.
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---
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# Consul Exec
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Command: `consul exec`
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The `exec` command provides a mechanism for remote execution. For example,
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this can be used to run the `uptime` command across all machines providing
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the `web` service.
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Remote execution works by specifying a job, which is stored in the KV store.
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Agents are informed about the new job using the [event system](/docs/commands/event.html),
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which propagates messages via the [gossip protocol](/docs/internals/gossip.html).
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As a result, delivery is best-effort, and there is **no guarantee** of execution.
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While events are purely gossip driven, remote execution relies on the KV store
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as a message broker. As a result, the `exec` command will not be able to
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properly function during a Consul outage.
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**Verbose output warning:** use care to make sure that your command does not
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produce a large volume of output. Writes to the KV store for this output go
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through the Consul servers and the Raft consensus algorithm, so having a large
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number of nodes in the cluster flow a large amount of data through the KV store
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could make the cluster unavailable.
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## Usage
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Usage: `consul exec [options] [-|command...]`
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The only required option is a command to execute. This is either given
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as trailing arguments, or by specifying '-'; stdin will be read to
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completion as a script to evaluate.
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The list of available flags are:
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* `-http-addr` - Address to the HTTP server of the agent you want to contact
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to send this command. If this isn't specified, the command will contact
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"127.0.0.1:8500" which is the default HTTP address of a Consul agent.
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* `-datacenter` - Datacenter to query. Defaults to that of agent. In version
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0.4, that is the only supported value.
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* `-prefix` - Key prefix in the KV store to use for storing request data.
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Defaults to "_rexec".
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* `-node` - Regular expression to filter nodes which should evaluate the event.
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* `-service` - Regular expression to filter to only nodes with matching services.
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* `-tag` - Regular expression to filter to only nodes with a service that has
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a matching tag. This must be used with `-service`. As an example, you may
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do "-service mysql -tag slave".
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* `-wait` - Specifies the period of time in which no agent's respond before considering
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the job finished. This is basically the quiescent time required to assume completion.
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This period is not a hard deadline, and the command will wait longer depending on
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various heuristics.
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* `-wait-repl` - Period to wait after writing the job specification for replication.
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This is a heuristic value and enables agents to do a stale read of the job. Defaults
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to 200msec.
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* `-verbose` - Enables verbose output.
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* `-token` - The ACL token to use during requests. This token must have access
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to the prefix in the KV store as well as exec "write" access for the _rexec
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event. Defaults to that of the agent.
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