159 lines
4.3 KiB
Markdown
159 lines
4.3 KiB
Markdown
---
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layout: "docs"
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page_title: "task Stanza - Job Specification"
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sidebar_current: "docs-job-specification-task"
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description: |-
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The "task" stanza creates an individual unit of work, such as a Docker
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container, web application, or batch processing.
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---
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# `task` Stanza
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The `task` stanza creates an individual unit of work, such as a Docker
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container, web application, or batch processing.
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```hcl
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job "docs" {
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group "example" {
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task "server" {
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# ...
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}
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}
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}
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```
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## `task` Parameters
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- `artifact` <code>([Artifact][]: nil)</code> - Defines an artifact to download
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before running the task. This may be specified multiple times to download
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multiple artifacts.
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- `config` `(map<string|string>: nil)` - Specifies the driver configuration,
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which is passed directly to the driver to start the task. The details of
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configurations are specific to each driver, so please see specific driver
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documentation for more information.
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- `constraint` <code>([Constraint][]: nil)</code> - Specifies user-defined
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constraints on the task. This can be provided multiple times to define
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additional constraints.
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- `driver` - Specifies the task driver that should be used to run the
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task. See the [driver documentation](/docs/drivers/index.html) for what
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is available. Examples include `docker`, `qemu`, `java`, and `exec`.
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- `env` <code>([Env][]: nil)</code> - Specifies environment variables that will
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be passed to the running process.
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- `kill_timeout` `(string: "5s")` - Specifies the duration to wait for an
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application to gracefully quit before force-killing. Nomad sends an `SIGINT`.
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If the task does not exit before the configured timeout, `SIGKILL` is sent to
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the task.
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- `logs` <code>([Logs][]: nil)</code> - Specifies logging configuration for the
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`stdout` and `stderr` of the task.
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- `meta` <code>([Meta][]: nil)</code> - Specifies a key-value map that annotates
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with user-defined metadata.
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- `resources` <code>([Resources][]: required)</code> - Specifies the minimum
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resource requirements such as RAM, CPU, disk, and network.
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- `service` <code>([Service][]: nil)</code> - Specifies integrations with
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[Consul][] for service discovery. Nomad automatically registers when a task
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is started and de-registers it when the task dies.
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- `user` `(string: <varies>)` - Specifies the user that will run the task. This
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defaults to the same user as the Nomad client. This can only be set on Linux
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platforms.
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## `task` Examples
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The following examples only show the `task` stanzas. Remember that the
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`task` stanza is only valid in the placements listed above.
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### Docker Container
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This example defines a task that starts a Docker container as a service. Docker
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is just one of many drivers supported by Nomad. Read more about drivers in the
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[Nomad drivers documentation](/docs/drivers/index.html).
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```hcl
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task "server" {
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driver = "docker"
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config {
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image = "hashicorp/http-echo"
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args = ["-text", "hello world"]
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}
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resources {
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network {
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mbits = 250
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}
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}
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}
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```
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### Metadata and Environment Variables
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This example uses custom metadata and environment variables to pass information
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to the task.
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```hcl
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task "server" {
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driver = "exec"
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config {
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command = "/bin/env"
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}
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meta {
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my-key = "my-value"
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}
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env {
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MY_KEY = "${meta.my-key}"
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}
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resources {
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cpu = 20
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}
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}
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```
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### Service Discovery
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This example creates a service in Consul. To read more about service discovery
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in Nomad, please see the [Nomad service discovery documentation][service].
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```hcl
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task "server" {
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driver = "docker"
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config {
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image = "hashicorp/http-echo"
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args = ["-text", "hello world"]
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}
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service {
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tags = ["default"]
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check {
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type = "tcp"
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interval = "10s"
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timeout = "2s"
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}
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}
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resources {
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cpu = 20
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}
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}
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```
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[artifact]: /docs/job-specification/artifact.html "Nomad artifact Job Specification"
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[consul]: https://www.consul.io/ "Consul by HashiCorp"
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[constraint]: /docs/job-specification/constraint.html "Nomad constraint Job Specification"
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[env]: /docs/job-specification/env.html "Nomad env Job Specification"
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[meta]: /docs/job-specification/meta.html "Nomad meta Job Specification"
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[resources]: /docs/job-specification/resources.html "Nomad resources Job Specification"
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[logs]: /docs/job-specification/logs.html "Nomad logs Job Specification"
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[service]: /docs/service-discovery/index.html "Nomad Service Discovery"
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