2015-09-20 22:31:33 +00:00
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---
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layout: "docs"
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page_title: "Drivers: Java"
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sidebar_current: "docs-drivers-java"
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description: |-
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The Java task driver is used to run Jars using the JVM.
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---
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# Java Driver
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Name: `java`
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2015-09-21 19:20:51 +00:00
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The `Java` driver is used to execute Java applications packaged into a Java Jar
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file. The driver currently requires the Jar file be accessible via
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HTTP from the Nomad client.
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## Task Configuration
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The `java` driver supports the following configuration in the job spec:
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* `jar_source` - **(Required)** The hosted location of the source Jar file. Must be accessible
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2015-10-15 21:40:08 +00:00
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from the Nomad client
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2015-10-16 19:43:06 +00:00
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* `args` - **(Optional)** The argument list for the `java` command, space separated.
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* `jvm_options` - **(Optional)** JVM options to be passed while invoking java. These options
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are passed not validated in any way in Nomad.
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## Client Requirements
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The `java` driver requires Java to be installed and in your systems `$PATH`.
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The `jar_source` must be accessible by the node running Nomad. This can be an
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internal source, private to your cluster, but it must be reachable by the client
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over HTTP.
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## Client Attributes
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The `java` driver will set the following client attributes:
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2015-09-23 19:16:43 +00:00
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* `driver.java` - Set to `1` if Java is found on the host node. Nomad determines
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this by executing `java -version` on the host and parsing the output
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* `driver.java.version` - Version of Java, ex: `1.6.0_65`
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* `driver.java.runtime` - Runtime version, ex: `Java(TM) SE Runtime Environment (build 1.6.0_65-b14-466.1-11M4716)`
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* `driver.java.vm` - Virtual Machine information, ex: `Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-466.1, mixed mode)`
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## Resource Isolation
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The resource isolation provided varies by the operating system of
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the client and the configuration.
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On Linux, Nomad will attempt to use cgroups, namespaces, and chroot
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to isolate the resources of a process. If the Nomad agent is not
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running as root many of these mechanisms cannot be used.
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2015-10-25 17:00:08 +00:00
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As a baseline, the Java jars will be run inside a Java Virtual Machine,
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providing a minimum amount of isolation.
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2015-09-20 22:31:33 +00:00
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