github.com/huiliang/nomad@v0.2.1-0.20151124023127-7a8b664699ff/website/source/docs/drivers/java.html.md (about)

     1  ---
     2  layout: "docs"
     3  page_title: "Drivers: Java"
     4  sidebar_current: "docs-drivers-java"
     5  description: |-
     6    The Java task driver is used to run Jars using the JVM.
     7  ---
     8  
     9  # Java Driver
    10  
    11  Name: `java`
    12  
    13  The `Java` driver is used to execute Java applications packaged into a Java Jar 
    14  file. The driver currently requires the Jar file be accessible via
    15  HTTP from the Nomad client. 
    16  
    17  ## Task Configuration
    18  
    19  The `java` driver supports the following configuration in the job spec:
    20  
    21  * `artifact_source` - The hosted location of the source Jar file. Must be
    22    accessible from the Nomad client
    23  
    24  * `checksum` - (Optional) The checksum type and value for the `artifact_source`
    25    image.  The format is `type:value`, where type is any of `md5`, `sha1`,
    26    `sha256`, or `sha512`, and the value is the computed checksum. If a checksum
    27    is supplied and does not match the downloaded artifact, the driver will fail
    28    to start
    29  
    30  * `args` - (Optional) A list of arguments to the `java` command.
    31  
    32  * `jvm_options` - (Optional) A list of JVM options to be passed while invoking
    33    java. These options are passed not validated in any way in Nomad.
    34  
    35  ## Client Requirements
    36  
    37  The `java` driver requires Java to be installed and in your systems `$PATH`.
    38  The `artifact_source` must be accessible by the node running Nomad. This can be an
    39  internal source, private to your cluster, but it must be reachable by the client 
    40  over HTTP. 
    41  
    42  ## Examples
    43  
    44  A simple config block to run a Java Jar:
    45  
    46  ```json
    47  # Define a task to run
    48  task "web" {
    49    # Run a Java Jar
    50    driver = "java"
    51  
    52    config {
    53      artifact_source = "https://dl.dropboxusercontent.com/u/1234/hello.jar"
    54      checksum = "md5:123445555555555"
    55      jvm_options = "-Xmx2048m -Xms256m"
    56    }
    57  ```
    58  
    59  ## Client Attributes
    60  
    61  The `java` driver will set the following client attributes:
    62  
    63  * `driver.java` - Set to `1` if Java is found on the host node. Nomad determines
    64  this by executing `java -version` on the host and parsing the output
    65  * `driver.java.version` - Version of Java, ex: `1.6.0_65`
    66  * `driver.java.runtime` - Runtime version, ex: `Java(TM) SE Runtime Environment (build 1.6.0_65-b14-466.1-11M4716)`
    67  * `driver.java.vm` - Virtual Machine information, ex: `Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-466.1, mixed mode)`
    68  
    69  ## Resource Isolation
    70  
    71  The resource isolation provided varies by the operating system of
    72  the client and the configuration.
    73  
    74  On Linux, Nomad will attempt to use cgroups, namespaces, and chroot
    75  to isolate the resources of a process. If the Nomad agent is not
    76  running as root many of these mechanisms cannot be used.
    77  
    78  As a baseline, the Java jars will be run inside a Java Virtual Machine,
    79  providing a minimum amount of isolation.
    80