Documentation

website/source/docs/drivers/docker.html.md

@@ -37,8 +37,15 @@ The following options are available for use in the job specification.
 
 * `command` - (Optional) The command to run when starting the container.
 
-* `args` - (Optional) A list of arguments to the optional `command`. If no
-  `command` is present, `args` are ignored.
+*   `args` - (Optional) A list of arguments to the optional `command`. If no
+    `command` is present, `args` are ignored. References to environment variables
+    or any [intepretable Nomad
+    variables](/docs/jobspec/index.html#interpreted_vars) will be interpreted
+    before launching the task. For example:
+
+    ```
+        args = ["$nomad.ip", "$MY_ENV", $meta.foo"]
+    ```
 
 * `labels` - (Optional) A key/value map of labels to set to the containers on
   start.

website/source/docs/drivers/exec.html.md

@@ -32,7 +32,14 @@ The `exec` driver supports the following configuration in the job spec:
   is supplied and does not match the downloaded artifact, the driver will fail
   to start
 
-* `args` - (Optional) A list of arguments to the `command`.
+*   `args` - (Optional) A list of arguments to the optional `command`.
+    References to environment variables or any [intepretable Nomad
+    variables](/docs/jobspec/index.html#interpreted_vars) will be interpreted
+    before launching the task. For example:
+
+    ```
+        args = ["$nomad.ip", "$MY_ENV", $meta.foo"]
+    ```
 
 ## Client Requirements
 

website/source/docs/drivers/java.html.md

@@ -27,7 +27,14 @@ The `java` driver supports the following configuration in the job spec:
   is supplied and does not match the downloaded artifact, the driver will fail
   to start
 
-* `args` - (Optional) A list of arguments to the `java` command.
+*   `args` - (Optional) A list of arguments to the optional `command`.
+    References to environment variables or any [intepretable Nomad
+    variables](/docs/jobspec/index.html#interpreted_vars) will be interpreted
+    before launching the task. For example:
+
+    ```
+        args = ["$nomad.ip", "$MY_ENV", $meta.foo"]
+    ```
 
 * `jvm_options` - (Optional) A list of JVM options to be passed while invoking
   java. These options are passed not validated in any way in Nomad.

website/source/docs/drivers/raw_exec.html.md

@@ -30,7 +30,14 @@ The `raw_exec` driver supports the following configuration in the job spec:
   is supplied and does not match the downloaded artifact, the driver will fail
   to start
 
-* `args` - (Optional) A list of arguments to the `command`.
+*   `args` - (Optional) A list of arguments to the optional `command`.
+    References to environment variables or any [intepretable Nomad
+    variables](/docs/jobspec/index.html#interpreted_vars) will be interpreted
+    before launching the task. For example:
+
+    ```
+        args = ["$nomad.ip", "$MY_ENV", $meta.foo"]
+    ```
 
 ## Client Requirements
 

website/source/docs/drivers/rkt.html.md

@@ -24,7 +24,14 @@ The `rkt` driver supports the following configuration in the job spec:
 
 * `command` - (Optional) A command to execute on the ACI.
 
-* `args` - (Optional) A list of arguments to the image.
+*   `args` - (Optional) A list of arguments to the optional `command`.
+    References to environment variables or any [intepretable Nomad
+    variables](/docs/jobspec/index.html#interpreted_vars) will be interpreted
+    before launching the task. For example:
+
+    ```
+        args = ["$nomad.ip", "$MY_ENV", $meta.foo"]
+    ```
 
 * `trust_prefix` - (Optional) The trust prefix to be passed to rkt. Must be
   reachable from the box running the nomad agent. If not specified, the image is

website/source/docs/jobspec/index.html.md

@@ -240,8 +240,20 @@ The `task` object supports the following keys:
   task transitons to the dead state. [Click
   here](/docs/jobspec/servicediscovery.html) to learn more about services.
 
-* `env` - A map of key/value representing environment variables that
-  will be passed along to the running process.
+*   `env` - A map of key/value representing environment variables that
+    will be passed along to the running process. Nomad variables are
+    interpreted when set in the environment variable values. See the table of
+    interpreted variables [here](#interpreted_vars).
+
+    For example the below environment map will be reinterpreted:
+
+    ```
+        env {
+            // The value will be interpreted by the client and set to the
+            // correct value.
+            NODE_CLASS = "$nomad.class"
+        }
+    ```
 
 * `resources` - Provides the resource requirements of the task.
   See the resources reference for more details.
@@ -336,7 +348,7 @@ restart {
 The `constraint` object supports the following keys:
 
 * `attribute` - Specifies the attribute to examine for the
-  constraint. See the table of attributes below.
+  constraint. See the table of attributes [below](#interpreted_vars).
 
 * `operator` - Specifies the comparison operator. Defaults to equality,
   and can be `=`, `==`, `is`, `!=`, `not`, `>`, `>=`, `<`, `<=`. The
@@ -368,7 +380,11 @@ The `constraint` object supports the following keys:
 
     Tasks within a task group are always co-scheduled.
 
-Below is a table documenting the variables that can be interpreted:
+### Interpreted Variables <a id="interpreted_vars"></a>
+
+Certain Nomad variables are interpretable for use in constraints, task
+environment variables and task arguments. Below is a table documenting the
+variables that can be interpreted:
 
 <table class="table table-bordered table-striped">
   <tr>