groovy docker exec error

FATAL: Cannot run program "docker": error=2, No such file or directory
java.io.IOException: Cannot run program "docker": error=2, No such file or directory
    at java.lang.ProcessBuilder.start(Unknown Source)
    at java.lang.Runtime.exec(Unknown Source)
    at java.lang.Runtime.exec(Unknown Source)
    at java.lang.Runtime.exec(Unknown Source)
    at org.codehaus.groovy.runtime.DefaultGroovyMethods.execute(DefaultGroovyMethods.java:12347)
    at org.codehaus.groovy.runtime.dgm$226.invoke(Unknown Source)
    at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:271)
    at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
    at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:42)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
    at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:112)
    at Script1.run(Script1.groovy:15)
    at groovy.lang.GroovyShell.evaluate(GroovyShell.java:650)
    at groovy.lang.GroovyShell.evaluate(GroovyShell.java:636)
    at hudson.plugins.groovy.SystemGroovy.perform(SystemGroovy.java:93)
    at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
    at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:785)
    at hudson.model.Build$BuildExecution.build(Build.java:199)
    at hudson.model.Build$BuildExecution.doRun(Build.java:160)
    at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:566)
    at hudson.model.Run.execute(Run.java:1678)
    at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
    at hudson.model.ResourceController.execute(ResourceController.java:88)
    at hudson.model.Executor.run(Executor.java:231)
Caused by: java.io.IOException: error=2, No such file or directory
    at java.lang.UNIXProcess.forkAndExec(Native Method)
    at java.lang.UNIXProcess.<init>(Unknown Source)
    at java.lang.ProcessImpl.start(Unknown Source)
    ... 24 more