JS7 JobScheduler

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Problem

Users may observe the following error message when initially running jobs:

UnknownKey: No such environment variable: COMPUTERNAME

This problem can occur if, for example, workflows have been used from JS7 - Download.

As a result, some jobs in the example workflows fail with the above error message.

Analysis

The error message indicates that an environment variable with the name COMPUTERNAME is used in a job. However this environment variable does not exist.

  • The reason lies with the JS7 - Job Resources from the Defaults.zip archive which is available from JS7 - Download. After being imported this archive is extracted to a JOC Cockpit folder with the name Defaults and a job resource with the name Default. Details can be found in the JS7 - Job Environment Variables article.

  • The Default job resource includes an argument with the name js7AgentHostname and an environment variable with the name JS7_AGENT_HOSTNAME. By default the argument is assigned the following value:

    js7AgentHostname = env('HOSTNAME', env('COMPUTERNAME'))
  • This expression first makes use of a HOSTNAME environment variable (available for most Unix systems) and if this does not exist uses the COMPUTERNAME environment variable (available for Windows systems). Therefore running a job that makes use of the Default job resource on a Unix OS that does not provide the HOSTNAME environment variable causes the error.

  • The HOSTNAME environment variable which is assumed from the Job Resource in fact is a bash variable and may not be available if another shell such as ksh or tsh is used or if the Agent's account has not been assigned the bash shell in /etc/passwd.

The assignment of the js7AgentHostname argument is performed in the Configuration view for Job Resources like this:


Solution

Modify the value of the js7AgentHostname argument as follows:

js7AgentHostname = env('HOSTNAME', env('COMPUTERNAME', ""))

Explanation:

  • The env() function makes use of two arguments: the first argument specifies an environment variable, the second argument specifies a default value if the environment variable does not exist.
  • Adding an empty default value - specified by two double quotes - as provided in the example above resolves the problem.
  • To apply changes deploy the job resource after modification.
  • As an alternative to this solution users can assign the /bin/bash shell to the user account used by the Agent.