Control characters appearing in job output in 0.6.0

I’m seeing control characters show up in coloured job output where previously there were none before. It seems that this could be somewhat related to #141.

Test environment

• Jenkins Version: 2.148
• AnsiColor Version: 0.6.0
• Hostsystem: Debian stretch

Expected behavior

Up until 0.6.0 I would only occasionally see [0m characters show up and they did not affect output. The following appears when testing against 0.5.3

Actual behavior

With 0.6.0 I now see more control characters and in some cases no colour output at all:

In more complex jobs with more varied colour output, the colour output will not be properly bounded and will leak into following lines.

Steps to reproduce the behavior

The above outputs were reproduced by running the following job using the pipeline library:

def label = "terraform-${UUID.randomUUID().toString()}"

podTemplate(label: label, inheritFrom: 'jnlp', containers: [
  containerTemplate(
      name: 'terraform',
      image: 'hashicorp/terraform',
      ttyEnabled: true,
      command: 'cat',
      alwaysPullImage: true,
  )
]) {
    node(label) {
        container('terraform'){
            ansiColor('xterm') {
                sh """
                 terraform plan
                """
            }
        }
    }
}

[fearnycompknowhow]

It seems that Terraform attempts to format the output using color. However, Jenkins does not output this formatting correctly and thus you see those unusual characters in the output.

Thanks to this thread, I was able to make Terraform omit those characters in the output by using the -no-color flag.

This options is available for at least three of the major Terraform functions: show, plan, and apply. It’s probably available for others, I just haven’t confirmed it.

[dwnusbaum]

I just released 0.6.2 with a change that should improve this issue. If you are still seeing it after the upgrade, please copy-and-paste some of the broken output from Jenkins here (preferably replacing literal occurrences of the ASCII character 0x1b with the text 0x1b so we can see what is happening to the escape sequences).