Jenkins pipeline capture output of jenkins steps - jenkins

Question

How can I archive (as a file) the console output of a jenkins pipeline step such as docker.build(someTag)?
Background:
I use jenkins pipelines to build a whole bunch of microservices.
I want to extract all the relevant information from the jenkins console into archived files, so that devs don't have to look at the console which confuses them. This works fine for sh steps were I can redirect stdout and stderr but how can I do something similar for a jenkins pipeline step?

Answer 1

As a workaround we use following LogRecorder class:
class LogRecorder implements Serializable {
def logStart
def logEnd
def currentBuild
def steps
LogRecorder(currentBuild) {
this.currentBuild = currentBuild
}
void start() {
logStart = currentBuild.getRawBuild().getLog(2000)
}
String stop() {
logEnd = currentBuild.getRawBuild().getLog(2000)
getLog()
}
String getLog() {
def logDiff = logEnd - logStart
return logDiff.join('\n')
}
}
Depending on your needs you may want to adjust the number of log lines in the calls to getLog().
Possible Usage:
LogRecorder logRecorder = new LogRecorder(currentBuild)
logRecorder.start()
docker.build(someTag)
testResult.stdOut = logRecorder.stop()
Please be aware that it may happen - most probably due to caching issues - that the very last line(s) of the log are sometimes missing. Maybe a sleep would help here. But so far this was not required here.

Answer 2

Here's what I'm using to capture the sha256 of the built docker image
docker.build(someTag)
def dockerSha256 = sh(returnStdout: true, script: "docker image inspect $someTag | jq .[0].Id").trim()
I'm using 'jq' to parse the json response
or the groovy way
def json = sh(returnStdout: true, script: "docker image inspect $someTag").trim()
def obj = new JsonSlurper().parseText(json)
println "raw json: " + obj
println "groovy docker sha256: " + obj[0].Id