Parse hocon file using shell script

Question

I have one hocon configuration created from JSON file. I need to parse the following hocon and extract the values

sample hocon file: sample.json

    nodes=[
    {
        host=myhostname
        name=myhostname
        ports {
            # debug port
            debug=9384
            # http Port on which app running
            http=9380
            # https Port on which app running
            https=9381
            # JMX port
            jmx=9383
        }
        type=app
        vm-args=[
            "-XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintClassHistogram",
            "-XX:+UseConcMarkSweepGC -XX:+UseParNewGC ",
            "-XX:+UseTLAB -XX:CMSInitiatingOccupancyFraction=80 -XX:+ExplicitGCInvokesConcurrent -verbose:gc",
            "-XX:SurvivorRatio=8 -XX:+UseNUMA -XX:TargetSurvivorRatio=80 -XX:MaxTenuringThreshold=15",
            "-Xmx3200m -Xms3200m -XX:NewSize=1664m -XX:MaxNewSize=1664m -Xss1024k",
            "-server"
        ]
    }
]
profile=java-dev
resources {
cfg-repository {
    branch-name=master
    commit-id=HEAD
    password=sigma123
    url="http://localhost:9890/gitcontainer/demo-cfg"
    username=sadmin
}
databases=[
    {
        connection-string="oracle03:1522:si12c"
        name=cm
        password=coresmp601
        username=coresmp601cm
    },
    {
        connection-string="oracle03:1522:si12c"
        name=am
        password=coresmp601
        username=coresmp601am
    }
]
idp {
    url="https://sohanb:8097/idp"
}
keystores=[
    {
        file-location="/home/smp/runtime/ssl"
        name=identity
        passphrase=kspass
    }
]
admin {
    password=sigma123
    url="http://punws-sohanb.net:9002/"
    username=sadmin
}
}

Now from this hocon file i want to extract the vm-args. I have tried different bash tools and sed/awk commands but no luck.

Please suggest!

user_1855579 · Answer

HOCON looks like JSON, but it's a wolf dressed in sheep clothes. In fact, HOCON configuration syntax is quite tricky, one can include multiple files, replace variables multiple times, merge variables, use environment variables, etc.

For this particular file, you could get what you want with awk/shell script, however if the file becomes more complex, or, if in the future you need to parse a more complex file, than you'd be better off with a tool that's specialized in parsing Hocon syntax. Such a tool exists, fortunately.

Use this tool: Hocon Config Printer

This tool fully parses Hocon syntax and outputs a regular JSON.

For your specific example, you can use:

hocon-config-printer sample.hocon.conf  | jq  '.nodes[0]."vm-args"'

Output:

[
  "-XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintClassHistogram",
  "-XX:+UseConcMarkSweepGC -XX:+UseParNewGC ",
  "-XX:+UseTLAB -XX:CMSInitiatingOccupancyFraction=80 -XX:+ExplicitGCInvokesConcurrent -verbose:gc",
  "-XX:SurvivorRatio=8 -XX:+UseNUMA -XX:TargetSurvivorRatio=80 -XX:MaxTenuringThreshold=15",
  "-Xmx3200m -Xms3200m -XX:NewSize=1664m -XX:MaxNewSize=1664m -Xss1024k",
  "-server"
]

Parse hocon file using shell script

2 Answers