Support for command scopes

[vladimirvivien]

By default, all commands listed in a crash-diag is executed on each machine specified in the FROM list. This issue is to introduce command scope to specify which machine gets the command.

For instance,

FROM hosts:"host0.local host1.local"
CAPTURE cmd:"command -param0 -param1" scope:"all"
COPY path:"/var/logs/log.txt" scope:"host0.local"
ENV JUMP="12.34.56.78"
RUN cmd:"ssh -i $HOME/.ssh/key_rsa -J user@$JUMP user@$FROM_HOST uptime" scope:"local"

Scopes

• All - means the command will be executed on all machines in the FROM list
• Host List - scope can be a list of machines where command will be executed
• Local - a local scope means the command will be executed once using the local machine (most likely using a shell runtime, see Support for multiple execution runtimes #54)