how to pass parameter to execute in chef?

Question

I'm new to chef. Recently, I'm studying the resources, I got a problem on how to pass parameter to command in execute in chef. Here's the details -- I searched this page -- https://discourse.chef.io/t/pass-parameter-to-bash-script-and-call-bash-scripts-in-chef-cookbook/10431 -- it looks using ruby variable format #{xxx} can pass a variable in recipe to the script in "execute" in recipe I made a test, first my recipe --

execf="haha"

file '/tmp/e.sh' do
    content '
#!/bin/bash
cat /tmp/e.log
DT=`date +%F" "%T`
echo $1" "${DT} >> /tmp/e.log
'
    mode '755'
    execf="e1"
    notifies :run, 'execute[e.sh]', :delayed
end

file '/tmp/e2.sh' do
    content '
#!/bin/bash
cat /tmp/e.log
DT=`date +%F" "%T`
echo $1" "${DT} >> /tmp/e.log
'
    mode '777'
    execf="e2"
    notifies :run, 'execute[e.sh]', :delayed
end

execute 'e.sh' do
    command '/tmp/e.sh #{execf}'
    action :nothing
end

I think -- this can record resouce "e.sh" or "e2.sh"'s runtime to e.log. And there's no syntax error when run "chef-client". But to my suprise -- the #{execf} -- is always a "" string while calling /tmp/e.sh... So in e.log, I can only see --

 2022-05-13 22:04:48
 2022-05-13 22:17:44
 2022-05-13 22:19:07

Only a "" was passing to the /tmp/e.sh as $1... At first I think maybe it's due to the execf is a local variable in ruby so I tried @execf and $execf ... but all didn't work. Maybe in recipe, I shouldn't use variable, but should use node attribute? But I can't find how to modify node attribute in resource... Please kind help. Thanks in advance for any idea.

Answer 1

The main issue is the use of single quotes ('') in the command. Single quotes in Ruby don't allow for interpolation of the variable #{execf}. You should rewrite it as:

execute 'e.sh' do
  command "/tmp/e.sh #{execf}"
  action :nothing
end

However variable assignment (such as execf="e1") in the file resources will not have any effect. You will get something like haha 2022-05-13 22:04:48 in the logs.

Edit

However variable assignment (such as execf="e1") in the file resources will not have any effect.

Turns out that the variable assignment from within resource is also compiled, and last assigned value is used.