cloud-init runcmd (using MAAS)

Question

I'm unable to run bash scripts in "runcmd:" that aren't inline.

runcmd:
    - [ bash, -c, echo "=========hello world=========" >>foo1.bar ]
    - [ bash, -c, echo "=========hello world=========" >>foo2.bar ]
    - [ bash, -c, /usr/local/bin/foo.sh ]

The first two lines are successfully run on the deployed Ubuntu instance. However, the foo.sh doesn't seem to run.

Here is /usr/local/bin/foo.sh:

#!/bin/bash
echo "=========hello world=========" >>foosh.bar

foo.sh has executable permissions for root and resides on the MAAS server.

I've looked at the following but they don't seem to sort out my issue:

• Cannot make bash script work from cloud-init
• run GO111MODULE=on go install . ./cmd/... in cloud init
• https://gist.github.com/aw/40623531057636dd858a9bf0f67234e8

Answer 1

Anything you run using runcmd must already exist on the filesystem. There is no provision for automatically fetching something from a remote host.

You have several options for getting files there. Two that come to mind immediately are:

• You could embed the script in your cloud-init configuration using the write-files directive:

  write_files:
    - path: /usr/local/bin/foo.sh
      permissions: '0755'
      content: |
        #!/bin/bash
        echo "=========hello world=========" >>foosh.bar
  
  runcmd:
    - [bash, /usr/local/bin/foo.sh]
  

• You could fetch the script from a remote location using curl (or similar tool):

  runcmd:
    - [curl, -o, /usr/local/bin/foo.sh, http://somewhere.example.com/foo.sh]
    - [bash, /usr/local/bin/foo.sh]