cloud-init runcmd (using MAAS) - bash

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
Any help or tips would be greatly appreciated.

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]