Add jq and curl

[mogul]

Changes proposed in this pull request:

• add jq and curl CLI utils (seems like their absence might be a problem)

Security considerations

None, these are well-understood CLI utilities that are being pulled from the upstream Alpine repository, which is updated frequently.

[markdboyd]

Why does this CLI image need those utilities? How would people use them in an actual CI workflow?

[mogul]

The action is also useful for running more complex scripts that assume the caller is already authenticated with cloud.gov and pointing to the appropriate space. Here's an example workflow and the script it points to. In this case the script is mainly using cf curl but you can imagine another one that needs to download a file or reference the result of a request during deployment. For those very simple needs, curl and jq will do.

[FuhuXia]

I would also like to add grep into the list as in

apk add --no-cache bash jq curl grep

We have a workflow step to monitor the output of a cf command, in which a script is relying on grep's --line-buffered option. The BusyBox grep that comes with Alpine version does not support this option. We have to install it in our run script after getting cloud-gov/cg-cli-tools. But installing a GNU grep here, not in our script as done here, is considered better for anyone like our team using grep.

Is it possible to add grep when merging this PR? @mogul @markdboyd

[mogul]

I'm okay with that; @markdboyd ...?

Also if there's a common pack of binutil-type stuff not covered by BusyBox, let's just go ahead and install it.

(And: Sorry for the breaking change, @FuhuXia !)

[mogul]

For example:
https://wiki.alpinelinux.org/wiki/How_to_get_regular_stuff_working

[markdboyd]

@mogul sure, feel free to add grep

[markdboyd]

@FuhuXia @mogul I just decided to create a separate PR for including grep: #24