HDM API

[oneiros]

Here are the first steps towards an API for HDM (#87).

For now it only allows to query for environments, nodes and keys, roughly reflecting the initial functionality of HDM from long ago.

The initial documentation is mostly autogenerated and can be previewed e.g. here: https://redocly.github.io/redoc/?url=https://raw.githubusercontent.com/betadots/hdm/issue-87/doc/openapi.yaml

At the very least, key search is still missing currently.

Also, the data returned is very limited. E.g. as the API is read-only I did not include the information if a file/value is writable. I also omitted the information if a file has been replaced from a git repo. I am not sure if these features mix well 😕

I am not sure what we discussed regarding encrypted values. For now I return them verbatim, i.e. no decryption is performed. This is the safest approach from a security perspective, but it severly limits the usefulness of the API.

In the end I believe one or more actual use-cases would help to find out what is actually missing or should be implemented differently. Maybe the foreman integration can be such a use-case.

Closes #87.

[tuxmea]

Search keys

The API does not need a key search implementation.
Use case for API is the Foreman integration.
Searching for keys will be done in the Foreman web UI.

Read-write

We dont need write support as we only show data within Foreman UI

Encrypted values

For Foreman integration showing encrypted values is sufficient.
We can consider a decrpytion at a later time if required by community and users.

Git dir keys

HDM can fetch keys from a git repo and shows that these keys are taken from git (when using HDM web UI).
We dont need this in API.

API endpoints

Within Foreman we select a node. A node can have a puppet environment configured (pinned) in Foreman. But this is optional.
Every node uses an environment and the environment is part of the PuppetDB node API endpoints.
We will rely on the PuppetDB node data to identify which environment is used by a node.

For Foreman we need the node endpoint to get a list of hiera keys and the key endpoint to show in which hierarchies we are able to find data for the requested key.

[rwaffen]

initial code looks okay for me.

[oneiros]

Within Foreman we select a node. A node can have a puppet environment configured (pinned) in Foreman. But this is optional.
Every node uses an environment and the environment is part of the PuppetDB node API endpoints.
We will rely on the PuppetDB node data to identify which environment is used by a node.

This was actually missing from my POC foreman and smart proxy plugins, mainly because I forgot about this but also because the API was just not there. I added a /nodes/{node}/keys and /nodes/{node}/keys/{key} endpoint that works just like what was there before but will take the environment from the node. I already updated the smart proxy and foreman plugins accordingly.

Since we opted to leave out everything else for now and the proof of concept works with what is already here, I will remove the draft status from this PR.