[Extensions] Parse configuration file of extensions during installation, pass this information to the Security Plugin

[stephen-crawford]

After merging #2594, we will need to have a way for core to parse the configuration files of extensions during installation and then pass that information to the Security plugin. Once in the Security plugin, a service account can be created based on the information provided in the extension's configuration files.

Completion of the issue will look like a PR which adds functionality for parsing a configuration file in core during bootstrap and then passing that information from core into the Security plugin. The base PR should include tests which demonstrate the successful parsing of a configuration file and creation of a payload which can be sent to the Security plugin.

A follow-up PR will need to be created after this issue is completed which adds the automatic handling of the created payload and the subsequent creation of the service account for the extension.

[stephen-crawford]

[Triage] This issue is part of the ongoing work with the extensions project.

[cwperks]

@scrawfor99 I have an open PR in core for an IdentityPlugin to extend the settings in extensions.yml: opensearch-project/OpenSearch#7526

Does that PR address this issue?

[stephen-crawford]

Hi @cwperks, I think that between that and the work that was already done in the ExtensionsManager class. This issue should be all set. This code gets most of the info we would realistically need:

 private ExtensionsSettings readFromExtensionsYml(Path filePath) throws IOException {
        Yaml yaml = new Yaml();
        try (InputStream inputStream = Files.newInputStream(filePath)) {
            Map<String, Object> obj = yaml.load(inputStream);
            if (obj == null) {
                inputStream.close();
                throw new IOException("extensions.yml is empty");
            }
            List<HashMap<String, ?>> unreadExtensions = new ArrayList<>((Collection<HashMap<String, ?>>) obj.get("extensions"));
            List<Extension> readExtensions = new ArrayList<Extension>();
            for (HashMap<String, ?> extensionMap : unreadExtensions) {
                try {
                    // checking to see whether any required fields are missing from extension.yml file or not
                    String[] requiredFields = {
                        "name",
                        "uniqueId",
                        "hostAddress",
                        "port",
                        "version",
                        "opensearchVersion",
                        "minimumCompatibleVersion" };
                    List<String> missingFields = Arrays.stream(requiredFields)
                        .filter(field -> !extensionMap.containsKey(field))
                        .collect(Collectors.toList());
                    if (!missingFields.isEmpty()) {
                        throw new IOException("Extension is missing these required fields : " + missingFields);
                    }