REST API: allow to fetch deployment/config status

[Thomas-Gelf]

I want to call director/config/deployment-status to fetch the following information:

• stage name currently active in Icinga
• config checksum related to that stage name
• activity log checksum related to that configuration

{
    "active_configuration": {
        "stage_name": "efc5e4b9-917b-4bef-8bb1-a20df25423d0",
        "config": "8de97b72fc5fd0035710f7c43684c8d9c1e2c1e4",
        "activity": "7e43cd096954324da4d282ebe530c0b89d2ba909"
    }
}

This should throw 500 in case Icinga isn't reachable. In case there is no active stage name related to the Director, active_configuration must be set to null.

When I pass one or more config_checksums, I also want to be able to distinct the following states:

• whether this configuration is currently active
• whether this configuration has ever been deployed
• whether this configuration has been deployed, but failed
• whether this configuration has been rendered, but not yet deployed, therefore it's undeployed
• whether this configuration checksum is completely unknown

Same goes for activitylog_checksum:

{
    "active_configuration": { /* ... */ },
    "configs": {
        "f7c4368de97b72fc5fd003571084c8d9c1e2c1e4": "unknown",
        "8de97b72fc5fd0035710f7c43c1e2c1e684c8d94": "active",
        "8d3684ce97b72fc5fd0035710f72c1ec48d9c1e4": "<unknown|undeployed|deployed|failed|active>",
    },
    "activites": {
        "7e43cd096954324da4d282ebe530c0b89d2ba909": "<unknown|undeployed|deployed|failed|active>"
    }
}

[Thomas-Gelf]

Implemented with #2188, thanks @gianlucapiccolo!