Implement dashboard backend

[maia-iyer]

Backend implementation of https://github.com/lumjjb/tornjak/issues/40

Four sections on the dashboard: a banner, a cluster metadata table, agent metadata table, and workload entry metadata table.

Necessary information for each section:

• Banner

  • number agents per cluster ["/api/tornjak/clusters/list"]
  • number workload entries per agent ["/api/agent/list" + "/api/entry/list"]
  • number workload entries per cluster ["/api/tornjak/clusters/list" + "/api/entry/list"]

• Cluster Metadata Table

  • Name ["/api/tornjak/clusters/list"]
  • Created at / Age ["/api/tornjak/clusters/list"]
  • Number of nodes (based on # agents) ["/api/tornjak/clusters/list"]
  • Number of WL entries ["/api/tornjak/clusters/list" + "/api/entry/list"]

• Agent Metadata Table

  • Name / SPIFFEID ["/api/agent/list"]
  • Agent Status ["/api/agent/list"]
  • Platform type ["/api/tornjak/agents/list"]
  • Cluster name (if assigned) ["/api/tornjak/agents/list"]
  • Number of WL entries ["/api/entry/list"]

• Workload Entry Metadata Table

  • SPIFFE ID ["/api/entry/list"]
  • Parent ID (agent SPIFFEID) ["/api/entry/list"]
  • Admin Flag ["/api/entry/list"]
  • Entry expiry time (based on expires-at) ["/api/entry/list"]
  • Platform type (Kubernetes, Docker or Unix) ["/api/entry/list" + "/api/tornjak/agents/list"]
  • Cluster name (if agent with Parent ID assigned) ["/api/entry/list" + "/api/tornjak/agents/list"]

API Todos

• Augment current api calls for clusters with time stamping
• "/api/tornjak/agents/list" to return mapping of agent SPIFFEID to Tornjak selector and cluster mapping
• "/api/entry/list" testing for filtered request