itzg/try-envoy-monitor-queries

This application tries out label-based selection of Envoys using MongoDB as the backing store. It also uses GraphQL SPQR to expose a GraphQL API.

Running locally

Setup

Start a MongoDB container by running the following in the workspace:

docker-compose up -d

Running

Run the main Spring Boot application class or start from the command-line with

mvn spring-boot:run

GraphQL operations

The application exposes a GraphQL endpoint that can be POSTed at http://localhost:8080/graphql, such as with curl:

curl --request POST \
  --url http://localhost:8080/graphql \
  --header 'content-type: application/json' \
  --data '{"query":"{\n  envoy {\n    id\n    labels\n  }\n}"}'

"Attach" Envoys

Envoys can be simulated by attaching with the mutation:

mutation AttachEnvoy($labels:[String!]!)
{
  attachEnvoy(labels:$labels) {
    id
  }
}

given the query variables:

{
	"labels": [
		"zone=west",
		"access=public",
		"supports=ping",
    "supports=http"
	]
}

For experimentation, you can "attach" several with the same labels and some more with varying the zone and supports options. For example, create a few with zone=west, zone=east, and one or two with the same zone(s) but change the supports to just supports=ssh.

Retrieve all "attached" Envoys

Use the query:

{
  envoy {
    id
    labels
  }
}

Retrieve a specific Envoy

{
  envoy(id:"5c2938ea1155d64a1cd2aa61") {
    id
    labels
  }
}

Find candidate Envoys

To simulate the selection of a particular Monitor to an available Envoy, the following query can be used:

query FindCandidates($labels:[String!]!)
{
  findCandidatesForMonitor(labels:$labels) {
    id
    labels
  }
}

with the query variables, such as:

{
  "labels": ["zone=west", "supports=ping"]
}

"Detach" all Envoys

mutation
{
  detachAllEnvoys {
    count
  }
}

Detach a specific Envoy

mutation
{
  detachEnvoy(id:"5c293ed41155d662341f7c26") {
    count
  }
}