The microservice should provide gRPC endpoints giving enough information to determine the health and the state of the cluster and its indices.
The code should rely as much as possible on the standard Go library (avoid fancy libraries).
Bonus: packaging of the full solution using a single helm chart

Sources

See docs/sources.md file.

Instructions

Start Elastic Search container and load sample data

In root project folder (requires docker-compose):

docker-compose up --build

Update docker host address in script/load-dataset.sh file if needed (default: localhost:9200)
In root project folder (requires curl)

./script/load-dataset.sh

Start gRPC Server and Client

run cmd/server.go
- optional flag -server-port : server listening port (default: 9000)
- optional flag -es-addr : elastic search server address (default: http://localhost:9200)
run cmd/client.go
- optional flag -server-port : server port (default: 9000)

Execution examples

Server start-up

$ go run server.go
{"level":"INFO","ts":"2021-01-03T14:30:31.889+0100","msg":"Starting grpc server."}
{"level":"INFO","ts":"2021-01-03T14:30:40.117+0100","msg":"finished unary call with code OK",
"grpc.start_time":"2021-01-03T14:30:40+01:00","system":"grpc","span.kind":"server",
"grpc.service":"proto.MonitorService","grpc.method":"ReadClusterHealth","grpc.code":"OK",
"grpc.time_ms":9.640000343322754}
{"level":"INFO","ts":"2021-01-03T14:30:40.127+0100","msg":"finished unary call with code OK",
"grpc.start_time":"2021-01-03T14:30:40+01:00","system":"grpc","span.kind":"server",
"grpc.service":"proto.MonitorService","grpc.method":"ReadIndicesInfo","grpc.code":"OK",
"grpc.time_ms":9.831999778747559}
^C{"level":"WARN","ts":"2021-01-03T14:31:21.327+0100","msg":"Stopping grpc server."}

Client start-up

$ go run client.go
2021/01/03 14:30:40 Cluster Health:

cluster_name: "docker-cluster"
status: YELLOW
number_of_nodes: 1
number_of_data_nodes: 1
active_primary_shards: 1
active_shards: 1
unassigned_shards: 1
active_shards_percent_as_number: 50
timestamp: 1609680640


2021/01/03 14:30:40 Indices Info:

indices: <
  health: YELLOW
  status: "open"
  index: "bank"
  uuid: "5_7liZyeQRWv2X2zB0Qn8w"
  pri: 1
  rep: 1
  docs_count: 1000
  store_size: 388312
  pri_store_size: 388312
>
timestamp: 1609680640

Tests

Tests for the Monitoring Service can be executed with the following command from the project root folder:

go test ./pkg/service