Ashvitha f95ffe0355
Allow HCP metrics collection for Envoy proxies
Co-authored-by: Ashvitha Sridharan <ashvitha.sridharan@hashicorp.com>
Co-authored-by: Freddy <freddygv@users.noreply.github.com>

Add a new envoy flag: "envoy_hcp_metrics_bind_socket_dir", a directory
where a unix socket will be created with the name
`<namespace>_<proxy_id>.sock` to forward Envoy metrics.

If set, this will configure:
- In bootstrap configuration a local stats_sink and static cluster.
  These will forward metrics to a loopback listener sent over xDS.

- A dynamic listener listening at the socket path that the previously
  defined static cluster is sending metrics to.

- A dynamic cluster that will forward traffic received at this listener
  to the hcp-metrics-collector service.


Reasons for having a static cluster pointing at a dynamic listener:
- We want to secure the metrics stream using TLS, but the stats sink can
  only be defined in bootstrap config. With dynamic listeners/clusters
  we can use the proxy's leaf certificate issued by the Connect CA,
  which isn't available at bootstrap time.

- We want to intelligently route to the HCP collector. Configuring its
  addreess at bootstrap time limits our flexibility routing-wise. More
  on this below.

Reasons for defining the collector as an upstream in `proxycfg`:
- The HCP collector will be deployed as a mesh service.

- Certificate management is taken care of, as mentioned above.

- Service discovery and routing logic is automatically taken care of,
  meaning that no code changes are required in the xds package.

- Custom routing rules can be added for the collector using discovery
  chain config entries. Initially the collector is expected to be
  deployed to each admin partition, but in the future could be deployed
  centrally in the default partition. These config entries could even be
  managed by HCP itself.
2023-03-10 13:52:54 -07:00
..
2019-03-27 08:54:56 -04:00
2019-03-27 08:54:56 -04:00
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2023-02-06 11:12:43 -08:00
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2022-09-06 10:28:59 -05:00

Consul API Client

This package provides the api package which provides programmatic access to the full Consul API.

The full documentation is available on Godoc.

Usage

Below is an example of using the Consul client. To run the example, you must first install Consul and Go.

To run the client API, create a new Go module.

go mod init consul-demo

Copy the example code into a file called main.go in the directory where the module is defined. As seen in the example, the Consul API is often imported with the alias capi.

package main

import (
	"fmt"

	capi "github.com/hashicorp/consul/api"
)

func main() {
	// Get a new client
	client, err := capi.NewClient(capi.DefaultConfig())
	if err != nil {
		panic(err)
	}

	// Get a handle to the KV API
	kv := client.KV()

	// PUT a new KV pair
	p := &capi.KVPair{Key: "REDIS_MAXCLIENTS", Value: []byte("1000")}
	_, err = kv.Put(p, nil)
	if err != nil {
		panic(err)
	}

	// Lookup the pair
	pair, _, err := kv.Get("REDIS_MAXCLIENTS", nil)
	if err != nil {
		panic(err)
	}
	fmt.Printf("KV: %v %s\n", pair.Key, pair.Value)
}

Install the Consul API dependency with go mod tidy.

In a separate terminal window, start a local Consul server.

consul agent -dev -node machine

Run the example.

go run .

You should get the following result printed to the terminal.

KV: REDIS_MAXCLIENTS 1000

After running the code, you can also view the values in the Consul UI on your local machine at http://localhost:8500/ui/dc1/kv