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Docs for Unix Domain Sockets (#10252) 

* Docs for Unix Domain Sockets

There are a number of cases where a user might wish to either 1)
expose a service through a Unix Domain Socket in the filesystem
('downstream') or 2) connect to an upstream service by a local unix
domain socket (upstream).
As of Consul (1.10-beta2) we've added new syntax and support to configure
the Envoy proxy to support this
To connect to a service via local Unix Domain Socket instead of a
port, add local_bind_socket_path and optionally local_bind_socket_mode
to the upstream config for a service:
    upstreams = [
      {
         destination_name = "service-1"
         local_bind_socket_path = "/tmp/socket_service_1"
         local_bind_socket_mode = "0700"
	 ...
      }
      ...
    ]
This will cause Envoy to create a socket with the path and mode
provided, and connect that to service-1
The mode field is optional, and if omitted will use the default mode
for Envoy. This is not applicable for abstract sockets. See
https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/core/v3/address.proto#envoy-v3-api-msg-config-core-v3-pipe
for details
NOTE: These options conflict the local_bind_socket_port and
local_bind_socket_address options. We can bind to an port or we can
bind to a socket, but not both.
To expose a service listening on a Unix Domain socket to the service
mesh use either the 'socket_path' field in the service definition or the
'local_service_socket_path' field in the proxy definition. These
fields are analogous to the 'port' and 'service_port' fields in their
respective locations.
    services {
      name = "service-2"
      socket_path = "/tmp/socket_service_2"
      ...
    }
OR
    proxy {
      local_service_socket_path = "/tmp/socket_service_2"
      ...
    }
There is no mode field since the service is expected to create the
socket it is listening on, not the Envoy proxy.
Again, the socket_path and local_service_socket_path fields conflict
with address/port and local_service_address/local_service_port
configuration entries.
Set up a simple service mesh with dummy services:
socat -d UNIX-LISTEN:/tmp/downstream.sock,fork UNIX-CONNECT:/tmp/upstream.sock
socat -v tcp-l:4444,fork exec:/bin/cat
services {
  name = "sock_forwarder"
  id = "sock_forwarder.1"
  socket_path = "/tmp/downstream.sock"
  connect {
    sidecar_service {
      proxy {
	upstreams = [
	  {
	    destination_name = "echo-service"
	    local_bind_socket_path = "/tmp/upstream.sock"
	    config {
	      passive_health_check {
		interval = "10s"
		max_failures = 42
	      }
	    }
	  }
	]
      }
    }
  }
}
services {
  name = "echo-service"
  port = 4444
  connect = { sidecar_service {} }
Kind = "ingress-gateway"
Name = "ingress-service"
Listeners = [
 {
   Port = 8080
   Protocol = "tcp"
   Services = [
     {
       Name = "sock_forwarder"
     }
   ]
 }
]
consul agent -dev -enable-script-checks -config-dir=./consul.d
consul connect envoy -sidecar-for sock_forwarder.1
consul connect envoy -sidecar-for echo-service -admin-bind localhost:19001
consul config write ingress-gateway.hcl
consul connect envoy -gateway=ingress -register -service ingress-service -address '{{ GetInterfaceIP "eth0" }}:8888' -admin-bind localhost:19002
netcat 127.0.0.1 4444
netcat 127.0.0.1 8080

Signed-off-by: Mark Anderson <manderson@hashicorp.com>

* fixup Unix capitalization

Signed-off-by: Mark Anderson <manderson@hashicorp.com>

* Update website/content/docs/connect/registration/service-registration.mdx

Co-authored-by: Blake Covarrubias <blake@covarrubi.as>

* Provide examples in hcl and json

Signed-off-by: Mark Anderson <manderson@hashicorp.com>

* Apply suggestions from code review

Co-authored-by: Blake Covarrubias <blake@covarrubi.as>

* One more fixup for docs

Signed-off-by: Mark Anderson <manderson@hashicorp.com>

Co-authored-by: Blake Covarrubias <blake@covarrubi.as>
This commit is contained in:
Mark Anderson 2021-06-04 18:54:31 -07:00 committed by hc-github-team-consul-core
parent d81aa604e3
commit 884135eae5
2 changed files with 140 additions and 1 deletions
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137
website/content/docs/connect/registration/service-registration.mdx
View File

@ -81,6 +81,7 @@ registering a proxy instance.
"destination_service_id": "redis1",
"local_service_address": "127.0.0.1",
"local_service_port": 9090,
"local_service_socket_path": "/tmp/redis.sock",
"mode": "transparent",
"transparent_proxy": {},
"config": {},
@ -117,6 +118,10 @@ registering a proxy instance.
Defaults to the port advertised by the service instance identified by
`destination_service_id` if it exists otherwise it may be empty in responses.
- `local_service_socket_path` - The path of a Unix domain socket to connect to the local application
instance. This is created by the application. This conflicts with `local_service_address`
and `local_service_port`. This is only supported when using Envoy for the proxy.
- `mode` `(string: "")` <sup>Beta</sup> - One of \`direct\` or \`transparent\`. Added in v1.10.0.
- `"transparent"` - represents that inbound and outbound application traffic is being
captured and redirected through the proxy. This mode does not enable the traffic redirection
@ -166,6 +171,8 @@ followed by documentation for each attribute.
"datacenter": "dc1",
"local_bind_address": "127.0.0.1",
"local_bind_port": 1234,
"local_bind_socket_path": "/tmp/redis_5678.sock",
"local_bind_socket_mode": "0700",
"config": {},
"mesh_gateway": {
"mode": "local"
@ -195,6 +202,12 @@ followed by documentation for each attribute.
- `local_bind_address` `(string: "")` - Specifies the address to bind a
local listener to for the application to make outbound connections to this
upstream. Defaults to `127.0.0.1`.
- `local_bind_socket_path` `(string: "")` - Specifies the path at which to bind a Unix
domain socket listener for the application to make outbound connections to
this upstream. This conflicts with specifying the local_bind_port
or local_bind_address. This is only supported when using Envoy as a proxy.
- `local_bind_socket_mode` `(string: "")` - Specifies the (optional) Unix octal
file permissions to use for the socket.
- `destination_type` `(string: "")` - Specifies the type of discovery
query to use to find an instance to connect to. Valid values are `service` or
`prepared_query`. Defaults to `service`.
@ -353,3 +366,127 @@ registrations](/docs/agent/services#service-definition-parameter-case).
the listener to be set up. If the port is not free then Envoy will not expose a listener for the path,
but the proxy registration will not fail.
- `protocol` `(string: "http")` - Sets the protocol of the listener. One of `http` or `http2`. For gRPC use `http2`.
### Unix Domain Sockets <sup>Beta</sup>
The following examples show additional configuration for Unix domain sockets.
Added in v1.10.0.
To connect to a service via local Unix Domain Socket instead of a
port, add `local_bind_socket_path` and optionally `local_bind_socket_mode`
to the upstream config for a service:
<Tabs>
<Tab heading="HCL">
```hcl
upstreams = [
{
destination_name = "service-1"
local_bind_socket_path = "/tmp/socket_service_1"
local_bind_socket_mode = "0700"
}
]
```
</Tab>
<Tab heading="JSON">
```json
"upstreams": [
{
"destination_name": "service-1",
"local_bind_socket_path": "/tmp/socket_service_1",
"local_bind_socket_mode": "0700"
}
]
```
</Tab>
</Tabs>
This will cause Envoy to create a socket with the path and mode
provided, and connect that to service-1.
The mode field is optional, and if omitted will use the default mode
for Envoy. This is not applicable for abstract sockets. See the
[Envoy documentation](https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/core/v3/address.proto#envoy-v3-api-msg-config-core-v3-pipe)
for details.
-> These options conflict with the `local_bind_socket_port` and
`local_bind_socket_address` options. For a given upstream the proxy can bind either to an IP port or
a Unix socket, but not both.
Similarly to expose a service listening on a Unix Domain socket to the service
mesh, use either the `socket_path` field in the service definition or the
`local_service_socket_path` field in the proxy definition. These
fields are analogous to the `port` and `service_port` fields in their
respective locations.
<Tabs>
<Tab heading="HCL">
```hcl
services {
name = "service-2"
socket_path = "/tmp/socket_service_2"
}
```
</Tab>
<Tab heading="JSON">
```json
"services": {
"name": "service-2",
"socket_path": "/tmp/socket_service_2"
}
```
</Tab>
</Tabs>
Or in the proxy definition:
<Tabs>
<Tab heading="HCL">
```hcl
services {
name = "socket_service_2"
connect {
sidecar_service {
proxy {
name = "service-2"
local_service_socket_path = "/tmp/socket_service_2"
...
}
}
}
}
```
</Tab>
<Tab heading="JSON">
```json
"services": {
"name": "socket_service_2",
"connect": {
"sidecar_service": {
"proxy": {
"name": "service-2",
"local_service_socket_path": "/tmp/socket_service_2"
...
}
}
}
}
```
</Tab>
</Tabs>
There is no mode field since the service is expected to create the
socket it is listening on, not the Envoy proxy.
Again, the `socket_path` and `local_service_socket_path` fields conflict
with `address`/`port` and `local_service_address`/`local_service_port`
configuration options.

2
website/content/docs/discovery/services.mdx
View File

@ -54,6 +54,7 @@ example shows all possible fields, but note that only a few are required.
}
},
"port": 8000,
"socket_path: "/tmp/redis.sock",
"enable_tag_override": false,
"checks": [
{
@ -68,6 +69,7 @@ example shows all possible fields, but note that only a few are required.
"destination_service_id": "redis1",
"local_service_address": "127.0.0.1",
"local_service_port": 9090,
"local_service_socket_path": "/tmp/redis.sock",
"mode": "transparent",
"transparent_proxy": {
"outbound_listener_port": 22500