measurement: ip query

Adds `ip` measurement (executable `netrics-ip`) to retrieve public IP
address and write as a result.

Measurement is added to default configuration, but easily disableable
by setting device environment variable `NETRICS_IP_QUERY=0`.

resolves #24

part of #3

pyproject.toml

@@ -28,6 +28,7 @@ netrics-dns-latency = "netrics.measurement.dns_latency:main"
 netrics-hops = "netrics.measurement.hops:main"
 netrics-hops-scamper = "netrics.measurement.hops:main"
 netrics-hops-traceroute = "netrics.measurement.hops_traceroute:main"
+netrics-ip = "netrics.measurement.ip:main"
 netrics-lml = "netrics.measurement.lml:main"
 netrics-lml-scamper = "netrics.measurement.lml:main"
 netrics-lml-traceroute = "netrics.measurement.lml_traceroute:main"

src/netrics/conf/include/measurements.yaml

@@ -11,6 +11,10 @@ hops-scamper:
   schedule: "H/5 * * * *"
   if: *scamper-on
 
+ip:
+  schedule: "H/5 * * * *"
+  unless: env.NETRICS_IP_QUERY | default('1') | int == 0
+
 lml:
   command: lml-traceroute
   schedule: "H/5 * * * *"

src/netrics/measurement/ip.py

@@ -0,0 +1,79 @@
+"""Retrieve public IP address from configured service."""
+import ipaddress
+import urllib
+
+from schema import Optional
+
+from netrics import task
+
+from .common import require_lan
+
+
+PARAMS = task.schema.extend('ipquery', {
+    Optional('service', default='https://api.ipify.org/'): task.schema.Text,
+})
+
+
+@task.param.require(PARAMS)
+@require_lan
+def main(params):
+    """Retrieve public IP address from configured service.
+
+    The local network is queried first to ensure operation.
+    (See: `require_lan`.)
+
+    An HTTP request is then made of the configured IP address service
+    (`service`).
+
+    This configured service is expected to return a response with status
+    `200` and body of the IP address (without additional content).
+
+    The IP address is written out as a structured result according to
+    configuration (`result`).
+
+    """
+    # initiate HTTP request
+    try:
+        response = urllib.request.urlopen(params.service)
+    except OSError as exc:
+        task.log.critical(
+            url=params.service,
+            error=str(exc),
+            msg='urlopen error',
+        )
+        return task.status.no_host
+
+    # check OK
+    if response.status != 200:
+        content = response.read()
+
+        if len(content) > 75:
+            content = content[:72] + '...'
+
+        task.log.critical(
+            url=params.service,
+            status=f'Error ({response.status})',
+            msg=content,
+        )
+
+        return task.status.no_host
+
+    # retrieve response
+    ip_addr = response.read().decode()
+
+    # validate response
+    try:
+        ipaddress.ip_address(ip_addr)
+    except ValueError as exc:
+        task.log.critical(
+            url=params.service,
+            response=ip_addr,
+            error=str(exc),
+            msg='service response error',
+        )
+        return task.status.software_error
+
+    # write result
+    task.result.write({'ipv4': ip_addr},
+                      label=params.result.label,
+                      annotate=params.result.annotate)