Merge ~woutervb/charm-graylog:bug/1818615 into ~graylog-charmers/charm-graylog:master

[Wouter van Bommel]

Determine default network interface

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[Xav Paice (xavpaice)]

couple of diff comments, plus Haw's review

review: Needs Fixing

Unmerged commits

909907e... by Wouter van Bommel on 2020-02-13

Determine default network interface

The behaviour around the rest_transport_uri has been changed in such a
way that it now is allowed to specify 0.0.0.0 as the default address.
This will trigger a piece of code that will substitute this address with
the ip address connected to the default gateway interface.
This should give the sane results in most situations, while it still
allows to be overridden.

This commit fixes bug: lp:1818615

diff --git a/config.yaml b/config.yaml
index d0d2649..4ac707e 100644
--- a/config.yaml
+++ b/config.yaml
@@ -35,16 +35,19 @@ options:
       Example: http://10.0.0.1:9000/
   rest_transport_uri:
     type: string
-    default: ""
+    default: "http://0.0.0.0:9001/api/"
     description: |
       If set, this will be promoted in the cluster discovery APIs. You will need
       to define this if your Graylog server is running behind a HTTP proxy that
-      is rewriting the scheme, host name, or URI. This must not contain a
-      wildcard address (0.0.0.0).
+      is rewriting the scheme, host name, or URI.
 
       For Graylog 2, this usually takes the form http://10.0.0.1:9001/api/.
       For Graylog 3 and higher, this is known as the 'http_publish_uri' and looks
       like http://10.0.0.1:9000/.
+      
+      If the ip address 0.0.0.0 is specified, the charm will attempt to deduct
+      the network interface that is used for connections to the default gateway and
+      use the associated ip address.
   index_replicas:
     type: int
     default: 0
diff --git a/lib/charms/layer/graylog/utils.py b/lib/charms/layer/graylog/utils.py
index cf89b61..a3e35bd 100644
--- a/lib/charms/layer/graylog/utils.py
+++ b/lib/charms/layer/graylog/utils.py
@@ -1,3 +1,6 @@
+import socket
+from urllib.parse import urlparse
+
 from charmhelpers.core import hookenv
 from charms.layer import snap
 
@@ -39,4 +42,33 @@ def validate_api_uri(uri):
             hookenv.log("Removing 'api/' from the configurted REST API options")
             uri = uri[:-4]
 
+    parsed_url = urlparse(uri)
+    if parsed_url.hostname == '0.0.0.0':
+        uri = parsed_url._replace(netloc='%s:%s' % (get_ip_address(),
+                                                    parsed_url.port))\
+            .geturl()
+
     return uri
+
+
+def get_ip_address():
+    """Determine the ip address that would be used for outgoing connection.
+
+    This function tries to determine the network ip address, that would be used
+    when access servers in the internet. It uses a dummy UDP connection todo
+    so.
+    As the connection itself is not made, it is safe to use any address.
+    """
+
+    # Start a socket via ipv4, using UDP
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+
+    # Make dummy attempt to ntp servers from the pool.ntp.org, we hard code one
+    # of them
+
+    sock.connect(("220.158.215.21", 123))
+
+    ip = sock.getsockname()[0]
+    sock.close()
+    print('Found ip [%s] to use' % ip)
+    return ip
diff --git a/reactive/graylog.py b/reactive/graylog.py
index b26ad96..0dead17 100644
--- a/reactive/graylog.py
+++ b/reactive/graylog.py
@@ -155,8 +155,8 @@ def configure_graylog():
                 db.set('web_listen_port', url.port)
                 hookenv.open_port(url.port)
 
-        if conf['rest_transport_uri']:
-            set_conf('rest_transport_uri', validate_api_uri(conf['rest_transport_uri']))
+        # We always call set this, so it gets a sensible default
+        set_conf('rest_transport_uri', validate_api_uri(conf['rest_transport_uri']))
 
         if conf['web_endpoint_uri']:
             set_conf('web_endpoint_uri', validate_api_uri(conf['web_endpoint_uri']))
@@ -164,8 +164,8 @@ def configure_graylog():
         if conf['web_listen_uri']:
             url = urlparse(conf['web_listen_uri'])
             set_conf('http_bind_address', url.netloc)
-        if conf['rest_transport_uri']:
-            set_conf('http_publish_uri', validate_api_uri(conf['rest_transport_uri']))
+        # We always call set this, so it gets a sensible default
+        set_conf('http_publish_uri', validate_api_uri(conf['rest_transport_uri']))
         if conf['web_endpoint_uri']:
             set_conf('http_external_uri', validate_api_uri(conf['web_endpoint_uri']))