Merge ~sajoupa/charm-telegraf:prometheus-client-default-port-9103 into charm-telegraf:master

[Laurent Sesquès]

when related with prometheus-client, if prometheus_output_port is unset, use :9103 by default instead of 9126

[Laurent Sesquès (sajoupa)]

pre-req MP: https://code.launchpad.net/~sajoupa/charm-telegraf/+git/telegraf-charm/+merge/397010

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

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

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

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[Haw Loeung (hloeung)]

LGTM

review: Approve (+1)

Unmerged commits

ea55458... by Laurent Sesquès on 2021-01-27

when related with prometheus-client, if prometheus_output_port is unset, use :9103 by default instead of 9126

3c4a87e... by Laurent Sesquès on 2021-01-27

small fix: move flag changes to the right if stanza for config.changed

f550c15... by Laurent Sesquès on 2021-01-27

Split prometheus_client output config out of the main config file. Allow a prometheus-client relation to prometheus even if prometheus_output_port is set (and use that port in the relation).

diff --git a/src/reactive/telegraf.py b/src/reactive/telegraf.py
index e2c0874..92998c7 100644
--- a/src/reactive/telegraf.py
+++ b/src/reactive/telegraf.py
@@ -1249,8 +1249,8 @@ def configure_prometheus_client_with_relation(prometheus):
         port = get_prometheus_port()
     else:
         # We have a relation with prometheus, but removed the port number config.
-        # Default to 9126.
-        port = "9126"
+        # Default to 9103.
+        port = "9103"
     # We'll iterate through the prometheus-client relation counterparts,
     # inform them of our address so that they scrape it, and get their egress subnets
     # so that we can allow them
diff --git a/src/tests/unit/test_telegraf.py b/src/tests/unit/test_telegraf.py
index 09e1575..9fcb1b3 100644
--- a/src/tests/unit/test_telegraf.py
+++ b/src/tests/unit/test_telegraf.py
@@ -1094,14 +1094,14 @@ def test_prometheus_client_output(mocker, monkeypatch, config):
     telegraf.configure_prometheus_client_with_relation(interface)
     expected = """
     [[outputs.prometheus_client]]
-  listen = ":9126"
+  listen = ":9103"
 """
     assert (
         configs_dir().join("prometheus_client.conf").read().strip() == expected.strip()
     )
     network_get_primary_address.assert_called_once_with("prometheus-client")
     interface.configure.assert_called_once_with(
-        "9126", hostname="foo", private_address="foo"
+        "9103", hostname="foo", private_address="foo"
     )