Merge ~cjwatson/txpkgupload:charm-send-sftp-port into txpkgupload:master

[Colin Watson]

charm: Tell haproxy to send to the SFTP port

The arrangements to use whatever port the client used are only actually necessary for FTP. On production, we're using iptables to redirect incoming traffic on port 22 to port 5022, and not specifying the port causes haproxy to send traffic to port 22 on the backend, which is not what we want to happen.

[Ines Almeida (ines-almeida)]

Makes sense

review: Approve

[Ines Almeida (ines-almeida)]

Maybe we should add a little more information to the comment about why we want the haproxy using the same port as the request for the FTP case. A quick "This is necessary for passive FTP requests" should suffice

[Colin Watson (cjwatson)]

I didn't notice that comment before merging this, but I addressed it in https://code.launchpad.net/~cjwatson/txpkgupload/+git/txpkgupload/+merge/455553.

diff --git a/charm/txpkgupload/reactive/txpkgupload.py b/charm/txpkgupload/reactive/txpkgupload.py
index 689aa90..ab13487 100644
--- a/charm/txpkgupload/reactive/txpkgupload.py
+++ b/charm/txpkgupload/reactive/txpkgupload.py
@@ -250,9 +250,6 @@ def configure_loadbalancer():
     ftp_port = config["ftp_port"]
     sftp_port = config["sftp_port"]
 
-    # Note that we don't send specific ports for the services.servers list.
-    # Not setting a port makes the haproxy use the same port used in the
-    # client's request.
     services = [
         {
             "service_name": "txpkgupload-ftp",
@@ -263,6 +260,8 @@ def configure_loadbalancer():
                 [
                     f"ftp_{unit_name}",
                     unit_ip,
+                    # Not setting a port makes haproxy use the same port
+                    # used in the client's request.
                     "",
                     server_options.replace("{port}", str(ftp_port)),
                 ]
@@ -277,7 +276,7 @@ def configure_loadbalancer():
                 [
                     f"sftp_{unit_name}",
                     unit_ip,
-                    "",
+                    sftp_port,
                     server_options.replace("{port}", str(sftp_port)),
                 ]
             ],