Make mastodon-streaming systemd unit templated (#24751)

Co-authored-by: Emelia Smith <ThisIsMissEm@users.noreply.github.com>

dist/mastodon-streaming.service

@@ -1,51 +1,12 @@
 [Unit]
 Description=mastodon-streaming
 After=network.target
+Wants=mastodon-streaming@4000.service
 
 [Service]
-Type=simple
-User=mastodon
-WorkingDirectory=/home/mastodon/live
-Environment="NODE_ENV=production"
-Environment="PORT=4000"
-ExecStart=/usr/bin/node ./streaming
-TimeoutSec=15
-Restart=always
-LimitNOFILE=65536
-# Proc filesystem
-ProcSubset=pid
-ProtectProc=invisible
-# Capabilities
-CapabilityBoundingSet=
-# Security
-NoNewPrivileges=true
-# Sandboxing
-ProtectSystem=strict
-PrivateTmp=true
-PrivateDevices=true
-PrivateUsers=true
-ProtectHostname=true
-ProtectKernelLogs=true
-ProtectKernelModules=true
-ProtectKernelTunables=true
-ProtectControlGroups=true
-RestrictAddressFamilies=AF_INET
-RestrictAddressFamilies=AF_INET6
-RestrictAddressFamilies=AF_NETLINK
-RestrictAddressFamilies=AF_UNIX
-RestrictNamespaces=true
-LockPersonality=true
-RestrictRealtime=true
-RestrictSUIDSGID=true
-RemoveIPC=true
-PrivateMounts=true
-ProtectClock=true
-# System Call Filtering
-SystemCallArchitectures=native
-SystemCallFilter=~@cpu-emulation @debug @keyring @ipc @memlock @mount @obsolete @privileged @resources @setuid
-SystemCallFilter=pipe
-SystemCallFilter=pipe2
-ReadWritePaths=/home/mastodon/live
+Type=oneshot
+ExecStart=/bin/echo "mastodon-streaming exists only to collectively start and stop mastodon-streaming@ instances, shimming over the migration to templated mastodon-streaming systemd unit"
+RemainAfterExit=yes
 
 [Install]
 WantedBy=multi-user.target

dist/mastodon-streaming@.service

@@ -0,0 +1,54 @@
+[Unit]
+Description=mastodon-streaming on port %I
+After=network.target
+# handles using `systemctl restart mastodon-streaming`
+PartOf=mastodon-streaming.service
+ReloadPropagatedFrom=mastodon-streaming.service
+
+[Service]
+Type=simple
+User=mastodon
+WorkingDirectory=/home/mastodon/live
+Environment="NODE_ENV=production"
+Environment="PORT=%i"
+ExecStart=/usr/bin/node ./streaming
+TimeoutSec=15
+Restart=always
+LimitNOFILE=65536
+# Proc filesystem
+ProcSubset=pid
+ProtectProc=invisible
+# Capabilities
+CapabilityBoundingSet=
+# Security
+NoNewPrivileges=true
+# Sandboxing
+ProtectSystem=strict
+PrivateTmp=true
+PrivateDevices=true
+PrivateUsers=true
+ProtectHostname=true
+ProtectKernelLogs=true
+ProtectKernelModules=true
+ProtectKernelTunables=true
+ProtectControlGroups=true
+RestrictAddressFamilies=AF_INET
+RestrictAddressFamilies=AF_INET6
+RestrictAddressFamilies=AF_NETLINK
+RestrictAddressFamilies=AF_UNIX
+RestrictNamespaces=true
+LockPersonality=true
+RestrictRealtime=true
+RestrictSUIDSGID=true
+RemoveIPC=true
+PrivateMounts=true
+ProtectClock=true
+# System Call Filtering
+SystemCallArchitectures=native
+SystemCallFilter=~@cpu-emulation @debug @keyring @ipc @memlock @mount @obsolete @privileged @resources @setuid
+SystemCallFilter=pipe
+SystemCallFilter=pipe2
+ReadWritePaths=/home/mastodon/live
+
+[Install]
+WantedBy=multi-user.target mastodon-streaming.service

dist/nginx.conf

@@ -8,7 +8,15 @@ upstream backend {
 }
 
 upstream streaming {
+    # Instruct nginx to send connections to the server with the least number of connections
+    # to ensure load is distributed evenly.
+    least_conn;
+
     server 127.0.0.1:4000 fail_timeout=0;
+    # Uncomment these lines for load-balancing multiple instances of streaming for scaling,
+    # this assumes your running the streaming server on ports 4000, 4001, and 4002:
+    # server 127.0.0.1:4001 fail_timeout=0;
+    # server 127.0.0.1:4002 fail_timeout=0;
 }
 
 proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=CACHE:10m inactive=7d max_size=1g;