Configure Systemd Socket Activation

as new way for Poseidon to accept connections. This should reduce our issues caused by deployments.

.github/workflows/ci.yml

@@ -208,9 +208,20 @@ jobs:
           ./poseidon | tee poseidon.log &
           until curl -s --fail http://localhost:7200/api/v1/health ; do sleep 1; done
           make e2e-test
-      - name: Run e2e recovery tests
+      - name: Setup Poseidon Socket
         run: |
           killall poseidon
+          mkdir -p ~/.config/systemd/user
+          cp ./.github/workflows/resources/poseidon-minimal.socket ~/.config/systemd/user/poseidon.socket
+          cat ./.github/workflows/resources/poseidon-minimal.service | envsubst > ~/.config/systemd/user/poseidon.service
+          systemctl --user daemon-reload
+          systemctl --user start poseidon.socket
+      - name: Print Poseidon Failure logs
+        if: failure()
+        run: journalctl -xen --no-pager
+      - name: Run e2e recovery tests
+        run: |
+          tail -f /var/log/syslog &
           make e2e-test-recovery
         if: ${{ success() || failure() }}
       - name: Convert coverage reports

.github/workflows/resources/poseidon-minimal.service

@@ -0,0 +1,12 @@
+# This is a minimal service definition to make use of the systemd socket activation in the e2e tests.
+# With Systemd socket activation, systemd sets up a listening socket on behalf of a service.
+# This is useful for zero downtime deployments as the systemd sockets hold up the connections while the service is restarting.
+
+[Unit]
+Requires=poseidon.socket
+
+[Service]
+WorkingDirectory=${GITHUB_WORKSPACE}
+ExecStart=${GITHUB_WORKSPACE}/poseidon
+Restart=always
+Environment="POSEIDON_SERVER_SYSTEMDSOCKETACTIVATION=TRUE"

.github/workflows/resources/poseidon-minimal.socket

@@ -0,0 +1,4 @@
+# This is a minimal socket definition to provide a systemd socket for the Poseidon e2e tests.
+
+[Socket]
+ListenStream = 7200