first commit

2026-09-09 23:15:49 +02:00
commit 71cd045e96
15 changed files with 570 additions and 0 deletions
@@ -0,0 +1,113 @@
+# tcp-echo
+
+Minimal .NET 8 TCP echo server. Every reply is prefixed with the instance identifier
+(`INSTANCE_ID` env var, falling back to the hostname), and a `[<id>] connected` line is sent on connect.
+
+Two instances are deployed behind Traefik:
+
+| Instance | INSTANCE_ID | External port |
+|----------|-------------|---------------|
+| a        | echo-a      | 9098          |
+| b        | echo-b      | 9099          |
+
+## Build and push
+
+Requires a prior `docker login gitea.eitczech.com`.
+
+```powershell
+./build-push.ps1 -Tag 1.0.0              # pushes gitea.eitczech.com/public/tcp-echo-server:1.0.0
+./build-push.ps1 -Tag 1.0.0 -AlsoLatest  # additionally pushes :latest
+```
+
+The manifests reference `gitea.eitczech.com/public/tcp-echo-server:latest`. To pin a specific tag either edit
+`k8s/instance-a.yaml` / `k8s/instance-b.yaml`, or after `kubectl apply -k` run:
+
+```sh
+kubectl -n tcp-echo set image deploy/tcp-echo-a deploy/tcp-echo-b tcp-echo=gitea.eitczech.com/public/tcp-echo-server:1.0.0
+```
+
+If the Gitea registry is private, create a pull secret in the namespace and reference it via `imagePullSecrets`.
+
+### Package description on Gitea
+
+The `Dockerfile` sets the standard OCI labels (`org.opencontainers.image.*`). Gitea reads them from the pushed
+image and shows them on the package page:
+
+| Label            | Shown as / effect                                                              |
+|------------------|--------------------------------------------------------------------------------|
+| `description`    | Package description text                                                       |
+| `source`         | Links the package to the repository with the same URL (repo must exist first)  |
+| `url`, `documentation`, `licenses`, `authors`, `vendor` | Metadata section on the package page   |
+| `version`, `revision`, `created` | Filled in by `build-push.ps1` from the tag, git commit and current time |
+
+To change the description, edit the `LABEL` in `Dockerfile` and rebuild. If the package was pushed before the
+repository existed, link it manually: package page -> **Settings** -> **Link to repository**.
+
+## Deploy
+
+```sh
+kubectl apply -k k8s/
+kubectl -n tcp-echo rollout status deploy/tcp-echo-a deploy/tcp-echo-b
+```
+
+`30-traefik-entrypoint.yaml` adds `tcpechoa` (9098) and `tcpechob` (9099) entrypoints to the k3s-managed
+Traefik (Traefik restarts once). For a Helm-managed Traefik, drop that file from `kustomization.yaml` and run:
+
+```sh
+helm upgrade traefik traefik/traefik -n kube-system --reuse-values -f k8s/traefik-values.yaml
+```
+
+If Traefik's Service is a LoadBalancer, make sure the cloud/VPS firewall allows TCP 9098 and 9099.
+
+## Test
+
+### Linux / macOS
+
+```sh
+$ nc <server-ip> 9098
+[echo-a] connected
+hello
+[echo-a] hello
+
+$ nc <server-ip> 9099
+[echo-b] connected
+hello
+[echo-b] hello
+```
+
+### Windows (PowerShell)
+
+Windows has no `nc`. Use the included script, which opens a TCP connection, prints the greeting,
+sends a message and prints the echoed reply:
+
+```powershell
+.	est-echo.ps1 -Server <server-ip> -Port 9098
+.	est-echo.ps1 -Server <server-ip> -Port 9099 -Message "ping"
+```
+
+Expected output:
+
+```
+Connecting to <server-ip>:9098 ...
+<- [echo-a] connected
+-> hello
+<- [echo-a] hello
+```
+
+Just to check the port is reachable (no echo):
+
+```powershell
+Test-NetConnection -ComputerName <server-ip> -Port 9098
+```
+
+For an interactive session, `telnet <server-ip> 9098` works if the Telnet Client feature is enabled
+(`Enable-WindowsOptionalFeature -Online -FeatureName TelnetClient`), or install `ncat` via `winget install Insecure.Nmap`.
+
+### Local test with Docker
+
+```powershell
+docker build -t tcp-echo:local .
+docker run --rm -d --name tcp-echo-test -e INSTANCE_ID=echo-local -p 9099:9099 tcp-echo:local
+.	est-echo.ps1 -Server localhost -Port 9099
+docker rm -f tcp-echo-test
+```