infra/stacks/terminal/main.tf
Viktor Barzin f4807a22f8 terminal: probe + alerts after Traefik replica routing-table skew
User reported "site loads but failed to connect on the tmux session". Root
cause was a Traefik replica (traefik-db7696fbf-ktjjz) that came up missing
the kubernetes_ingress-derived router for terminal.viktorbarzin.me — only
the IngressRoute CRDs registered. About 1/3 of /token preflight requests
landed on that replica and got 404 with router="-", and WS upgrades
intermittently failed the same way, so the lobby iframe stayed stuck on
"Failed to connect. Retrying...". `kubectl delete pod` on the bad replica
restored the missing router and unblocked the user.

This commit adds the long-term mitigation:

stacks/terminal/main.tf
  - kubernetes_cron_job_v1.webterminal_probe runs every 5min, hits
    /token + /ws via Cloudflare and the in-cluster ttyd Service, pushes
    4 gauges to Pushgateway (token_status, ws_status, ttyd_status,
    last_success_timestamp). Verified the probe end-to-end:
      token=302 ws=302 ttyd=200 ok=1

stacks/monitoring/modules/monitoring/prometheus_chart_values.tpl
  - Webterminal group: WebterminalTokenDegraded (warning, 10m),
    WebterminalWebsocketDegraded (critical, 10m),
    WebterminalTtydUnreachable (critical, 10m),
    WebterminalProbeStale (warning, 15m).
  - Traefik Router Parity group: TraefikRouterCountSkew fires when any
    Traefik replica's router count diverges from siblings for >10m —
    catches the same class of issue cluster-wide, not just for terminal.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-17 10:04:26 +00:00

484 lines
15 KiB
HCL

variable "tls_secret_name" {
type = string
sensitive = true
}
resource "kubernetes_namespace" "terminal" {
metadata {
name = "terminal"
labels = {
"istio-injection" : "disabled"
tier = local.tiers.aux
"keel.sh/enrolled" = "true"
}
}
lifecycle {
# KYVERNO_LIFECYCLE_V1: goldilocks-vpa-auto-mode ClusterPolicy stamps this label on every namespace
ignore_changes = [metadata[0].labels["goldilocks.fairwinds.com/vpa-update-mode"]]
}
}
module "tls_secret" {
source = "../../modules/kubernetes/setup_tls_secret"
namespace = kubernetes_namespace.terminal.metadata[0].name
tls_secret_name = var.tls_secret_name
}
# Service + Endpoints to reverse-proxy to ttyd at 10.0.10.10:7681
resource "kubernetes_service" "terminal" {
metadata {
name = "terminal"
namespace = kubernetes_namespace.terminal.metadata[0].name
labels = {
app = "terminal"
}
}
spec {
port {
name = "http"
port = 80
target_port = 7681
}
}
}
resource "kubernetes_endpoints" "terminal" {
metadata {
name = "terminal"
namespace = kubernetes_namespace.terminal.metadata[0].name
}
subset {
address {
ip = "10.0.10.10"
}
port {
name = "http"
port = 7681
}
}
}
module "ingress" {
source = "../../modules/kubernetes/ingress_factory"
dns_type = "proxied"
namespace = kubernetes_namespace.terminal.metadata[0].name
name = "terminal"
tls_secret_name = var.tls_secret_name
auth = "required"
extra_annotations = {
"gethomepage.dev/enabled" = "true"
"gethomepage.dev/name" = "Terminal"
"gethomepage.dev/description" = "Web terminal (ttyd)"
"gethomepage.dev/icon" = "mdi-console"
"gethomepage.dev/group" = "Infrastructure"
"gethomepage.dev/pod-selector" = ""
}
}
# Read-only terminal session at terminal-ro.viktorbarzin.me
resource "kubernetes_service" "terminal_ro" {
metadata {
name = "terminal-ro"
namespace = kubernetes_namespace.terminal.metadata[0].name
labels = {
app = "terminal-ro"
}
}
spec {
port {
name = "http"
port = 80
target_port = 7682
}
}
}
resource "kubernetes_endpoints" "terminal_ro" {
metadata {
name = "terminal-ro"
namespace = kubernetes_namespace.terminal.metadata[0].name
}
subset {
address {
ip = "10.0.10.10"
}
port {
name = "http"
port = 7682
}
}
}
# Clipboard image upload service (same-origin path routing)
resource "kubernetes_service" "clipboard_upload" {
metadata {
name = "clipboard-upload"
namespace = kubernetes_namespace.terminal.metadata[0].name
labels = {
app = "clipboard-upload"
}
}
spec {
port {
name = "http"
port = 80
target_port = 7683
}
}
}
resource "kubernetes_endpoints" "clipboard_upload" {
metadata {
name = "clipboard-upload"
namespace = kubernetes_namespace.terminal.metadata[0].name
}
subset {
address {
ip = "10.0.10.10"
}
port {
name = "http"
port = 7683
}
}
}
# IngressRoute for /clipboard/* on terminal.viktorbarzin.me → clipboard-upload service
resource "kubernetes_manifest" "clipboard_ingressroute" {
manifest = {
apiVersion = "traefik.io/v1alpha1"
kind = "IngressRoute"
metadata = {
name = "clipboard-upload"
namespace = kubernetes_namespace.terminal.metadata[0].name
}
spec = {
entryPoints = ["websecure"]
routes = [{
match = "Host(`terminal.viktorbarzin.me`) && PathPrefix(`/clipboard/`)"
kind = "Rule"
middlewares = [
{
name = "authentik-forward-auth"
namespace = "traefik"
},
{
name = "clipboard-strip-prefix"
namespace = kubernetes_namespace.terminal.metadata[0].name
}
]
services = [{
name = "clipboard-upload"
port = 80
}]
}]
tls = {
secretName = var.tls_secret_name
}
}
}
}
resource "kubernetes_manifest" "clipboard_strip_prefix" {
manifest = {
apiVersion = "traefik.io/v1alpha1"
kind = "Middleware"
metadata = {
name = "clipboard-strip-prefix"
namespace = kubernetes_namespace.terminal.metadata[0].name
}
spec = {
stripPrefix = {
prefixes = ["/clipboard"]
}
}
}
}
module "ingress_ro" {
source = "../../modules/kubernetes/ingress_factory"
dns_type = "proxied"
namespace = kubernetes_namespace.terminal.metadata[0].name
name = "terminal-ro"
tls_secret_name = var.tls_secret_name
auth = "required"
extra_annotations = {
"gethomepage.dev/enabled" = "true"
"gethomepage.dev/name" = "Terminal (Read-Only)"
"gethomepage.dev/description" = "Read-only web terminal (ttyd)"
"gethomepage.dev/icon" = "mdi-console"
"gethomepage.dev/group" = "Infrastructure"
"gethomepage.dev/pod-selector" = ""
}
}
# === Multi-session lobby on terminal.viktorbarzin.me ===
#
# Application code (frontend, tmux-api, clipboard-upload, DevVM
# systemd units / scripts / config) lives in a separate Forgejo repo:
# https://forgejo.viktorbarzin.me/viktor/terminal-lobby
#
# That repo's ./scripts/deploy.sh ships everything to wizard@10.0.10.10
# and restarts ttyd / ttyd-ro / tmux-api / clipboard-upload. This stack
# only owns the Kubernetes side: Services, Endpoints pointing at
# 10.0.10.10:{7681,7682,7683,7684}, the IngressRoutes, and the Traefik
# middlewares that gate everything behind Authentik forward-auth.
#
# Service map (DevVM):
# ttyd :7681 → serves lobby + xterm WS
# ttyd-ro :7682 → read-only mirror at terminal-ro.viktorbarzin.me
# clipboard-upload :7683 → POST /upload, returns saved path
# tmux-api :7684 → GET /sessions, DELETE /sessions/<n>,
# POST /sessions/<n>/rename, GET /whoami
# Service+Endpoints → tmux-api on the DevVM (port 7684).
resource "kubernetes_service" "tmux_api" {
metadata {
name = "tmux-api"
namespace = kubernetes_namespace.terminal.metadata[0].name
labels = {
app = "tmux-api"
}
}
spec {
port {
name = "http"
port = 80
target_port = 7684
}
}
}
resource "kubernetes_endpoints" "tmux_api" {
metadata {
name = "tmux-api"
namespace = kubernetes_namespace.terminal.metadata[0].name
}
subset {
address {
ip = "10.0.10.10"
}
port {
name = "http"
port = 7684
}
}
}
# IngressRoute: /api/sessions/* on terminal.viktorbarzin.me → tmux-api
# service. Path-prefix specificity beats the catch-all `module.ingress`
# (terminal.viktorbarzin.me → ttyd) above, so the lobby HTML reaches
# tmux-api directly while everything else flows to ttyd.
resource "kubernetes_manifest" "tmux_api_ingressroute" {
manifest = {
apiVersion = "traefik.io/v1alpha1"
kind = "IngressRoute"
metadata = {
name = "tmux-api"
namespace = kubernetes_namespace.terminal.metadata[0].name
}
spec = {
entryPoints = ["websecure"]
routes = [{
match = "Host(`terminal.viktorbarzin.me`) && PathPrefix(`/api/sessions/`)"
kind = "Rule"
middlewares = [
{
name = "authentik-forward-auth"
namespace = "traefik"
},
{
name = "tmux-api-strip-prefix"
namespace = kubernetes_namespace.terminal.metadata[0].name
}
]
services = [{
name = "tmux-api"
port = 80
}]
}]
tls = {
secretName = var.tls_secret_name
}
}
}
}
resource "kubernetes_manifest" "tmux_api_strip_prefix" {
manifest = {
apiVersion = "traefik.io/v1alpha1"
kind = "Middleware"
metadata = {
name = "tmux-api-strip-prefix"
namespace = kubernetes_namespace.terminal.metadata[0].name
}
spec = {
stripPrefix = {
prefixes = ["/api/sessions"]
}
}
}
}
# =============================================================================
# Webterminal probe (added 2026-05-17 after a Traefik replica came up with a
# partial routing table — only the IngressRoute CRDs registered; the
# kubernetes_ingress for terminal.viktorbarzin.me was missing, so ~70% of
# /token requests routed to that replica returned 404 with router="-". The
# lobby's WebSocket retry loop kept the user stuck on "Failed to connect.
# Retrying..." because Cloudflare → that replica → 404 broke /token and the
# /ws upgrade intermittently.
#
# The probe exercises the full external path (Cloudflare → Traefik → ttyd
# Service) every 5 minutes and pushes 4 gauges to Pushgateway:
# webterminal_probe_token_status — HTTP status of GET /token (want 302)
# webterminal_probe_ws_status — HTTP status of WS upgrade /ws (want 302)
# webterminal_probe_ttyd_status — In-cluster ttyd /token (want 200)
# webterminal_probe_last_success_timestamp — Unix ts of last fully-OK run
#
# Alerts live in monitoring/prometheus_chart_values.tpl group "Webterminal".
# =============================================================================
resource "kubernetes_cron_job_v1" "webterminal_probe" {
metadata {
name = "webterminal-probe"
namespace = kubernetes_namespace.terminal.metadata[0].name
}
spec {
concurrency_policy = "Forbid"
failed_jobs_history_limit = 3
successful_jobs_history_limit = 1
schedule = "*/5 * * * *"
job_template {
metadata {}
spec {
backoff_limit = 1
ttl_seconds_after_finished = 600
template {
metadata {
labels = {
app = "webterminal-probe"
}
}
spec {
restart_policy = "OnFailure"
container {
name = "probe"
image = "docker.io/library/alpine:3.20"
image_pull_policy = "IfNotPresent"
resources {
requests = {
cpu = "10m"
memory = "32Mi"
}
limits = {
memory = "96Mi"
}
}
env {
name = "TARGET_HOST"
value = "terminal.viktorbarzin.me"
}
env {
name = "PUSHGATEWAY"
value = "http://prometheus-prometheus-pushgateway.monitoring:9091/metrics/job/webterminal-probe"
}
command = ["/bin/sh", "-c", <<-EOT
set -u
apk add --no-cache curl python3 >/dev/null 2>&1
# Probe 1 — HTTP GET /token (Cloudflare → Traefik → ttyd).
# Without an Authentik cookie the response MUST be 302
# (forward-auth redirect). 404 means a Traefik router is
# missing on the replica that received the request.
TOKEN_STATUS=$(curl -sk -o /dev/null -w "%%{http_code}" \
--max-time 10 \
"https://$${TARGET_HOST}/token?arg=probe" || echo 0)
# Probe 2 — WebSocket upgrade to /ws. Same expectation: 302.
# 404 here is what produced "Failed to connect" in the lobby
# iframe. Use Python for a true Upgrade request — curl's
# synthetic upgrade headers don't always trigger the WS path
# through every Cloudflare POP.
WS_STATUS=$(python3 - <<'PYEOF' 2>/dev/null || echo 0
import ssl, socket, base64, os
try:
ctx = ssl.create_default_context()
ctx.check_hostname = False
ctx.verify_mode = ssl.CERT_NONE
ctx.set_alpn_protocols(["http/1.1"])
sock = socket.create_connection((os.environ["TARGET_HOST"], 443), timeout=10)
ssock = ctx.wrap_socket(sock, server_hostname=os.environ["TARGET_HOST"])
key = base64.b64encode(os.urandom(16)).decode()
req = (
"GET /ws?arg=probe HTTP/1.1\r\n"
f"Host: {os.environ['TARGET_HOST']}\r\n"
"Upgrade: websocket\r\n"
"Connection: Upgrade\r\n"
f"Sec-WebSocket-Key: {key}\r\n"
"Sec-WebSocket-Version: 13\r\n"
"Sec-WebSocket-Protocol: tty\r\n"
f"Origin: https://{os.environ['TARGET_HOST']}\r\n"
"\r\n"
)
ssock.sendall(req.encode())
ssock.settimeout(5)
data = ssock.recv(2048)
ssock.close()
first = data.split(b"\r\n")[0].decode("ascii", "ignore")
parts = first.split()
print(parts[1] if len(parts) >= 2 and parts[1].isdigit() else 0)
except Exception:
print(0)
PYEOF
)
# Probe 3 — ttyd Service ClusterIP. Bypasses Cloudflare /
# Traefik / Authentik so we can tell whether the failure mode
# is "ttyd down" vs "edge proxy misrouting".
TTYD_STATUS=$(curl -s -o /dev/null -w "%%{http_code}" \
--max-time 5 -H "X-authentik-username: probe" \
"http://terminal.terminal.svc.cluster.local/token" || echo 0)
OK=0
if [ "$$TOKEN_STATUS" = "302" ] && [ "$$WS_STATUS" = "302" ] && [ "$$TTYD_STATUS" = "200" ]; then
OK=1
fi
NOW=$(date +%s)
cat <<METRICS | curl -sf --max-time 10 --data-binary @- "$$PUSHGATEWAY" >/dev/null 2>&1 || true
# HELP webterminal_probe_token_status HTTP status from GET /token via Cloudflare.
# TYPE webterminal_probe_token_status gauge
webterminal_probe_token_status $${TOKEN_STATUS:-0}
# HELP webterminal_probe_ws_status HTTP status from WebSocket upgrade /ws via Cloudflare.
# TYPE webterminal_probe_ws_status gauge
webterminal_probe_ws_status $${WS_STATUS:-0}
# HELP webterminal_probe_ttyd_status HTTP status from in-cluster ttyd /token.
# TYPE webterminal_probe_ttyd_status gauge
webterminal_probe_ttyd_status $${TTYD_STATUS:-0}
# HELP webterminal_probe_last_success_timestamp Unix ts of last fully-OK probe.
# TYPE webterminal_probe_last_success_timestamp gauge
webterminal_probe_last_success_timestamp $$([ "$$OK" = "1" ] && echo "$$NOW" || echo 0)
METRICS
echo "probe: token=$${TOKEN_STATUS} ws=$${WS_STATUS} ttyd=$${TTYD_STATUS} ok=$${OK}"
EOT
]
}
}
}
}
}
}
}
# CI retrigger 2026-05-16T13:42:57+00:00 — bulk enrollment apply (pipeline #689 killed)
# CI retrigger v2 2026-05-16T13:46:35+00:00