fix: recover mempool frontend after backend address changes

2026-09-15 02:49:06 -04:00
parent 700d39c425
commit b35409ca74
9 changed files with 244 additions and 149 deletions
@@ -0,0 +1,56 @@
+#!/bin/sh
+# Resolve the backend again after container IP changes. Run after upstream
+# placeholder substitution, so the repair also works on an existing container.
+set -eu
+conf=${1:-/etc/nginx/conf.d/nginx-mempool.conf}
+resolv=${2:-/etc/resolv.conf}
+backend=${BACKEND_MAINNET_HTTP_HOST:-127.0.0.1}
+port=${BACKEND_MAINNET_HTTP_PORT:-8999}
+resolver=$(awk '/^nameserver/ { print $2; exit }' "$resolv")
+[ -n "$resolver" ] || { echo 'No DNS resolver configured' >&2; exit 1; }
+case "$resolver" in *:*) resolver="[$resolver]" ;; esac
+case "$backend" in *[!a-zA-Z0-9._-]*|'') echo 'Invalid backend hostname' >&2; exit 1 ;; esac
+case "$port" in *[!0-9]*|'') echo 'Invalid backend port' >&2; exit 1 ;; esac
+
+tmp=$(mktemp "${conf}.archy.XXXXXX")
+trap 'rm -f "$tmp"' EXIT HUP INT TERM
+awk -v backend="$backend" -v port="$port" -v resolver="$resolver" '
+  BEGIN {
+    base = "http://" backend ":" port
+    print "# Archipelago: refresh backend DNS after container replacement."
+    print "resolver " resolver " valid=5s ipv6=off; # archy-dns"
+    print "resolver_timeout 3s; # archy-dns"
+  }
+  /# Archipelago: refresh backend DNS/ || /# archy-dns/ { next }
+  /^[[:space:]]*location[[:space:]]/ { location = $2 }
+  /^[[:space:]]*proxy_pass[[:space:]]/ && index($2, base) == 1 {
+    target = $2
+    sub(/;$/, "", target)
+    path = substr(target, length(base) + 1)
+    if (location != "/api/v1/ws" && location != "/ws" && location != "/api/v1" && location != "/api/") {
+      print "Unexpected backend location: " location > "/dev/stderr"
+      failed = 1; exit 1
+    }
+    if (path != "/" && path != "/api/v1" && path != "/api/v1/") {
+      print "Unexpected backend URI mapping" > "/dev/stderr"
+      failed = 1; exit 1
+    }
+    # Explicitly preserve prefix substitution and query arguments. A variable
+    # proxy_pass without a URI forwards the rewritten URI and original args.
+    print "\t\tset $mp_backend " backend ";"
+    if (path != location)
+      print "\t\trewrite ^" location "(.*)$ " path "$1 break;"
+    print "\t\tproxy_pass http://$mp_backend:" port ";"
+    count++
+    next
+  }
+  /proxy_pass http:\/\/\$mp_backend:/ { count++ }
+  { print }
+  END {
+    if (failed || count != 4) {
+      print "Expected four backend proxies; refusing an incomplete DNS repair" > "/dev/stderr"
+      exit 1
+    }
+  }
+' "$conf" > "$tmp"
+cat "$tmp" > "$conf"