chore: more scripting

bin/heroku-tailscale-start.sh

@@ -1,61 +1,123 @@
 #!/usr/bin/env bash
 
-set -e
+set -eo pipefail
 
-if [ -z "$TAILSCALE_AUTH_KEY" ]; then
-  echo "[tailscale]: Will not be available because TAILSCALE_AUTH_KEY is not set"
+readonly TAILSCALE_DISABLE="${TAILSCALE_DISABLE:-0}"
+readonly TAILSCALE_DEBUG="${TAILSCALE_DEBUG:-false}"
+if [ "${TAILSCALE_DEBUG}" = "true" ]; then
+  set -ux
+fi
+readonly TAILSCALE_AUTH_KEY="${TAILSCALE_AUTH_KEY:-}"
+readonly ALL_PROXY_IP_PORT="localhost:1055"
+readonly TAILSCALED_CLEANUP="${TAILSCALED_CLEANUP:-}"
+readonly TAILSCALED_VERBOSE="${TAILSCALED_VERBOSE:--1}"
+readonly TAILSCALE_ADVERTISE_TAGS="${TAILSCALE_ADVERTISE_TAGS:-}"
+readonly TAILSCALE_ADDITIONAL_ARGS="${TAILSCALE_ADDITIONAL_ARGS:---timeout=15s}"
+#  --accept-dns=true
+#  --accept-routes=false
+#  --advertise-exit-node=false
+#  --shields-up=false
+#  --timeout=15s
+
+# Usage:
+#   cmd="$(stringify_args $*)"
+stringify_args() {
+  local old_ifs; old_ifs="$IFS" IFS=' ';
+  local args; args="$*"; IFS="$old_ifs"
+  echo "$args"
+}
+topic()    { echo "-----> $(stringify_args "$@")" >&2 ; }
+info()     { echo "       $(stringify_args "$@")" >&2 ; }
+debug()    { if [ "$TAILSCALE_DEBUG" = "true" ]; then echo -e "[DEBUG]       $(stringify_args "$@")" >&2 ; fi ; }
+error()    { echo " !     $(stringify_args "$@")" ;  >&2 exit 1  ; }
+indent() {
+  local command; command='s/^/       /'
+  case $(uname) in
+    Darwin) sed -l "$command";;
+    *)      sed -u "$command";;
+  esac
+}
+
+if [ "${TAILSCALE_DISABLE}" = "1" ]; then
+  info "[tailscale]: Is disabled via TAILSCALE_DISABLE"
+  exit 0
+fi
+if [ -z "${TAILSCALE_AUTH_KEY}" ]; then
+  info "[tailscale]: Will not be available because TAILSCALE_AUTH_KEY is not set"
   exit 0
 fi
 
+build_tailscale_hostname() {
+  if [ -z "$HEROKU_APP_NAME" ]; then
+    hostname
+  else
+    # Only use the first 8 characters of the commit sha.
+    # Swap the . and _ in the dyno with a - since tailscale doesn't
+    # allow for periods.
+    local dyno="${DYNO:-}"
+    dyno=${dyno//./-}
+    dyno=${dyno//_/-}
+    echo "heroku-$HEROKU_APP_NAME-${HEROKU_SLUG_COMMIT:0:8}-$dyno"
+  fi
+}
+
+readonly TAILSCALE_HOSTNAME="${TAILSCALE_HOSTNAME:-"$(build_tailscale_hostname)"}"
+
+run_cmd() {
+  local cmd
+  cmd="$*"
+  debug "cmd=${cmd}"
+  eval "$cmd"
+}
+
 wait_for_tailscale_running() {
   local timeout
-  timeout=5     # Timeout in seconds
+  timeout=50    # Timeout in tenths of a second
   local interval
-  interval=0.5  # Interval between checks
+  interval=5    # 0.5 second intervals (expressed in tenths)
   local elapsed
   elapsed=0
 
   while [ "$elapsed" -lt "$timeout" ]; do
-    if tailscale status -json | grep -q 'Running'; then
+    if tailscale status -json | grep -q 'Running' &> /dev/null; then
       return 0
     fi
-    sleep "$interval"
-    elapsed=$(echo "$elapsed + $interval" | bc)
+    sleep 0.5 # fake decimal math
+    elapsed=$((elapsed + interval))
   done
 
   return 1
 }
 
-if [ -z "$TAILSCALE_HOSTNAME" ]; then
-  if [ -z "$HEROKU_APP_NAME" ]; then
-    TAILSCALE_HOSTNAME=$(hostname)
+main() {
+  topic "[tailscale] starting up"
+  # see https://tailscale.com/kb/1107/heroku
+  if [ "${TAILSCALED_CLEANUP}" = "true" ]; then
+    echo "[tailscale]: tailscaled -cleanup"
+    run_cmd tailscaled -cleanup
+  fi
+
+  debug "[tailscale]: tailscaled --tun --socks5-server &"
+  run_cmd tailscaled \
+    -verbose "${TAILSCALED_VERBOSE}" \
+    --tun=userspace-networking \
+    --socks5-server=$ALL_PROXY_IP_PORT \
+    &
+  debug "[tailscale]: tailscale up"
+  run_cmd tailscale up \
+    --auth-key="${TAILSCALE_AUTH_KEY}" \
+    --hostname="${TAILSCALE_HOSTNAME}" \
+    --advertise-tags="${TAILSCALE_ADVERTISE_TAGS}" \
+    "${TAILSCALE_ADDITIONAL_ARGS}"
+  debug "[tailscale]: tailscale started"
+
+  export ALL_PROXY="socks5://${ALL_PROXY_IP_PORT}/"
+
+  if wait_for_tailscale_running; then
+    info "[tailscale]: Connected to tailnet as hostname=$TAILSCALE_HOSTNAME; SOCKS5 proxy available at ${ALL_PROXY_IP_PORT}"
   else
-    # Only use the first 8 characters of the commit sha.
-    # Swap the . and _ in the dyno with a - since tailscale doesn't
-    # allow for periods.
-    DYNO=${DYNO//./-}
-    DYNO=${DYNO//_/-}
-    TAILSCALE_HOSTNAME="heroku-$HEROKU_APP_NAME-${HEROKU_SLUG_COMMIT:0:8}-$DYNO"
+    info "[tailscale]: Warning - Backend did not reach 'Running' state within timeout"
   fi
-fi
-# see https://tailscale.com/kb/1107/heroku
-echo "[tailscale]: tailscaled -cleanup"
-tailscaled -cleanup
-echo "[tailscale]: tailscaled --tun --socks5-server &"
-ALL_PROXY_IP_PORT="localhost:1055"
-tailscaled -verbose "${TAILSCALED_VERBOSE:--1}" --tun=userspace-networking --socks5-server=$ALL_PROXY_IP_PORT &
-echo "[tailscale]: tailscale up"
-tailscale up \
-  --auth-key="${TAILSCALE_AUTH_KEY}" \
-  --hostname="${TAILSCALE_HOSTNAME}" \
-  --advertise-tags="${TAILSCALE_ADVERTISE_TAGS:-}" \
-  "${TAILSCALE_ADDITIONAL_ARGS:---timeout=15s}"
-echo "[tailscale]: tailscale started"
-
-export ALL_PROXY="socks5://${ALL_PROXY_IP_PORT}/"
-
-if wait_for_tailscale_running; then
-  echo "[tailscale]: Connected to tailnet as hostname=$TAILSCALE_HOSTNAME; SOCKS5 proxy available at ${ALL_PROXY_IP_PORT}"
-else
-  echo "[tailscale]: Warning - Backend did not reach 'Running' state within timeout"
-fi
+}
+
+main