Improve buildkite error reporting

This will make it _much_ easier to pinpoint where that error annotation
is coming from.

lib/buildkite_support.sh

@@ -9,30 +9,31 @@ else
  die "No sha256sum/shasum available!"
 fi
 
-# Helper function to kill execution when something goes wrong
-function die() {
- echo "ERROR: ${1}" >&2
+function job_link() {
+ echo -n "${BUILDKITE_BUILD_URL}#${BUILDKITE_JOB_ID}"
+}
+
+function buildkite_annotation() {
  if which buildkite-agent >/dev/null 2>/dev/null; then
- # By default, the annotation context is unique to the message
- local CONTEXT=$(echo "${1}" | ${SHASUM})
- if [[ "$#" -gt 1 ]]; then
- CONTEXT="${2}"
+ # By default, the annotation context is unique to the message and buildkite job
+ local CONTEXT=$(echo "${2}" "${BUILDKITE_JOB_ID}" | ${SHASUM})
+ if [[ "$#" -gt 2 ]]; then
+ CONTEXT="${3}"
  fi
- buildkite-agent annotate --context="${CONTEXT}" --style=error "${1}"
+ buildkite-agent annotate --context="${CONTEXT}" --style="${1}" "${2} ([job]($(job_link)))"
  fi
+}
+
+# Helper function to kill execution when something goes wrong
+function die() {
+ echo "ERROR: ${1}" >&2
+ buildkite_annotation "error" "$@"
  exit 1
 }
 
 function warn() {
  echo "WARN: ${1}" >&2
- if which buildkite-agent >/dev/null 2>/dev/null; then
- # By default, the annotation context is unique to the message
- local CONTEXT=$(echo "${1}" | ${SHASUM})
- if [[ "$#" -gt 1 ]]; then
- CONTEXT="${2}"
- fi
- buildkite-agent annotate --context="${CONTEXT}" --style=warning "${1}"
- fi
+ buildkite_annotation "warning" "$@"
 }
 
 # Helper function to collect a buildkite array