Migrate Rally release job to Buildkite (#1720)

.buildkite/release-docker/pipeline.yml

@@ -1,3 +1,14 @@
 steps:
-  - label: "Release Docker Artifacts for Rally :docker:"
-    command: echo "TODO"
+  - input: "Build parameters"
+    fields:
+      - text: "RELEASE_VERSION"
+        key: "RELEASE_VERSION"
+        default: ""
+        hint: "The version to release e.g. '2.8.0'."
+
+  - wait
+  - label: "Release Docker Artifacts for Rally"
+    command: bash .buildkite/release-docker/run.sh
+    # Run on GCP to use `docker`
+    agents:
+      provider: gcp

.buildkite/release-docker/run.sh

@@ -0,0 +1,47 @@
+#!/usr/bin/env bash
+
+set -eo pipefail
+
+# based on https://gist.github.com/sj26/88e1c6584397bb7c13bd11108a579746?permalink_comment_id=4155247#gistcomment-4155247
+function retry {
+  local retries=$1
+  shift
+  local cmd=($@)
+  local cmd_string="${@}"
+  local count=0
+
+  # be lenient with non-zero exit codes, to allow retries
+  set +o errexit
+  set +o pipefail
+  until "${cmd[@]}"; do
+    retcode=$?
+    wait=$(( 2 ** count ))
+    count=$(( count + 1))
+    if [[ $count -le $retries ]]; then
+      printf "Command [%s] failed. Retry [%d/%d] in [%d] seconds.\n" "$cmd_string" $count $retries $wait
+      sleep $wait
+    else
+      printf "Exhausted all [%s] retries for command [%s]. Exiting.\n" "$cmd_string" $retries
+      # restore settings to fail immediately on error
+      set -o errexit
+      set -o pipefail
+      return $retcode
+    fi
+  done
+  # restore settings to fail immediately on error
+  set -o errexit
+  set -o pipefail
+  return 0
+}
+
+set +x
+RELEASE_VERSION=$(buildkite-agent meta-data get RELEASE_VERSION)
+# login to docker registry
+DOCKER_PASSWORD=$(vault read -field token /secret/ci/elastic-rally/release/docker-hub-rally)
+retry 5 docker login -u elasticmachine -p $DOCKER_PASSWORD
+unset DOCKER_PASSWORD
+
+set -x
+export TERM=dumb
+export LC_ALL=en_US.UTF-8
+./release-docker.sh "$RELEASE_VERSION"