Periodic Prow Job to Update Istio Dependency SHA (#400)

Automatic merge from submit-queue

Periodic Prow Job to Update Istio Dependency SHA

An example PR created is istio/istio#588

Notice that it reads SHA from stable branch of each dependency. For the entire dependency update scheme to be automated, it also needs the fast-forward jobs that move stable up-to-date with master, which will be done in another PR shortly after.

**Release note**:

```release-note
NONE
```

prow/config.yaml

@@ -658,3 +658,24 @@ periodics:
     - name: e2e-testing-kubeconfig
       secret:
         secretName: e2e-testing-kubeconfig
+
+- interval: 10m
+  agent: kubernetes
+  name: test-infra-update-deps
+  spec:
+    containers:
+    - image: gcr.io/istio-testing/prowbazel:0.1.7
+      args:
+      - "--repo=github.com/istio/test-infra=master"
+      - "--clean"
+      env:
+      - name: GOOGLE_APPLICATION_CREDENTIALS
+        value: /etc/service-account/service-account.json
+      volumeMounts:
+      - name: oauth
+        mountPath: /etc/github
+        readOnly: true
+    volumes:
+    - name: oauth
+      secret:
+        secretName: oauth-token

prow/test-infra-update-deps.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+# Copyright 2017 Istio Authors
+
+#   Licensed under the Apache License, Version 2.0 (the "License");
+#   you may not use this file except in compliance with the License.
+#   You may obtain a copy of the License at
+
+#       http://www.apache.org/licenses/LICENSE-2.0
+
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS,
+#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#   See the License for the specific language governing permissions and
+#   limitations under the License.
+
+
+#######################################################
+# Crontab dependency update script triggered by Prow. #
+#######################################################
+
+# Exit immediately for non zero status
+set -e
+# Check unset variables
+set -u
+# Print commands
+set -x
+
+echo "=== Building Binary that Updates Istio Dependency ==="
+bazel build //toolbox/deps_update:update_deps
+
+git config --global user.email "istio.testing@gmail.com"
+git config --global user.name "istio-bot"
+
+echo "=== Updating Dependency of Istio ==="
+./bazel-bin/toolbox/deps_update/update_deps \
+--repo=istio \
+--token_file=/etc/github/oauth \
+--hub=gcr.io/istio-testing