ci-operator/templates/openshift/installer/cluster-launch-installer-*:…

… Random Azure regions

Shard over four regions to increase our capacity, because Azure allows
auto-bumps for vCPU limits up to 200 in each region, but it's a longer
process to get the limits raised beyond that in a single region.  This
sets us up for more lease-restriction relaxing after 78ade84 (Prow:
drop max azure CI clusters to 5, 2019-09-18, #5074) and 594930f
(Prow: increase max Azure CI clusters to 20, 2019-09-18, #5084).  We
may want per-region quotas, but for the moment I'm just hoping that
our random choices are even enough that an Azure-wide quota is
sufficient.  And conveniently, $RANDOM runs from 0 through 32767 [1],
so our modulo 4 value is evenly weighted :).

The change to Bash is because Bash supports $RANDOM [1], but POSIX
does not [2].  We already use RANDOM in
openshift-installer-master-presubmits.yaml since ca464ed
(openshift/installer: add IaaS-agnostic E2E test, 2019-06-20, #4148).

Ideally we'd be loading the set of region choices (and possibly
weights) from some shared location somewhat like ca464ed has
things.  And we'd be reporting the chosen region in a structured way
for convenient monitoring.  But the plan is to break up these
templates into more composable chunks soon anyway, so I'm ok if we
aren't all that DRY in the short term.

[1]: https://www.gnu.org/savannah-checkouts/gnu/bash/manual/bash.html#index-RANDOM
[2]: https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xcu_chap02.html#tag_23_02_05_03

ci-operator/templates/openshift/installer/cluster-launch-installer-e2e.yaml

@@ -656,8 +656,6 @@ objects:
         value: us-east-1
       - name: AZURE_AUTH_LOCATION
         value: /etc/openshift-installer/osServicePrincipal.json
-      - name: AZURE_REGION
-        value: centralus
       - name: GCP_REGION
         value: us-east1
       - name: GCP_PROJECT
@@ -685,7 +683,7 @@ objects:
       - name: INSTALL_INITIAL_RELEASE
       - name: RELEASE_IMAGE_INITIAL
       command:
-      - /bin/sh
+      - /bin/bash
       - -c
       - |
         #!/bin/sh
@@ -759,6 +757,14 @@ objects:
           ${SSH_PUB_KEY}
         EOF
         elif [[ "${CLUSTER_TYPE}" == "azure4" ]]; then
+            case $((RANDOM % 4)) in
+            0) AZURE_REGION=centralus;;
+            1) AZURE_REGION=eastus;;
+            2) AZURE_REGION=eastus2;;
+            3) AZURE_REGION=westus;;
+            *) echo >&2 "invalid Azure region index"; exit 1;;
+            esac
+
             cat > /tmp/artifacts/installer/install-config.yaml << EOF
         apiVersion: v1
         baseDomain: ${BASE_DOMAIN:-ci.azure.devcluster.openshift.com}

ci-operator/templates/openshift/installer/cluster-launch-installer-src.yaml

@@ -265,8 +265,6 @@ objects:
         value: us-east-1
       - name: AZURE_AUTH_LOCATION
         value: /etc/openshift-installer/osServicePrincipal.json
-      - name: AZURE_REGION
-        value: centralus
       - name: GCP_REGION
         value: us-east1
       - name: GCP_PROJECT
@@ -304,7 +302,7 @@ objects:
       - name: HOME
         value: /tmp
       command:
-      - /bin/sh
+      - /bin/bash
       - -c
       - |
         #!/bin/sh
@@ -369,6 +367,14 @@ objects:
           ${SSH_PUB_KEY}
         EOF
         elif [[ "${CLUSTER_TYPE}" == "azure4" ]]; then
+            case $((RANDOM % 4)) in
+            0) AZURE_REGION=centralus;;
+            1) AZURE_REGION=eastus;;
+            2) AZURE_REGION=eastus2;;
+            3) AZURE_REGION=westus;;
+            *) echo >&2 "invalid Azure region index"; exit 1;;
+            esac
+
             cat > /tmp/artifacts/installer/install-config.yaml << EOF
         apiVersion: v1
         baseDomain: ${BASE_DOMAIN:-ci.azure.devcluster.openshift.com}