Add back support for etcd 2.2.1

WORKSPACE

@@ -185,3 +185,21 @@ http_file(
     sha256 = "1934ebb9f9f6501f706111b78e5e321a7ff8d7792d3d96a76e2d01874e42a300",
     urls = ["https://github.com/etcd-io/etcd/releases/download/v3.4.13/etcd-v3.4.13-linux-arm64.tar.gz"],
 )
+
+#=============================================================================
+# Build etcd from source
+# This picks up a number of critical bug fixes, for example:
+#  * Caching of /etc/hosts https://github.com/golang/go/issues/13340
+#  * General GC etc improvements
+#  * Misc security fixes that are not backported
+
+# Download via HTTP
+go_repository(
+    name = "etcd_v2_2_1_source",
+    urls = ["https://github.com/etcd-io/etcd/archive/v2.2.1.tar.gz"],
+    sha256 = "1c0ce63812ef951f79c0a544c91f9f1ba3c6b50cb3e8197de555732454864d05",
+    importpath = "github.com/coreos/etcd",
+    strip_prefix = "etcd-2.2.1/",
+    build_external = "vendored",
+    build_file_proto_mode = "disable_global",
+)

images/BUILD

@@ -7,6 +7,16 @@ load(
     "container_push",
 )
 
+# Layer for etcd 2.2.1, the version of etcd2 that was originally recommended
+container_layer(
+    name = "etcd-2.2.1-layer-amd64",
+    directory = "/opt/etcd-v2.2.1-linux-amd64/",
+    files = [
+        "@etcd_v2_2_1_source//:etcd",
+        "@etcd_v2_2_1_source//etcdctl",
+    ],
+)
+
 load("etcd.bzl", "supported_etcd_arch_and_version")
 
 # Layer for etcd 3.1.12, as used in k8s 1.10
@@ -52,6 +62,7 @@ container_image(
     directory = "/opt",
     layers = select({
         "@io_bazel_rules_go//go/platform:amd64": [
+            "etcd-2.2.1-layer-amd64",
             "etcd-3.1.12-layer-amd64",
             "etcd-3.2.18-layer-amd64",
             "etcd-3.2.24-layer-amd64",

test/integration/BUILD.bazel

@@ -12,6 +12,8 @@ go_test(
         "upgradedowngrade_test.go",
     ],
     data = [
+        "@etcd_v2_2_1_source//:etcd",
+        "@etcd_v2_2_1_source//etcdctl:etcdctl",
         "//:etcd-v3.1.12-linux-amd64_etcd",
         "//:etcd-v3.1.12-linux-amd64_etcdctl",
         "//:etcd-v3.2.18-linux-amd64_etcd",