e2e: deploy Nomad from testing framework (#6949)

The e2e framework instantiates clients for Nomad/Consul but the
provisioning of the actual Nomad cluster is left to Terraform. The
Terraform provisioning process uses `remote-exec` to deploy specific
versions of Nomad so that we don't have to bake an AMI every time we
want to test a new version. But Terraform treats the resulting
instances as immutable, so we can't use the same tooling to update the
version of Nomad in-place. This is a prerequisite for upgrade testing.

This changeset extends the e2e framework to provide the option of
deploying Nomad (and, in the future, Consul/Vault) with specific
versions to running infrastructure. This initial implementation is
focused on deploying to a single cluster via `ssh` (because that's our
current need), but provides interfaces to hook the test run at the
start of the run, the start of each suite, or the start of a given
test case.

The input JSON for configuring provisioning targets can be generated
by Terraform (or written by hand). That will be under a separate PR.

e2e/e2e_test.go

@@ -1,8 +1,13 @@
+// This package exists to wrap our e2e provisioning and test framework so that it
+// can be run via 'go test ./e2e'. See './framework/framework.go'
 package e2e
 
 import (
+	"os"
 	"testing"
 
+	"github.com/hashicorp/nomad/e2e/framework"
+
 	_ "github.com/hashicorp/nomad/e2e/affinities"
 	_ "github.com/hashicorp/nomad/e2e/clientstate"
 	_ "github.com/hashicorp/nomad/e2e/connect"
@@ -19,5 +24,9 @@ import (
 )
 
 func TestE2E(t *testing.T) {
-	RunE2ETests(t)
+	if os.Getenv("NOMAD_E2E") == "" {
+		t.Skip("Skipping e2e tests, NOMAD_E2E not set")
+	} else {
+		framework.Run(t)
+	}
 }

e2e/framework/case.go

@@ -5,6 +5,7 @@ import (
 
 	capi "github.com/hashicorp/consul/api"
 	"github.com/hashicorp/nomad/api"
+	"github.com/hashicorp/nomad/e2e/framework/provisioning"
 )
 
 // TestSuite defines a set of test cases and under what conditions to run them
@@ -58,7 +59,7 @@ func (c Constraints) matches(env Environment) error {
 
 // TC is the base test case which should be embedded in TestCase implementations.
 type TC struct {
-	cluster *ClusterInfo
+	cluster *provisioning.ClusterInfo
 }
 
 // Nomad returns a configured nomad api client
@@ -77,6 +78,6 @@ func (tc *TC) Name() string {
 	return tc.cluster.Name
 }
 
-func (tc *TC) setClusterInfo(info *ClusterInfo) {
+func (tc *TC) setClusterInfo(info *provisioning.ClusterInfo) {
 	tc.cluster = info
 }