dockerclient: Agent supported Docker versions from client min,API Versions

dockerclient: Finding agent supported Docker versions by getting the default client version and if the min API version is present, add all the clients between min API version and API version supported, else follow current logic
utils: reuse the semantic version comparator to compare Docker API versions with only major and minor versions too

Author: sharanyad

agent/engine/dockerclient/dockerclientfactory.go

@@ -17,10 +17,19 @@ import (
 	"errors"
 
 	"github.com/aws/amazon-ecs-agent/agent/engine/dockeriface"
+	"github.com/aws/amazon-ecs-agent/agent/utils"
 	log "github.com/cihub/seelog"
 	docker "github.com/fsouza/go-dockerclient"
 )
 
+const (
+	// minDockerAPILinux is the min Docker API version supported by agent
+	minDockerAPILinux = Version_1_17
+	// minAPIVersionKey is the docker.Env key for min API version
+	minAPIVersionKey  = "MinAPIVersion"
+	// apiVersionKey is the docker.Env key for API version
+	apiVersionKey	  = "ApiVersion"
+)
 // Factory provides a collection of docker remote clients that include a
 // recommended client version as well as a set of alternative supported
 // docker clients.
@@ -110,6 +119,11 @@ func (f *factory) getClient(version DockerVersion) (dockeriface.Client, error) {
 // findDockerVersions loops over all known API versions and finds which ones
 // are supported by the docker daemon on the host
 func findDockerVersions(endpoint string) map[DockerVersion]dockeriface.Client {
+	// if the client version returns a min version and api version, then use it to return
+	// Docker versions
+	if clients, ok := findDockerVersionsfromMinMaxVersions(endpoint); ok {
+		return clients
+	}
 	clients := make(map[DockerVersion]dockeriface.Client)
 	for _, version := range getKnownAPIVersions() {
 		client, err := newVersionedClient(endpoint, string(version))
@@ -121,8 +135,54 @@ func findDockerVersions(endpoint string) map[DockerVersion]dockeriface.Client {
 		err = client.Ping()
 		if err != nil {
 			log.Infof("Failed to ping with Docker version %s: %v", version, err)
+			continue
 		}
 		clients[version] = client
 	}
 	return clients
 }
+
+func findDockerVersionsfromMinMaxVersions(endpoint string) (map[DockerVersion]dockeriface.Client, bool) {
+	clients := make(map[DockerVersion]dockeriface.Client)
+	// get a Docker client with the default supported version
+	client, err := newVersionedClient(endpoint, string(minDockerAPILinux))
+	if err != nil {
+		log.Infof("Error while creating client: %v", err)
+		return nil, false
+	}
+
+	clientVersion, err := client.Version()
+	if err != nil {
+		log.Infof("Error while getting client version: %v", err)
+		return nil, false
+	}
+
+	// check if the docker.Env obj has MinAPIVersion key
+	if clientVersion.Exists(minAPIVersionKey) {
+		minAPIVersion := clientVersion.Get(minAPIVersionKey)
+		apiVersion := clientVersion.Get(apiVersionKey)
+		for _, version := range getKnownAPIVersions() {
+			lessThanMinCheck := "<"+minAPIVersion
+			moreThanMaxCheck := ">"+apiVersion
+			minVersionCheck, minErr := utils.Version(version).Matches(lessThanMinCheck)
+			maxVersionCheck, maxErr := utils.Version(version).Matches(moreThanMaxCheck)
+			if minErr != nil || maxErr != nil {
+				log.Infof("Error while comparing Docker API versions: %v, %v", minErr, maxErr)
+				continue
+			}
+			// do not add the version when it is less than min api version or greater
+			// than api version
+			if minVersionCheck || maxVersionCheck {
+				continue
+			}
+			client, err := newVersionedClient(endpoint, string(version))
+			if err != nil {
+				log.Infof("Error while creating client: %v", err)
+				continue
+			}
+			clients[version] = client
+		}
+		return clients, true
+	}
+	return nil, false
+}

agent/engine/dockerclient/dockerclientfactory_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/aws/amazon-ecs-agent/agent/engine/dockeriface/mocks"
 	"github.com/golang/mock/gomock"
 	"github.com/stretchr/testify/assert"
+	docker "github.com/fsouza/go-dockerclient"
 )
 
 const expectedEndpoint = "expectedEndpoint"
@@ -35,7 +36,8 @@ func TestGetDefaultClientSuccess(t *testing.T) {
 		if version == string(getDefaultVersion()) {
 			mockClient = expectedClient
 		}
-		mockClient.EXPECT().Ping()
+		mockClient.EXPECT().Version().Return(&docker.Env{}, nil).AnyTimes()
+		mockClient.EXPECT().Ping().AnyTimes()
 
 		return mockClient, nil
 	}
@@ -59,6 +61,7 @@ func TestFindSupportedAPIVersions(t *testing.T) {
 	// Ensure that agent pings all known versions of Docker API
 	for i := 0; i < len(allVersions); i++ {
 		mockClients[string(allVersions[i])] = mock_dockeriface.NewMockClient(ctrl)
+		mockClients[string(allVersions[i])].EXPECT().Version().Return(&docker.Env{}, nil).AnyTimes()
 		mockClients[string(allVersions[i])].EXPECT().Ping()
 	}
 
@@ -92,3 +95,35 @@ func TestVerifyAgentVersions(t *testing.T) {
 		assert.True(t, isKnown(agentVersion))
 	}
 }
+
+func TestFindSupportedAPIVersionsFromMinAPIVersions(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	agentVersions := getAgentVersions()
+	allVersions := getKnownAPIVersions()
+
+	// Set up the mocks and expectations
+	mockClients := make(map[string]*mock_dockeriface.MockClient)
+
+	// Ensure that agent pings all known versions of Docker API
+	for i := 0; i < len(allVersions); i++ {
+		mockClients[string(allVersions[i])] = mock_dockeriface.NewMockClient(ctrl)
+		mockClients[string(allVersions[i])].EXPECT().Version().Return(&docker.Env{"MinAPIVersion=1.12","ApiVersion=1.27"}, nil).AnyTimes()
+		mockClients[string(allVersions[i])].EXPECT().Ping().AnyTimes()
+	}
+
+	// Define the function for the mock client
+	// For simplicity, we will pretend all versions of docker are available
+	newVersionedClient = func(endpoint, version string) (dockeriface.Client, error) {
+		return mockClients[version], nil
+	}
+
+	factory := NewFactory(expectedEndpoint)
+	actualVersions := factory.FindSupportedAPIVersions()
+
+	assert.Equal(t, len(agentVersions), len(actualVersions))
+	for i := 0; i < len(actualVersions); i++ {
+		assert.Equal(t, agentVersions[i], actualVersions[i])
+	}
+}

agent/engine/dockerclient/dockerclientfactory_unix_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/aws/amazon-ecs-agent/agent/engine/dockeriface/mocks"
 	"github.com/golang/mock/gomock"
 	"github.com/stretchr/testify/assert"
+	docker "github.com/fsouza/go-dockerclient"
 )
 
 func TestGetClientCached(t *testing.T) {
@@ -29,7 +30,8 @@ func TestGetClientCached(t *testing.T) {
 
 	newVersionedClient = func(endpoint, version string) (dockeriface.Client, error) {
 		mockClient := mock_dockeriface.NewMockClient(ctrl)
-		mockClient.EXPECT().Ping()
+		mockClient.EXPECT().Version().Return(&docker.Env{}, nil).AnyTimes()
+		mockClient.EXPECT().Ping().AnyTimes()
 		return mockClient, nil
 	}
 

agent/engine/dockerclient/dockerclientfactory_windows_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/aws/amazon-ecs-agent/agent/engine/dockeriface/mocks"
 	"github.com/golang/mock/gomock"
 	"github.com/stretchr/testify/assert"
+	docker "github.com/fsouza/go-dockerclient"
 )
 
 func TestGetClientMinimumVersion(t *testing.T) {
@@ -34,7 +35,8 @@ func TestGetClientMinimumVersion(t *testing.T) {
 		if version == string(MinDockerAPIWindows) {
 			mockClient = expectedClient
 		}
-		mockClient.EXPECT().Ping()
+		mockClient.EXPECT().Version().Return(&docker.Env{}, nil).AnyTimes()
+		mockClient.EXPECT().Ping().AnyTimes()
 		return mockClient, nil
 	}
 

agent/utils/compare_versions.go

@@ -20,6 +20,9 @@ import (
 	"strings"
 )
 
+// zeroPatch is a string to append patch number zero if the major minor version lacks it
+const zeroPatch = ".0"
+
 type Version string
 
 type semver struct {
@@ -93,6 +96,9 @@ func (lhs Version) Matches(selector string) (bool, error) {
 
 func parseSemver(version string) (semver, error) {
 	var result semver
+	if ok := checkForNoPatch(version); ok {
+		version += zeroPatch
+	}
 	// 0.0.0-some-prealpha-stuff.1+12345
 	versionAndMetadata := strings.SplitN(version, "+", 2)
 	// [0.0.0-some-prealpha-stuff.1, 12345]
@@ -128,6 +134,12 @@ func parseSemver(version string) (semver, error) {
 	return result, nil
 }
 
+func checkForNoPatch(version string) bool {
+	versionParts := strings.Split(version, ".")
+	// Only major and minor versions are present
+	return len(versionParts) == 2
+}
+
 // compareSemver compares two semvers, 'lhs' and 'rhs', and returns -1 if lhs is less
 // than rhs, 0 if they are equal, and 1 lhs is greater than rhs
 func compareSemver(lhs, rhs semver) int {

agent/utils/compare_versions_test.go

@@ -185,6 +185,11 @@ func TestVersionMatches(t *testing.T) {
 			selector:       ">=1.5.0",
 			expectedOutput: true,
 		},
+		{
+			version:	"1.17",
+			selector:	"<1.12",
+			expectedOutput: false,
+		},
 	}
 
 	for i, testCase := range testCases {