Docker instance plugin (#469)

Signed-off-by: Nicolas Degory <[email protected]>

Author: ndegory

Makefile

@@ -131,6 +131,7 @@ endif
 	$(call build_binary,infrakit-instance-terraform,github.com/docker/infrakit/examples/instance/terraform)
 	$(call build_binary,infrakit-instance-vagrant,github.com/docker/infrakit/examples/instance/vagrant)
 	$(call build_binary,infrakit-instance-maas,github.com/docker/infrakit/examples/instance/maas)
+	$(call build_binary,infrakit-instance-docker,github.com/docker/infrakit/examples/instance/docker)
 	$(call build_binary,infrakit-event-time,github.com/docker/infrakit/examples/event/time)
 
 cli: build-cli

dockerfiles/Dockerfile.build

@@ -1,6 +1,6 @@
 FROM golang:1.8-alpine
 
-RUN apk add --update git make
+RUN apk add --update git make gcc musl-dev
 RUN go get github.com/rancher/trash
 
 WORKDIR /go/src/github.com/docker/infrakit

examples/instance/docker/README.md

@@ -0,0 +1,122 @@
+InfraKit Instance Plugin - Docker
+=================================
+
+[InfraKit](https://github.com/docker/infrakit) plugins for creating and managing Docker containers.
+
+## Instance plugin
+
+The InfraKit instance plugin creates and monitors Docker containers.
+
+### Example
+
+Based on the [default](https://github.com/docker/infrakit/tree/master/cmd/group) Group
+plugin:
+```console
+$ build/infrakit-group-default
+INFO[0000] Starting discovery
+INFO[0000] Starting plugin
+INFO[0000] Starting
+INFO[0000] Listening on: unix:///run/infrakit/plugins/group.sock
+INFO[0000] listener protocol= unix addr= /run/infrakit/plugins/group.sock err= <nil>
+```
+
+and the [Vanilla](https://github.com/docker/infrakit/tree/master/pkg/example/flavor/vanilla) Flavor plugin:
+```console
+$ build/infrakit-flavor-vanilla
+INFO[0000] Starting plugin
+INFO[0000] Listening on: unix:///run/infrakit/plugins/flavor-vanilla.sock
+INFO[0000] listener protocol= unix addr= /run/infrakit/plugins/flavor-vanilla.sock err= <nil>
+```
+
+We will use a basic configuration that creates a single instance:
+```console
+$ cat << EOF > aws-vanilla.json
+{
+  "ID": "docker-example",
+  "Properties": {
+    "Allocation": {
+      "Size": 1
+    },
+    "Instance": {
+      "Plugin": "instance-docker",
+      "Properties": {
+        "Config": {
+          "Image": "alpine:3.5"
+        },
+        "HostConfig": {
+          "AutoRemove": true
+        },
+        "Tags": {
+          "Name": "infrakit-example"
+        }
+      }
+    },
+    "Flavor": {
+      "Plugin": "flavor-vanilla",
+      "Properties": {
+        "Init": [
+          "sh -c \"echo 'Hello, World!' > /hello\""
+        ]
+      }
+    }
+  }
+}
+EOF
+```
+
+For the structure of `Config` `HostConfig`, see the plugin properties definition below.
+
+Finally, instruct the Group plugin to start watching the group:
+```console
+$ build/infrakit group watch docker-vanilla.json
+watching docker-example
+```
+
+In the console running the Group plugin, we will see input like the following:
+```
+INFO[1208] Watching group 'docker-example'
+INFO[1219] Adding 1 instances to group to reach desired 1
+INFO[1219] Created instance i-ba0412a2 with tags map[infrakit.config_sha:dUBtWGmkptbGg29ecBgv1VJYzys= infrakit.group:aws-example]
+```
+
+Additionally, the CLI will report the newly-created instance:
+```console
+$ build/infrakit group inspect docker-example
+ID                             	LOGICAL                        	TAGS
+90e6f3de4918                   	elusive_leaky                  	Name=infrakit-example,infrakit.config_sha=dUBtWGmkptbGg29ecBgv1VJYzys=,infrakit.group=docker-example
+```
+
+Retrieve the name of the container and connect to it with an exec
+
+```console
+$ docker exec -ti elusive_leaky cat /hello
+Hello, World!
+```
+
+### Plugin properties
+
+The plugin expects properties in the following format:
+```json
+{
+  "Tags": {
+  },
+  "Config": {
+  },
+  "HostConfig": {
+  },
+  "NetworkAttachments": [
+  ]
+}
+```
+
+The `Tags` property is a string-string mapping of labels to apply to all Docker containers that are created.
+`Config` follows the structure of the type by the same name in the
+[Docker go SDK](https://github.com/docker/docker/blob/master/api/types/container/config.go).
+`HostConfig` follows the structure of the type by the same name in the
+[Docker go SDK](https://github.com/docker/docker/blob/master/api/types/container/host_config.go).
+`NetworkAttachments` is an array of [NetworkResource](https://github.com/docker/docker/blob/master/api/types/types.go).
+
+### LogicalID
+
+To take advantage of the Docker networking DNS, the InfraKit logicalID is mapped to the Docker container hostname (and not its IP).
+The plugin is compatible with both allocation methods, logical IDs (cattles) or group size (pets).

examples/instance/docker/builder.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/docker/docker/client"
+	"github.com/docker/infrakit/pkg/spi/instance"
+	"github.com/spf13/pflag"
+)
+
+const (
+	defaultDockerURL        = "unix:///var/run/docker.sock"
+	defaultDockerAPIVersion = "1.25"
+)
+
+type options struct {
+	dockerURL        string
+	dockerAPIVersion string
+	//todo: add TLS options
+	retries int
+}
+
+// Builder is a ProvisionerBuilder that creates a Docker instance provisioner
+type Builder struct {
+	client  *client.Client
+	options options
+}
+
+// Flags returns the flags required.
+func (b *Builder) Flags() *pflag.FlagSet {
+	flags := pflag.NewFlagSet("docker", pflag.PanicOnError)
+	flags.StringVar(&b.options.dockerURL, "url", defaultDockerURL, "Docker API URL")
+	flags.StringVar(&b.options.dockerAPIVersion, "version", defaultDockerAPIVersion, "Docker API version")
+	flags.IntVar(&b.options.retries, "retries", 5, "Number of retries for Docker API operations")
+	return flags
+}
+
+// BuildInstancePlugin creates an instance Provisioner configured with the Flags.
+func (b *Builder) BuildInstancePlugin(namespaceTags map[string]string) (instance.Plugin, error) {
+	if b.client == nil {
+		defaultHeaders := map[string]string{"User-Agent": "InfraKit"}
+		cli, err := client.NewClient(b.options.dockerURL, b.options.dockerAPIVersion, nil, defaultHeaders)
+		if err != nil {
+			return nil, fmt.Errorf("failed to connect to Docker on [%s]\n%v", b.options.dockerURL, err)
+		}
+		b.client = cli
+	}
+	return NewInstancePlugin(b.client, namespaceTags), nil
+}
+
+type logger struct {
+	logger *log.Logger
+}
+
+func (l logger) Log(args ...interface{}) {
+	l.logger.Println(args...)
+}