feat: docker in docker support (#785)

* feat: docker in docker support

* fix: pr comments

Dockerfile

@@ -1,7 +1,12 @@
 FROM golang:1.10
 RUN apt-get update && \
-	apt-get install -y rpm git && \
+	apt-get install -y rpm git apt-transport-https curl gnupg2 software-properties-common && \
+	curl -fsSL https://download.docker.com/linux/debian/gpg | apt-key add - && \
+	add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/debian $(lsb_release -cs) stable" && \
+	apt-get update && apt-get install -y docker-ce &&\
 	rm -rf /var/lib/apt/lists/*
-COPY goreleaser /goreleaser
-ENTRYPOINT ["/goreleaser"]
-
+COPY goreleaser /bin/goreleaser
+COPY entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh
+ENTRYPOINT ["/entrypoint.sh"]
+CMD [ "-h" ]

entrypoint.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+
+if [ -n $DOCKER_USERNAME ] && [ -n $DOCKER_PASSWORD ]; then
+    echo "Login to the docker..."
+    docker login -u $DOCKER_USERNAME -p $DOCKER_PASSWORD
+fi
+
+goreleaser $@

internal/pipeline/docker/docker.go

@@ -100,10 +100,11 @@ func doRun(ctx *context.Context) error {
 }
 
 func process(ctx *context.Context, docker config.Docker, artifact artifact.Artifact) error {
-	tmp, err := ioutil.TempDir("", "goreleaserdocker")
+	tmp, err := ioutil.TempDir(ctx.Config.Dist, "goreleaserdocker")
 	if err != nil {
 		return errors.Wrap(err, "failed to create temporaty dir")
 	}
+	defer os.RemoveAll(tmp)
 	log.Info("tempdir: " + tmp)
 	// nolint:prealloc
 	var images []string

www/content/introduction.md

@@ -42,13 +42,17 @@ scoop install goreleaser
 ### Using Docker
 
 You can use Docker to do simple releases. Currently, the provided docker
-image does not provide support for docker-in-docker and snapcraft.
+image does not provide support for snapcraft.
 
 ```console
-$ docker run \
+$ docker run --rm --privileged \
   -v $PWD:/go/src/github.com/user/repo \
+  -v /var/run/docker.sock:/var/run/docker.sock \
   -w /go/src/github.com/user/repo \
-  goreleaser/goreleaser --help
+  -e GITHUB_TOKEN \
+  -e DOCKER_USERNAME \
+  -e DOCKER_PASSWORD \
+  goreleaser/goreleaser release
 ```
 
 Note that the image will almost always have the last stable Go version.