Merge pull request #79 from jelmersnoeck/multi-stage-builds

Scratch image + multistage builds.

Dockerfile

@@ -11,10 +11,16 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+FROM golang:1.9.2
 
-FROM fedora
+WORKDIR /go/src/github.com/kubernetes-incubator/descheduler
+COPY . .
+RUN make
+
+FROM scratch
 
 MAINTAINER Avesh Agarwal <avagarwa@redhat.com>
 
-COPY _output/bin/descheduler /bin/descheduler
-CMD ["/bin/descheduler --help"]
+COPY --from=0 /go/src/github.com/kubernetes-incubator/descheduler/_output/bin/descheduler /bin/descheduler
+
+CMD ["/bin/descheduler", "--help"]

Dockerfile.dev

@@ -0,0 +1,20 @@
+# Copyright 2017 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+FROM scratch
+
+MAINTAINER Avesh Agarwal <avagarwa@redhat.com>
+
+COPY _output/bin/descheduler /bin/descheduler
+
+CMD ["/bin/descheduler", "--help"]

Makefile

@@ -30,9 +30,12 @@ IMAGE:=descheduler:$(VERSION)
 all: build
 
 build:
-	go build ${LDFLAGS} -o _output/bin/descheduler github.com/kubernetes-incubator/descheduler/cmd/descheduler 
+	CGO_ENABLED=0 go build ${LDFLAGS} -o _output/bin/descheduler github.com/kubernetes-incubator/descheduler/cmd/descheduler
 
-image: build
+dev-image: build
+	docker build -f Dockerfile.dev -t $(IMAGE) .
+
+image:
 	docker build -t $(IMAGE) .
 
 clean:

README.md

@@ -56,10 +56,20 @@ in `kube-system` namespace.
 
 First we create a simple Docker image utilizing the Dockerfile found in the root directory:
 
+```
+$ make dev-image
+```
+
+This creates an image based off the binary we've built before. To build both the
+binary and image in one step you can run the following command:
+
 ```
 $ make image
 ```
 
+This eliminates the need to have Go installed locally and builds the binary
+within it's own container.
+
 ### Create a cluster role
 
 To give necessary permissions for the descheduler to work in a pod, create a cluster role:
@@ -150,7 +160,7 @@ $ kubectl create -f descheduler-job.yaml
 ```
 
 ## Policy and Strategies
- 
+
 Descheduler's policy is configurable and includes strategies to be enabled or disabled.
 Three strategies, `RemoveDuplicates`, `LowNodeUtilization`, `RemovePodsViolatingInterPodAntiAffinity` are currently implemented.
 As part of the policy, the parameters associated with the strategies can be configured too.
@@ -232,12 +242,12 @@ strategies:
 
 When the descheduler decides to evict pods from a node, it employs following general mechanism:
 
-* Critical pods (with annotations scheduler.alpha.kubernetes.io/critical-pod) are never evicted. 
+* Critical pods (with annotations scheduler.alpha.kubernetes.io/critical-pod) are never evicted.
 * Pods (static or mirrored pods or stand alone pods) not part of an RC, RS, Deployment or Jobs are
 never evicted because these pods won't be recreated.
 * Pods associated with DaemonSets are never evicted.
 * Pods with local storage are never evicted.
-* Best efforts pods are evicted before Burstable and Guaranteed pods. 
+* Best efforts pods are evicted before Burstable and Guaranteed pods.
 
 ### Pod disruption Budget (PDB)
 Pods subject to Pod Disruption Budget (PDB) are not evicted if descheduling violates its pod
@@ -248,7 +258,7 @@ disruption budget (PDB). The pods are evicted by using eviction subresource to h
 This roadmap is not in any particular order.
 
 * Strategy to consider taints and tolerations
-* Consideration of pod affinity 
+* Consideration of pod affinity
 * Strategy to consider pod life time
 * Strategy to consider number of pending pods
 * Integration with cluster autoscaler