Merge pull request #84 from infosiftr/nsswitch.conf

Add bare-bones "/etc/nsswitch.conf" for "netgo" to know it should check "/etc/hosts" before doing DNS lookups

Author: yosifkit

17.06/Dockerfile

@@ -3,6 +3,12 @@ FROM alpine:3.6
 RUN apk add --no-cache \
 		ca-certificates
 
+# set up nsswitch.conf for Go's "netgo" implementation (which Docker explicitly uses)
+# - https://github.com/docker/docker-ce/blob/v17.09.0-ce/components/engine/hack/make.sh#L149
+# - https://github.com/golang/go/blob/go1.9.1/src/net/conf.go#L194-L275
+# - docker run --rm debian:stretch grep '^hosts:' /etc/nsswitch.conf
+RUN [ ! -e /etc/nsswitch.conf ] && echo 'hosts: files dns' > /etc/nsswitch.conf
+
 ENV DOCKER_CHANNEL stable
 ENV DOCKER_VERSION 17.06.2-ce
 # TODO ENV DOCKER_SHA256

17.07/Dockerfile

@@ -3,6 +3,12 @@ FROM alpine:3.6
 RUN apk add --no-cache \
 		ca-certificates
 
+# set up nsswitch.conf for Go's "netgo" implementation (which Docker explicitly uses)
+# - https://github.com/docker/docker-ce/blob/v17.09.0-ce/components/engine/hack/make.sh#L149
+# - https://github.com/golang/go/blob/go1.9.1/src/net/conf.go#L194-L275
+# - docker run --rm debian:stretch grep '^hosts:' /etc/nsswitch.conf
+RUN [ ! -e /etc/nsswitch.conf ] && echo 'hosts: files dns' > /etc/nsswitch.conf
+
 ENV DOCKER_CHANNEL edge
 ENV DOCKER_VERSION 17.07.0-ce
 # TODO ENV DOCKER_SHA256

17.09/Dockerfile

@@ -3,6 +3,12 @@ FROM alpine:3.6
 RUN apk add --no-cache \
 		ca-certificates
 
+# set up nsswitch.conf for Go's "netgo" implementation (which Docker explicitly uses)
+# - https://github.com/docker/docker-ce/blob/v17.09.0-ce/components/engine/hack/make.sh#L149
+# - https://github.com/golang/go/blob/go1.9.1/src/net/conf.go#L194-L275
+# - docker run --rm debian:stretch grep '^hosts:' /etc/nsswitch.conf
+RUN [ ! -e /etc/nsswitch.conf ] && echo 'hosts: files dns' > /etc/nsswitch.conf
+
 ENV DOCKER_CHANNEL stable
 ENV DOCKER_VERSION 17.09.0-ce
 # TODO ENV DOCKER_SHA256

17.10-rc/Dockerfile

@@ -3,6 +3,12 @@ FROM alpine:3.6
 RUN apk add --no-cache \
 		ca-certificates
 
+# set up nsswitch.conf for Go's "netgo" implementation (which Docker explicitly uses)
+# - https://github.com/docker/docker-ce/blob/v17.09.0-ce/components/engine/hack/make.sh#L149
+# - https://github.com/golang/go/blob/go1.9.1/src/net/conf.go#L194-L275
+# - docker run --rm debian:stretch grep '^hosts:' /etc/nsswitch.conf
+RUN [ ! -e /etc/nsswitch.conf ] && echo 'hosts: files dns' > /etc/nsswitch.conf
+
 ENV DOCKER_CHANNEL test
 ENV DOCKER_VERSION 17.10.0-ce-rc1
 # TODO ENV DOCKER_SHA256

Dockerfile.template

@@ -3,6 +3,12 @@ FROM alpine:%%ALPINE-VERSION%%
 RUN apk add --no-cache \
 		ca-certificates
 
+# set up nsswitch.conf for Go's "netgo" implementation (which Docker explicitly uses)
+# - https://github.com/docker/docker-ce/blob/v17.09.0-ce/components/engine/hack/make.sh#L149
+# - https://github.com/golang/go/blob/go1.9.1/src/net/conf.go#L194-L275
+# - docker run --rm debian:stretch grep '^hosts:' /etc/nsswitch.conf
+RUN [ ! -e /etc/nsswitch.conf ] && echo 'hosts: files dns' > /etc/nsswitch.conf
+
 ENV DOCKER_CHANNEL %%DOCKER-CHANNEL%%
 ENV DOCKER_VERSION %%DOCKER-VERSION%%
 # TODO ENV DOCKER_SHA256