Latest Alpine image seg faults

[zoidyzoidzoid]

± docker run -it --rm memcached:1.4.37-alpine -o modern -m 32
Unable to find image 'memcached:1.4.37-alpine' locally
1.4.37-alpine: Pulling from library/memcached
6f821164d5b7: Pull complete
338fbb6cf27a: Pull complete
0930cf93b5b2: Pull complete
7bdbb30d4915: Pull complete
54c1d5e73dc6: Pull complete
Digest: sha256:ae33b9e8b100774d92277df779bc0d72bae81a2f62741106e7ea4cd683e2a507
Status: Downloaded newer image for memcached:1.4.37-alpine
± echo $?
139

± docker run -it --rm memcached:1.4.36-alpine -o modern -m 32
Unable to find image 'memcached:1.4.36-alpine' locally
1.4.36-alpine: Pulling from library/memcached
6f821164d5b7: Already exists
338fbb6cf27a: Already exists
714c5ae9370a: Pull complete
3a1e7538d8c8: Pull complete
952bb42ade1c: Pull complete
Digest: sha256:00b68b00139155817a8b1d69d74865563def06b3af1e6fc79ac541a1b2f6b961
Status: Downloaded newer image for memcached:1.4.36-alpine
^CSignal handled: Interrupt.

± echo $?
0

[tianon]

Seems to be something specifically to do with -o modern -- I can only reproduce by including that. 😕

[zoidyzoidzoid]

And still happens with 14.39 😞

Think it's us or upstream Alpine image?

[tianon]

For compiling memcached itself, we make no changes from Debian to Alpine, so it's bound to be something odd happening between memcached and musl. 😞

Can it be reproduced with the Alpine package of memcached? (https://pkgs.alpinelinux.org/package/v3.6/main/x86_64/memcached)

That would at least help us confirm that it's not something we're doing odd, and is instead more likely something musl-related.

Here's our full Debian->Alpine diff, for context:

--- debian/Dockerfile	2017-07-05 11:14:17.003901806 -0700
+++ alpine/Dockerfile	2017-07-05 11:14:17.002901835 -0700
@@ -1,25 +1,25 @@
-FROM debian:jessie-slim
+FROM alpine:3.5
 
 # add our user and group first to make sure their IDs get assigned consistently, regardless of whatever dependencies get added
-RUN groupadd -r memcache && useradd -r -g memcache memcache
+RUN adduser -D memcache
 
 ENV MEMCACHED_VERSION 1.4.39
 ENV MEMCACHED_SHA1 9d6f77f4f9f1b50289882fd88851dece7699c74b
 
 RUN set -x \
-	&& buildDeps=' \
+	&& apk add --no-cache --virtual .build-deps \
 		ca-certificates \
-		dpkg-dev \
+		coreutils \
+		cyrus-sasl-dev \
+		dpkg-dev dpkg \
 		gcc \
-		libc6-dev \
+		libc-dev \
 		libevent-dev \
-		libsasl2-dev \
+		libressl \
+		linux-headers \
 		make \
 		perl \
-		wget \
-	' \
-	&& apt-get update && apt-get install -y $buildDeps --no-install-recommends \
-	&& rm -rf /var/lib/apt/lists/* \
+		tar \
 	&& wget -O memcached.tar.gz "https://memcached.org/files/memcached-$MEMCACHED_VERSION.tar.gz" \
 	&& echo "$MEMCACHED_SHA1  memcached.tar.gz" | sha1sum -c - \
 	&& mkdir -p /usr/src/memcached \
@@ -32,10 +32,15 @@
 	&& make -j "$(nproc)" \
 	&& make install \
 	&& cd / && rm -rf /usr/src/memcached \
-	&& apt-mark manual \
-		libevent-2.0-5 \
-		libsasl2-2 \
-	&& apt-get purge -y --auto-remove $buildDeps \
+	&& runDeps="$( \
+		scanelf --needed --nobanner --recursive /usr/local \
+			| awk '{ gsub(/,/, "\nso:", $2); print "so:" $2 }' \
+			| sort -u \
+			| xargs -r apk info --installed \
+			| sort -u \
+	)" \
+	&& apk add --virtual .memcached-rundeps $runDeps \
+	&& apk del .build-deps \
 	&& memcached -V
 
 COPY docker-entrypoint.sh /usr/local/bin/

[zoidyzoidzoid]

It's happening on edge with the packaged memcached when using -o modern as well. 😞

docker run -it --rm alpine:edge                                                                                                                                  
/ # apk add --no-cache memcached
/ # memcached -V
memcached 1.4.39

/ # memcached -u root -o modern
Segmentation fault (core dumped)

On 3.6.2 it behaves as expected because it uses 1.4.36:

docker run -it --rm alpine
/ # cat /etc/alpine-release
3.6.2
/ # apk add --no-cache memcached
/ # memcached -V
memcached 1.4.36
/ # memcached -u root -o modern
^CSignal handled: Interrupt.

[dormando]

ahh sorry, I thought I'd responded for some reason.

Not sure why that was missing... I just installed musl locally, compiled libevent with musl, then compiled memcached and was able to get it to crash... but it can't build memcached-debug under musl sadly :/

I was able to do a quick bisect and narrowed it down to d184b4b08f92d0171c8a3a3f03fa22e33c6aaa55 - dunno what I did just yet but that does seem to be where it's segfaulting so I must've done something stupid.

[dormando]

found it, followed up in the linked issue. would appreciate some testing.