Crash with --experimental_remote_download_outputs=toplevel #8508
Description
Description of the problem / feature request:
When using --experimental_remote_download_outputs=toplevel, and having a cache return a 500, bazel crashes. I would expect it to recover in this case and fall back to retrying the request, or worst case doing the build locally. Without this flag it does seem to be resilient to this.
ERROR: /root/.cache/bazel/_bazel_root/c99f8fb4c845b3aae6d69f1a3c75aa35/external/com_google_protobuf/BUILD:388:1: Linking of rule '@com_google_protobuf//:protoc' failed due to unexpected I/O exception: 504 Gateway Time-out
<html>
<head><title>504 Gateway Time-out</title></head>
<body bgcolor="white">
<center><h1>504 Gateway Time-out</h1></center>
<hr><center>nginx/1.15.3</center>
</body>
</html>
com.google.devtools.build.lib.remote.blobstore.http.HttpException: 504 Gateway Time-out
<html>
<head><title>504 Gateway Time-out</title></head>
<body bgcolor="white">
<center><h1>504 Gateway Time-out</h1></center>
<hr><center>nginx/1.15.3</center>
</body>
</html>
at com.google.devtools.build.lib.remote.blobstore.http.HttpDownloadHandler.channelRead0(HttpDownloadHandler.java:116)
at com.google.devtools.build.lib.remote.blobstore.http.HttpDownloadHandler.channelRead0(HttpDownloadHandler.java:41)
at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:359)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:345)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:337)
at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:438)
at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:323)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:297)
at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:253)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:359)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:345)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:337)
at io.netty.handler.ssl.SslHandler.unwrap(SslHandler.java:1476)
at io.netty.handler.ssl.SslHandler.decodeJdkCompatible(SslHandler.java:1225)
at io.netty.handler.ssl.SslHandler.decode(SslHandler.java:1272)
at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:502)
at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:441)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:278)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:359)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:345)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:337)
at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:286)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:359)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:345)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:337)
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1408)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:359)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:345)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:930)
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163)
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:677)
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:612)
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:529)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:491)
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:905)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Unknown Source)
Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.
bazel run TARGET when pointing at an unhealthy http cache and passing --experimental_remote_download_outputs=toplevel
What operating system are you running Bazel on?
macOS
What's the output of bazel info release?
release 0.26.0
cc @buchgr