treewide: stop using LZ4 for initrd compression
There are two issues at play here: One is a bug in pierrec/lz4 when
using the legacy framing format [1]. This bit us when we hit a broken
size region with CL:2130, taking hours to debug.
The other is the fact that the Linux LZ4 frame format has significant
design issues [2], especially with concatenanted initrds.
The first issue could be fixed by switching to a different LZ4
implementation (we do even have the reference impl in the monorepo) but
there is no API to generate the legacy frame format and things like [3],
a patch carried by Ubuntu to fix more edge cases just do not inspire
confidence in such a solution.
Thus, this CL switches over to using zstd for compressing initrds.
Zstd is slower than LZ4 for decompressing, but it still decompresses at
multiple GB/s per core while having a much better compression ratio.
It also doesn't have any Linux-specific bits and Linux uses the
reference implementation for decoding, which should make it much more
robust. So overall I think this is a good tradeoff.
[1] https://github.com/pierrec/lz4/issues/156
[2] https://github.com/lz4/lz4/issues/956#issuecomment-736705712
[3] https://launchpadlibrarian.net/507407918/0001-unlz4-Handle-0-size-chunks-discard-trailing-padding-.patch
Change-Id: I69cf69f2f361de325f4b39f2d3644ee729643716
Reviewed-on: https://review.monogon.dev/c/monogon/+/2313
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
diff --git a/cloud/agent/e2e/BUILD.bazel b/cloud/agent/e2e/BUILD.bazel
index 2ed2ad5..fa03d66 100644
--- a/cloud/agent/e2e/BUILD.bazel
+++ b/cloud/agent/e2e/BUILD.bazel
@@ -16,7 +16,7 @@
"//metropolis/pkg/pki",
"//metropolis/proto/api",
"@com_github_cavaliergopher_cpio//:cpio",
- "@com_github_pierrec_lz4_v4//:lz4",
+ "@com_github_klauspost_compress//zstd",
"@org_golang_google_grpc//:go_default_library",
"@org_golang_google_grpc//credentials",
"@org_golang_google_protobuf//proto",