sh: ./elastic-agent: not found when trying to run the elastic agent on Alpine Linux-CodePudding

I'm trying to configure the Elastic Agent on a docker container running another service. The container is based on Alpine Linux, yet I can't run the elastic-agent agent command after downloading and extracting the agent : it complains about a "not found" file, while the file actually exists!

Here's a minimal reproductible example

docker run --rm -it alpine sh
# cd /opt
# wget https://artifacts.elastic.co/downloads/beats/elastic-agent/elastic-agent-7.14.2-linux-x86_64.tar.gz
# tar xvf elastic-agent-7.14.2-linux-x86_64.tar.gz
# cd elastic-agent-7.14.2-linux-x86_64/
# ./elastic-agent
sh: ./elastic-agent: not found
# ls -la
total 8452
drwxr-xr-x    3 root     root          4096 Nov 18 17:38 .
drwxr-xr-x    1 root     root          4096 Nov 18 17:38 ..
-rw-r--r--    1 root     root            41 Sep 15 17:00 .build_hash.txt
-rw-r--r--    1 root     root            41 Sep 15 17:00 .elastic-agent.active.commit
-rw-r--r--    1 root     root         13675 Sep 15 16:54 LICENSE.txt
-rw-r--r--    1 root     root       8586842 Sep 15 16:54 NOTICE.txt
-rw-r--r--    1 root     root           866 Sep 15 17:00 README.md
drwxr-xr-x    3 root     root          4096 Nov 18 17:38 data
lrwxrwxrwx    1 root     root            39 Nov 18 17:38 elastic-agent -> data/elastic-agent-574c21/elastic-agent
-rw-r--r--    1 root     root          9020 Sep 15 16:55 elastic-agent.reference.yml
-rw-------    1 root     root          9017 Sep 15 16:55 elastic-agent.yml
# ./data/elastic-agent-574c21/elastic-agent
sh: ./data/elastic-agent-574c21/elastic-agent: not found

I'm running on an x86_64 host as can be seen with the kernel version or package repos:

# uname -a
Linux 59ae07b0dca8 5.10.47-linuxkit #1 SMP Sat Jul 3 21:51:47 UTC 2021 x86_64 Linux
# apk update
fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/main/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/community/x86_64/APKINDEX.tar.gz
v3.14.3-14-g9234faeb0d [https://dl-cdn.alpinelinux.org/alpine/v3.14/main]
v3.14.3-12-g13e0706e2c [https://dl-cdn.alpinelinux.org/alpine/v3.14/community]
OK: 14942 distinct packages available

At it seems the binary can link to libraries correctly:

# ldd  ./data/elastic-agent-574c21/elastic-agent
    /lib64/ld-linux-x86-64.so.2 (0x7f1868c2f000)
    libpthread.so.0 => /lib64/ld-linux-x86-64.so.2 (0x7f1868c2f000)
    libdl.so.2 => /lib64/ld-linux-x86-64.so.2 (0x7f1868c2f000)
    libc.so.6 => /lib64/ld-linux-x86-64.so.2 (0x7f1868c2f000)

It also has the permissions to execute

# ls -la /usr/local/bin/elastic-agent-7.14.2-linux-x86_64/data/elastic-agent-574c21/
total 57244
drwxr-xr-x    3 root     root          4096 Nov 18 17:38 .
drwxr-xr-x    3 root     root          4096 Nov 18 17:38 ..
drwxr-xr-x    2 root     root          4096 Nov 18 17:38 downloads
-rwxr-xr-x    1 root     root      58603536 Sep 15 17:00 elastic-agent

strace does not seem to help neither

# strace -f ./elastic-agent
execve("./elastic-agent", ["./elastic-agent"], 0x7fff9e17bee8 /* 7 vars */) = -1 ENOENT (No such file or directory)
strace: exec: No such file or directory
    exited with 1

Am I missing something? Could Alpine prevent a binary from starting under some conditions?

Thanks for your help!

CodePudding user response：

The problem seems to be that the compiled version of elastic-agent that you downloaded requires libc. Alpine linux uses muslc.

One can install glibc in alpine using https://stackoverflow.com/a/38433396/5666087. And then elastic-agent appears to work.

FROM alpine
WORKDIR /opt
RUN wget -qO - https://artifacts.elastic.co/downloads/beats/elastic-agent/elastic-agent-7.14.2-linux-x86_64.tar.gz \
    | tar xz
# Add glibc
RUN wget -q -O /etc/apk/keys/sgerrand.rsa.pub https://alpine-pkgs.sgerrand.com/sgerrand.rsa.pub \
    && wget -q https://github.com/sgerrand/alpine-pkg-glibc/releases/download/2.28-r0/glibc-2.28-r0.apk \
    && apk add glibc-2.28-r0.apk \
    && rm glibc-2.28-r0.apk

And run the resulting image (let's assume it is named elastic):

docker run --rm -it elastic /opt/elastic-agent-7.14.2-linux-x86_64/elastic-agent