Running docker-in-docker with QEMU emulation produce... | moby/moby

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NOTE: perhaps there's an existing issue for this already (I need to search), but posting the information in case we need it later 😂

For testing, I just started a dind container using --platform=linux/arm64 (on Docker Desktop, running on an Intel machine). This runs the container with QEMU to allow running containers with a non-matching architecture (on a "best effort" base).

docker run -it --rm --privileged -v /var/lib/docker --platform=linux/arm64 docker:dind --iptables=false

When doing so, multiple errors are printed, both in the daemon logs during startup, as well as when (e.g.) running docker version or docker info;

ERRO[0000] failure getting variant                       error="getCPUInfo for pattern: Cpu architecture: not found"

So, generally, this is somewhat expected, but wondering if we;

can (should?) make this less noisy
could we detect the "emulation" and produce more "correct" information?
perhaps perform this only once during the daemon's lifecycle (instead of trying to parse (and error) multiple times (this is somewhat separate from the error itself, but perhaps a sync.Once wouldn't hurt for this).

In case we want to write a test for this, here's the output of /proc/cpuinfo;

cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 60
model name	: Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
stepping	: 3
cpu MHz		: 3987.822
cache size	: 8192 KB
physical id	: 0
siblings	: 1
core id		: 0
cpu cores	: 1
apicid		: 0
initial apicid	: 0
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht pbe syscall nx pdpe1gb lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid pni pclmulqdq dtes64 ds_cpl ssse3 sdbg fma cx16 xtpr pcid sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm fsgsbase bmi1 avx2 bmi2 erms xsaveopt arat
bugs		: cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit srbds
bogomips	: 7975.64
clflush size	: 64
cache_alignment	: 64
address sizes	: 39 bits physical, 48 bits virtual
power management:

processor	: 1
vendor_id	: GenuineIntel
cpu family	: 6
model		: 60
model name	: Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
stepping	: 3
cpu MHz		: 3987.822
cache size	: 8192 KB
physical id	: 1
siblings	: 1
core id		: 0
cpu cores	: 1
apicid		: 1
initial apicid	: 1
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht pbe syscall nx pdpe1gb lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid pni pclmulqdq dtes64 ds_cpl ssse3 sdbg fma cx16 xtpr pcid sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm fsgsbase bmi1 avx2 bmi2 erms xsaveopt arat
bugs		: cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit srbds
bogomips	: 7950.24
clflush size	: 64
cache_alignment	: 64
address sizes	: 39 bits physical, 48 bits virtual
power management:

processor	: 2
vendor_id	: GenuineIntel
cpu family	: 6
model		: 60
model name	: Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
stepping	: 3
cpu MHz		: 3987.822
cache size	: 8192 KB
physical id	: 2
siblings	: 1
core id		: 0
cpu cores	: 1
apicid		: 2
initial apicid	: 2
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht pbe syscall nx pdpe1gb lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid pni pclmulqdq dtes64 ds_cpl ssse3 sdbg fma cx16 xtpr pcid sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm fsgsbase bmi1 avx2 bmi2 erms xsaveopt arat
bugs		: cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit srbds
bogomips	: 8054.40
clflush size	: 64
cache_alignment	: 64
address sizes	: 39 bits physical, 48 bits virtual
power management:

processor	: 3
vendor_id	: GenuineIntel
cpu family	: 6
model		: 60
model name	: Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
stepping	: 3
cpu MHz		: 3987.822
cache size	: 8192 KB
physical id	: 3
siblings	: 1
core id		: 0
cpu cores	: 1
apicid		: 3
initial apicid	: 3
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht pbe syscall nx pdpe1gb lm constant_tsc rep_good nopl xtopology nonstop_tsc cpuid pni pclmulqdq dtes64 ds_cpl ssse3 sdbg fma cx16 xtpr pcid sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm fsgsbase bmi1 avx2 bmi2 erms xsaveopt arat
bugs		: cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit srbds
bogomips	: 7845.03
clflush size	: 64
cache_alignment	: 64
address sizes	: 39 bits physical, 48 bits virtual
power management:

Reproduce the issue with the provided docker run command using --platform=linux/arm64, then inspect daemon startup, docker version, and docker info output. Start at the getCPUInfo failure and compare it with the supplied /proc/cpuinfo data. Done is not defined: the issue proposes reducing noise, improving emulation information, or avoiding repeated parsing without choosing an expected behavior.

Written by the indexing model from the issue text.

Running docker-in-docker with QEMU emulation produces some noisy errors

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