Currently the spec states that the arch property in config.json should conform with the Go language spec. However, this spec only covers the following architectures: amd64, 386 and arm.

Since one of the goals of the Open Container Project is to support multiple architectures, and given the fact that, at least for ARM [1], it is very common to have different versions and different extensions depending on the SoC, the current list is insufficient.

Common architectures include armv5, armv6 and armv7a. The list could be further expanded by adding armv5, mips and powerpc. Another dimention that should be put into consideration is whether or not the architecture features a floating point unit, which will require architecture specifiers such as armv7ahf, armv6hf, mipseletc.

A good source of conventions can be found in the source code of the Open Embedded project [2]. Doing a quick grep for available architecture specifiers (AVAILTUNES) yields the following list:

aarch64,aarch64_be,arm1136jfs,arm920t,arm926ejs,arm9tdmi,armv4,armv4b,armv4t,armv4tb,armv5,armv5b,armv5b-vfp,armv5e,armv5eb,armv5eb-vfp,armv5ehfb-vfp,armv5ehf-vfp,armv5e-vfp,armv5hfb-vfp,armv5hf-vfp,armv5t,armv5tb,armv5tb-vfp,armv5te,armv5teb,armv5teb-vfp,armv5tehfb-vfp,armv5tehf-vfp,armv5te-vfp,armv5thfb-vfp,armv5thf-vfp,armv5t-vfp,armv5-vfp,armv6,armv6b,armv6b-novfp,armv6hf,armv6hfb,armv6-novfp,armv6t,armv6tb,armv6tb-novfp,armv6thf,armv6thfb,armv6t-novfp,armv7a,armv7ab,armv7ab-neon,armv7ahf,armv7ahfb,armv7ahfb-neon,armv7ahf-neon,armv7ahf-neon-vfpv4,armv7a-neon,armv7at,armv7atb,armv7atb-neon,armv7athf,armv7athfb,armv7athfb-neon,armv7athf-neon,armv7athf-neon-vfpv4,armv7at-neon,c3,core2-32,core2-64,core2-64-x32,corei7-32,corei7-64,corei7-64-x32,cortexa15,cortexa15hf,cortexa15hf-neon,cortexa15-neon,cortexa15t,cortexa15thf,cortexa15thf-neon,cortexa15t-neon,cortexa5,cortexa5hf,cortexa5hf-neon,cortexa5-neon,cortexa5t,cortexa5thf,cortexa5thf-neon,cortexa5t-neon,cortexa7,cortexa7hf,cortexa7hf-neon,cortexa7hf-neon-vfpv4,cortexa7-neon,cortexa7t,cortexa7thf,cortexa7thf-neon,cortexa7thf-neon-vfpv4,cortexa7t-neon,cortexa8,cortexa8hf,cortexa8hf-neon,cortexa8-neon,cortexa8t,cortexa8thf,cortexa8thf-neon,cortexa8t-neon,cortexa9,cortexa9hf,cortexa9hf-neon,cortexa9-neon,cortexa9t,cortexa9thf,cortexa9thf-neon,cortexa9t-neon,cortexm1,cortexm3,cortexr4,ep9312,i586,i586-nlp-32,iwmmxt,mips,mips32,mips32el,mips32el-nf,mips32-nf,mips32r2,mips32r2el,mips64,mips64el,mips64el-n32,mips64el-nf,mips64el-nf-n32,mips64-n32,mips64-nf,mips64-nf-n32,mipsel,mipsel-nf,mips-nf,powerpc,powerpc64,powerpc-nf,ppc476,ppc603e,ppc64e5500,ppc64e6500,ppc64p5,ppc64p6,ppc64p7,ppc7400,ppce300c2,ppce300c3,ppce300c3-nf,ppce500,ppce500mc,ppce500v2,ppce5500,ppce6500,ppcp5,ppcp6,ppcp7,sh3,sh3eb,sh4,sh4a,sh4aeb,sh4eb,strongarm,x86,x86-64,x86-64-x32,xscale,xscale-be

The above list is not exhaustive of the variations that each platform can have but it should be a good start of available architectures.

Something to note is that the Open Embedded project uses x86-64 instead of amd64. Currently all built the images in the docker registry have their Arch field set to amd64 so it might be a sensible exception.

[1] https://en.wikipedia.org/wiki/List_of_instruction_sets#ARM
[2] https://github.com/openembedded/oe-core/tree/master/meta/conf/machine/include