TARGETARCH cannot have a value set

[mdonkers]

Bug Report

Which version of the demo you are using? (please provide either a specific
#944

Symptom

Docker build is failing after the OTel Collector Dockerfile got updated

$ docker build --platform linux/amd64 -t otelcol -f src/otelcollector/Dockerfile .
[+] Building 0.7s (14/19)                                                                                                                                                                            docker:default
 => [internal] load .dockerignore                                                                                                                                                                              0.0s
 => => transferring context: 1.18kB                                                                                                                                                                            0.0s
 => [internal] load build definition from Dockerfile                                                                                                                                                           0.0s
 => => transferring dockerfile: 997B                                                                                                                                                                           0.0s
 => [internal] load metadata for docker.io/library/alpine:latest                                                                                                                                               0.4s
 => [internal] load metadata for docker.io/library/golang:latest                                                                                                                                               0.4s
 => [internal] load metadata for docker.io/library/alpine:3.16                                                                                                                                                 0.0s
 => [build 1/7] FROM docker.io/library/golang:latest@sha256:cfc9d1b07b1ef4f7a4571f0b60a99646a92ef76adb7d9943f4cb7b606c6554e2                                                                                   0.0s
 => [internal] load build context                                                                                                                                                                              0.0s
 => => transferring context: 294B                                                                                                                                                                              0.0s
 => [certs 1/2] FROM docker.io/library/alpine:3.16                                                                                                                                                             0.0s
 => [stage-2 1/4] FROM docker.io/library/alpine@sha256:82d1e9d7ed48a7523bdebc18cf6290bdb97b82302a8a9c27d4fe885949ea94d1                                                                                        0.0s
 => CACHED [build 2/7] RUN curl -L -o /builder https://github.com/open-telemetry/opentelemetry-collector/releases/download/cmd%2Fbuilder%2Fv0.81.0/ocb_0.81.0_linux_arm64                                      0.0s
 => CACHED [build 3/7] RUN chmod +x /builder                                                                                                                                                                   0.0s
 => CACHED [build 4/7] WORKDIR /build                                                                                                                                                                          0.0s
 => CACHED [build 5/7] COPY ./src/otelcollector/manifest.yml ./                                                                                                                                                0.0s
 => ERROR [build 6/7] RUN /builder --config ./manifest.yml --output-path /build/_build                                                                                                                         0.3s
------
 > [build 6/7] RUN /builder --config ./manifest.yml --output-path /build/_build:
0.226 /bin/sh: 1: /builder: Exec format error
------
Dockerfile:15
--------------------
  13 |     ENV GOARCH=arm64
  14 |     ENV CGO_ENABLED=0
  15 | >>> RUN /builder --config ./manifest.yml --output-path /build/_build
  16 |     RUN ls /build/_build
  17 |     
--------------------
ERROR: failed to solve: process "/bin/sh -c /builder --config ./manifest.yml --output-path /build/_build" did not complete successfully: exit code: 126

As can be seen in the output, even though --platform=linux/amd64 is specified, the Dockerfile pulls the arm64 version of Builder.

What is the expected behavior?

Successful Docker build

What is the actual behavior?

A build failure with the above exception

Reproduce

Try to build the OTel Collector Docker image on a non-arm64 machine.

It only works fine when supplying the TARGETARCH parameter directly, as in --build-arg="TARGETARCH=amd64" Not entirely sure why it does work for you build system, perhaps because of the type of runner.

[mdonkers]

Additionally, see also this blog from Docker, where they describe the use of the parameters: https://www.docker.com/blog/faster-multi-platform-builds-dockerfile-cross-compilation-guide/
There TARGETARCH is also defined without default.

[julianocosta89]

I can reproduce this on Ubuntu 22.04.