Enable integration tests with Daphne Helper

[cjpatton]

Partially addresses #2389.

Also, remove code for testing against Daphne running locally.

[cjpatton]

Reviewer note: This tag was created manually. It matches the commit that was checked out when the image was built. In the future we will add publishing the container to CI.

[cjpatton]

@branlwyd can you take a look at the CI failure? It's a bit cryptic:

[inahga]

It actually failed a test further above--this job step just fails the job if a failure as detected earlier. The true error is here https://github.com/divviup/janus/actions/runs/8744950821/job/23999640943?pr=3030#step:14:411, where it complains:

Error response from daemon: Could not find the file /logs in container 99f04f6724ae4b56b30a8a6185505212813810d3c83e31fbc0ccb1d92821b183
thread 'daphne::janus_in_process_daphne' panicked at library/core/src/panicking.rs:144:5:
thread 'daphne::janus_in_process_daphne' panicked at /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/testcontainers-0.15.0/src/core/container.rs:143:17:
container 99f04f6724ae4b56b30a8a6185505212813810d3c83e31fbc0ccb1d92821b183 does not expose port 8788

n.b. I think the second does not expose port 8788 is the true error, and the container logs guard is inducing a double-panic because the container doesn't actually exist at the time of drop.

[divergentdave]

The actual error message is a couple steps above, container <hash> does not expose port 8788, but that's misleading. I tried running the container, and I get the following:

WARNING: The requested image's platform (linux/arm64) does not match the detected host platform (linux/amd64/v4) and no specific platform was requested
exec /bin/bash: exec format error

Unpacking the image, I see that both /bin/bash and /service are indeed ELF executables for ARM aarch64, so this is just an issue with missing images for Intel architectures.

[inahga]

Ah, nice find. Yeah if you built it locally with docker build on an ARM macbook it's going to yield a linux/arm64 image. Perhaps the best way around that is to set an explicit target in Daphne's build step cargo build --target x86_64-unknown-linux-gnu.

[divergentdave]

I don't think it would be worth hardcoding a target in the Dockerfile, since the whole base image needs to match the architecture as well, and whatever (docker-)machine is used for building needs to be able to run that architecture.

[inahga]

Ah right, Rust cross-compilation is not as fool-proof as I had hoped, you still need a platform-specific linker.