flake: dogfood build_image tar/gzip failure downloading tools

[flake-investigator]

CI Run Link: https://github.com/coder/coder/actions/runs/22573678608/job/65410736265
Commit: 978e397c98ab45116ab9218a2157cd3199b10c95 (author: Lukasz)

Failing job:

• Workflow: dogfood
• Job: build_image (run_attempt=2)
• Step: Build and push Non-Nix image
• Completed at: 2026-03-02T14:38:21Z (same-day as alert)

Failure evidence:

#34 3.670 gzip: stdin: not in gzip format
#34 3.670 tar: Child returned status 1
#34 3.670 tar: Error is not recoverable: exiting now
#34 ERROR: process "/bin/bash -c curl --silent --show-error --location --output /usr/local/bin/cloud_sql_proxy ... \
  curl --silent --show-error --location "https://github.com/wagoodman/dive/releases/download/v${DIVE_VERSION}/dive_${DIVE_VERSION}_linux_amd64.tar.gz" | \
  tar --extract --gzip --directory=/usr/local/bin --file=- dive && ..." did not complete successfully: exit code: 2

Dockerfile context (dogfood/coder/Dockerfile ~lines 301-340) shows multiple curl | tar downloads for tool releases; the first tar pipe is the dive release download.

Root cause classification: Infrastructure / third-party download flake

• tar failed because curl returned non-gzip content (likely an HTML error/redirect or transient GitHub release outage). No code-level build change or test failure indicated.
• Failure is in the Docker build image step, not a test run.

Assignment analysis:

• No test function applies; this is a dogfood image build failure in dogfood/coder/Dockerfile.
• CODEOWNERS has no dogfood entry.
• git log --oneline -10 --follow dogfood/coder/Dockerfile shows the most recent human change:
  • 6248520130 — “chore(dogfood): update Rust from 1.86.0 to 1.93.1” (Michael Suchacz)
• Assigning to @ibetitsmike as the most recent non-bot modifier of the dogfood Dockerfile.

Duplicate search (coder/internal):

• Searched: "gzip: stdin", "tar: Error is not recoverable", "dogfood build_image", "Dockerfile dogfood", "Build and push Non-Nix image".
• No matching issues found. Closest was flake: e2e-test/test ssh #218 (curl 403 in e2e install.sh) but unrelated to dogfood Dockerfile downloads.

Suggested next steps:

• Add --fail and retry/backoff to the tool downloads (e.g., curl --fail --retry 5 --retry-all-errors), or verify specific release URLs are healthy.
• Consider splitting the tool downloads so the log shows which asset failed.