feat: bind to 127.0.0.1 by default instead of 0.0.0.0

[bfirsh]

Summary

• Default port binding changed from 0.0.0.0 to 127.0.0.1 across all commands, preventing prediction endpoints from being accidentally exposed to the entire network during development.
• Added --host flag to cog serve and host:port syntax to cog run -p so users can opt into binding to all interfaces when needed.

Changes

File	Change
pkg/docker/command/command.go	Added HostIP field to Port struct
pkg/docker/docker.go	Uses port.HostIP (default 127.0.0.1) instead of hardcoded ""
pkg/docker/run.go	GetHostPortForContainer now accepts a hostIP parameter
pkg/docker/run_test.go	Updated tests + added new test cases for default and all-interfaces binding
pkg/cli/serve.go	Added --host flag (default 127.0.0.1)
pkg/cli/run.go	-p flag supports host:port syntax (e.g. -p 0.0.0.0:8888), defaults to 127.0.0.1
pkg/predict/predictor.go	cog predict/cog train bind to 127.0.0.1

User-facing behavior

Command	Before	After
cog serve	Binds to 0.0.0.0	Binds to 127.0.0.1. Use --host 0.0.0.0 to expose.
cog run -p 8888	Binds to 0.0.0.0:8888	Binds to 127.0.0.1:8888. Use -p 0.0.0.0:8888 to expose.
cog predict / cog train	Binds to 0.0.0.0	Binds to 127.0.0.1

Test plan

• All 853 Go unit tests pass
• 0 lint issues

[ask-bonk]

LGTM

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[ask-bonk]

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[ask-bonk]

Changes default port binding from 0.0.0.0 to 127.0.0.1 across Docker container operations, with a new --host flag for cog serve and HostIP support in the port abstraction.

Issues found:

1. cog exec -p silently breaks backward compatibility. pkg/cli/exec.go creates command.Port without setting HostIP. Since docker.go now defaults empty HostIP to 127.0.0.1, cog exec -p 8888 now binds to localhost instead of all interfaces, with no escape hatch for users who need network exposure. Consider adding host:port parsing to the -p flag here, or an explicit --host flag for cog exec.

2. Misleading URL when explicitly binding to all interfaces. pkg/cli/serve.go substitutes localhost when --host 0.0.0.0 is used, which hides the fact that the server is exposed to the entire network. The displayed URL should reflect the actual binding or include a warning.

[ask-bonk]

I'm Bonk, and I've done a quick review of your PR.

Summary: Changes default Docker port binding from 0.0.0.0 to 127.0.0.1, adds --host flag to cog serve, and threads HostIP through the port abstraction.

Issues (highest severity first):

1. cog exec -p backward compatibility break — pkg/cli/exec.go:123 creates command.Port without HostIP, so it silently falls through to the new 127.0.0.1 default. Users who previously relied on cog exec -p 8888 being reachable from the network now have no escape hatch. Consider adding host:port syntax support or a --host flag to cog exec.

2. Misleading serve URL when binding to all interfaces — pkg/cli/serve.go:173-176 displays http://localhost:port even when --host 0.0.0.0 is explicitly passed, which masks the security implication that the server is exposed to the entire network.

I posted the full review as a top-level PR comment because the batch review API returned a 422 (likely stale line numbers). You can view it here: #2812 (comment)

github run

[michaeldwan]

Review

Real security improvement — localhost-by-default is the right call, applied centrally at the bind site, with docs regenerated. One blocker and a few should-fix items below.

Blocker

cog exec -p lost its host:port override in the merge. Commit a4aec985 added host:port parsing (-p 0.0.0.0:8000) and a HostIP to pkg/cli/run.go. Main renamed cog run → cog exec (ba48ff8e); during the merge (88bde6bd) git couldn't carry those changes into the renamed exec.go, so the current loop is the old strconv.Atoi(portString) with no HostIP and no host:port syntax. Because docker.go now defaults empty HostIP to 127.0.0.1, cog exec -p 8888 jupyter notebook silently became localhost-only with no escape hatch — contradicting the commit message's stated intent ("Support host:port syntax in cog run -p"). exec.go isn't in this diff, so this can't be an inline comment — please restore the host:port parsing from the original run.go diff and update the --publish help text.

Should-fix (inline below)

• docker.go — the core HostIP propagation change has no unit test.
• run.go — exact-string HostIP match is brittle; fall back to the single binding when only one exists.
• command.go — extract a shared DefaultHostIP constant ("127.0.0.1" is duplicated in 5 sites).
• serve.go — remote-Docker (DOCKER_HOST=tcp://…) users get silent breakage; no warning.

Nits (inline below)

• serve.go:20 — package var named host is generic; serveHost/bindHost is clearer.
• serve.go:174 — IPv6 --host values produce malformed display URLs (missing brackets); displayHost logic is also untested.
• run_test.go — duplicated mock scaffolding, not table-driven; missing edge cases (custom IP, IPv6, inspect returning empty HostIP).

cog predict/cog train hardcoding 127.0.0.1 is intended (local-only) and correct. pkg/registry_testhelpers using 0.0.0.0 directly via nat.PortBinding is correctly unaffected.

[ask-bonk]

LGTM

github run

[ask-bonk]

LGTM

github run

[ask-bonk]

APIError: Bad Request: AiError: AiError: Invalid data for image - reason invalid base64 encoding (aad49186-90be-4eb7-8a90-c388fee5327e)

github run

[ask-bonk]

APIError: Bad Request: AiError: AiError: Invalid data for image - reason invalid base64 encoding (67ef8603-4189-4822-9de4-14041877885e)

github run