Backports (cherry-picks) a merged PR from main (v4) to the v3 branch of buildkite/agent, translating v4 code back to v3 conventions. Use when asked to backport, cherry-pick, or port a PR or commit to v3.
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Backports (cherry-picks) a merged PR from main (v4) to the v3 branch of buildkite/agent, translating v4 code back to v3 conventions. Use when asked to backport, cherry-pick, or port a PR or commit to v3.
Cherry-picking a PR to v3
Since August 2026, main is the v4 codebase. Stable v3 releases come from the
v3 branch. A change that needs to reach customers in v3 must first merge to
main, then be backported as a second PR against v3 with the same changes
translated back to v3 conventions.
Workflow
Identify the merged PR/commit on main to backport. Never cherry-pick the
v4 merge commit (8aea45a, PR #3807) itself — it is the entire v4 delta.
Apply the change onto v3: with jj, jj duplicate <rev> -d v3 (then
jj edit the duplicate to resolve conflicts); with git, branch off v3
and git cherry-pick -x --no-commit <sha>. Resolve conflicts by
translating the code as described below. PRs in this repo merge as
two-parent merge commits, and the change lives in the constituent
commit(s), not the merge commit: jj duplicate of the merge commit
produces an empty commit, and git cherry-pick refuses it without
-m 1. Select the PR's constituent commit(s) instead.
Translate all v4-isms back to v3 (see checklist).
Raise the backport PR against v3. Keep the description concise: state
that it is a backport of the original PR (with a link) and note any
translation deviations. Do not duplicate the original PR's full
description — reviewers can follow the link.
Do not touch the VERSION file unless a release is explicitly requested.
Translation checklist (v4 → v3)
1. Import paths
The module changed major version. Rewrite every import:
Also check string-valued package paths, not just imports: tracer names
(otel.Tracer("github.com/buildkite/agent/...")), linker flags, generated
protobuf go_package_prefix, doc links. Never change the v3 branch's
go.mod module declaration.
2. urfave/cli: v3 → v1
main uses github.com/urfave/cli/v3; the v3 branch uses
github.com/urfave/cli (v1). Flags and commands are pointers in cli v3 but
values in cli v1, and env vars are declared differently:
// main (cli v3)
&cli.StringFlag{
Name: "note",
Usage: "A descriptive note to record why the agent is paused",
Sources: cli.EnvVars("BUILDKITE_AGENT_PAUSE_NOTE"),
}
// v3 branch (cli v1)
cli.StringFlag{
Name: "note",
Usage: "A descriptive note to record why the agent is paused",
EnvVar: "BUILDKITE_AGENT_PAUSE_NOTE",
}
main (cli v3)
v3 branch (cli v1)
import "github.com/urfave/cli/v3"
import "github.com/urfave/cli"
&cli.Command{...}
cli.Command{...}
[]*cli.Command
[]cli.Command
&cli.StringFlag{...} (and Bool/Int/etc.)
cli.StringFlag{...}
Sources: cli.EnvVars("X")
EnvVar: "X"
Commands: []*cli.Command{...} (subcommands)
Subcommands: []cli.Command{...}
StringSliceFlag{Value: []string{}}
StringSliceFlag{Value: &cli.StringSlice{}}
cli.Exit(...)
cli.NewExitError(...)
flag.Names()
flag.GetName()
3. Action signatures and context
cli v3 actions receive a context.Context; cli v1 actions do not:
Named action functions translate the same way:
func fooAction(ctx context.Context, c *cli.Command) error becomes
func fooAction(c *cli.Context) error with ctx := context.Background()
inside. Do not change v3's shared setup helpers to accept *cli.Command.
Do not copy the cli v3 command-cloning workaround into v3 tests.
Behavioral differences — don't backport v4 breaks by accident
A conflict may signal a deliberate v4 behavior change, not just code drift.
Preserve v3 behavior unless changing it is the explicit purpose of the
backport:
Tracing/metrics: v3 still has Datadog/OpenTracing and DogStatsD
(TracingBackend, TracingServiceName); v4 is OpenTelemetry-only
(OpenTelemetryTracing, TelemetryServiceName). Map config fields back.
Cancellation flags: v3 has --cancel-grace-period and
--signal-grace-period-seconds; v4 replaced them with
--cancel-signal-timeout and --cancel-cleanup-timeout.
Experiments: v4 promoted or removed several experiments (normalized
artifact upload paths, resolve-commit-after-checkout, etc.). A v4 diff may
lack an experiment guard because the behavior is unconditional there; the
v3 backport may need to keep or add the guard.
Hook ordering: v4 reverses post-hook order by default; v3 does not.
Commit verification: v4 defaults to strict and only supports
strict/off; v3 supports the older empty/warn/strict values.
SSH host keys: v4 uses GIT_SSH_COMMAND with
StrictHostKeyChecking=accept-new; v3 still uses ssh-keyscan and
known_hosts.
Removed in v4, still in v3: deprecated Docker integration, deprecated
artifact flags (follow-symlinks), plugin env aliases, header-times
streamer/API. If the v4 patch assumes these are gone, the v3 backport
needs a v3-specific integration point.
Output: v4 intentionally changed some output (e.g. meta-data get
gained a trailing newline). Don't pull such compatibility breaks into v3.
