Start long-running processes (web servers, daemons) without blocking the
HTTP request. Leverages envd's existing background process support
(context.Background(), List, Connect, SendSignal RPCs) and wires it
through the host agent and control plane layers.
New API surface:
- POST /v1/capsules/{id}/exec with background:true → 202 {pid, tag}
- GET /v1/capsules/{id}/processes → list running processes
- DELETE /v1/capsules/{id}/processes/{selector} → kill by PID or tag
- WS /v1/capsules/{id}/processes/{selector}/stream → reconnect to output
The {selector} param auto-detects: numeric = PID, string = tag.
Tags are auto-generated as "proc-" + 8 hex chars if not provided.
envd crashes with "fatal error: bad summary data" after Firecracker
snapshot/restore because the page allocator radix tree is inconsistent
when vCPUs are frozen mid-allocation. The port scanner goroutine
allocates heavily every second, making it the primary trigger.
Add POST /snapshot/prepare to envd — the host agent calls it before
vm.Pause to quiesce continuous goroutines and force GC. On restore,
PostInit restarts the port subsystem via the existing /init endpoint.
- New PortSubsystem abstraction with Start/Stop/Restart lifecycle
- Context-based goroutine cancellation (replaces irreversible channel close)
- Context-aware Signal to prevent scanner/forwarder deadlock
- Fix forwarder goroutine leak (was spinning forever on closed channel)
- Kill socat children on stop to prevent orphans across snapshots
- Fix double cmd.Wait panic (exec.Command instead of CommandContext)
- COPY now supports multiple sources: COPY a.txt b.txt /dest/
Last argument is always destination (matches Dockerfile semantics).
- COPY resolves relative destinations against current WORKDIR.
- WRENN_DEFAULT_ROOTFS_SIZE env var (e.g. 5G, 2Gi, 1000M, 512Mi)
controls template rootfs expansion. Used both at agent startup
(EnsureImageSizes) and after FlattenRootfs (shrink then re-expand).
- Pre-build now sets WORKDIR /home/wrenn-user after USER switch.
- Extracted archive files get chmod a+rX for readability.
- Path traversal validation on COPY sources.
Implement three new recipe commands for the admin template builder:
- USER <name>: creates the user (adduser + passwordless sudo), switches
execution context so subsequent RUN/START commands run as that user
via su wrapping. Last USER becomes the template's default_user.
- COPY <src> <dst>: copies files from an uploaded build archive
(tar/tar.gz/zip) into the sandbox. Source paths validated against
traversal. Ownership set to the current USER.
- ENV persistence: accumulated env vars stored in templates.default_env
(JSONB) and injected via PostInit when sandboxes are created from the
template, mirroring Docker's image metadata approach.
Supporting changes:
- Pre-build creates wrenn-user as default (via USER command)
- WORKDIR now creates the directory if it doesn't exist (mkdir -p)
- Per-step progress updates (ProgressFunc callback) for live UI
- Multipart form support on POST /v1/admin/builds for archive upload
- Proto: default_user/default_env fields on Create/ResumeSandboxRequest
- Host agent: SetDefaults calls PostInitWithDefaults on envd
- Control plane: reads template defaults, passes on sandbox create/resume
- Frontend: file upload widget, recipe copy button, keyword colors for
USER/COPY, fixed Svelte whitespace stripping in step display
- Admin panel defaults to /admin/templates instead of /admin/hosts
- Migration adds default_user and default_env to templates and
template_builds tables
Wire envd's existing PTY process capabilities through the full stack:
hostagent proto (4 new RPCs: PtyAttach, PtySendInput, PtyResize, PtyKill),
envdclient, sandbox manager, and a new WebSocket endpoint at
GET /v1/sandboxes/{id}/pty with bidirectional JSON message protocol.
Sessions use tag-based identity for disconnect/reconnect support,
base64-encoded PTY data for binary safety, and a 120s inactivity timeout.
After restoring a VM from snapshot, envd had already completed its initial
MMDS poll, so the metadata files in /run/wrenn/ and env vars retained values
from the original sandbox. Call POST /init after WaitUntilReady on both
resume and create-from-template paths to trigger envd to re-read MMDS.
