kyleandClaude Opus 5.5
5e55fe4c66
Task 04 added dependencies to toolkit and its git add line left out the lock file, so the driver stopped on an unclean tree. The lock change is folded into task 04's commit. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
90 lines
4.4 KiB
Markdown
90 lines
4.4 KiB
Markdown
# M3b task 12: the egress proxy's lifecycle
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**Branch:** `m3b` (run `git switch m3b`; `git status --short` must be empty, otherwise stop)
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**Commit subject:** `brokerd: start and remove the egress proxy for http_fetch`
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## Goal
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For an `http_fetch` call, the tool's container still has no network. Before it runs, `brokerd`
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makes a directory for this call, starts the egress proxy (task 08) in its own container with a
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network and that directory mounted, and waits for the proxy's socket. The tool's container gets the
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same directory. Afterwards, **on every path**, the proxy's container and the directory are removed.
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Spec section 6, "`http_fetch`".
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## Files
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- Copy: `crates/brokerd/tests/container_egress.rs`
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- Modify: `crates/brokerd/src/container.rs`, `docs/implementer-log.md`
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## Interfaces (added to `container.rs`)
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```rust
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pub const EGRESS_WAIT: Duration = Duration::from_secs(5);
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impl Podman {
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/// The same runtime with another wait for the proxy's socket, for tests.
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pub fn with_egress_wait(self, egress_wait: Duration) -> Podman;
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}
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```
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`Podman` gains a private field `egress_wait`, set to `EGRESS_WAIT` by `new`.
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## `run`, now
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After step 2 of task 11 (name, input, limit):
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- `spec.egress()` is `None` → exactly as before: `tool_args(…, None)` and run the container.
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- `spec.egress()` is `Some(hosts)` → start the proxy (below), and on success run the container
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with `tool_args(spec, &runner, &name, Some(&dir))`.
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### Starting the proxy: every step and exit
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Use a **guard**: a private struct holding the proxy's container name (`<name>-egress`) and the
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directory, whose `Drop` runs `podman rm -f <name>-egress` (the helper from task 11) and then
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`remove_dir_all(dir)` (log an error other than `NotFound`). Create the guard **first**, before
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anything can fail, so that every return below cleans up by dropping it, and keep it alive until
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the tool's container has finished.
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1. `dir = egress_dir.join(&name)`. Make `egress_dir` (and its parents) with mode 0700
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(`DirBuilder::new().recursive(true).mode(0o700)`), then set its mode to 0700 anyway (it may
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have existed). If `dir` already exists, it was left by a crash: `remove_dir_all` it (a
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`NotFound` is fine). Then create `dir` with mode 0700, not recursively. Any failure → log
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`brokerd: cannot make {dir}: {e}` + `"\n"` + `RUNBOOK`, return
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`Err(RunError::Unavailable(CANNOT_START))`.
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2. Run `podman` with `podman::egress_args(&runner, &name, &dir, hosts)`, standard input and output
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null, standard error piped, with `.output()`. It does not succeed → log
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`brokerd: podman could not start {name}-egress: {stderr}` + `"\n"` + `RUNBOOK`, return
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`Unavailable(CANNOT_START)`. It cannot be started at all → the same log as task 11 step 3, and
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the same answer.
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3. Wait until `dir.join("egress.sock")` exists, checking every 20 ms, for at most `egress_wait`.
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It does not appear → log `brokerd: {name}-egress did not make its socket within {ms} ms` +
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`"\n"` + `RUNBOOK`, return `Unavailable(CANNOT_START)`.
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4. Return the guard. Run the tool's container as in task 11. Whatever it answers, the guard is
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dropped after it, removing the proxy and the directory.
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So for a successful call the fake sees exactly three `podman` calls: `run -d …` (the proxy),
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`run --rm -i …` (the tool), `rm -f <name>-egress`. For a tool past its time limit it sees the
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proxy's run, the tool's run, `kill <name>`, `rm -f <name>`, then `rm -f <name>-egress`.
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## Steps
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- [ ] **1. Copy.** `git switch m3b`, then
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`cp docs/plans/M3b/files/crates/brokerd/tests/container_egress.rs crates/brokerd/tests/`
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- [ ] **2. See it fail.** `cargo test -p brokerd --test container_egress`. Expected: it does not
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compile (`with_egress_wait` does not exist).
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- [ ] **3. Write the code.** Run `cargo fmt --all`. `container.rs` must stay under 500 lines.
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- [ ] **4. See it pass.** `cargo test -p brokerd --test container_egress --test container`.
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Expected: 6 and 11 passed. Run them ten times; they must pass every time.
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- [ ] **5. Walk the exits.** For each of the four steps, say how the guard cleans up after it.
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- [ ] **6. Run the gate.** `make gate`. Expected last line: `gate: ok`.
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- [ ] **7. Log and commit.** `git add crates/brokerd docs/implementer-log.md Cargo.lock && git commit`
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## Done when
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- Both suites pass ten times running; `make gate` prints `gate: ok`.
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## Stop and report if
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- A path leaves the proxy's container or the directory behind, and a guard does not fix it.
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- The tool's container would get a network.
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