Crate conmonrs 

A pod level OCI container runtime monitor for Linux.

A container engine like CRI-O starts one conmonrs per pod and talks to it over a Cap’n Proto RPC interface on a UNIX socket, which this crate serves. The crate is the server only, the Go client lives in the same repository under pkg/client. The repository holds the full documentation:

• https://github.com/containers/conmon-rs/blob/main/README.md on what conmon-rs does.
• https://github.com/containers/conmon-rs/blob/main/docs/architecture.md on how the server and the client work together.
• https://github.com/containers/conmon-rs/blob/main/docs/install.md on how to install, verify and build it.
• https://github.com/containers/conmon-rs/blob/main/docs/server.md on the command line.
• https://github.com/containers/conmon-rs/blob/main/docs/protocols.md on the RPCs and the attach and streaming protocols.
• https://github.com/containers/conmon-rs/blob/main/README.md#documentation on the other documents, like configuring CRI-O, logging and troubleshooting.

Modules

async_fd 🔒

Waiting for descriptors which tokio has no type of its own for, like pidfds, terminals, epoll and inotify instances.

attach 🔒

The attach sockets of the containers, see the attach socket section of docs/protocols.md: the stdin of the clients towards the container and the container output towards the clients.

channel 🔒

A bounded channel with any number of senders and receivers, for the stdio channels of the containers and the stdin of their attach clients.

child_reaper 🔒

Child process reaping and management.

config 🔒

Configuration related structures.

conmon_capnp

The generated Cap’n Proto RPC interface.

container_io 🔒

The stdio of the containers and execs, pipes or a terminal, which the server reads into the log drivers, the attach clients and the output of the execs.

container_log 🔒

The log drivers of the containers, which write the container output to the CRI log files or to journald.

exec_start 🔒

Starting an exec, of an exec_sync or a streaming one alike: the IO of the process, the PID file of its runtime and the runtime call, up to the registration of the process.

fs_util 🔒

File system helpers.

init 🔒

The setup of the server process before it serves: umask, OOM score, open files limit, malloc and transparent huge pages, the standard streams and the descriptors it inherited, its working directory and the subreaper flag, and giving the runtime calls the OOM score, huge pages setting and open files limits the server started with.

journal 🔒

A client for the native journal protocol (https://systemd.io/JOURNAL_NATIVE_PROTOCOL/) and a tracing writer which forwards the server logs to journald.

listener 🔒

Helpers for the listening sockets of the server: private sockets, socket paths of any length and the errors of the accept loops.

mutex 🔒

Lock helpers.

oom_watcher 🔒

Watching the cgroup of a container process for OOM kills, through the memory events of the unified hierarchy of cgroup v2. A host with cgroup v1, or with both in a hybrid setup, runs its containers without the detection.

process 🔒

Signalling, waiting for and reaping child processes without hitting another process which reused their PID.

random_id 🔒

Random IDs, for the tokens of the streaming server, which a client has to know to connect, and for names which must not collide.

rpc 🔒

The Cap’n Proto RPC interface of the server, one method for each call of proto/conmon.capnp.

runtime_args 🔒

The command line of the OCI runtime for a create, a restore or an exec.

server 🔒

The server process: its start and fork, its logging, the RPC socket it serves and its shutdown on a signal.

streaming_server 🔒

The streaming server of exec, attach and port forward sessions: the URLs with their one time tokens and the HTTP server their clients connect to.

tail 🔒

A buffer which keeps only the end of what got written to it.

telemetry 🔒

The OpenTelemetry tracing of the server, built with the tracing feature: the exporter of the spans and the trace context the clients pass with their requests.

terminal 🔒

Terminal console functionalities.

util 🔒

Small helpers which modules share that do not depend on each other otherwise.

version 🔒

Version information of conmonrs, for --version and the version RPC.

Functions

run

Run conmonrs: print the version or start the server, depending on the command line.