core

Configuration

Core reads one YAML file, given by --config or ERU_CONFIG_PATH (default /etc/eru/core.yaml). The file is loaded with gopkg.in/yaml.v3; the default and required struct tags declared on the fields in types/config.go are applied by utils/config.go, so absent keys fall back to their default and unknown keys are ignored.

core.yaml.sample in the repo root is a working starting point. Every key below is grouped the way that file groups them.

Durations are Go duration strings (30s, 5m).

Server

Key Type Default Meaning
bind string 5001 gRPC listen address. Must be host:port — use :5001 to listen on all interfaces
lock_timeout duration 30s TTL of every distributed lock core takes (pod, node, workload)
global_timeout duration 300s Deadline for long transactions: deploy, realloc, remove, remap, the metrics scrape
connection_timeout duration 10s Engine connect/ping deadline, and the interval between engine-cache liveness sweeps
ha_keepalive_interval duration 16s TTL of the node-status-watcher election key; see Operations
statsd string — host:port of a statsd server. Empty disables statsd; Prometheus is unaffected
profile string — host:port for the HTTP server exposing /metrics and net/http/pprof. Empty disables it
max_concurrency int 100000 Size of the goroutine pools core uses for fan-out work
store string etcd Metadata backend: etcd or redis
sentry_dsn string — Sentry DSN. Empty disables Sentry
probe_target string 8.8.8.8:80 UDP dial target used to learn core’s own outbound address when bind has no explicit IP

Auth

auth is the credential the gRPC server requires. If username is empty, core installs no auth interceptor and the API is open.

auth:
    username: admin
    password: password
Key Type Default Meaning
auth.username string — Metadata key clients must send
auth.password string — Expected value of that metadata key

gRPC

Key Type Default Meaning
grpc.max_concurrent_streams int 100 grpc.MaxConcurrentStreams on the server
grpc.max_recv_msg_size int 20971520 Max received message size, in bytes (20 MiB)
grpc.service_discovery_interval duration 15s How often WatchServiceStatus re-pushes the instance list. Values under 1s are replaced by 15s. Clients are told to expect a push at most every 2× this
grpc.service_heartbeat_interval duration 15s TTL and refresh period of this instance’s /services/<addr> registration

Store — etcd

Used when store is etcd (the default). Ignored when --embedded-storage supplies an in-process cluster, except for prefix, which still namespaces the keys.

Key Type Default Meaning
etcd.machines list of string — (required) etcd client endpoints
etcd.prefix string /eru Namespace prepended to every key core reads or writes
etcd.lock_prefix string __lock__/eru Namespace for lock keys
etcd.ca string — Path to the CA file. TLS is enabled only when ca, cert and key are all set
etcd.cert string — Path to the client certificate
etcd.key string — Path to the client key
etcd.auth.username string — etcd username
etcd.auth.password string — etcd password

Store — redis

Used when store is redis. Core relies on redis keyspace notifications for its watch streams, so the server must have them enabled.

Key Type Default Meaning
redis.addr string localhost:6379 Redis address
redis.lock_prefix string /lock Prefix for lock keys
redis.db int 0 Redis database index; also the db number in the keyspace-notification channel

Git / SCM

Only needed for BuildImage with the SCM build method. If scm_type is unset, core logs a warning at startup and an SCM build that names a repo fails with ErrNoSCMSetting; RAW and EXIST builds still work.

Key Type Default Meaning
git.scm_type string — github or gitlab; anything else leaves the SCM client unset, which only disables SCM builds
git.private_key string — Path to the SSH private key used to clone
git.token string — API token, sent as the Authorization header when fetching artifacts
git.clone_timeout duration 300s Clone deadline

SSH

Core’s own key pair for every node it drives over SSH — containerd://, cocoon:// and process://. The key is per core, not per node.

Key Type Default Meaning
ssh.private_key string — Path to the private key core authenticates with
ssh.user string root Login user, overridden by a user@ prefix in the node endpoint
ssh.known_hosts string — Path to a known_hosts file. Empty accepts any host key

Registry

Shared by every engine: the containerd engine hands these to its resolver and to the BuildKit session, the process engine renders them as oras flags. The cocoon engine leaves registry auth to cocoon’s own config on the node.

Key Type Default Meaning
registry.hub string — Registry host used when building image references
registry.namespace string — Path segment between host and app name: hub/namespace/appname:tag
registry.auths map — Credentials keyed by registry host: {username, password}
registry.plain_http list of string — Registry hosts served without TLS

Build

Key Type Default Meaning
build.node_filter.podname string — Build only in this pod
build.node_filter.includes list of string — Build only on these nodes
build.node_filter.excludes list of string — Never build on these nodes
build.node_filter.labels map of string — Build only on nodes carrying these labels
build.node_filter.all bool false Also consider nodes that are down or bypassed

BuildImage picks the most idle node of that selection. A request may carry its own node_filter, which is intersected into the configured one: naming a pod or a label value the config rules out is rejected with ErrInvaildNodeFilter, and all is never taken from the request. With nothing configured, every node is a candidate.

Containerd

Key Type Default Meaning
containerd.socket string /run/containerd/containerd.sock Node-side path of containerd’s API socket, forwarded to core over SSH
containerd.namespace string eru containerd namespace every eru container lives in
containerd.buildkit string /run/buildkit/buildkitd.sock buildkitd address on a build node: a socket path is forwarded over the same SSH connection, a tcp:// address is dialed directly
containerd.stop_timeout duration 10s Grace period between the stop signal and SIGKILL; a forced stop ignores it

Process

Key Type Default Meaning
process.root string /var/lib/eru/process Node directory holding the per-workload overlays and the artifact cache
process.stop_timeout duration 10s Rendered as TimeoutStopSec= on every unit: how long systemd waits after SIGTERM before it kills the workload

Cocoon

Key Type Default Meaning
cocoon.binary string cocoon The cocoon command core runs on the node; a sudo wrapper works
cocoon.root string /var/lib/eru/cocoon Node directory holding the durable copy of each VM’s meta record
cocoon.run_dir string /var/lib/cocoon/run cocoon’s run_dir; the guest console socket path in the meta file derives from it
cocoon.cgroup_parent string cocoon.slice cocoon’s cgroup_parent; the VM’s cgroup scope in the meta file derives from it

Scheduler

These feed the built-in cpumem resource plugin.

Key Type Default Meaning
scheduler.sharebase int 100 How many pieces one CPU core is divided into, i.e. the resolution of fractional CPU requests
scheduler.maxshare int -1 How many cores may be used as shared (fragmented) cores; -1 means no limit
scheduler.max_deploy_count int 10000 Declared in the config struct, but no code in core reads it today

Resource plugins

Key Type Default Meaning
resource_plugin.dir string — Directory scanned for plugins. Empty means only the built-in cpumem plugin is loaded
resource_plugin.call_timeout duration 30s Deadline for a single binary-plugin invocation
resource_plugin.whitelist list of string — If set, only these plugin names are consulted when reading or fixing node resource info (GetNodeResource, GetPodResource). Allocation always consults every loaded plugin

See Resource plugins for the contract these files must satisfy.

Log

Key Type Default Meaning
log.level string info zerolog level: trace, debug, info, warn, error, …
log.use_json bool false Emit JSON on stdout instead of the console writer. Ignored when log.filename is set — file logs are always JSON
log.filename string — Log to this file with rotation instead of stdout
log.maxsize int 500 Rotate after this many megabytes
log.max_age int 28 Keep rotated files this many days
log.max_backups int 3 Keep at most this many rotated files

Keys core no longer reads

core.yaml.sample still shows the first; older configs may carry all three. Each is silently ignored:

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