shardmand — Shardman configuration daemon
shardmand [common_options] [--system-bus] [
--user
]user_name
Here common_options are:
[--cluster-name cluster_name] [--log-level error | warn | info | debug ] [--retries ] [retries_number--session-timeout ] [seconds--store-endpoints ] [store_endpoints--store-ca-file ] [store_ca_file--store-cert-file ] [store_cert_file--store-key ] [client_private_key--store-timeout ] [duration--version] [ -h | --help ]
shardmand is a
Shardman configuration daemon. It runs on each
node in a Shardman cluster, subscribes for changes
of shardman/cluster0/data/ladle and
shardman/cluster0/data/cluster keys in the etcd store
(cluster0 is the default cluster name used by
Shardman utils) and manages
Shardman services on the node where it is
running according to the configuration described in these JSON documents.
shardmand manages systemd services for shardman units. On startup and when one of the monitored etcd keys changes, shardmand reconfigures services as follows:
It calculates the expected node configuration, i. e., the list of
services expected to run and their configurations, from the
shardman/cluster0/data/ladle and
shardman/cluster0/data/cluster values.
It loads the list of running Shardman services from systemd and their existing environment and properties files.
It stops services that are not expected to run. This can be a service that belongs to a cluster with the same name, but a different UUID, or a service whose description is no longer present in the expected node configuration. For shardman-keeper services, shardmand purges their data directory.
If a service should be running, but its environment is different from the expected, shardmand overwrites the environment file and restarts the service. If a service should be running, but it is not running or not enabled, shardmand enables and starts it.
Also, a separate thread of shardmand periodically
updates the shardman/cluster0/data/shardmand/NODENAME etcd key with
the ClusterUUID of the last cluster to which
the configuration of services was applied. So, before the
shardmanctl nodes add command tries to
initialize new stolon clusters for a clover,
the command can ensure that no alive stolon
services from a previous cluster configuration are left on all nodes in the clover.
All Shardman services are managed by
shardmand@cluster0.service, so when it is
started, stopped or restarted, it also starts, stops or
restarts all other Shardman
services (including DBMS instances).
The meaning of the command-line options is as follows:
Avoid enabling individual Shardman services
manually (besides shardmand@cluster0.service).
They are supposed to be disabled and started by shardmand.
If shardmand@cluster0.service is disabled,
but other services are enabled, after reboot this can lead to inconsistent
cluster state.
--system-busSets shardmand to manage services with a system bus. By default, this is done with a user bus.
shardmand systemd service can be
installed either as a user unit or a system unit.
shardmand
manages user or system systemd units accordingly. A usual name of a shardmand
systemd service is shardmand@CLUSTER_NAME.service.
shardmand connects to a D-Bus to manage systemd units.
When shardmand is run as
a system service, it manages system systemd units and must connect
to a system bus. When run as a user service, it manages user
systemd units and must connect to a user bus. When
shardmand is run as a system service,
set the --system-bus option.
--user user_name
Sets shardmand to change UID and GID to the UID and GID of the specified user after connecting to a D-Bus.
shardmand common options are optional parameters
that are not specific to the utility. They specify
etcd connection settings, cluster name and a few more settings.
By default shardmand tries to connect to
the etcd store 127.0.0.1:2379 and use the cluster0
cluster name. The default log level is info.
-h, --help
Show brief usage information
--cluster-name cluster_name
Specifies the name for a cluster to operate on.
The default is cluster0.
--log-level level
Specifies the log verbosity. Possible values of
level are (from minimum to maximum):
error,
warn, info and
debug. The default is info.
--retries number
Specifies how many times shardmanctl retries a failing etcd request. If an etcd request fails, most likely, due to a connectivity issue, shardmanctl retries it the specified number of times before reporting an error. The default is 5.
--session-timeout seconds
Specifies the session timeout for shardmanctl locks. If there is no connectivity between shardmanctl and the etcd store for the specified number of seconds, the lock is released. The default is 30.
--store-endpoints string
Specifies the etcd address in the format:
http[s]://address[:port](,http[s]://address[:port])*.
The default is http://127.0.0.1:2379.
--store-ca-file string
Verify the certificate of the HTTPS-enabled etcd store server using this CA bundle
--store-cert-file string
Specifies the certificate file for client identification by the etcd store
--store-key string
Specifies the private key file for client identification by the etcd store
--store-timeout duration
Specifies the timeout for a etcd request. The default is 5 seconds.
--version
Show shardman-utils version information
A shardmand service reads the environment from
/var/lib/pgpro/sdm-14/data/shardmand-cluster0.env.
The following environment variables affect the behavior of
shardmand.
shardmand manages
*.env and *.props files for
other Shardman services located in the
/var/lib/pgpro/sdm-14/data directory.
So all manual changes to these files get overwritten.
SDM_CLUSTER_NAME
An alternative to setting the --cluster-name
option
SDM_LOG_LEVEL
An alternative to setting the --log-level
option
SDM_RETRIES
An alternative to setting the --retries
option
SDM_SYSTEM_BUS
An alternative to setting the --system-bus
option
SDM_STORE_ENDPOINTS
An alternative to setting the --store-endpoints
option
SDM_STORE_CA_FILE
An alternative to setting the --store-ca-file
option
SDM_STORE_CERT_FILE
An alternative to setting the --store-cert-file
option
SDM_STORE_KEY
An alternative to setting the --store-key
option
SDM_STORE_TIMEOUT
An alternative to setting the --store-timeout
option
SDM_SESSION_TIMEOUT
An alternative to setting the --session-timeout
option
SDM_USER
An alternative to setting the --user
option
shardmand settings
are usually specified in the
/var/lib/pgpro/sdm-14/data/shardmand-cluster0.env file.
If you want shardmand to connect
to an etcd cluster at hosts n1-n3 using port 2379 and
all Shardman services to use
the debug log level, you can use the following
env file:
SDM_STORE_ENDPOINTS=http://n1:2379,http://n2:2379,http://n3:2379 SDM_LOG_LEVEL=debug
Note that you need to restart shardmand@cluster0
service to apply new settings from the env file.
To look at shardmand logs, you can use a journalctl command:
$journalctl -u shardmand@cluster0.service
You can restart all Shardman
services on a node using a systemctl command:
$systemctl restart shardmand@cluster0.service