Satellite
Satellite is an agent written in Go for collecting health information in a kubernetes cluster. It is both a library and an application. As a library, it can be used as a basis for a custom monitoring solution. The health status information is collected in the form of a time series and persisted to the sqlite backend. Additional backends are supported via an interface.
The original design goals are:
- lightweight periodic testing
- high availability and resilience to network partitions
- no single point of failure
- history of health data as a time series
The agents communicate over a [Gossip] protocol implemented by serf.
Dependencies
Installation
There are currently no binary distributions available.
Building from source
Satellite manages dependencies via godep which is also a prerequisite for building. Another prerequisite is Go version 1.7+.
- Install Go
- Install godep
- Setup GOPATH
- Run
go get github.com/gravitational/satellite - Run
cd $GOPATH/src/github.com/gravitational/satellite - Run
make
How to use it
$ satellite help
usage: satellite [<flags>] <command> [<args> ...]
Cluster health monitoring agent
Flags:
--help Show help (also see --help-long and --help-man).
--debug Enable verbose mode
Commands:
help [<command>...]
Show help.
agent [<flags>]
Start monitoring agent
status [<flags>]
Query cluster status
version
Display version
$ satellite agent help
usage: satellite agent [<flags>]
Start monitoring agent
Flags:
--help Show context-sensitive help (also try --help-long and --help-man).
--debug Enable verbose mode
--rpc-addr=127.0.0.1:7575 List of addresses to bind the RPC listener to (host:port), comma-separated
--kube-addr="http://127.0.0.1:8080"
Address of the kubernetes API server
--kubelet-addr="http://127.0.0.1:10248"
Address of the kubelet
--docker-addr="/var/run/docker.sock"
Path to the docker daemon socket
--nettest-image="gcr.io/google_containers/nettest:1.8"
Name of the image to use for networking test
--name=NAME Agent name. Must be the same as the name of the local serf node
--serf-rpc-addr="127.0.0.1:7373"
RPC address of the local serf node
--initial-cluster=INITIAL-CLUSTER
Initial cluster configuration as a comma-separated list of peers
--state-dir=STATE-DIR Directory to store agent-specific state
--tags=TAGS Define a tags as comma-separated list of key:value pairs
--etcd-servers=http://127.0.0.1:2379
List of etcd endpoints (http://host:port), comma separated
--etcd-cafile=ETCD-CAFILE SSL Certificate Authority file used to secure etcd communication
--etcd-certfile=ETCD-CERTFILE SSL certificate file used to secure etcd communication
--etcd-keyfile=ETCD-KEYFILE SSL key file used to secure etcd communication
--influxdb-database=INFLUXDB-DATABASE
Database to connect to
--influxdb-user=INFLUXDB-USER Username to use for connection
--influxdb-password=INFLUXDB-PASSWORD
Password to use for connection
--influxdb-url=INFLUXDB-URL URL of the InfluxDB endpoint
$ satellite agent --name=my-host --tags=role:master
$ satellite help status
usage: satellite status [<flags>]
Query cluster status
Flags:
--help Show context-sensitive help (also try --help-long and --help-man).
--debug Enable verbose mode
--rpc-port=7575 Local agent RPC port
--pretty Pretty-print the output
--local Query the status of the local nodeYou can then query the status of the cluster or that of the local node by issuing a status query:
$ satellite status --prettyresulting in:
{
"status": "degraded",
"nodes": [
{
"name": "example.domain",
"member_status": {
"name": "example.domain",
"addr": "192.168.178.32:7946",
"status": "alive",
"tags": {
"role": "node"
}
},
"status": "degraded",
"probes": [
{
"checker": "docker",
"status": "running"
},
...
]
}
],
"timestamp": "2016-03-03T12:19:44.757110373Z",
"summary": "master node unavailable"
}Out of the box, the agent requires at least a single master node (agent with role:master). The test will mark the cluster as degraded if no master is available.
Connect the agent to InfluxDB database monitoring:
$ satellite agent --tags=role:master \
--state-dir=/var/run/satellite \
--influxdb-database=monitoring \
--influxdb-url=http://localhost:8086