Command And Control system for async management of servers, containers, workstations...basically anything that runs an operating system.
Steward is a Command & Control backend system for Servers, IOT and Edge platforms where the network link for reaching them can be reliable like local networks, or totally unreliable like satellite links. An end node can even be offline when you give it a command, and Steward will make sure that the command is delivered when the node comes online.
Example use cases:
As long as you can do something as an operator on in a shell on a system you can do the same with Steward in a secure way to one or all end nodes (servers) in one go with one single message/command.
NB Expect the main branch to have breaking changes. If stability is needed, use the released packages, and read the release notes where changes will be explained.
socket
file
Command And Control anything like Servers, Containers, VM's or others by creating and sending messages with methods who will describe what to do. Steward will then take the responsibility for making sure that the message are delivered to the receiver, and that the method specified are executed with the given parameters defined. An example of a message.
An example of a request method to feed into the system. All fields are explained in detail further down in the document.
[
{
"directory":"/var/cli/command_result/",
"fileName": "some-file-name.result",
"toNode": "ship1",
"method":"REQCliCommand",
"methodArgs": ["bash","-c","sleep 5 & tree ./"],
"replyMethod":"REQToFileAppend",
"ACKTimeout":5,
"retries":3,
"replyACKTimeout":5,
"replyRetries":3,
"methodTimeout": 10
}
]
If the receiver toNode
is down when the message was sent, it will be retried until delivered within the criterias set for timeouts
and retries
. The state of each message processed is handled by the owning steward instance where the message originated, and no state about the messages are stored in the NATS message broker.
Since the initial connection from a Steward node is outbound towards the central NATS message broker no inbound firewall openings are needed.
All code in this repository are to be concidered not-production-ready, and the use is at your own responsibility and risk. The code are the attempt to concretize the idea of a purely async management system where the controlling unit is decoupled from the receiving unit, and that that we know the state of all the receiving units at all times.
Also read the license file for further details.
Expect the main branch to have breaking changes. If stability is needed, use the released packages, and read the release notes where changes will be explained.
Send Commands with Request Methods to control your servers by passing a messages that will have guaranteed delivery based on the criteries set, and when/if the receiving node is available. The result of the method executed will be delivered back to you from the node you sent it from.
Steward uses NATS as message passing architecture for the commands back and forth from nodes. Delivery is guaranteed within the criterias set. All of the processes in the system are running concurrently, so if something breaks or some process is slow it will not affect the handling and delivery of the other messages in the system.
A node can be a server running any host operating system, a container living in the cloud somewhere, a Rapsberry Pi, or something else that needs to be controlled that have an operating system installed.
Steward can be compiled to run on all major architectures like x86, amd64,arm64, ppc64 and more, with for example operating systems like Linux, OSX, Windows.
The idea for how to handle processes, messages and errors are based on Joe Armstrongs idea behind Erlang described in his Thesis https://erlang.org/download/armstrong_thesis_2003.pdf.
Joe's document describes how to build a system where everything is based on sending messages back and forth between processes in Erlang, and where everything is done concurrently.
I used those ideas as inspiration for building a fully concurrent system to control servers or container based systems by passing messages between processes asynchronously to execute methods, handle errors, or handle the retrying if something fails.
Steward is written in the programming language Go with NATS as the message broker.
With existing solutions there is often either a push or a pull kind of setup to control the nodes.
In a push setup the commands to be executed is pushed to the receiver, but if a command fails because for example a broken network link it is up to you as an administrator to detect those failures and retry them at a later time until it is executed successfully.
In a pull setup an agent is installed at the Edge unit, and the configuration or commands to execute locally are pulled from a central repository. With this kind of setup you can be pretty certain that sometime in the future the node will reach it's desired state, but you don't know when. And if you want to know the current state you will need to have some second service which gives you that information.
In it's simplest form the idea about using an event driven system as the core for management of Edge units is that the sender/publisher are fully decoupled from the receiver/subscriber. We can get an acknowledge message if a message is received or not, and with this functionality we will at all times know the current state of the receiving end.
All parts of the system like processes, method handlers, messages, error handling are running concurrently.
If one process hangs on a long running message method it will not affect the rest of the system.
Steward instances with the same Nodename will automatically load balance the handling of messages on a given subject, and any given message will only be handled once by one instance.
TODO: Make a diagram here...
New Request Messages in Json/Yaml format can be delivered by the user to Steward in the following ways:
nc -U tmp/steward.sock < msg.yaml
.readfolder
of Steward.nc localhost:8888 < msg.yaml
.Tue Sep 21 09:17:55 2021, info: toNode: ship2, fromNode: central, method: REQOpProcessList: max retries reached, check if node is up and running and if it got a subscriber for the given REQ type
The error logs can be read on the central server in the directory <steward-home>/data/errorLog
.
The handling of all messages is done by spawning up a process for handling the message in it's own thread. This allows us to down on the individual message level keep the state for each message both in regards to ACK's, error handling, send retries, and rerun of a method for a message if the first run was not successful.
Processes for handling messages on a host can be restarted upon failure, or asked to just terminate and send a message back to the operator that something have gone seriously wrong. This is right now just partially implemented to test that the concept works, where the error action is action=no-action.
Publisher Processes on a node for handling new messages for new nodes will automatically be spawned when needed if it does not already exist.
Messages not fully processed or not started yet will be automatically rehandled if the service is restarted since the current state of all the messages being processed are stored on the local node in a key value store until they are finished.
All messages processed by a publisher will be written to a log file after they are processed, with all the information needed to recreate the same message if needed, or it can be used for auditing.
All handling down to the process and message level are handled concurrently. So if there are problems handling one message sent to a node on a subject it will not affect the messages being sent to other nodes, or other messages sent on other subjects to the same host.
Message types of both ACK and NACK, so we can decide if we want or don't want an Acknowledge if a message was delivered succesfully. Example: We probably want an ACK when sending some REQCLICommand to be executed, but we don't care for an acknowledge NACK when we send an REQHello event. If a message are ACK or NACK type are defined by the value of the ACKTimeout for each individual message:
Default timeouts to wait for ACK messages and max attempts to retry sending a message are specified upon startup. This can be overridden on the message level.
Timeouts can be specified on both the message, and the method.
Example of a message with timeouts set:
[
{
"directory":"/some/result/directory/",
"fileName":"my-syslog.log",
"toNode": "ship2",
"methodArgs": ["bash","-c","tail -f /var/log/syslog"],
"replyMethod":"REQToFileAppend",
"method":"REQCliCommandCont",
"ACKTimeout":3,
"retries":3,
"methodTimeout": 60
}
]
In the above example, the values set meaning:
tail -f ./tmp.log
run for 60 seconds before it is terminated.If no timeout are specified in a message the defaults specified in the etc/config.yaml are used.
Instead of solely depending in the ack timeout the RetryWait can be used. RetryWait specifies the time in seconds to wait between retries.
[
{
"directory":"/some/result/directory/",
"fileName":"my-syslog.log",
"toNode": "ship2",
"methodArgs": ["bash","-c","tail -f /var/log/syslog"],
"replyMethod":"REQToFileAppend",
"method":"REQCliCommandCont",
"ACKTimeout":3,
"RetryWait":10,
"retries":3,
"methodTimeout": 60
}
]
This is the same as the previos example, but it will also wait another 10 seconds after it noticed that an ACK was not received before the message is retried.
The flow will be like this:
Steward supports both the use of flags with values set at startup, and the use of a config file.
string
string array
string
string array
string
string array
int
int
int
int
int
int
string
string
The various timeouts for the Nats messages can be controlled via the configuration file or flags.
If the network media is a high latency. satellite links it will make sense to adjust the client timeout to reflect the latency
-natsConnOptTimeout int
default nats client conn timeout in seconds (default 20)
The interval in seconds the nats client should try to reconnect to the nats-server if the connection is lost.
-natsConnectRetryInterval int
default nats retry connect interval in seconds. (default 10)
Jitter values.
-natsReconnectJitter int
default nats ReconnectJitter interval in milliseconds. (default 100)
-natsReconnectJitterTLS int
default nats ReconnectJitterTLS interval in seconds. (default 5)
You can choose to enable compression of the payload in the Nats messages.
-compression string
compression method to use. defaults to no compression, z = zstd, g = gzip. Undefined value will default to no compression
When starting a Steward instance with compression enabled it is the publishing of the message payload that is compressed.
The subscribing instance of Steward will automatically detect if the message is compressed or not, and decompress it if needed.
With other words, Steward will by default receive and handle both compressed and uncompressed messages, and you decide on the publishing side if you want to enable compression or not.
Steward support two serialization formats when sending messages. By default it uses the Go spesific GOB format, but serialization with CBOR are also supported.
A benefit of using CBOR is the size of the messages when transferred.
To enable CBOR serialization either start steward by setting the serialization flag:
./steward -serialization="cbor" <other flags here...>
Or edit the config file <steward directory>/etc/config.toml
and set:
Serialization = "cbor"
Messages can be automatically scheduled to be read and executed at startup of Steward.
A folder named startup will be present in the working directory of Steward, and you put the messages to be executed at startup here.
Messages put in the startup folder will not be sent to the broker but handled locally, and only (eventually) the reply message from the Request Method called will be sent to the broker.
Normally the fromNode field is automatically filled in with the node name of the node where a message originated. Since messages within the startup folder is not received from another node via the normal message path we need to specify the fromNode field within the message for where we want the reply delivered.
As an example. If You want to place a message on the startup folder of node1 and send the result to node2. Specify node2 as the fromNode, and node1 as the toNode
Since messages used in startup folder are ment to be delivered locally we can simply things a bit by setting the toNode field value of the message to local.
[
{
"toNode": "local",
"fromNode": "central",
"method": "REQCliCommand",
"methodArgs": [
"bash",
"-c",
"curl localhost:2111/metrics"
],
"replyMethod": "REQToConsole",
"methodTimeout": 10
}
]
We can also make the request method run for as long as the Steward instance itself is running. We can do that by setting the methodTimeout field to a value of -1
.
This can make sense if you for example wan't to continously ping a host, or continously run a script on a node.
[
{
"toNode": "ship1",
"fromNode": "central",
"method": "REQCliCommandCont",
"methodArgs": [
"bash",
"-c",
"nc -lk localhost 8888"
],
"replyMethod": "REQToConsole",
"methodTimeout": 10,
}
]
This message is put in the ./startup
folder on node1.
We send the message to ourself, hence specifying ourself in the toNode
field.
We specify the reply messages with the result to be sent to the console on central in the fromNode
field.
In the example we start a TCP listener on port 8888, and we want the method to run for as long as Steward is running. So we set the methodTimeout to -1
.
Methods with their MethodArgs can be scheduled to be run any number of times. Meaning you can send the message once, and the method will be re-called at the interval specified with the schedule field. A max run time for the schedule must also be specified.
schedule : [int type value for interval in seconds, int type value for total run time in seconds]
schedule can also be used with messages specified in the startup folder.
Example below will be run each 2nd seconds, with a total run of 5 seconds:
[
{
"toNodes": ["central"],
"method": "REQCliCommand",
"methodArgs": [
"bash",
"-c",
"hostname && curl -v http://edgeos.raalabs.tech"
],
"replyMethod": "REQToConsole",
"ACKTimeout": 5,
"retries": 3,
"replyACKTimeout": 5,
"replyRetries": 5,
"methodTimeout": 5,
"replyMethodTimeout": 120,
"directory": "debug",
"fileName": "test.txt",
"schedule": [2,5]
}
]
Get a list of the running processes.
[
{
"directory":"test/dir",
"fileName":"test.result",
"toNode": "ship2",
"method":"REQOpProcessList",
"methodArgs": [],
"replyMethod":"REQToFileAppend",
}
]
Start up a process. Takes the REQ method to start as it's only argument.
[
{
"directory":"test/dir",
"fileName":"test.result",
"toNode": "ship2",
"method":"REQOpProcessStart",
"methodArgs": ["REQHttpGet"],
"replyMethod":"REQToFileAppend",
}
]
Stop a process. Takes the REQ method, receiving node name, kind publisher/subscriber, and the process ID as it's arguments.
[
{
"directory":"test/dir",
"fileName":"test.result",
"toNode": "ship2",
"method":"REQOpProcessStop",
"methodArgs": ["REQHttpGet","ship2","subscriber","199"],
"replyMethod":"REQToFileAppend",
}
]
Run CLI command on a node. Linux/Windows/Mac/Docker-container or other.
Will run the command given, and return the stdout output of the command when the command is done.
[
{
"directory":"some/cli/command",
"fileName":"cli.result",
"toNode": "ship2",
"method":"REQnCliCommand",
"methodArgs": ["bash","-c","docker ps -a"],
"replyMethod":"REQToFileAppend",
}
]
Run CLI command on a node. Linux/Windows/Mac/Docker-container or other.
Will run the command given, and return the stdout output of the command continously while the command runs. Uses the methodTimeout to define for how long the command will run.
[
{
"directory":"some/cli/command",
"fileName":"cli.result",
"toNode": "ship2",
"method":"REQCliCommandCont",
"methodArgs": ["bash","-c","docker ps -a"],
"replyMethod":"REQToFileAppend",
"methodTimeout":10,
}
]
NB: A github issue is filed on not killing all child processes when using pipes https://github.com/golang/go/issues/23019. This is relevant for this request type.
And also a new issue registered https://github.com/golang/go/issues/50436
TODO: Check in later if there are any progress on the issue. When testing the problem seems to appear when using sudo, or tcpdump without the -l option. So for now, don't use sudo, and remember to use -l with tcpdump
which makes stdout line buffered. timeout
in front of the bash command can also be used to get around the problem with any command executed.
Tail log files on some node, and get the result for each new line read sent back in a reply message. Uses the methodTimeout to define for how long the command will run.
[
{
"directory": "/my/tail/files/",
"fileName": "tailfile.log",
"toNode": "ship2",
"method":"REQTailFile",
"methodArgs": ["/var/log/system.log"],
"methodTimeout": 10
}
]
Scrape web url, and get the html sent back in a reply message. Uses the methodTimeout for how long it will wait for the http get method to return result.
[
{
"directory": "web",
"fileName": "web.html",
"toNode": "ship2",
"method":"REQHttpGet",
"methodArgs": ["https://web.ics.purdue.edu/~gchopra/class/public/pages/webdesign/05_simple.html"],
"replyMethod":"REQToFile",
"ACKTimeout":10,
"retries": 3,
"methodTimeout": 3
}
]
REQ Method are DEPRECATED Schedule scraping of a web web url, and get the html sent back in a reply message. Uses the methodTimeout for how long it will wait for the http get method to return result.
The methodArgs also takes 3 arguments:
The example below will scrape the URL specified every 30 seconds for 10 minutes.
[
{
"directory": "web",
"fileName": "web.html",
"toNode": "ship2",
"method":"REQHttpGet",
"methodArgs": ["https://web.ics.purdue.edu/~gchopra/class/public/pages/webdesign/05_simple.html","30","10"],
"replyMethod":"REQToFile",
"ACKTimeout":10,
"retries": 3,
"methodTimeout": 3
}
]
Send Hello messages.
All nodes have the flag option to start sending Hello message to the central server. The structure of those messages looks like this.
[
{
"toNode": "central",
"method":"REQHello"
}
]
Copy a file from one node to another node.
[
{
"directory": "copy",
"fileName": "copy.log",
"toNodes": ["central"],
"method":"REQCopySrc",
"methodArgs": ["./testbinary","ship1","./testbinary-copied","500000","20","0770"],
"methodTimeout": 10,
"replyMethod":"REQToConsole"
}
]
To copy from a remote node to the local node, you specify the remote nodeName in the toNode field, and the message will be forwarded to the remote node. The copying request will then be picked up by the remote node's REQCopySrc handler, and the copy session will then be handled from the remote node.
Method for receiving error logs for Central error logger.
NB: This is not to be used by users. Use REQToFileAppend instead.
Don't send a reply message.
An example could be that you send a REQCliCommand
message to some node, and you specify replyMethod: REQNone
if you don't care about the resulting output from the original method.
This is a method that can be used to get the data of the message printed to console where Steward is running.
Default is to print to stdout, but printing to stderr can be done by setting the value of methodArgs to "methodArgs": ["stderr"]
.
If used as a replyMethod set the replyMethodArgs "replyMethodArgs": ["stderr"],
.
[
{
"directory": "web",
"fileName": "web.html",
"toNode": "ship2",
"method":"REQHttpGet",
"methodArgs": ["https://web.ics.purdue.edu/~gchopra/class/public/pages/webdesign/05_simple.html"],
"replyMethod":"REQToConsole",
"ACKTimeout":10,
"retries": 3,
"methodTimeout": 3
}
]
Append the output of the reply message to a log file specified with the directory
and fileName
fields.
If the value of the directory field is not prefixed with ./
or /
the directory structure file will be created within the steward data folder specified in the config file.
[
{
"directory":"test/dir",
"fileName":"test.result",
"toNode": "ship2",
"method":"REQOpProcessList",
"methodArgs": [],
"replyMethod":"REQToFileAppend",
}
]
If there is already a file at the specified path with the specified name, and if that file is a socket, then the request method will automatically switch to socket communication and write to the socket instead of normal file writing.
Write the output of the reply message to a file specified with the directory
and fileName
fields, where the writing will write over any existing content of that file.
If the value of the directory field is not prefixed with ./
or /
the directory structure file will be created within the steward data folder specified in the config file.
[
{
"directory":"test/dir",
"fileName":"test.result",
"toNode": "ship2",
"method":"REQOpProcessList",
"methodArgs": [],
"replyMethod":"REQToFile",
}
]
If there is already a file at the specified path with the specified name, and if that file is a socket, then the request method will automatically switch to socket communication and write to the socket instead of normal file writing.
Same as REQToFile, but will not send an ACK when a message is delivered.
ReqCliCommand is a bit special in that it can be used as both method and replyMethod
The final result, if any, of the replyMethod will be sent to the central server.
By using the {{STEWARD_DATA}}
you can grab the output of your initial request method, and then use it as input in your reply method.
NB: The echo command in the example below will remove new lines from the data. To also keep any new lines we need to put escaped quotes around the template variable. Like this:
\"{{STEWARD_DATA}}\"
Example of usage:
[
{
"directory":"cli_command_test",
"fileName":"cli_command.result",
"toNode": "ship2",
"method":"REQCliCommand",
"methodArgs": ["bash","-c","tree"],
"replyMethod":"REQCliCommand",
"replyMethodArgs": ["bash", "-c","echo \"{{STEWARD_DATA}}\" > apekatt.txt"],
"replyMethodTimeOut": 10,
"ACKTimeout":3,
"retries":3,
"methodTimeout": 10
}
]
Or the same using bash's herestring:
[
{
"directory":"cli_command_test",
"fileName":"cli_command.result",
"toNode": "ship2",
"method":"REQCliCommand",
"methodArgs": ["bash","-c","tree"],
"replyMethod":"REQCliCommand",
"replyMethodArgs": ["bash", "-c","cat <<< {{STEWARD_DATA}} > hest.txt"],
"replyMethodTimeOut": 10,
"ACKTimeout":3,
"retries":3,
"methodTimeout": 10
}
]
-centralNodeName
flag.Main authentication and authorization are done on the subject level with NATS. Each node have a unique public and private key pair, where the individual publics keys are either allowed or denied to subscribe/publish on a subject in an authorization file on the Nats-server.
Some request types, like REQCliCommand also allow authorization of the message payload. The payload of the message can be checked against a list of allowed or denied commands configured in a main Access List on the central server.
With each message created a signature will also be created with the private key of the node, and the signature is then attached to the message. NB: The keypair used for the signing of messages are a separate keypair used only for signing messages, and are not the same pair that is used for authentication with the NATS server.
The nodes will have a copy of the allowed public signing keys from the central server, and when a message is received, the signature is checked against the allowed public keys. If the signature is valid, the message is allowed to be processed further, otherwise it is denied if signature checking is enabled.
Steward can be used either with no authorization at all, with signature checks only, or with ACL and signature checks. The features can be enabled or disabled in the config.yaml file.
All nodes will generate a private and a public key pair only used for signing messages. For building a complete database of all the public keys in the system and to be able to distribute them to other nodes, each node will send it's public key to the central server as the payload in the REQHello messages. The received keys will be stored in the central server's database.
For storing the keys on the central server two databases are involved.
If new keys are allowed into or deleted from the system, one attempt will be done to push the updated key database to all current nodes heard from in the network. If the push fails, the nodes will get the update the next time they ask for it based on the key update interval set on each node.
The interval of the updates can be controlled with it's own config or flag REQKeysRequestUpdateInterval
Will allow a key to be added to the system by moving the key from the NO_ACK_DB to the ACK_DB.
Will remove the specified keys from the ACK_DB.
The interval of the updates can be controlled with it's own config or flag REQAclRequestUpdateInterval
NB: The update process is initiated by the end nodes on a timed interval. No ACL updates are initiaded from the central server.
Several Request methods exists for handling the management of the active Acl's on the central server.
If the element specified is prefixed with grp_ it will be treated as a group, otherwise it will be treated as a single node or command.
Groups or nodes do not have to exist to be used with an acl. The acl will be created with the elements specifed, and if a non existing group was specified you will have an Acl that is not yet functional, but it will become functional as soon as you add elements to the group's.
Takes the methodArgs: ["host or group of hosts", "src or group of src","cmd or group of cmd"]
Takes the methodArgs: ["host or group of hosts", "src or group of src","cmd or group of cmd"]
Takes the methodArgs: ["host or group of hosts", "src or group of src"]
Takes the methodArgs: ["nodegroup name", "node name"]
Takes the methodArgs: ["nodegroup name", "node name"]
Takes the methodArgs: ["nodegroup name"]
Takes the methodArgs: ["commandgroup name", "command"]
Takes the methodArgs: ["commandgroup name", "command"]
Takes the methodArgs: ["commandgroup name"]
Creates an export of the current Acl's database, and delivers it to the requesting node with the replyMethod specified.
Imports the Acl given in JSON format in the first argument of the methodArgs.
The location of the config file are given via an env variable at startup (default "./etc/).
env CONFIG_FOLDER </myconfig/folder/here> <steward binary>
The different fields and their type in the config file. The fields of the config file can also be set by providing flag values at startup. Use the -help
flag to get all the options.
Check Appendix-A for a list of the flags/config options, and their usage.
NB Running Steward like this is perfect for testing in a local test environment, but is not something you would wan't to do in production.
Download the nats-server from https://github.com/nats-io/nats-server/releases/
Or use the curl (replace the version information with wanted version):
curl -L https://github.com/nats-io/nats-server/releases/download/vX.Y.Z/nats-server-vX.Y.Z-linux-amd64.zip -o nats-server.zip
Unpack:
unzip nats-server.zip -d nats-server
Start the nats server listening on local interfaces and port 4222.
./nats-server -D
You can either build Steward from source or download from release which is a compiled binary.
Steward is written in Go, so you need Go installed to compile it. You can get Go at https://golang.org/dl/.
When Go is installed:
Clone the repository:
git clone https://github.com/RaaLabs/steward.git
.
Change directory and build:
cd ./steward/cmd/steward
go build -o steward
Release binaries for several architechures are available at https://github.com/RaaLabs/steward/releases
NB: Remember to run the nats setup above before running the steward binary.
Steward will create some directories for things like configuration file and other state files. By default it will create those files in the directory where you start Steward. So create individual directories for each Steward instance you want to run below.
Start up a central server which will act as your master server for things like logs and authorization.
mkdir central & cd central
env CONFIG_FOLDER=./etc/ <path-to-steward-binary-here> --nodeName="central" --centralNodeName="central"
Start up a node that will attach to the central node
mkdir ship1 & cd ship1
env CONFIG_FOLDER=./etc/ <path-to-steward-binary-here> --nodeName="ship1" --centralNodeName="central"
You can get all the options with ./steward --help
Steward will by default create the data and config directories needed in the current folder. This can be changed by using the different flags or editing the config file.
You can also run multiple instances of Steward on the same machine. For testing you can create sub folders for each steward instance, go into each folder and start steward. When starting each Steward instance make sure you give each node a unique --nodeName
.
You can now go to one of the folders for nodes started, and inject messages into the socket file ./tmp/steward.sock
with the nc tool.
Example on Mac:
nc -U ./tmp/steward.sock < reqnone.msg
Example on Linux:
nc -NU ./tmp/steward.sock < reqnone.msg
A complete example to start a central node called central
.
env CONFIG_FOLDER=./etc/ ./steward \
-nodeName="central" \
-defaultMessageRetries=3 \
-defaultMessageTimeout=5 \
-subscribersDataFolder="./data" \
-centralNodeName="central" \
-IsCentralErrorLogger=true \
-subscribersDataFolder="./var" \
-brokerAddress="127.0.0.1:4222"
And start another node that will be managed via central.
env CONFIG_FOLDER=./etc/ ./steward \
-nodeName="ship1" \
-startPubREQHello=200 \
-centralNodeName="central" \
-promHostAndPort=":12112" \
-brokerAddress="127.0.0.1:4222"
NB: By default Steward creates it's folders like ./etc
, ./var
, and ./data
in the folder you're in when you start it. If you want to run multiple instances on the same machine you should create separate folders for each instance, and start Steward when you're in that folder. The location of the folders can also be specified within the config file.
Nkey's can be used for authentication, and you use the nkeySeedFile
flag to specify the seed file to use.
Read more in the sections below on how to generate nkey's.
The broker for messaging is Nats-server from https://nats.io. Download, run it, and use the -brokerAddress
flag on Steward to point to the ip and port:
-brokerAddress="nats://10.0.0.124:4222"
There is a lot of different variants of how you can setup and confiure Nats. Full mesh, leaf node, TLS, Authentication, and more. You can read more about how to configure the Nats broker called nats-server at https://nats.io/.
port: 4222
tls {
cert_file: "some.crt"
key_file: "some.key"
}
authorization: {
users = [
{
# central
nkey: <USER_NKEY_HERE>
permissions: {
publish: {
allow: ["some.>","errorCentral.>"]
}
subscribe: {
allow: ["some.>","errorCentral.>"]
}
}
}
{
# node1
nkey: <USER_NKEY_HERE>
permissions: {
publish: {
allow: ["central.>"]
}
subscribe: {
allow: ["central.>","some.node1.>","some.node10'.>"]
}
}
}
{
# node10
nkey: <USER_NKEY_HERE>
permissions: {
publish: {
allow: ["some.node1.>","errorCentral.>"]
}
subscribe: {
allow: ["central.>"]
}
}
}
]
}
The official docs for nkeys can be found here https://docs.nats.io/nats-server/configuration/securing_nats/auth_intro/nkey_auth.
Generate private (seed) and public (user) key pair:
nk -gen user -pubout
Generate a public (user) key from a private (seed) key file called seed.txt
.
nk -inkey seed.txt -pubout > user.txt
More example configurations for the nats-server are located in the doc folder in this repository.
Steward can also use an existing SSH ED25519 private key for authentication with the flag -nkeyFromED25519SSHKeyFile="full-path-to-ssh-private-key". The SSH key will be converted to an Nkey if the option is used. The Seed and the User file will be stored in the socketFolder which by default is at ./tmp
Check Appendix-B for message fields and their explanation.
The API for sending a message from one node to another node is by sending a structured JSON or YAML object into a listener port in of of the following ways.
steward.sock
. By default lives in the ./tmp
directorync -U ./tmp/steward.sock < myMessage.json
socket
fileIn JSON:
[
{
"directory":"/var/steward/cli-command/executed-result",
"fileName": "some.log",
"toNode": "ship1",
"method":"REQCliCommand",
"methodArgs": ["bash","-c","sleep 3 & tree ./"],
"ACKTimeout":10,
"retries":3,
"methodTimeout": 4
}
]
Or in YAML:
---
- toNodes:
- ship1
method: REQCliCommand
methodArgs:
- bash
- "-c"
- "
cat <<< $'[{
\"directory\": \"metrics\",
\"fileName\": \"edgeAgent.prom\",
\"fromNode\":\"metrics\",
\"toNode\": \"ship1\",
\"method\":\"REQHttpGetScheduled\",
\"methodArgs\": [\"http://127.0.0.1:8080/metrics\",
\"60\",\"5000000\"],\"replyMethod\":\"REQToFile\",
\"ACKTimeout\":10,
\"retries\": 3,\"methodTimeout\": 3
}]'>scrape-metrics.msg
"
replyMethod: REQToFile
ACKTimeout: 5
retries: 3
replyACKTimeout: 5
replyRetries: 3
methodTimeout: 5
directory: system
fileName: system.log
[
{
"directory":"cli-command-executed-result",
"fileName": "some.log",
"toNode": "ship1",
"method":"REQCliCommand",
"methodArgs": ["bash","-c","sleep 3 & tree ./"],
"ACKTimeout":10,
"retries":3,
"methodTimeout": 4
},
{
"directory":"cli-command-executed-result",
"fileName": "some.log",
"toNode": "ship2",
"method":"REQCliCommand",
"methodArgs": ["bash","-c","sleep 3 & tree ./"],
"ACKTimeout":10,
"retries":3,
"methodTimeout": 4
}
]
[
{
"directory": "httpget",
"fileName": "finn.no.html",
"toNodes": ["central","ship2"],
"method":"REQHttpGet",
"methodArgs": ["https://finn.no"],
"replyMethod":"REQToFile",
"ACKTimeout":5,
"retries":3,
"methodTimeout": 5
}
]
[
{
"directory": "./my/log/files/",
"fileName": "some.log",
"toNode": "ship2",
"method":"REQTailFile",
"methodArgs": ["./test.log"],
"ACKTimeout":5,
"retries":3,
"methodTimeout": 200
}
]
[
{
"directory":"system",
"fileName":"system.log",
"toNodes": ["ship2"],
"method":"REQCliCommand",
"methodArgs": ["bash","-c","rm -rf /usr/local/steward/lib/incomingBuffer.db & systemctl restart steward"],
"replyMethod":"REQToFileAppend",
"ACKTimeout":30,
"retries":1,
"methodTimeout": 30
}
]
You can save the content to myfile.JSON and append it to the socket
file:
nc -U ./steward.sock < example/toShip1-REQCliCommand.json
<nodename>.<method>.<event>
Example:
ship3.REQCliCommand.EventACK
For ACK messages (using the reply functionality in NATS) we append the .reply
to the subject.
ship3.REQCliCommand.EventACK.reply
Nodename: Are the hostname of the device. This do not have to be resolvable via DNS, it is just a unique name for the host to receive the message.
Event: Desribes if we want and Acknowledge or No Acknowledge when the message was delivered :
EventACK
EventNACK
Info: The field Event are present in both the Subject structure and the Message structure. This is due to Event being used in both the naming of a subject, and for specifying message type to allow for specific processing of a message.
Method: Are the functionality the message provide. Example could be for example REQCliCommand
or REQHttpGet
For Hello Message to a node named "central" of type Event and there is No Ack.
central.REQHello.EventNACK
For CliCommand message to a node named "ship1" of type Event and it wants an Ack.
ship1.REQCliCommand.EventACK
If messages have been sent, and not picked up by a node it might make sense to have some method to clear messages on a node. This could either be done by message ID, and/or time duration.
// RingBufferPermStore enable or disable the persisting of
// messages being processed to local db.
RingBufferPersistStore bool
// RingBufferSize
RingBufferSize int
// The configuration folder on disk
ConfigFolder string
// The folder where the socket file should live
SocketFolder string
// TCP Listener for sending messages to the system
TCPListener string
// HTTP Listener for sending messages to the system
HTTPListener string
// The folder where the database should live
DatabaseFolder string
// some unique string to identify this Edge unit
NodeName string
// the address of the message broker
BrokerAddress string
// NatsConnOptTimeout the timeout for trying the connect to nats broker
NatsConnOptTimeout int
// nats connect retry
NatsConnectRetryInterval int
// NatsReconnectJitter in milliseconds
NatsReconnectJitter int
// NatsReconnectJitterTLS in seconds
NatsReconnectJitterTLS int
// REQKeysRequestUpdateInterval in seconds
REQKeysRequestUpdateInterval int
// REQAclRequestUpdateInterval in seconds
REQAclRequestUpdateInterval int
// The number of the profiling port
ProfilingPort string
// host and port for prometheus listener, e.g. localhost:2112
PromHostAndPort string
// set to true if this is the node that should receive the error log's from other nodes
DefaultMessageTimeout int
// Default value for how long can a request method max be allowed to run.
DefaultMethodTimeout int
// default amount of retries that will be done before a message is thrown away, and out of the system
DefaultMessageRetries int
// Publisher data folder
SubscribersDataFolder string
// central node to receive messages published from nodes
CentralNodeName string
// Path to the certificate of the root CA
RootCAPath string
// Full path to the NKEY's seed file
NkeySeedFile string
// NkeyPublicKey
NkeyPublicKey string `toml:"-"`
// The host and port to expose the data folder
ExposeDataFolder string
// Timeout for error messages
ErrorMessageTimeout int
// Retries for error messages.
ErrorMessageRetries int
// Compression
Compression string
// Serialization
Serialization string
// SetBlockProfileRate for block profiling
SetBlockProfileRate int
// EnableSocket for enabling the creation of a steward.sock file
EnableSocket bool
// EnableTUI will enable the Terminal User Interface
EnableTUI bool
// EnableSignatureCheck
EnableSignatureCheck bool
// EnableAclCheck
EnableAclCheck bool
// IsCentralAuth
IsCentralAuth bool
// EnableDebug will also enable printing all the messages received in the errorKernel
// to STDERR.
EnableDebug bool
// KeepPublishersAliveFor number of seconds.
// Timer that will be used for when to remove the sub process
// publisher. The timer is reset each time a message is published with
// the process, so the sub process publisher will not be removed until
// it have not received any messages for the given amount of time.
KeepPublishersAliveFor int
// Make the current node send hello messages to central at given interval in seconds
StartPubREQHello int
// Enable the updates of public keys
EnableKeyUpdates bool
// Enable the updates of acl's
EnableAclUpdates bool
// Start the central error logger.
IsCentralErrorLogger bool
// Subscriber for hello messages
StartSubREQHello bool
// Subscriber for text logging
StartSubREQToFileAppend bool
// Subscriber for writing to file
StartSubREQToFile bool
// Subscriber for writing to file without ACK
StartSubREQToFileNACK bool
// Subscriber for reading files to copy
StartSubREQCopySrc bool
// Subscriber for writing copied files to disk
StartSubREQCopyDst bool
// Subscriber for Echo Request
StartSubREQPing bool
// Subscriber for Echo Reply
StartSubREQPong bool
// Subscriber for CLICommandRequest
StartSubREQCliCommand bool
// Subscriber for REQToConsole
StartSubREQToConsole bool
// Subscriber for REQHttpGet
StartSubREQHttpGet bool
// Subscriber for REQHttpGetScheduled
StartSubREQHttpGetScheduled bool
// Subscriber for tailing log files
StartSubREQTailFile bool
// Subscriber for continously delivery of output from cli commands.
StartSubREQCliCommandCont bool
// The node to send the message to.
ToNode Node `json:"toNode" yaml:"toNode"`
// ToNodes to specify several hosts to send message to in the
// form of an slice/array.
// The ToNodes field is only a concept that exists when messages
// are injected f.ex. on a socket, and there they are directly
//converted into separate node messages for each node, and from
// there the ToNodes field is not used any more within the system.
// With other words, a message that exists within Steward is always
// for just for a single node.
ToNodes []Node `json:"toNodes,omitempty" yaml:"toNodes,omitempty"`
// The actual data in the message. This is typically where we
// specify the cli commands to execute on a node, and this is
// also the field where we put the returned data in a reply
// message.
Data []string `json:"data" yaml:"data"`
// Method, what request type to use, like REQCliCommand, REQHttpGet..
Method Method `json:"method" yaml:"method"`
// Additional arguments that might be needed when executing the
// method. Can be f.ex. an ip address if it is a tcp sender, or the
// shell command to execute in a cli session.
MethodArgs []string `json:"methodArgs" yaml:"methodArgs"`
// ReplyMethod, is the method to use for the reply message.
// By default the reply method will be set to log to file, but
// you can override it setting your own here.
ReplyMethod Method `json:"replyMethod" yaml:"replyMethod"`
// Additional arguments that might be needed when executing the reply
// method. Can be f.ex. an ip address if it is a tcp sender, or the
// shell command to execute in a cli session.
ReplyMethodArgs []string `json:"replyMethodArgs" yaml:"replyMethodArgs"`
// IsReply are used to tell that this is a reply message. By default
// the system sends the output of a request method back to the node
// the message originated from. If it is a reply method we want the
// result of the reply message to be sent to the central server, so
// we can use this value if set to swap the toNode, and fromNode
// fields.
IsReply bool `json:"isReply" yaml:"isReply"`
// From what node the message originated
FromNode Node
// ACKTimeout for waiting for an ack message
ACKTimeout int `json:"ACKTimeout" yaml:"ACKTimeout"`
// Resend retries
Retries int `json:"retries" yaml:"retries"`
// The ACK timeout of the new message created via a request event.
ReplyACKTimeout int `json:"replyACKTimeout" yaml:"replyACKTimeout"`
// The retries of the new message created via a request event.
ReplyRetries int `json:"replyRetries" yaml:"replyRetries"`
// Timeout for long a process should be allowed to operate
MethodTimeout int `json:"methodTimeout" yaml:"methodTimeout"`
// Timeout for long a process should be allowed to operate
ReplyMethodTimeout int `json:"replyMethodTimeout" yaml:"replyMethodTimeout"`
// Directory is a string that can be used to create the
//directory structure when saving the result of some method.
// For example "syslog","metrics", or "metrics/mysensor"
// The type is typically used in the handler of a method.
Directory string `json:"directory" yaml:"directory"`
// FileName is used to be able to set a wanted name
// on a file being saved as the result of data being handled
// by a method handler.
FileName string `json:"fileName" yaml:"fileName"`
// PreviousMessage are used for example if a reply message is
// generated and we also need a copy of the details of the the
// initial request message.
PreviousMessage *Message