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# Streaming and replication reference
This document contains advanced streaming options and suggested deployment options for production.
If you haven't already done so, we suggest you first go through the
[quick introduction to streaming](https://github.com/netdata/netdata/blob/master/docs/metrics-storage-management/enable-streaming.md)
, for your first, basic parent child setup.
## Configuration
There are two files responsible for configuring Netdata's streaming capabilities: `stream.conf` and `netdata.conf`.
From within your Netdata config directory (typically `/etc/netdata`), [use `edit-config`](https://github.com/netdata/netdata/blob/master/docs/configure/nodes.md) to
open either `stream.conf` or `netdata.conf`.
```
sudo ./edit-config stream.conf
sudo ./edit-config netdata.conf
```
### `stream.conf`
The `stream.conf` file contains three sections. The `[stream]` section is for configuring child nodes.
The `[API_KEY]` and `[MACHINE_GUID]` sections are both for configuring parent nodes, and share the same settings.
`[API_KEY]` settings affect every child node using that key, whereas `[MACHINE_GUID]` settings affect only the child
node with a matching GUID.
The file `/var/lib/netdata/registry/netdata.public.unique.id` contains a random GUID that **uniquely identifies each
node**. This file is automatically generated by Netdata the first time it is started and remains unaltered forever.
#### `[stream]` section
| Setting | Default | Description |
|-------------------------------------------------|---------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `enabled` | `no` | Whether this node streams metrics to any parent. Change to `yes` to enable streaming. |
| [`destination`](#destination) | | A space-separated list of parent nodes to attempt to stream to, with the first available parent receiving metrics, using the following format: `[PROTOCOL:]HOST[%INTERFACE][:PORT][:SSL]`. [Read more →](#destination) |
| `ssl skip certificate verification` | `yes` | If you want to accept self-signed or expired certificates, set to `yes` and uncomment. |
| `CApath` | `/etc/ssl/certs/` | The directory where known certificates are found. Defaults to OpenSSL's default path. |
| `CAfile` | `/etc/ssl/certs/cert.pem` | Add a parent node certificate to the list of known certificates in `CAPath`. |
| `api key` | | The `API_KEY` to use as the child node. |
| `timeout seconds` | `60` | The timeout to connect and send metrics to a parent. |
| `default port` | `19999` | The port to use if `destination` does not specify one. |
| [`send charts matching`](#send-charts-matching) | `*` | A space-separated list of [Netdata simple patterns](https://github.com/netdata/netdata/blob/master/libnetdata/simple_pattern/README.md) to filter which charts are streamed. [Read more →](#send-charts-matching) |
| `buffer size bytes` | `10485760` | The size of the buffer to use when sending metrics. The default `10485760` equals a buffer of 10MB, which is good for 60 seconds of data. Increase this if you expect latencies higher than that. The buffer is flushed on reconnect. |
| `reconnect delay seconds` | `5` | How long to wait until retrying to connect to the parent node. |
| `initial clock resync iterations` | `60` | Sync the clock of charts for how many seconds when starting. |
| `parent using h2o` | `no` | Set to yes if you are connecting to parent trough it's h2o webserver/port. Currently there is no reason to set this to `yes` unless you are testing the new h2o based netdata webserver. When production ready this will be set to `yes` as default. |
### `[API_KEY]` and `[MACHINE_GUID]` sections
| Setting | Default | Description |
|-----------------------------------------------|----------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `enabled` | `no` | Whether this API KEY enabled or disabled. |
| [`allow from`](#allow-from) | `*` | A space-separated list of [Netdata simple patterns](https://github.com/netdata/netdata/blob/master/libnetdata/simple_pattern/README.md) matching the IPs of nodes that will stream metrics using this API key. [Read more →](#allow-from) |
| `default history` | `3600` | The default amount of child metrics history to retain when using the `ram` memory mode. |
| [`default memory mode`](#default-memory-mode) | `ram` | The [database](https://github.com/netdata/netdata/blob/master/database/README.md) to use for all nodes using this `API_KEY`. Valid settings are `dbengine`, `ram`, or `none`. [Read more →](#default-memory-mode) |
| `health enabled by default` | `auto` | Whether alerts and notifications should be enabled for nodes using this `API_KEY`. `auto` enables alerts when the child is connected. `yes` enables alerts always, and `no` disables alerts. |
| `default postpone alarms on connect seconds` | `60` | Postpone alerts and notifications for a period of time after the child connects. |
| `default health log history` | `432000` | History of health log events (in seconds) kept in the database. |
| `default proxy enabled` | | Route metrics through a proxy. |
| `default proxy destination` | | Space-separated list of `IP:PORT` for proxies. |
| `default proxy api key` | | The `API_KEY` of the proxy. |
| `default send charts matching` | `*` | See [`send charts matching`](#send-charts-matching). |
#### `destination`
A space-separated list of parent nodes to attempt to stream to, with the first available parent receiving metrics, using
the following format: `[PROTOCOL:]HOST[%INTERFACE][:PORT][:SSL]`.
- `PROTOCOL`: `tcp`, `udp`, or `unix`. (only tcp and unix are supported by parent nodes)
- `HOST`: A IPv4, IPv6 IP, or a hostname, or a unix domain socket path. IPv6 IPs should be given with brackets
`[ip:address]`.
- `INTERFACE` (IPv6 only): The network interface to use.
- `PORT`: The port number or service name (`/etc/services`) to use.
- `SSL`: To enable TLS/SSL encryption of the streaming connection.
To enable TCP streaming to a parent node at `203.0.113.0` on port `20000` and with TLS/SSL encryption:
```conf
[stream]
destination = tcp:203.0.113.0:20000:SSL
```
#### `send charts matching`
A space-separated list of [Netdata simple patterns](https://github.com/netdata/netdata/blob/master/libnetdata/simple_pattern/README.md) to filter which charts are streamed.
The default is a single wildcard `*`, which streams all charts.
To send only a few charts, list them explicitly, or list a group using a wildcard. To send _only_ the `apps.cpu` chart
and charts with contexts beginning with `system.`:
```conf
[stream]
send charts matching = apps.cpu system.*
```
To send all but a few charts, use `!` to create a negative match. To send _all_ charts _but_ `apps.cpu`:
```conf
[stream]
send charts matching = !apps.cpu *
```
#### `allow from`
A space-separated list of [Netdata simple patterns](https://github.com/netdata/netdata/blob/master/libnetdata/simple_pattern/README.md) matching the IPs of nodes that
will stream metrics using this API key. The order is important, left to right, as the first positive or negative match is used.
The default is `*`, which accepts all requests including the `API_KEY`.
To allow from only a specific IP address:
```conf
[API_KEY]
allow from = 203.0.113.10
```
To allow all IPs starting with `10.*`, except `10.1.2.3`:
```conf
[API_KEY]
allow from = !10.1.2.3 10.*
```
> If you set specific IP addresses here, and also use the `allow connections` setting in the `[web]` section of
> `netdata.conf`, be sure to add the IP address there so that it can access the API port.
#### `default memory mode`
The [database](https://github.com/netdata/netdata/blob/master/database/README.md) to use for all nodes using this `API_KEY`.
Valid settings are `dbengine`, `ram`, , or `none`.
- `dbengine`: The default, recommended time-series database (TSDB) for Netdata. Stores recent metrics in memory, then
efficiently spills them to disk for long-term storage.
- `ram`: Stores metrics _only_ in memory, which means metrics are lost when Netdata stops or restarts. Ideal for
streaming configurations that use ephemeral nodes.
- `none`: No database.
When using `default memory mode = dbengine`, the parent node creates a separate instance of the TSDB to store metrics
from child nodes. The [size of _each_ instance is configurable](https://github.com/netdata/netdata/blob/master/docs/store/change-metrics-storage.md) with the `page
cache size` and `dbengine multihost disk space` settings in the `[global]` section in `netdata.conf`.
### `netdata.conf`
| Setting | Default | Description |
|--------------------------------------------|-------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `[global]` section | | |
| `memory mode` | `dbengine` | Determines the [database type](https://github.com/netdata/netdata/blob/master/database/README.md) to be used on that node. Other options settings include `none`, and `ram`. `none` disables the database at this host. This also disables alerts and notifications, as those can't run without a database. |
| `[web]` section | | |
| `mode` | `static-threaded` | Determines the [web server](https://github.com/netdata/netdata/blob/master/web/server/README.md) type. The other option is `none`, which disables the dashboard, API, and registry. |
| `accept a streaming request every seconds` | `0` | Set a limit on how often a parent node accepts streaming requests from child nodes. `0` equals no limit. If this is set, you may see `... too busy to accept new streaming request. Will be allowed in X secs` in Netdata's `error.log`. |
### Basic use cases
This is an overview of how the main options can be combined:
| target | memory<br/>mode | web<br/>mode | stream<br/>enabled | exporting | alerts | dashboard |
|--------------------|:---------------:|:------------:|:------------------:|:-------------------------------------:|:------------:|:---------:|
| headless collector | `none` | `none` | `yes` | only for `data source = as collected` | not possible | no |
| headless proxy | `none` | not `none` | `yes` | only for `data source = as collected` | not possible | no |
| proxy with db | not `none` | not `none` | `yes` | possible | possible | yes |
| central netdata | not `none` | not `none` | `no` | possible | possible | yes |
### Per-child settings
While the `[API_KEY]` section applies settings for any child node using that key, you can also use per-child settings
with the `[MACHINE_GUID]` section.
For example, the metrics streamed from only the child node with `MACHINE_GUID` are saved in memory, not using the
default `dbengine` as specified by the `API_KEY`, and alerts are disabled.
```conf
[API_KEY]
enabled = yes
default memory mode = dbengine
health enabled by default = auto
allow from = *
[MACHINE_GUID]
enabled = yes
memory mode = ram
health enabled = no
```
### Streaming compression
[](https://github.com/netdata/netdata/releases/latest)
[](https://github.com/netdata/netdata/releases/latest)
#### OS dependencies
* Streaming compression is based on [lz4 v1.9.0+](https://github.com/lz4/lz4). The [lz4 v1.9.0+](https://github.com/lz4/lz4) library must be installed in your OS in order to enable streaming compression. Any lower version will disable Netdata streaming compression for compatibility purposes between the older versions of Netdata agents.
To check if your Netdata Agent supports stream compression run the following GET request in your browser or terminal:
```
curl -X GET http://localhost:19999/api/v1/info | grep 'Stream Compression'
```
**Output**
```
"buildinfo": "dbengine|Native HTTPS|Netdata Cloud|ACLK Next Generation|New Cloud Protocol Support|ACLK Legacy|TLS Host Verification|Machine Learning|Stream Compression|protobuf|JSON-C|libcrypto|libm|LWS v3.2.2|mosquitto|zlib|apps|cgroup Network Tracking|EBPF|perf|slabinfo",
```
> Note: If your OS doesn't support Netdata compression the `buildinfo` will not contain the `Stream Compression` statement.
To check if your Netdata Agent has stream compression enabled, run the following GET request in your browser or terminal:
```
curl -X GET http://localhost:19999/api/v1/info | grep 'stream-compression'
```
**Output**
```
"stream-compression": "enabled"
```
Note: The `stream-compression` status can be `"enabled" | "disabled" | "N/A"`.
A compressed data packet is determined and decompressed on the fly.
#### Limitations
This limitation will be withdrawn asap and is work-in-progress.
The current implementation of streaming data compression can support only a few number of dimensions in a chart with names that cannot exceed the size of 16384 bytes. In case your instance hit this limitation, the agent will deactivate compression during runtime to avoid stream corruption. This limitation can be seen in the error.log file with the sequence of the following messages:
```
netdata INFO : STREAM_SENDER[child01] : STREAM child01 [send to my.parent.IP]: connecting...
netdata INFO : STREAM_SENDER[child01] : STREAM child01 [send to my.parent.IP]: initializing communication...
netdata INFO : STREAM_SENDER[child01] : STREAM child01 [send to my.parent.IP]: waiting response from remote netdata...
netdata INFO : STREAM_SENDER[child01] : STREAM_COMPRESSION: Compressor Reset
netdata INFO : STREAM_SENDER[child01] : STREAM child01 [send to my.parent.IP]: established communication with a parent using protocol version 5 - ready to send metrics...
...
netdata ERROR : PLUGINSD[go.d] : STREAM_COMPRESSION: Compression Failed - Message size 27847 above compression buffer limit: 16384 (errno 9, Bad file descriptor)
netdata ERROR : PLUGINSD[go.d] : STREAM_COMPRESSION: Deactivating compression to avoid stream corruption
netdata ERROR : PLUGINSD[go.d] : STREAM_COMPRESSION child01 [send to my.parent.IP]: Restarting connection without compression
...
netdata INFO : STREAM_SENDER[child01] : STREAM child01 [send to my.parent.IP]: connecting...
netdata INFO : STREAM_SENDER[child01] : STREAM child01 [send to my.parent.IP]: initializing communication...
netdata INFO : STREAM_SENDER[child01] : STREAM child01 [send to my.parent.IP]: waiting response from remote netdata...
netdata INFO : STREAM_SENDER[child01] : Stream is uncompressed! One of the agents (my.parent.IP <-> child01) does not support compression OR compression is disabled.
netdata INFO : STREAM_SENDER[child01] : STREAM child01 [send to my.parent.IP]: established communication with a parent using protocol version 4 - ready to send metrics...
netdata INFO : WEB_SERVER[static4] : STREAM child01 [send]: sending metrics...
```
#### How to enable stream compression
Netdata Agents are shipped with data compression enabled by default. You can also configure which streams will use compression.
With enabled stream compression, a Netdata Agent can negotiate streaming compression with other Netdata Agents. During the negotiation of streaming compression both Netdata Agents should support and enable compression in order to communicate over a compressed stream. The negotiation will result into an uncompressed stream, if one of the Netdata Agents doesn't support **or** has compression disabled.
To enable stream compression:
1. Edit `stream.conf` by using the `edit-config` script:
`/etc/netdata/edit-config stream.conf`.
2. In the `[stream]` section, set `enable compression` to `yes`.
```
# This is the default stream compression flag for an agent.
[stream]
enable compression = yes | no
```
| Parent | Stream compression | Child |
|--------------------------------------|--------------------|--------------------------------------|
| Supported & Enabled | compressed | Supported & Enabled |
| (Supported & Disabled)/Not supported | uncompressed | Supported & Enabled |
| Supported & Enabled | uncompressed | (Supported & Disabled)/Not supported |
| (Supported & Disabled)/Not supported | uncompressed | (Supported & Disabled)/Not supported |
In case of parents with multiple children you can select which streams will be compressed by using the same configuration under the `[API_KEY]`, `[MACHINE_GUID]` section.
This configuration uses AND logic with the default stream compression configuration under the `[stream]` section. This means the stream compression from child to parent will be enabled only if the outcome of the AND logic operation is true (`default compression enabled` && `api key compression enabled`). So both should be enabled to get stream compression otherwise stream compression is disabled.
```
[API_KEY]
enable compression = yes | no
```
Same thing applies with the `[MACHINE_GUID]` configuration.
```
[MACHINE_GUID]
enable compression = yes | no
```
### Securing streaming with TLS/SSL
Netdata does not activate TLS encryption by default. To encrypt streaming connections, you first need to [enable TLS
support](https://github.com/netdata/netdata/blob/master/web/server/README.md#enabling-tls-support) on the parent. With encryption enabled on the receiving side, you
need to instruct the child to use TLS/SSL as well. On the child's `stream.conf`, configure the destination as follows:
```
[stream]
destination = host:port:SSL
```
The word `SSL` appended to the end of the destination tells the child that connections must be encrypted.
> While Netdata uses Transport Layer Security (TLS) 1.2 to encrypt communications rather than the obsolete SSL protocol,
> it's still common practice to refer to encrypted web connections as `SSL`. Many vendors, like Nginx and even Netdata
> itself, use `SSL` in configuration files, whereas documentation will always refer to encrypted communications as `TLS`
> or `TLS/SSL`.
#### Certificate verification
When TLS/SSL is enabled on the child, the default behavior will be to not connect with the parent unless the server's
certificate can be verified via the default chain. In case you want to avoid this check, add the following to the
child's `stream.conf` file:
```
[stream]
ssl skip certificate verification = yes
```
#### Trusted certificate
If you've enabled [certificate verification](#certificate-verification), you might see errors from the OpenSSL library
when there's a problem with checking the certificate chain (`X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY`). More
importantly, OpenSSL will reject self-signed certificates.
Given these known issues, you have two options. If you trust your certificate, you can set the options `CApath` and
`CAfile` to inform Netdata where your certificates, and the
|
