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213 lines
13 KiB
Markdown
213 lines
13 KiB
Markdown
## vmagent
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`vmagent` is a tiny but brave agent, which helps you collecting metrics from various sources
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and storing them to [VictoriaMetrics](https://github.com/VictoriaMetrics/VictoriaMetrics).
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<img alt="vmagent" src="vmagent.png">
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### Motivation
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While VictoriaMetrics provides an efficient solution to store and observe metrics, our users needed something fast
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and RAM friendly to scrape metrics from Prometheus-compatible exporters to VictoriaMetrics.
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Also, we found that users’ infrastructure is like snowflakes - never alike, and we decided to add more flexibility
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to `vmagent` (like the ability to push metrics instead of pulling them). We did our best and plan to do even more.
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### Features
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* Can be used as drop-in replacement for Prometheus for scraping targets such as [node_exporter](https://github.com/prometheus/node_exporter).
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See [Quick Start](#quick-start) for details.
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* Can add, remove and modify labels via Prometheus relabeling. See [these docs](#relabeling) for details.
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* Accepts data via all the ingestion protocols supported by VictoriaMetrics:
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* Influx line protocol via `http://<vmagent>:8429/write`. See [these docs](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-send-data-from-influxdb-compatible-agents-such-as-telegraf).
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* JSON lines import protocol via `http://<vmagent>:8429/api/v1/import`. See [these docs](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-import-time-series-data).
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* Graphite plaintext protocol if `-graphiteListenAddr` command-line flag is set. See [these docs](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-send-data-from-graphite-compatible-agents-such-as-statsd).
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* OpenTSDB telnet and http protocols if `-opentsdbListenAddr` command-line flag is set. See [these docs](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-send-data-from-opentsdb-compatible-agents).
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* Prometheus remote write protocol via `http://<vmagent>:8429/api/v1/write`.
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* Can replicate collected metrics simultaneously to multiple remote storage systems.
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* Works in environments with unstable connections to remote storage. If the remote storage is unavailable, the collected metrics
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are buffered at `-remoteWrite.tmpDataPath`. The buffered metrics are sent to remote storage as soon as connection
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to remote storage is recovered. The maximum disk usage for the buffer can be limited with `-remoteWrite.maxDiskUsagePerURL`.
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* Uses lower amounts of RAM, CPU, disk IO and network bandwidth comparing to Prometheus.
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### Quick Start
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Just download `vmutils-*` archive from [releases page](https://github.com/VictoriaMetrics/VictoriaMetrics/releases), unpack it
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and pass the following flags to `vmagent` binary in order to start scraping Prometheus targets:
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* `-promscrape.config` with the path to Prometheus config file (it is usually located at `/etc/prometheus/prometheus.yml`)
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* `-remoteWrite.url` with the remote storage endpoint such as VictoriaMetrics. Multiple `-remoteWrite.url` args can be set in parallel
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in order to replicate data concurrently to multiple remote storage systems.
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Example command line:
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```
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/path/to/vmagent -promscrape.config=/path/to/prometheus.yml -remoteWrite.url=https://victoria-metrics-host:8428/api/v1/write
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```
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If you need collecting only Influx data, then the following command line would be enough:
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```
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/path/to/vmagent -remoteWrite.url=https://victoria-metrics-host:8428/api/v1/write
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```
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Then send Influx data to `http://vmagent-host:8429/write`. See [these docs](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/README.md#how-to-send-data-from-influxdb-compatible-agents-such-as-telegraf) for more details.
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`vmagent` is also available in [docker images](https://hub.docker.com/r/victoriametrics/vmagent/).
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Pass `-help` to `vmagent` in order to see the full list of supported command-line flags with their descriptions.
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### Use cases
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#### IoT and Edge monitoring
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`vmagent` can run and collect metrics in IoT and industrial networks with unreliable or scheduled connections to the remote storage.
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It buffers the collected data in local files until the connection to remote storage becomes available and then sends the buffered
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data to the remote storage. It re-tries sending the data to remote storage on any errors.
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The maximum buffer size can be limited with `-remoteWrite.maxDiskUsagePerURL`.
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`vmagent` works on various architectures from IoT world - 32-bit arm, 64-bit arm, ppc64, 386, amd64.
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See [the corresponding Makefile rules](https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmagent/Makefile) for details.
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#### Drop-in replacement for Prometheus
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If you use Prometheus only for scraping metrics from various targets and forwarding these metrics to remote storage,
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then `vmagent` can replace such Prometheus setup. Usually `vmagent` requires lower amounts of RAM, CPU and network bandwidth comparing to Prometheus for such setup.
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See [these docs](#how-to-collect-metrics-in-prometheus-format) for details.
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#### Replication and high availability
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`vmagent` replicates the collected metrics among multiple remote storage instances configured via `-remoteWrite.url` args.
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If a single remote storage instance temporarily goes out of service, then the collected data remains available in another remote storage instances.
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`vmagent` buffers the collected data in files at `-remoteWrite.tmpDataPath` until the remote storage becomes available again.
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Then it sends the buffered data to the remote storage in order to prevent data gaps in the remote storage.
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#### Relabeling and filtering
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`vmagent` can add, remove or update labels on the collected data before sending it to remote storage. Additionally,
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it can remove unneeded samples via Prometheus-like relabeling before sending the collected data to remote storage.
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See [these docs](#relabeling) for details.
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#### Splitting data streams among multiple systems
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`vmagent` supports splitting of the collected data among muliple destinations with the help of `-remoteWrite.urlRelabelConfig`,
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which is applied independently for each configured `-remoteWrite.url` destination. For instance, it is possible to replicate or split
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data among long-term remote storage, short-term remote storage and real-time analytical system [built on top of Kafka](https://github.com/Telefonica/prometheus-kafka-adapter).
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Note that each destination can receive its own subset of the collected data thanks to per-destination relabeling via `-remoteWrite.urlRelabelConfig`.
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### How to collect metrics in Prometheus format
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Pass the path to `prometheus.yml` to `-promscrape.config` command-line flag. `vmagent` takes into account the following
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sections from [Prometheus config file](https://prometheus.io/docs/prometheus/latest/configuration/configuration/):
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* `global`
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* `scrape_configs`
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All the other sections are ignored, including [remote_write](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#remote_write) section.
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Use `-remoteWrite.*` command-line flags instead for configuring remote write settings.
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The following scrape types in [scrape_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config) section are supported:
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* `static_configs` - for scraping statically defined targets. See [these docs](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#static_config) for details.
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* `file_sd_configs` - for scraping targets defined in external files aka file-based service discover.
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See [these docs](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#file_sd_config) for details.
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The following service discovery mechanisms will be added to `vmagent` soon:
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* [kubernetes_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#kubernetes_sd_config)
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* [ec2_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#ec2_sd_config)
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* [gce_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#gce_sd_config)
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* [consul_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#consul_sd_config)
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* [dns_sd_config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#dns_sd_config)
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File feature requests at [our issue tracker](https://github.com/VictoriaMetrics/VictoriaMetrics/issues) if you need other service discovery mechanisms to be supported by `vmagent`.
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### Adding labels to metrics
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Labels can be added to metrics via the following mechanisms:
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* Via `global -> external_labels` section in `-promscrape.config` file. These labels are added only to metrics scraped from targets configured in `-promscrape.config` file.
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* Via `-remoteWrite.label` command-line flag. These labels are added to all the collected metrics before sending them to `-remoteWrite.url`.
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### Relabeling
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`vmagent` supports [Prometheus relabeling](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config).
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Additionally it provides the following extra actions:
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* `replace_all`: replaces all the occurences of `regex` in the values of `source_labels` with the `replacement` and stores the result in the `target_label`.
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* `labelmap_all`: replaces all the occurences of `regex` in all the label names with the `replacement`.
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The relabeling can be defined in the following places:
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* At `scrape_config -> relabel_configs` section in `-promscrape.config` file. This relabeling is applied to targets when parsing the file during `vmagent` startup
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or during config reload after sending `SIGHUP` signal to `vmagent` via `kill -HUP`.
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* At `scrape_config -> metric_relabel_configs` section in `-promscrape.config` file. This relabeling is applied to metrics after each scrape for the configured targets.
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* At `-remoteWrite.relabelConfig` file. This relabeling is aplied to all the collected metrics before sending them to remote storage.
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* At `-remoteWrite.urlRelabelConfig` files. This relabeling is applied to metrics before sending them to the corresponding `-remoteWrite.url`.
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Read more about relabeling in the following articles:
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* [Life of a label](https://www.robustperception.io/life-of-a-label)
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* [Discarding targets and timeseries with relabeling](https://www.robustperception.io/relabelling-can-discard-targets-timeseries-and-alerts)
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* [Dropping labels at scrape time](https://www.robustperception.io/dropping-metrics-at-scrape-time-with-prometheus)
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* [Extracting labels from legacy metric names](https://www.robustperception.io/extracting-labels-from-legacy-metric-names)
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* [relabel_configs vs metric_relabel_configs](https://www.robustperception.io/relabel_configs-vs-metric_relabel_configs)
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### Monitoring
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`vmagent` exports various metrics in Prometheus exposition format at `http://vmagent-host:8429/metrics` page. It is recommended setting up regular scraping of this page
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either via `vmagent` itself or via Prometheus, so the exported metrics could be analyzed later.
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`vmagent` also exports target statuses at `http://vmagent-host:8429/targets` page in plaintext format.
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### Troubleshooting
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* It is recommended increasing the maximum number of open files in the system (`ulimit -n`) when scraping big number of targets,
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since `vmagent` establishes at least a single TCP connection per each target.
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* It is recommended increasing `-remoteWrite.queues` if `vmagent` collects more than 100K samples per second
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and `vmagent_remotewrite_pending_data_bytes` metric exported by `vmagent` at `/metrics` page constantly grows.
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* `vmagent` buffers scraped data at `-remoteWrite.tmpDataPath` directory until it is sent to `-remoteWrite.url`.
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The directory can grow big when remote storage is unvailable during extended periods of time and if `-remoteWrite.maxDiskUsagePerURL` isn't set.
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If you don't want sending all the data from the directory to remote storage, just stop `vmagent` and delete the directory.
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### How to build from sources
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It is recommended using [binary releases](https://github.com/VictoriaMetrics/VictoriaMetrics/releases) - `vmagent` is located in `vmutils-*` archives there.
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#### Development build
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1. [Install Go](https://golang.org/doc/install). The minimum supported version is Go 1.12.
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2. Run `make vmagent` from the root folder of the repository.
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It builds `vmagent` binary and puts it into the `bin` folder.
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#### Production build
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1. [Install docker](https://docs.docker.com/install/).
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2. Run `make vmagent-prod` from the root folder of the repository.
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It builds `vmagent-prod` binary and puts it into the `bin` folder.
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#### Building docker images
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Run `make package-vmagent`. It builds `victoriametrics/vmagent:<PKG_TAG>` docker image locally.
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`<PKG_TAG>` is auto-generated image tag, which depends on source code in the repository.
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The `<PKG_TAG>` may be manually set via `PKG_TAG=foobar make package-vmagent`.
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