87 lines
3.6 KiB
Text
87 lines
3.6 KiB
Text
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include::../../libbeat/docs/shared-docker.asciidoc[]
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[float]
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[[monitoring-host]]
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==== Monitor the host machine
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When executing Metricbeat in a container, there are some important
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things to be aware of if you want to monitor the host machine or other
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containers. Let's walk-through some examples using Docker as our container
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orchestration tool.
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This example highlights the changes required to make the system module
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work properly inside of a container. This enables Metricbeat to monitor the
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host machine from within the container.
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["source","sh",subs="attributes"]
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----
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docker run \
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--mount type=bind,source=/proc,target=/hostfs/proc,readonly \ <1>
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--mount type=bind,source=/sys/fs/cgroup,target=/hostfs/sys/fs/cgroup,readonly \ <2>
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--mount type=bind,source=/,target=/hostfs,readonly \ <3>
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--net=host <4>
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{dockerimage} -system.hostfs=/hostfs
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----
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<1> Metricbeat's <<metricbeat-module-system,system module>> collects much of its data through the Linux proc
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filesystem, which is normally located at `/proc`. Because containers
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are isolated as much as possible from the host, the data inside of the
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container's `/proc` is different than the host's `/proc`. To account for this, you
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can mount the host's `/proc` filesystem inside of the container and tell
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Metricbeat to look inside the `/hostfs` directory when looking for `/proc` by
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using the `-system.hostfs=/hostfs` CLI flag.
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<2> By default, cgroup reporting is enabled for the
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<<metricbeat-metricset-system-process,system process metricset>>, so you need
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to mount the host's cgroup mountpoints within the container. They need to be
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mounted inside the directory specified by the `-system.hostfs` CLI flag.
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<3> If you want to be able to monitor filesystems from the host by using the
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<<metricbeat-metricset-system-filesystem,system filesystem metricset>>, then those filesystems need to be mounted inside
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of the container. They can be mounted at any location.
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<4> The <<metricbeat-metricset-system-network,system network metricset>> uses data from `/proc/net/dev`, or
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`/hostfs/proc/net/dev` when using `-system.hostfs=/hostfs`. The only way
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to make this file contain the host's network devices is to use the `--net=host`
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flag. This is due to Linux namespacing; simply bind mounting the host's `/proc`
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to `/hostfs/proc` is not sufficient.
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NOTE: The special filesystems +/proc+ and +/sys+ are only available if the
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host system is running Linux. Attempts to bind-mount these filesystems will
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fail on Windows and MacOS.
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[float]
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[[monitoring-service]]
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==== Monitor a service in another container
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Next, let's look at an example of monitoring a containerized service from a
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Metricbeat container.
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["source","sh",subs="attributes"]
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----
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docker run \
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--network=mysqlnet \ <1>
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-e MYSQL_PASSWORD=secret \ <2>
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{dockerimage}
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----
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<1> Placing the Metricbeat and MySQL containers on the same Docker network
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allows Metricbeat access to the exposed ports of the MySQL container, and
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makes the hostname `mysql` resolvable to Metricbeat.
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<2> If you do not want to hardcode certain values into your Metricbeat
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configuration, then you can pass them into the container either as environment
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variables or as command line flags to Metricbeat (see the `-E` CLI flag in <<command-line-options>>).
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The mysql module configuration would look like this:
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[source,yaml]
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----
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metricbeat.modules:
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- module: mysql
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metricsets: ["status"]
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hosts: ["tcp(mysql:3306)/"] <1>
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username: root
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password: ${MYSQL_PASSWORD} <2>
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----
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<1> The `mysql` hostname will resolve to the address of a container
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named `mysql` on the `mysqlnet` Docker network.
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<2> The `MYSQL_PASSWORD` variable will be evaluated at startup. If the variable
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is not set, this will lead to an error at startup.
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