2.3.21 Data that can be collected on Docker environment

(1) Overview of the Docker environment

The Docker environment available with Linux allows you to operate multiple Linux environments within a single Linux system by virtualizing the Linux environments and treating them like software. Because a Docker container shares resources with the host OS, the overhead of running applications is smaller compared to that incurred with virtual machines.

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(2) Docker environment structure

The Docker environment resembles a Solaris zone (which provides a workspace for applications) in structure.

The Docker environment is made up of Docker container environments and a host (Docker host) environment that manages the Docker container environments.

PFM - Agent for Platform allows you to collect information on the Docker host environment and Docker container environments.

PFM - Agent for Platform supports the following Docker environment:

Docker host OS version

• Red Hat Enterprise Linux(R) Server 7.1 or later

• CentOS 7.1 or later

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(3) Process monitoring in the Docker host environment

If you are running PFM - Agent for Platform in the Docker host environment, you can collect information on processes running inside the Docker containers.

By setting the ALL Container Collection for Process property, you can select whether to collect information about processes running inside Docker containers. The following settings are available for the ALL Container Collection for Process property:

Yes

If you select this setting, information^# about processes running inside both the Docker host environment and Docker container environments is collected.

No

If you select this setting, only information about processes running inside the Docker host environment is collected.

The ALL Container Collection for Process property is set to Yes by default.

The figure below shows process information collected when PFM - Agent for Platform runs on the Docker host environment.

Figure 2‒16: Process information collected on the Docker host environment

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(4) Process monitoring in the Docker container environment

When PFM - Agent for Platform is running in a Docker container environment, PFM - Agent for Platform only collects process information about the Docker container environment in which it is running, regardless of the setting specified for the ALL Container Collection for Process property. The figure below shows process information collected when PFM - Agent for Platform runs on the Docker container environment.

Figure 2‒17: Process information collected on the Docker container environment

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(5) Notes on the Docker host environment

Keep the following in mind when you have installed PFM - Agent for Platform on the Docker host environment to collect information about processes running on it:

• By using the Docker Engine API, PFM - Agent for Platform communicates with the Docker Engine according to the default setting specified for the UNIX domain socket. For this reason, the UNIX domain socket settings of the Docker Engine API must not be edited. If you change the default UNIX domain socket settings, PFM - Agent for Platform can no longer communication with the Docker Engine, in which case N/A is stored in the Virtual Env ID field of all processes obtained with the PD record, PD_APSI record, and PD_APS record.

• If one or more errors occur while PFM - Agent for Platform is communicating with the Docker Engine to collect record information, or if a Docker container is started or shut down while PFM - Agent for Platform is communicating with the Docker Engine, PFM - Agent for Platform might not be able determine whether some of the processes are running on the Docker host or a Docker container. In this case, N/A is stored in the Virtual Env ID field of the PD record, PD_APSI record, and PD_APS record of these processes.

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(6) Notes on the Docker container environment

Keep the following in mind when you have installed PFM - Agent for Platform on the Docker container environment to collect performance information on it:

• For notes regarding the installation of PFM - Agent for Platform in a Docker container environment, see the Release Notes.

• Owing to the characteristics of the Docker environment, a separate application environment is provided. Due to this, the following information cannot be obtained:

  • Information about Docker container environments other than that in which PFM - Agent for Platform has been installed

• If you want to connect to a PFM - Manager in another host environment (that is, a host that is different from the one that manages the Docker container environment in which PFM - Agent for Platform is installed), you need to first fix the IP address of the Docker container environment by means of port forwarding, and then enable another host environment to access PFM - Agent for Platform.

• The ID of each process running in the Docker container environment varies between the Docker host environment and Docker container environments.

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