Docker For Mac Unknown Blob

In Docker, a volume is simply a directory on disk or in another Container. Lifetimes are not managed and until very recently there were only local-. I have a custom docker registry running in a container bound to localhost like this. It connects and starts to push the image and then I get err.code='blob unknown'. Even if disk IO looks ok on Docker Desktop for Mac, it is not even close to.

Estimated reading time: 5 minutes

Tascam us 428 drivers for mac. The journald logging driver sends container logs to thesystemd journal.Log entries can be retrieved using the journalctl command, through use of thejournal API, or using the docker logs command.

In addition to the text of the log message itself, the journald log driverstores the following metadata in the journal with each message:

Field	Description
`CONTAINER_ID`	The container ID truncated to 12 characters.
`CONTAINER_ID_FULL`	The full 64-character container ID.
`CONTAINER_NAME`	The container name at the time it was started. If you use `docker rename` to rename a container, the new name is not reflected in the journal entries.
`CONTAINER_TAG`, `SYSLOG_IDENTIFIER`	The container tag (log tag option documentation).
`CONTAINER_PARTIAL_MESSAGE`	A field that flags log integrity. Improve logging of long log lines.

Usage

To use the journald driver as the default logging driver, set the log-driverand log-opt keys to appropriate values in the daemon.json file, which islocated in /etc/docker/ on Linux hosts orC:ProgramDatadockerconfigdaemon.json on Windows Server. For more aboutconfiguring Docker using daemon.json, seedaemon.json.

The following example sets the log driver to journald:

Restart Docker for the changes to take effect.

To configure the logging driver for a specific container, use the --log-driverflag on the docker run command.

Options

Use the --log-opt NAME=VALUE flag to specify additional journald loggingdriver options.

Option	Required	Description
`tag`	optional	Specify template to set `CONTAINER_TAG` and `SYSLOG_IDENTIFIER` value in journald logs. Refer to log tag option documentation to customize the log tag format.
`labels`	optional	Comma-separated list of keys of labels, which should be included in message, if these labels are specified for the container.
`env`	optional	Comma-separated list of keys of environment variables, which should be included in message, if these variables are specified for the container.
`env-regex`	optional	Similar to and compatible with env. A regular expression to match logging-related environment variables. Used for advanced log tag options.

If a collision occurs between label and env keys, the value of the env takesprecedence. Each option adds additional fields to the attributes of a loggingmessage.

Below is an example of the logging options required to log to journald.

This configuration also directs the driver to include in the payload the labellocation, and the environment variable TEST. If the --env 'TEST=false'or --label location=west arguments were omitted, the corresponding key wouldnot be set in the journald log.

Note regarding container names

The value logged in the CONTAINER_NAME field is the name of the container thatwas set at startup. If you use docker rename to rename a container, the newname is not reflected in the journal entries. Journal entries continueto use the original name.

Retrieve log messages with `journalctl`

Use the journalctl command to retrieve log messages. You can apply filterexpressions to limit the retrieved messages to those associated with a specificcontainer:

You can use additional filters to further limit the messages retrieved. The -bflag only retrieves messages generated since the last system boot:

The -o flag specifies the format for the retried log messages. Use -o jsonto return the log messages in JSON format.

View logs for a container with a TTY enabled

If TTY is enabled on a container you may see [10B blob data] in the outputwhen retrieving log messages.The reason for that is that r is appended to the end of the line andjournalctl doesn’t strip it automatically unless --all is set:

Retrieve log messages with the `journal` API

This example uses the systemd Python module to retrieve containerlogs:

Journald, docker, logging, driver

Article ID: KB000957

Issue

Docker containers will not execute on nodes running Docker 18.09.x and error out with:

Note: `/bin/ucp-tool` is PID 1 in the example above. This portion of the error will change depending on the container.

Prerequisites

Docker 18.09.x

Root Cause

This error is caused by the presence of MountFlags=slave in the docker SystemD unit file. This flag, which was helpful in Docker EE versions prior to 17.06.2-ee-5 running on RHEL kernels 3.10.0-514 and earlier, prevents containerd from accessing resources in container namespaces.

Resolution

You can verify that MountFlags=slave option is present by:

Reviewing the docker unit file:
If it is, then either edit the unit file directly or check for the presence of .conf files in the /etc/systemd/system/docker.service.d directory. For example:
Removing this option by deleting the .conf file and restarting the Docker daemon should resolve the issue:

If the issue persists, please reboot the node.

What's Next

See: https://github.com/moby/moby/issues/38174#issuecomment-440902064