Logs and troubleshooting

Estimated reading time: 11 minutes

Here is information about how to diagnose and troubleshoot problems, send logs and communicate with the Docker for Mac team, use our forums and Knowledge Hub, browse and log issues on GitHub, and find workarounds for known problems.

Docker Knowledge Hub

Looking for help with Docker for Mac? Check out the Docker Knowledge Hub for knowledge base articles, FAQs, and technical support for various subscription levels.

Diagnose problems, send feedback, and create GitHub issues

If you encounter problems for which you do not find solutions in this documentation, on Docker for Mac issues on GitHub, or the Docker for Mac forum, we can help you troubleshoot the log data.

Choose whale menu --> Diagnose & Feedback from the menu bar.

Diagnose & Feedback

Select Diagnose. It runs diagnostics, shows results, and uploads the results to Docker. A diagnostic ID is generated, which must be provided when communicating with the Docker Team. Optionally, you can open an issue on GitHub using the uploaded results and ID as a basis.

Diagnostics & Feedback with ID

If you click Report an issue, this opens Docker for Mac issues on GitHub in your web browser in a “create new issue” template, to be completed before submission.

issue template

Check the logs

In addition to using the diagnose and feedback option to submit logs, you can browse the logs yourself.

Use the command line to view logs

To view Docker for Mac logs at the command line, type this command in a terminal window or your favorite shell.

$ syslog -k Sender Docker

Alternatively, you can send the output of this command to a file. The following command redirects the log output to a file called my_docker_logs.txt.

$ syslog -k Sender Docker > ~/Desktop/my_docker_logs.txt

Use the Mac Console for log queries

Macs provide a built-in log viewer. You can use the Mac Console System Log Query to check Docker app logs.

The Console lives on your Mac hard drive in Applications > Utilities. You can bring it up quickly by just searching for it with Spotlight Search.

To find all Docker app log messages, do the following.

  1. From the Console menu, choose File > New System Log Query...

    Mac Console search for Docker app

    • Name your search (for example Docker)
    • Set the Sender to Docker
  2. Click OK to run the log query.

Mac Console display of Docker app search results

You can use the Console Log Query to search logs, filter the results in various ways, and create reports.

For example, you could construct a search for log messages sent by Docker that contain the word hypervisor then filter the results by time (earlier, later, now).

The diagnostics and usage information to the left of the results provide auto-generated reports on packages.

Troubleshooting

Make sure certificates are set up correctly

Docker for Mac ignores certificates listed under insecure registries, and does not send client certificates to them. Commands like docker run that attempt to pull from the registry produces error messages on the command line, like this:

Error response from daemon: Get http://192.168.203.139:5858/v2/: malformed HTTP response "\x15\x03\x01\x00\x02\x02"

As well as on the registry. For example:

2017/06/20 18:15:30 http: TLS handshake error from 192.168.203.139:52882: tls: client didn't provide a certificate
2017/06/20 18:15:30 http: TLS handshake error from 192.168.203.139:52883: tls: first record does not look like a TLS handshake

For more about using client and server side certificates, see Adding TLS certificates in the Getting Started topic.

Docker for Mac does not start if Mac user account and home folder are renamed after installing the app

If, after installing Docker for Mac, you change the name of your macOS user account and home folder, Docker for Mac fails to start. To solve this problem, uninstall and reinstall Docker for Mac under the new user account.

See also, the discussion on the issue docker/for-mac#1209 and Do I need to reinstall Docker for Mac if I change the name of my macOS account? in the FAQs.

Volume mounting requires file sharing for any project directories outside of /Users

If you are using mounted volumes and get runtime errors indicating an application file is not found, access to a volume mount is denied, or a service cannot start, such as when using Docker Compose, you might need to enable file sharing.

Volume mounting requires shared drives for projects that live outside of the /Users directory. Go to whale menu --> Preferences --> File sharing and share the drive that contains the Dockerfile and volume.

Incompatible CPU detected

Docker for Mac requires a processor (CPU) that supports virtualization and, more specifically, the Apple Hypervisor framework. Docker for Mac is only compatible with Macs that have a CPU that supports the Hypervisor framework. Most Macs built in 2010 and later support it, as described in the Apple Hypervisor Framework documentation about supported hardware:

Generally, machines with an Intel VT-x feature set that includes Extended Page Tables (EPT) and Unrestricted Mode are supported.

To check if your Mac supports the Hypervisor framework, run this command in a terminal window.

sysctl kern.hv_support

If your Mac supports the Hypervisor Framework, the command prints kern.hv_support: 1.

If not, the command prints kern.hv_support: 0.

See also, Hypervisor Framework Reference in the Apple documentation, and Docker for Mac system requirements in What to know before you install.

Workarounds for common problems

  • If Docker for Mac fails to install or start properly:

    • Make sure you quit Docker for Mac before installing a new version of the application ( whale menu --> Quit Docker). Otherwise, you get an “application in use” error when you try to copy the new app from the .dmg to /Applications.

    • Restart your Mac to stop / discard any vestige of the daemon running from the previously installed version.

    • Run the uninstall commands from the menu.

  • If docker commands aren’t working properly or as expected, you may need to unset some environment variables, to make sure you are not using the legacy Docker Machine environment in your shell or command window. Unset the DOCKER_HOST environment variable and related variables.

  • Network connections fail if the macOS Firewall is set to “Block all incoming connections”. You can enable the firewall, but bootpd must be allowed incoming connections so that the VM can get an IP address.

  • For the hello-world-nginx example, Docker for Mac must be running to get to the webserver on http://localhost/. Make sure that the Docker whale is showing in the menu bar, and that you run the Docker commands in a shell that is connected to the Docker for Mac Engine (not Engine from Toolbox). Otherwise, you might start the webserver container but get a “web page not available” error when you go to localhost. For more on distinguishing between the two environments, see Docker for Mac vs. Docker Toolbox.

  • If you see errors like Bind for 0.0.0.0:8080 failed: port is already allocated or listen tcp:0.0.0.0:8080: bind: address is already in use:

    • These errors are often caused by some other software on the Mac using those ports.

    • Run lsof -i tcp:8080 to discover the name and pid of the other process and decide whether to shut the other process down, or to use a different port in your docker app.

Known issues

  • IPv6 is not (yet) supported on Docker for Mac.

    A workaround is provided that auto-filters out the IPv6 addresses in DNS server lists and enables successful network accesss. For example, 2001:4860:4860::8888 would become 8.8.8.8. To learn more, see these issues on GitHub and Docker for Mac forums:

  • You might encounter errors when using docker-compose up with Docker for Mac (ValueError: Extra Data). We’ve identified this is likely related to data and/or events being passed all at once rather than one by one, so sometimes the data comes back as 2+ objects concatenated and causes an error.

  • Force-ejecting the .dmg after running Docker.app from it can cause the whale icon to become unresponsive, Docker tasks to show as not responding in the Activity Monitor, and for some processes to consume a large amount of CPU resources. Reboot and restart Docker to resolve these issues.

  • Docker does not auto-start on login even when it is enabled in whale
menu --> Preferences. This is related to a set of issues with Docker helper, registration, and versioning.

  • Docker for Mac uses the HyperKit hypervisor (https://github.com/docker/hyperkit) in macOS 10.10 Yosemite and higher. If you are developing with tools that have conflicts with HyperKit, such as Intel Hardware Accelerated Execution Manager (HAXM), the current workaround is not to run them at the same time. You can pause HyperKit by quitting Docker for Mac temporarily while you work with HAXM. This allows you to continue work with the other tools and prevent HyperKit from interfering.

  • If you are working with applications like Apache Maven that expect settings for DOCKER_HOST and DOCKER_CERT_PATH environment variables, specify these to connect to Docker instances through Unix sockets. For example:

    export DOCKER_HOST=unix:///var/run/docker.sock
    
  • docker-compose 1.7.1 performs DNS unnecessary lookups for localunixsocket.local which can take 5s to timeout on some networks. If docker-compose commands seem very slow but seem to speed up when the network is disabled, try appending 127.0.0.1 localunixsocket.local to the file /etc/hosts. Alternatively you could create a plain-text TCP proxy on localhost:1234 using:

    docker run -d -v /var/run/docker.sock:/var/run/docker.sock -p 127.0.0.1:1234:1234 bobrik/socat TCP-LISTEN:1234,fork UNIX-CONNECT:/var/run/docker.sock
    

    and then export DOCKER_HOST=tcp://localhost:1234.

  • There are a number of issues with the performance of directories bind-mounted with osxfs. In particular, writes of small blocks, and traversals of large directories are currently slow. Additionally, containers that perform large numbers of directory operations, such as repeated scans of large directory trees, may suffer from poor performance. Applications that behave in this way include:

    • rake
    • ember build
    • Symfony
    • Magento
    • Zend Framework
    • PHP applications that use Composer to install dependencies in a vendor folder

    As a work-around for this behavior, you can put vendor or third-party library directories in Docker volumes, perform temporary file system operations outside of osxfs mounts, and use third-party tools like Unison or rsync to synchronize between container directories and bind-mounted directories. We are actively working on osxfs performance using a number of different techniques. To learn more, see the topic on Performance issues, solutions, and roadmap.

  • If your system does not have access to an NTP server, then after a hibernate the time seen by Docker for Mac may be considerably out of sync with the host. Furthermore, the time may slowly drift out of sync during use. To manually reset the time after hibernation, run:

    docker run --rm --privileged alpine hwclock -s
    

    Or, to resolve both issues, you can add the local clock as a low-priority (high stratum) fallback NTP time source for the host. To do this, edit the host’s /etc/ntp-restrict.conf to add:

    server 127.127.1.1              # LCL, local clock
    fudge  127.127.1.1 stratum 12   # increase stratum
    

    Then restart the NTP service with:

    sudo launchctl unload /System/Library/LaunchDaemons/org.ntp.ntpd.plist
    sudo launchctl load /System/Library/LaunchDaemons/org.ntp.ntpd.plist
    
mac, troubleshooting, logs, issues