Solutions to common problems.

Browser cannot open Green Metrics Tool Frontend / ERR_CONNECTION_REFUSED

When you are getting an unexpected result when accessing localhost / *.internal domain or a different website gets served / 404 / 403 check:

  • Caching problem, please open Developer tools in your browser and check the Disable Cache option under Network
  • Not having the hostname set correctly in /etc/hosts for development: green-coding-postgres-container

  • Not accessing the Green Metrics Tool with the additional supplied port:
  • It could be that you have other containers running and the port is overloaded, so that some other service serves content on that port. Check your docker ps -a
  • Also check lsof -i | grep PORTNUMBER to look if something on your host OS is serving content on that port


  • Hostname of container correct? docker ps tells you the container name, which is also the hostname
  • Are the containers on the same network? Check with docker inspect CONTAINER_ID
  • Can access the container through browser when mapping the ports to the host OS? (See also debug mode for this)

Working docker compose setup, but not in GMT

  • Some features that are standard of the compose file might not be implemented. Check our Docs if a feature you need is implemented.
  • Are you accessing with http://localhost ? This will not work in the GMT as it makes an internal network for the containers and does not know anything about the host machines. Please use the container names here.

Run fails because volumes, environment or ports are in the usage_scenario.yml

  • If you just copied your docker-compose.yml and wanted to reuse it but do not need the functionality, then consider using the --skip-unsafe flag.
  • If you need the functionality then consider the --allow-unsafe flag

Run on macOS fails

Either with the error Base exception occurred in no element found or xml.parsers.expat.ExpatError

This is due to a current bug with the reading of the XML output of the powermetrics reporter.

Easiest fix: Just try the run again. The error happens seldomly and is random.

Please consult this ticket for current status of the bugfix

Submodule issues

If you run into any conflicts just deinit and reinit the submodule in question:

git submodule deinit FOLDER -f
git submodule update --init FOLDER
git submodule init FOLDER

cpu.stat failed to open

The full error looks something like this:

Error:  RuntimeError occured in  Stderr on CpuUtilizationCgroupContainerProvider was NOT empty: b'Error - file /sys/fs/cgroup/user.slice/user-1003.slice/[email protected]/user.slice/docker-6e18a15cbc237c9ff76af70cc8ef16c3c5b9f002a989f74cf0c7a22b5c8e4c9f.scope/cpu.stat failed to open: errno: 2'

This is because a container has exited during the run of the GMT or you are running your docker client not in rootless mode.

  • If not using rootless mode: Please turn all cgroup providers off, by commenting them out in the config.yml
  • If using rootless mode: Please keep the container alive by having a shell always open

A way to do this with the GMT directly without changing your containers would be the command command. See usage_scenario.yml →

An example where we use this command to keep a container alive is here:

Stderr on {} was NOT empty

An error occured in a metric provider either during boot or during the runtime.

This is most likely because the metric provider is not working on your system:

  • You turned on a metrics provider for a different OS (Linux / macOS / Windows)
  • You did not configure the metric provide correctly. See metric-providers →
  • The metric provider cannot be run on your system. This happens for instance in VMs when CPU frequency, cgroups, RAPL or something else is not readable. Please turn the corresponding metric provider off in the config.yml and try again. If you think the provider should work, please shoot us an email.

Process had bad returncode: 1

If your process fails in the GMT and it has a format in which quotes are present, for example like this:

command: grep "asd" /tmp/myfile

Then try running the command in a shell. It might be that some quote escaping is confusing the subprocess library.


command: grep "asd" /tmp/myfile
shell: sh

Or, if you can, also ditch the quotes:

command: grep asd /tmp/myfile

rdmsr:open: No such file or directory

Your msr kernel module is not loaded. Since this is an uncommon setup for the distributions we support this is not part of the installation.

Please run sudo modprobe msr for a quick-fix.

We recommend adding it to the /etc/modules if you use the tool on a regular basis.

Failing to compile LM sensors

On Ubuntu 20.04, the glib does not contain the function g_string_replace:

Building binaries ...
Installing ./metric_providers/lm_sensors/metric-provider-binary ...
make: Entering directory '/home/user/green-metrics-tool/metric_providers/lm_sensors'
gcc source.c chips.c -o3 -Wall -Llib -lsensors -lglib-2.0 -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -o metric-provider-binary
source.c: In function ‘main’:
source.c:326:17: warning: implicit declaration of function ‘g_string_replace’; did you mean ‘g_tree_replace’? [-Wimplicit-function-declaration]
  326 |                 g_string_replace(chip_feature_str, " ", "-", 0);
      |                 ^~~~~~~~~~~~~~~~
      |                 g_tree_replace
/usr/bin/ld: /tmp/cc0Vs2qj.o: in function `main':
source.c:(.text+0xbcc): undefined reference to `g_string_replace'
collect2: error: ld returned 1 exit status
make: *** [Makefile:8: binary] Error 1
make: Leaving directory '/home/user/green-metrics-tool/metric_providers/lm_sensors'

To resolve this, update the glib package:

sudo apt install libglib2.0-dev

However, if the error is still present after this command, it might be that
it is not possible to use lm_sensors on your system. Comment out the section of the
install script that mentions it and comment it out of your config.yml.

General tips

  • Always check container logs with docker compose logs. Sometimes streaming logs does not work that well when orchestrating multiple containers and polling the directly gives you all logs.
  • Add the --debug switch to your local calls to the to enter the stepping debug mode of the tool.
  • Add --allow-unsafe to the call to and ports to your usage_scenario.yml → to access containers through your browser in the host OS to check if the containers are delivering the expected output.
  • Rebuild the containers with docker compose down -v and then docker compose up -d
  • Re-run the script to get new configuration changes that you maybe have not yet applied after an update