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vnStat in a container

vnStat is a network traffic monitor that uses the network interface statistics provided by the kernel as information source. This means that vnStat won't actually be sniffing any traffic and also ensures light use of system resources regardless of network traffic rate.

By default, traffic statistics are stored on a five minute level for the last 48 hours, on a hourly level for the last 4 days, on a daily level for the last 2 full months and on a yearly level forever. The data retention durations are fully user configurable. Total seen traffic and a top days listing is also provided.

See the official webpage or the GitHub repository for additional details and output examples. An example of the included image output is also available.

Container content

  • vnStat daemon (vnstatd) is running as the primary process
  • lighttpd provides vnStat image output (vnstati) via http (port 8685 on all interfaces by default)
    • json and Prometheus compatible metrics endpoints are also available as alternative
  • vnStat command line (vnstat)

Supported tags

Version specific tags are available starting from 2.7 with the latest release being the same as latest tag. latest and dev are automatically built at least once every month to include possible build time dependency updates.

Building the container

docker build -t vergoh/vnstat .

Running the container

docker run -d \
    --restart=unless-stopped \
    --network=host \
    -e HTTP_PORT=8685 \
    -v /etc/localtime:/etc/localtime:ro \
    -v /etc/timezone:/etc/timezone:ro \
    --name vnstat \
    vergoh/vnstat
  • --network=host is necessary for accessing the network interfaces of the Docker host instead of being limited to monitoring the container specific interface
  • Volumes /etc/localtime and /etc/timezone are used to configure the container to use the same time zone as the host is using
    • Alternatively the TZ environment variable can be used (-e TZ=) with a supported value, localtime and timezone volumes are overridden if used in combination
  • --privileged may need to be used if the date within the container starts from 1970
    • The proper solution would be to update libseccomp2 to a more recent version than currently installed
  • The http server binds by default to all interfaces using the port specified with the HTTP_PORT variable. As --network=host needs to be enabled, the usual Docker port mapping with -p or --publish isn't available with this container. Visibility of the http server can be restricted using firewall rules or binding the http server to a specific IP address using the HTTP_BIND variable. Localhost access can be enforced by setting HTTP_BIND as 127.0.0.1
    • See the full list of available environment variables below
    • Alternatively see the two container solution with unprivileged http server using docker compose explained below
  • Image output is available at http://localhost:8685/ (using default port)
  • JSON output is available at http://localhost:8685/json.cgi (using default port)
  • Prometheus compatible metrics endpoint is available at http://localhost:8685/metrics (using default port)
  • Add -v some_local_directory:/var/lib/vnstat to map the database directory to the local filesystem if easier access/backups is needed

Command line interface can be accessed with:

docker exec vnstat vnstat --help

docker-compose.yml

Two example docker compose files are provided:

docker-compose.yml is the more simple example with both the vnStat daemon and the httpd running in the same container. While this example works without changes for most users, it results in the httpd also using host networking which may not be a wanted feature for some users.

docker-compose_isolated_httpd.yml consist of two containers running from the same image. The vnStat daemon is running in the first container (vnstat) with host networking in order to access all network interfaces but doesn't provide any services or bind to ports. The second container (vnstati) doesn't use host networking but provides the httpd which accesses the statistics using a shared volume in read-only mode.

Environment variables

Name Description Default value
HTTP_PORT Port of the http server, use 0 to disable http server 8685
HTTP_BIND IP address for the http server to bind, use 127.0.0.1 to bind only to localhost and prevent remote access *, all addresses
HTTP_LOG Http server log output file, use /dev/stdout for output to console and /dev/null to disable logging /dev/stdout
SERVER_NAME Name of the server in the web page title Output of hostname command
LARGE_FONTS Use large fonts in images (0: no, 1: yes) 0
CACHE_TIME Cache created images for given number of minutes (0: disabled) 1
DARK_MODE Black background and inverted image colors, 0: disabled, 1: enabled without rx/tx color inversion, 2: enabled for all colors (available starting from version 2.12) 0
PAGE_REFRESH Page auto refresh interval in seconds (0: disabled) 0
RUN_VNSTATD Start vnStat daemon (0: no, 1: yes) 1
INDEX_IMAGES_PER_ROW Number of images to show per row on the index page when the database contains more than one interface (1000: auto fit) (available starting from version 2.13) 1
INDEX_IMAGE_OUTPUT Image output to use on index page when the database contains more than one interface (available starting from version 2.13) hs
INDEX_SHOWN_INTERFACES Regular expression pattern for selecting which interfaces are shown on the index page when the database contains more than one interface. Leave empty or unset to disable filter. All not shown interfaces will still be monitored. (available starting from version 2.13) unset
INDEX_HIDDEN_INTERFACES Regular expression pattern for selecting which interfaces are hidden from the index page when the database contains more than one interface. Leave empty or unset to disable filter. All hidden interfaces will still be monitored. (available starting from version 2.13) unset
EXCLUDE_PATTERN Extended regular expression pattern for excluding interfaces from getting monitored. For example, ^docker|^veth|^br-|^lxc would exclude interface names starting with docker, veth, br- and lxc. unset
TZ Set time zone (list of supported values), overrides configuration from possible /etc/localtime and /etc/timezone volumes unset
VNSTAT_ prefix All vnstat.conf configurations can be modified using a VNSTAT_ prefixed variable followed with the configuration keyword. For example, changing CRx (color for received data) to 79C999 (pale teal) can be done by defining VNSTAT_CRx=79C999. Variable name is case sensitive. unset

Deprecated environment variables

Name Description Default value
RATE_UNIT Used traffic rate unit, 0: bytes, 1: bits. Deprecated. Use VNSTAT_RateUnit instead. 1
INTERFACE Default interface for queries, leave empty or unset for automatic selection. Deprecated. Use VNSTAT_Interface instead. unset
INTERFACE_ORDER Interface order when multiple interfaces are shown, 0: alphabetical by name, 1: alphabetical by alias. Deprecated. Use VNSTAT_InterfaceOrder instead. 0
QUERY_MODE Default command line query when none is specified, see QueryMode in documentation for supported values. Deprecated. Use VNSTAT_QueryMode instead. 0

Usage tips

Add descriptive interface name

docker exec vnstat vnstat -i eno3 --setalias "Basement switch"

Stop monitoring unnecessary interface

docker exec vnstat vnstat -i br-20f8582bfc70 --remove --force

Add interface for monitoring

  1. Check that the interface is visible on the list of available interfaces:

    docker exec vnstat vnstat --iflist

  2. Add the interface

    docker exec vnstat vnstat -i br-20f8582bfc70 --add

  3. The daemon will notice the change within 5 minutes and start monitoring the interface

Troubleshooting

  • All images show no data available after the container has been started.

    • The database write interval is 5 minutes so it will take up to 5 minutes for the initial data to become available.

  • Is the container running?

    docker ps

  • What does the container log?

    docker logs vnstat

  • Using a Synology NAS and timezone isn't correct?

    • Use /etc/TZ:/etc/localtime:ro instead of /etc/localtime:/etc/localtime:ro or use the TZ environment variable.

  • Container log shows Latest database update is in the future (db: 2037-04-03 18:16:49 > now: 1970-01-01 02:00:00) or something similar with now being in 1970.

    • Use --privileged or upgrade libseccomp2 to a much more recent version.