Billmonger

Billmonger is a dead simple PDF one-page invoice generator written in Go. The intention is to make the generated invoices look professional and have them be repeatable. You can use your own company logo and two company colors as part of the invoice, and each invoice is configurable with a single YAML file.

Billmonger makes many assumptions to keep things simple. Some of them are:

• You will have two company colors or use two generic colors
• You will not invoice for more than about a dozen items
• The billing period is a month (semi-configurable)
• The bill due date is a month boundary
• Everything on the bill is the same currency
• Filenames will be output in a standard way

Current limitations:

• Has tax support with one rate for all entries. May eventually support different rates for different line items.

The Problem This Solves

You have a small business and need to regularly generate bills, perhaps as a contractor. Your bills are fairly similar but may have different line items. This will generate a nice A4 PDF that looks professional and is easily customizable to your business.

What It Looks Like

The sample billing.example.yaml file provided will generate a PDF file that looks like this:

Configuration

Configuration is done in the YAML file (billing.yaml by default). This describes the bill and the billables to be reported. It supports a couple of templating features that make reporting items easier. These are Go template functions and are to be put inside double curly braces anywhere in the YAML file. Interpretation of the template happens before YAML processing. Examples:

• {{ endOfNextMonth }}: This will be substituted with the end day of the month following the current month.
• {{ endOfThisMonth }}: This will be substituted with the end day of the current month.
• {{ billingPeriod }}: This will be substituted with the current month's beginning and end dates.

CLI Flags

billmonger currently takes a single CLI flag, to tell it which config file to use to run the bill. The default is billing.yaml, but you may specify otherwise like so:

$ ./billmonger -c my-other-config.yaml

You may ask for help on the command line in the semi-standard way:

$ ./billmonger --help
usage: billmonger [<flags>]

Flags:
      --help            Show context-sensitive help (also try --help-long and
                        --help-man).
  -c, --config-file="billing.yaml"
                        The YAML config file to use
  -b, --billing-date="2019-12-29"
                        The date to assume the bill is written on
  -o, --output-dir="."  The output directory to use. Overriden by config file.

Installation

There is not much to install! You may use the binaries provided on the Releases tab on GitHub. Or you may use Go tools to install it yourself. In general you only need to have the binary, a billing.yaml file, and your image assets in order to run Billmonger. It is not sensitive to installation path.

Using Docker

You can run Billmonger from the command line. But some folks have found that it's useful to run it from a Docker container directly. This is also supported!

The following assumes that you have a directory in your current path called ./billmonger/invoices where you would like to output PDF files from Billmonger. You can substitute this for any other local path that is convenient.

We will also need to be able to mount the config file from our local filesystem into the Docker container. In the example below this file also lives in ./billmonger/invoices

Similarly, we may want to mount assets like the logo files from a different local directory. This is assumed to be ./billmonger/assets in this example. In order to use assets from this path, you need to include assets/ in the image filename in your config file.

1. Run docker build . --tag billmonger and then ...
2. Run

   docker run \
     --volume ${PWD}/billmonger/invoices:/invoices \
     --volume ${PWD}/billmonger/assets:/assets \
     billmonger \
       --output-dir /invoices \
       --config-file /invoices/billing.example.yaml
   

In order to make this all easier to run, you may want to alias the docker run command something like this:

alias='docker run --volume ${PWD}/billmonger/invoices:/invoices --volume ${PWD}/billmonger/assets:/assets billmonger --output-dir /invoices'

Saving that in your .profile will make it permanently available. Having done that, you can then run the following at any time:

billmonger --config-file /invoices/billing.example.yaml

Be sure to run it from the local path where you mounted the config file.