feat: update the readme

scripts/src/wgrib2/readme.md

@@ -1,28 +1,105 @@
-# Data is in grib2 format, need the wgrib2 to read the file
+# Running Climate Forecast Script (cmc)
 
-* for now can just build the component on every run to get up and running
-* shortly after should cache an artifact and only build if the artifact doesn't
-  exist.
+## Background
 
+The cmc scripts will:
+* download the data from the environment canada hpfx server
+* extract the grib2 data into the various T1... T4, and P1 ... P4 files
 
-# local install
+Each file contains a series of lat longs and values for data that has been
+extracted from the grib2 data.
 
+
+## Prerequisites
+
+The script requires the wgrib2 binary to extract data from the various grib2
+formatted files.
+
+The github action run is tied to this repository which has a cached binary
+artifact with the grib2 binary compiled for x86 linux as well as github
+actions to build the various artifacts.
+
+https://github.com/franTarkenton/wgrib2-Cygwin-Build
+
+The actions will grab the binary from the repo, however when running locally
+you will have to either download the binary (if running under WSL), or compile
+it yourself.
+
+
+
+### Compile WGRIB2 Utility - Local development
+
+To run / debug the scripts locally you will need a binary wgrib2 utility.
+
+* Navigate to the wgrib folder
+```
+cd scripts/src/wgrib2
+```
+
+* get the source code, extract it, and change to that directory
 ```
 wget -c ftp://ftp.cpc.ncep.noaa.gov/wd51we/wgrib2/wgrib2.tgz
 tar -xzvf wgrib2.tgz
 cd grib2
+```
+
+* Ensure you have the required dependencies
+
+``` sh
+sudo apt install -y build-essential libaec-dev zlib1g-dev libcurl4-openssl-dev libboost-dev curl wget zip unzip bzip2 gfortran gcc g++ cmake
+```
+
+* set compiler flag env vars and compile
+```
 export CC=gcc
 export FC=gfortran
 make
-# test
-grib2/wgrib2 -config
-# use
-export PATH=$PATH;$(pwd)/grib2
 ```
 
-or just get the binary 
+* copy the binary to the expected directory
+
+```
+cp wgrib2/wgrib2 ../.
+
+```
+
+* verify that things are setup
+
+```
+# return the the root of the project directory
+cd ../../../../
+
+# update paths
+export PATH=$PATH:$(pwd)/scripts/src/wgrib2
+
+# test the binary - should return usage details.
+wgrib2
+```
+
+* cleanup - assuming working
+```
+rm -rf ./scripts/src/wgrib2/grib2
+```
+
+### Download the Binary
+
+or... rather than compile you can just download the binary from the repo
+mentioned previously
+
+* download the binary
+
+```
+curl -L -o scripts/src/wgrib2/wgrib2 https://github.com/franTarkenton/wgrib2-Cygwin-Build/releases/download/20230203-0000/wgrib2
+```
+
+* set the executable flag, and add dir to PATHS
+```
+chmod +x scripts/src/wgrib2/wgrib2
+export PATH=$PATH:$(pwd)/scripts/src/wgrib2
+```
 
+* test
 ```
-curl -L -o wgrib2 https://github.com/franTarkenton/wgrib2-Cygwin-Build/releases/download/20230203-0000/wgrib2
+wgrib2
 ```