feat(100DaysOfCode): ✨ go-r1-day-45 and docker improvements

.code-config

@@ -1,3 +1,3 @@
-COUNTER=44
+COUNTER=45
 ROUND=1
 LANGUAGE=go

content/docs/docker.md

@@ -40,6 +40,34 @@ docker build --pull --rm -f ".devcontainer/Dockerfile" -t codespace:latest ".dev
 
 `gh repo clone microsoft/vscode-dev-containers` and then copy the `script-library` directory to `${ProjectDirectory}/.devcontainer/script-library`
 
+## Syntax Tips
+
+### Installing Apps
+
+Use an environment variable to cleanup the dockerfile install commands.
+
+```dockerfile
+# Additonal applications to install
+ENV ADDITIONAL_APPS \
+    curl \
+    g++ \
+    gcc \
+    gettext \
+    git \
+    locales \
+    locales-all \
+    make \
+    nano \
+    openssh-client \
+    rsync
+RUN apt -yqq install ${ADDITIONAL_APPS} --no-install-recommends  \
+    && apt-get -yqq autoremove \
+	&& rm -rf /var/lib/apt/lists/*
+
+```
+
+
+
 ## Best Practice
 
 ### Smaller Layers

content/posts/2021/2021-06-23-go-R1-day-45.md

@@ -0,0 +1,85 @@
+---
+date: 2021-06-23T19:50:48-05:00
+title: Go R1 Day 45
+slug: go-r1-day-45
+area: go
+round: 1
+day_counter: 45
+tags:
+  - tech
+  - development
+  - 100DaysOfCode
+  - golang
+  - microblog
+images: [/images/r1-d45-main-calling-run.png]
+typora-root-url: ../../../static
+typora-copy-images-to:  ../../../static/images
+---
+
+## progress
+
+- Worked through merging flags and the "run" approach from Mat Ryer.
+- Used ff for parsing.
+
+The resulting logic seems correct with main being very simple with:
+
+```go
+package main
+import(
+    "io"
+    "flag"
+    "os"
+    "github.com/peterbourgon/ff/v3"
+    "github.com/peterbourgon/ff/v3/ffcli"
+    "github.com/peterbourgon/ff/v3/fftoml"
+)
+const (
+ // exitFail is the exit code if the program
+ // fails.
+ exitFail           = 1
+)
+
+// main configuration from Matt Ryer with minimal logic, passing to run, to allow easier CLI tests
+func main() {
+ if err := run(os.Args, os.Stdout); err != nil {
+  fmt.Fprintf(os.Stderr, "%s\n", err)
+  os.Exit(exitFail)
+ }
+}
+```
+
+The run function then handles the actual parsing:
+
+```go
+func run(args []string, stdout io.Writer) error {
+ if len(args) == 0 {
+  return errors.New("no arguments")
+ }
+  flags := flag.NewFlagSet(args[0], flag.ExitOnError)
+ flag.BoolVar(&debug, "debug", false, "sets log level to debug")
+
+if err := ff.Parse(flags, args,
+  ff.WithEnvVarNoPrefix(),
+  ff.WithConfigFileFlag("config"),
+  ff.WithConfigFileParser(fftoml.Parser),
+ ); err != nil {
+  return err
+ }
+ if debug {
+  logLevel = "debug"
+ }
+  // proceed with initialization of logger and other tools
+  return nil
+```
+
+I like this approach, as the examples by Mat show how you can end up testing the inputs and variations on flags as well.
+The example from his blog post showed how easy it became with:
+
+```go
+err := run([]string{"program", "-v", "-debug=true", "-another=2"})
+```
+
+## links
+
+- [Why you shouldn't use func main in Go by Mat Ryer - PACE.](https://pace.dev/blog/2020/02/12/why-you-shouldnt-use-func-main-in-golang-by-mat-ryer.html)
+- [ff · pkg.go.dev](https://pkg.go.dev/github.com/peterbourgon/ff)