feat: add new emit-metrics action (#65)

Author: ianbotsf

.github/actions/emit-metrics/action.yml

@@ -0,0 +1,77 @@
+name: Emit Metrics
+description: Emit metrics using the kat tool
+inputs:
+  namespace:
+    description: The CloudWatch namespace in which to emit metrics
+    required: true
+  dimensions:
+    description: |-
+      The dimensions to include with emitted metrics, as a collection of `name=value` pairs. Multiple dimensions are
+      delimited by newlines (`\n`) and whitespace is trimmed from before/after each `name=value` pair. When passing
+      multiple dimensions, make sure to use YAML's block literal syntax (`|` or `|-`).
+
+      For example:
+      ```
+      dimensions: |
+        Artifact=foo-artifact
+        Platform=Kotlin/JVM
+        Variant=External
+      ```
+    required: true
+  metrics:
+    description: |-
+      The metrics to emit into the given namespace and using the specified dimensions. Individual metrics are written in
+      the form of `<name>:<value>[:<unit>]` where:
+      * <name> is the metric name and may include spaces but not colons (`:`)
+      * <value> is the numeric value of the metric
+      * <unit> is the CloudWatch unit name (if omitted, `None` is assumed)
+
+      Multiple metrics are delimited by newlines (`\n`) and whitespace is trimmed from before/after each metric
+      specification. When passing multiple metrics, make sure to use YAML's block literal syntax (`|` or `|-`).
+
+      For example:
+      ```
+      metrics: |
+        BuildTime:4.532:Seconds
+        BuildSucceeded:1:Count
+      ```
+    required: true
+
+runs:
+  using: composite
+  steps:
+    - name: Verify kat exists
+      shell: bash
+      run: which kat || ( echo "Cannot find kat installation. Did you forget to run setup-kat first?" && exit 1 )
+    - name: Emit Metrics
+      shell: bash
+      run: |
+        # Trim a string and echo the result
+        trim() {
+          # args:
+          #   $1 the string to trim
+
+          echo -n "$1" | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//'
+        }
+
+        # Convert a newline-delimited string into a single-line string delimited by spaces with each element prefixed
+        format() {
+          # args:
+          #   $1 the prefix for each element
+          #   $2 the newline-delimited string
+
+          PROCESSED=""
+          IFS=$'\n'; ARR=($2); unset IFS
+          for ITEM in "${ARR[@]}"; do
+            PROCESSED="$PROCESSED $1 \"$(trim "$ITEM")\""
+          done
+          echo -n "$(trim "$PROCESSED")"
+        }
+
+        NAMESPACE="--namespace \"${{ inputs.namespace }}\""
+        DIMENSIONS="$(format "--dimension" "${{ inputs.dimensions }}")"
+        METRICS="$(format "--metric" "${{ inputs.metrics }}")"
+        CMD="kat metrics emit $NAMESPACE $DIMENSIONS $METRICS"
+
+        echo "Executing command \"$CMD\""
+        eval "$CMD"