[chore] add shellcheck CI script (aws-observability#396)

* [chore] add shellcheck CI script

* sudo to install shellcheck, perhaps?

* Fix shellcheck quoting issues and ignore .github/workflows too

Author: johnbley

.github/workflows/ci-shellcheck.yml

@@ -0,0 +1,22 @@
+name: "Continuous Build (shellcheck)"
+
+on: [push, pull_request]
+
+jobs:
+  shellcheck:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Install shell check
+        run: sudo apt update && sudo apt install --assume-yes shellcheck
+
+      - name: Run shellcheck
+        run: >-
+          find . -type f |
+          grep -v '.git' |
+          xargs -n 30 file |
+          grep -i shell |
+          awk -F':' '{print $1}' |
+          xargs shellcheck
+

python/src/otel/otel_sdk/otel-instrument

@@ -89,19 +89,19 @@ export PYTHONPATH="$LAMBDA_RUNTIME_DIR:$PYTHONPATH";
 
 # - Set the trace exporter
 
-if [ -z ${OTEL_TRACES_EXPORTER} ]; then
+if [ -z "${OTEL_TRACES_EXPORTER}" ]; then
     export OTEL_TRACES_EXPORTER=otlp_proto_http;
 fi
 
 # - Set the metrics exporter
 
-if [ -z ${OTEL_METRICS_EXPORTER} ]; then
+if [ -z "${OTEL_METRICS_EXPORTER}" ]; then
     export OTEL_METRICS_EXPORTER=none;
 fi
 
 # - Set the service name
 
-if [ -z ${OTEL_SERVICE_NAME} ]; then
+if [ -z "${OTEL_SERVICE_NAME}" ]; then
     export OTEL_SERVICE_NAME=$AWS_LAMBDA_FUNCTION_NAME;
 fi
 
@@ -135,7 +135,7 @@ fi
 
 export LAMBDA_RESOURCE_ATTRIBUTES="cloud.region=$AWS_REGION,cloud.provider=aws,faas.name=$AWS_LAMBDA_FUNCTION_NAME,faas.version=$AWS_LAMBDA_FUNCTION_VERSION";
 
-if [ -z ${OTEL_RESOURCE_ATTRIBUTES} ]; then
+if [ -z "${OTEL_RESOURCE_ATTRIBUTES}" ]; then
     export OTEL_RESOURCE_ATTRIBUTES=$LAMBDA_RESOURCE_ATTRIBUTES;
 else
     export OTEL_RESOURCE_ATTRIBUTES="$LAMBDA_RESOURCE_ATTRIBUTES,$OTEL_RESOURCE_ATTRIBUTES";