feat(.github/workflows/general.yml): improving file a bit (mostly adding comments) (#201)

.github/workflows/general.yml

@@ -1,5 +1,7 @@
+# The name of your workflow. GitHub displays the names of your workflows on your repository's "Actions" tab
 name: Rust
 
+# To automatically trigger the workflow
 on:
   # NB: this differs from the book's project!
   # These settings allow us to run this specific CI pipeline for PRs against
@@ -17,25 +19,49 @@ env:
   SQLX_VERSION: 0.6.2
   SQLX_FEATURES: "rustls,postgres"
 
+# A workflow run is made up of one or more jobs, which run in parallel by default
+# Each job runs in a runner environment specified by runs-on
 jobs:
+  # Unique identifier of our job (`job_id`)
   test:
+    # Sets the name `Test` for the job, which is displayed in the GitHub UI
     name: Test
+    # Containers must run in Linux based operating systems
     runs-on: ubuntu-latest
+    # Service containers to run with the `test` container job
     services:
+      # Label used to access the service container
       postgres:
+        # Docker Hub image 
         image: postgres:14
+        # Environment variables scoped only for the `postgres` element
         env:
           POSTGRES_USER: postgres
           POSTGRES_PASSWORD: password
           POSTGRES_DB: postgres
+        # When you map ports using the ports keyword, GitHub uses the --publish command to publish the container’s ports to the Docker host
+        # Opens tcp port 5432 on the host and service container
         ports:
           - 5432:5432
     steps:
-      - uses: actions/checkout@v3
-      - uses: dtolnay/rust-toolchain@stable
-      - uses: Swatinem/rust-cache@v2
+        # Downloads a copy of the code in your repository before running CI tests
+      - name: Check out repository code
+        # The uses keyword specifies that this step will run v3 of the actions/checkout action. 
+        # This is an action that checks out your repository onto the runner, allowing you to run scripts or other actions against your code (such as build and test tools).
+        # You should use the checkout action any time your workflow will run against the repository's code.
+        uses: actions/checkout@v3
+
+       # This GitHub Action installs a Rust toolchain using rustup. It is designed for one-line concise usage and good defaults.
+      - name: Install the Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+
+      # A GitHub Action that implements smart caching for rust/cargo projects with sensible defaults.
+      - name: Rust Cache Action
+        uses: Swatinem/rust-cache@v2
         with:
+          # An additional cache key that is added alongside the automatic `job`-based cache key and can be used to further differentiate jobs. default: empty
           key: sqlx-${{ env.SQLX_VERSION }}
+
       - name: Install sqlx-cli
         run:
             cargo install sqlx-cli
@@ -43,13 +69,20 @@ jobs:
             --features ${{ env.SQLX_FEATURES }}
             --no-default-features
             --locked
+            # The --locked flag can be used to force Cargo to use the packaged Cargo.lock file if it is available. 
+            # This may be useful for ensuring reproducible builds, to use the exact same set of dependencies that were available when the package was published. 
+            # It may also be useful if a newer version of a dependency is published that no longer builds on your system, or has other problems
+
+      - name: Install postgresql-client
+        run: sudo apt-get update && sudo apt-get install postgresql-client -y
+
       - name: Migrate database
-        run: |
-          sudo apt-get install libpq-dev -y
-          SKIP_DOCKER=true ./scripts/init_db.sh
+        run: SKIP_DOCKER=true ./scripts/init_db.sh
+
       - name: Run tests
         run: cargo test
 
+  # `fmt` container job
   fmt:
     name: Rustfmt
     runs-on: ubuntu-latest
@@ -57,10 +90,12 @@ jobs:
       - uses: actions/checkout@v3
       - uses: dtolnay/rust-toolchain@stable
         with:
+          # Specific to dtolnay/rust-toolchain: Comma-separated string of additional components to install
           components: rustfmt
       - name: Enforce formatting
         run: cargo fmt --check
 
+  # `clippy` container job
   clippy:
     name: Clippy
     runs-on: ubuntu-latest
@@ -88,13 +123,14 @@ jobs:
             --features ${{ env.SQLX_FEATURES }}
             --no-default-features
             --locked
+      - name: Install postgresql-client
+        run: sudo apt-get update && sudo apt-get install postgresql-client -y
       - name: Migrate database
-        run: |
-          sudo apt-get install libpq-dev -y
-          SKIP_DOCKER=true ./scripts/init_db.sh
+        run: SKIP_DOCKER=true ./scripts/init_db.sh
       - name: Linting
         run: cargo clippy -- -D warnings
 
+  # `coverage` container job
   coverage:
     name: Code coverage
     runs-on: ubuntu-latest
@@ -111,13 +147,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v3
       - uses: dtolnay/rust-toolchain@stable
-      - name: Install libpq
+      - name: Install postgresql-client
         run: sudo apt-get update && sudo apt-get install postgresql-client -y
       - uses: Swatinem/rust-cache@v2
         with:
           key: sqlx-${{ env.SQLX_VERSION }}
-      - name: Install tarpaulin
-        run: cargo install cargo-tarpaulin
       - name: Install sqlx-cli
         run:
           cargo install sqlx-cli
@@ -128,4 +162,4 @@ jobs:
       - name: Migrate database
         run: SKIP_DOCKER=true ./scripts/init_db.sh
       - name: Generate code coverage
-        run: cargo tarpaulin --verbose --workspace
+        run: cargo install cargo-tarpaulin && cargo tarpaulin --verbose --workspace