Properly manage timestamps of profile files (#89)

.github/workflows/run_tests.yml

@@ -3,6 +3,7 @@ on: [pull_request]
 
 env:
   RUST_LOG: debug
+  RUST_BACKTRACE: 1
 
 jobs:
   test:
@@ -13,4 +14,4 @@ jobs:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
       - uses: Swatinem/rust-cache@v2
-      - run: cargo test --all-features
+      - run: cargo test --all-features -- --nocapture

Cargo.toml

@@ -40,10 +40,12 @@ ctrlc = "^3.4"
 env_logger = "^0.10"
 filetime = "^0.2"
 flate2 = "1.0.28"
+homedir = "0.2.1"
 indicatif = "^0.17"
 log = "^0.4"
 reqwest = { version = "^0.11", default-features = false, features = ["json", "blocking", "rustls-tls"] }
 serde = { version = "^1.0", features = ["derive"] }
+serde_json = "1.0.115"
 tar = "0.4.40"
 tempfile = "^3.8"
 termimad = "0.29.0"

docs/src/tutorial/run.md

@@ -114,6 +114,25 @@ In this way, you can detect from inside the pipeline if you are in a profile or
 This is useful if you want to keep the outputs of different profiles separate,
 for instance.
 
+### File modification times when using profiles
+`make` tracks file creation times to determine if it has to re-run pipelines again.
+This means that if you move files around, like Kerblam! does when it applies
+profiles, `make` will always re-run your pipelines, even if you run the same
+pipeline with the same profile back-to-back.
+
+To avoid this, Kerblam! will keep track of the last-run profile in your
+projects and update the timestamps of the moved files
+**only when strictly necessary**.
+
+This means that the profile files will get updated timestamps only when they
+actually need to be updated, which is:
+- When you use a profile for the first time;
+- When you switch from one profile to a different one;
+- When you don't use a profile, but you just used one the previous run;
+
+To track what was the last profile used, Kerblam! creates a file in
+`$HOME/.cache/kerblam/` for each of your projects.
+
 ## Sending additional arguments to make or bash
 You can send additional arguments to either `make` or `bash` after what
 Kerblam! sets by default by specifying them after kerblam's own `run` arguments:
@@ -147,4 +166,3 @@ kerblam run my_pipe -- -- arg_1 arg_2 ...
 The first `--` is "eaten up" by Kerblam!, and the second one is passed to the
 containerization engine, telling it to pass `arg_1`, `arg_2` etc... as-is to
 the entrypoint.
-