Background

This repository holds the code written as part of reading the "Zero to production" Rust book.

Changes

This repo has a few changes when compared to the official code provided in the book. These are:

1. Using a newer version of sqlx-cli locally
2. Using a newer version of sqlx-cli in our GitHub pipeline -- the official code uses an older version 0.5 which didn't require any additional TLS related features to be provided during installation
3. The official version uses docker which is a royal PITA to set up on Mac M1 given the lack of a proper CLI version (I really didn't want to use Docker desktop). This version uses podman which works pretty well on both Linux and Mac.
4. Removing dependency on the chrono crate in favor of time to get rid of the security vulnerability.
5. Additional documentation where required to specify why something was done the way it was done.
6. Integration with Jaegar to show traces in a web dashboard. Please ensure you have a instance of Jaegar running locally. The command I use is podman run -d -p6831:6831/udp -p6832:6832/udp -p16686:16686 -p14268:14268 jaegertracing/all-in-one:latest. By default, this integration is disabled -- to enable it run with JAEGAR_ENABLED=true cargo run. Results can be viewed on the Jaegar Dashboard

Podman setup

I use the following command to initialize the podman machine, you can choose your own settings. If needed, you can drop the existing default machine by running the below command:

podman machine stop # to stop if running
podman machine rm -f # remove the default machine
podman machine init --cpus 4 --disk-size 40 --memory 14000 --now # create a shiny new machine

Testing

How do we go about testing this application? The simplest would be to run the cargo test command which will run both our integration and unit tests. My usual testing session looks something like the below:

# Start the docker container locally and perform migration
REMOVE_CONTAINER=true ./scripts/init_db.sh

# Run test without stdout enabled
cargo test

# Run test with stdout enabled for debugging tests
TEST_LOG=1 cargo test | bunyan

# Start up the server with trace log level enabled
RUST_LOG=trace cargo run

# Run a couple of successful and failure curl commands
curl -X POST http://localhost:8080/subscriptions -H "Content-Type: application/x-www-form-urlencoded" -d "name=Sanjay&email=sanjay@hotmail.com" # works

curl -X POST http://localhost:8080/subscriptions -H "Content-Type: application/x-www-form-urlencoded" -d "name=Sanjay&email=sanjay@hotmail.com" # fails; same email

curl -X POST http://localhost:8080/subscriptions -H "Content-Type: application/x-www-form-urlencoded" -d "name=Sanjay&email=sa@hotmail.com" # Works, same name but different emails so fine!

If you would like to build the docker image for our app locally and test it as a container, the following commands should do the trick:

podman build --platform linux/amd64 --tag zero2prod --file Dockerfile . 

podman run -p 8080:8080 zero2prod | bunyan # If you don't have bunyan installed, I would recommend getting it installed via brew

References

• Basic Usage For Opentelemetry crate
• Customizing Jaegar tracer
• Local Jaegar UI

Errors Encountered And Their Fix

Release is not valid yet (when running podman build command)

This seems to be a known issue which requires a restart -- worked for me. https://askubuntu.com/questions/1059217/getting-release-is-not-valid-yet-while-updating-ubuntu-docker-container