Rust Cloudflare Worker Logging 📋 # Rust Cloudflare Worker Logging 📋 #

📹 Rust Cloudflare Worker Logging: Video #

🖥 Rust Cloudflare Worker Logging: Code #

console_error_panic_hook #

    
1 use cfg_if::cfg_if;
2 
3 cfg_if! {
4     // https://github.com/rustwasm/console_error_panic_hook#readme
5     if #[cfg(feature = "console_error_panic_hook")] {
6         extern crate console_error_panic_hook;
7         pub use self::console_error_panic_hook::set_once as set_panic_hook;
8     } else {
9         #[inline]
10         pub fn set_panic_hook() {}
11     }
12 }

  

    
1 mod utils;
2 
3 /* TRUNCATED... */
4 
5 #[event(fetch)]
6 async fn main(req: Request, env: Env, _ctx: Context) -> Result<Response> {
7     utils::set_panic_hook();
8 
9     /* TRUNCATED... */
10 }

  

    
11 # ...TRUNCATED
12 
13 [lib]
14 crate-type = ["cdylib"]
15 
16 [features]
17 default = ["console_error_panic_hook"]
18 
19 [dependencies]
20 cfg-if = "1.0.0"
21 chrono = "0.4.24"
22 chrono-tz = "0.8.2"
23 console_error_panic_hook = { version = "0.1.1", optional = true }
24 reqwest = { version = "0.11.18", features = ["json"] }
25 rmp = "^0.8"
26 rmp-serde = "1.1.1"
27 serde = "1"
28 worker = "0.0.17"
29 
30 # TRUNCATED...

  

Logtail Request Log Example Code #

    
1 mod utils;
2 
3 use chrono::{DateTime, Utc};
4 use reqwest::header::CONTENT_TYPE;
5 use rmp_serde::Serializer;
6 use serde::{Deserialize, Serialize};
7 use std::collections::HashMap;
8 use worker::*;
9 
10 #[derive(Debug, PartialEq, Deserialize, Serialize)]
11 struct LogDataItem {
12     pathname: String,
13     request_details: String,
14 }
15 
16 #[derive(Debug, PartialEq, Deserialize, Serialize)]
17 struct LogData {
18     dt: String,
19     level: String,
20     message: String,
21     item: LogDataItem,
22 }
23 
24 async fn log_request(req: &Request, env: &Env) {
25     let pathname = req.path();
26     let timestamp = Date::now().to_string();
27     let request_details = format!(
28         "{timestamp} - [{pathname}], located at: {:?}, within: {}",
29         req.cf().coordinates().unwrap_or_default(),
30         req.cf().region().unwrap_or("unknown region".into())
31     );
32     console_log!("{request_details}");
33 
34     let date_time: DateTime<Utc> = match DateTime::parse_from_rfc3339(&timestamp) {
35         Ok(value) => value.into(),
36         Err(_) => Utc::now(),
37     };
38 
39     let log_data = LogData {
40         dt: date_time.to_rfc3339(),
41         level: String::from("info"),
42         message: "worker request".to_string(),
43         item: LogDataItem {
44             pathname,
45             request_details,
46         },
47     };
48 
49     let mut buffer = Vec::new();
50     log_data
51         .serialize(&mut Serializer::new(&mut buffer).with_struct_map())
52         .expect("Unable to serialize log data");
53     let logtail_source_token = env
54         .secret("LOGTAIL_SOURCE_TOKEN")
55         .expect("LOGTAIL_SOURCE_TOKEN must be defined")
56         .to_string();
57 
58     let client = reqwest::Client::new();
59     let _ = client
60         .post("https://in.logs.betterstack.com")
61         .header(CONTENT_TYPE, "application/msgpack")
62         .bearer_auth(logtail_source_token)
63         .body::<Vec<u8>>(buffer)
64         .send()
65         .await;
66 }
67 
68 // TRUNCATED...
69 
70 #[event(fetch)]
71 async fn main(req: Request, env: Env, _ctx: Context) -> Result<Response> {
72     utils::set_panic_hook();
73 
74     log_request(&req, &env).await;
75 
76     // TRUNCATED...
77 }

  

Message Pack Crates #

    
11 # ...TRUNCATED
12 [dependencies]
13 cfg-if = "1.0.0"
14 chrono = "0.4.24"
15 chrono-tz = "0.8.2"
16 console_error_panic_hook = { version = "0.1.1", optional = true }
17 reqwest = { version = "0.11.18", features = ["json"] }
18 rmp = "^0.8"
19 rmp-serde = "1.1.1"
20 serde = "1"
21 worker = "0.0.17"
22 
23 # TRUNCATED...

  

Follow the link in the next session for the full code.

🔗 Rust Cloudflare Worker Logging: Links #

• Article on getting started with Rust Cloudflare workers
• GitHub repo with full code 
• console_error_panic_hook docs 
• rmp_serde (Rust Message Pack) crate docs 
• Logtail signup 
• Cloudflare Logpush 
• wrangler tail command docs 
• Twitter handle: @askRodney 

🏁 Rust Cloudflare Worker Logging: Summary #

Is there a source map feature for Rust WASM? #

When writing code in Rust and compiling to WASM, if the WASM module panics, you should see a console error. This will be in the browser or Terminal, depending on the environment you are running the module in. Either way, by default, the error message will show you which line of WASM code the error originated from. This is not ideal, as the Rust source will be where you want to focus your debugging efforts! console_error_panic_hook is a crate you can run in debug mode to output the line of Rust code which caused the panic. Check the project GitHub page (https://github.com/rustwasm/console_error_panic_hook#readme) to get going with it.

Is there a Rust Message Pack crate? #

rmp_serde is a popular and useful Rust crate for generating Message Pack data arrays. We saw that you might decide to use it with a logging service, like Logtail. That is because Message Pack provides a more efficient data structure than the JSON alternative.

How can you use Logtail with Rust WASM? #

Although Logtail does not have a Rust SDK (at the time of writing), it does have a REST API. You can use the Rust reqwest package to push your request logs into the Logtail dashboard. For convenience, you might also like to use the rmp_serde crate, which can serialize your log data into the Message Pack format, for efficient transport.

🙏🏽 Feedback #

Have you found the post useful? Would you prefer to see posts on another topic instead? Then get in touch with ideas for new posts. Also, if you like my writing style, get in touch if I can write some posts for your company site on a consultancy basis. Read on to find ways to get in touch, further below. If you want to support posts similar to this one and can spare a few dollars, euros or pounds, please consider supporting me through Buy me a Coffee.

Rodney

@askRodney

Just dropped a new video on adding request logging to a 🦀 Rust Cloudflare worker using

@LogTailHQ.

We also see how to get more useful error messages for Rust WASM panics.

Hope you find it useful!#learnrust #askRodneyhttps://t.co/WFV1lGiysE

— Rodney (@askRodney) June 20, 2023

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