handling a crate::Error example (Azure#612)

Co-authored-by: Cameron Taggart <cameron.taggart@gmail.com>

Author: cataggar

services/README.md

@@ -21,6 +21,8 @@ There are a few examples:
 - azure_mgmt_vmware
     - [private_cloud_list](mgmt/vmware/examples/private_cloud_list.rs)
 - azure_svc_batch
+    - [create_task](svc/batch/examples/create_task.rs)
+    - [create_task_thiserror](svc/batch/examples/create_task_thiserror.rs)
     - [list_pools](svc/batch/examples/list_pools.rs)
 
 These services are in their own [Rust workspace](Cargo.toml), so you need to change to the `services` directory to run these examples.

services/svc/batch/examples/create_task_thiserror.rs

@@ -0,0 +1,96 @@
+/*
+Creates a batch job and task using the data plane APIs
+
+This example shows how to do error handling when you wish
+to match any error from azure_svc_batch crate.
+
+cargo run --package azure_svc_batch --example create_task_thiserror
+*/
+
+use azure_identity::token_credentials::AzureCliCredential;
+use azure_svc_batch::models::{JobAddParameter, PoolInformation, TaskAddParameter};
+use std::sync::Arc;
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("please specify batch account")]
+    AccountNameRequired,
+    #[error("please specify region")]
+    RegionRequired,
+    #[error("please specify pool id")]
+    PoolIdRequired,
+    #[error("please specify job id")]
+    JobIdRequired,
+    #[error("please specify task id")]
+    TaskIdRequired,
+    #[error("batch error")]
+    Batch(#[source] azure_svc_batch::Error),
+}
+
+/// Any azure_svc_batch error ths is not mapped to a specific error
+/// is mapped to Error::Batch by default with a `?`, which performs an `into()`.
+impl<T: Into<azure_svc_batch::Error>> From<T> for Error {
+    fn from(error: T) -> Self {
+        Self::Batch(error.into())
+    }
+}
+
+async fn run() -> Result<(), Error> {
+    let account_name = std::env::args().nth(1).ok_or(Error::AccountNameRequired)?;
+    let region = std::env::args().nth(2).ok_or(Error::RegionRequired)?;
+    let pool_id = std::env::args().nth(3).ok_or(Error::PoolIdRequired)?;
+    let job_id = std::env::args().nth(4).ok_or(Error::JobIdRequired)?;
+    let task_id = std::env::args().nth(5).ok_or(Error::TaskIdRequired)?;
+
+    let endpoint = format!("https://{}.{}.batch.azure.com", account_name, region);
+    let scopes = &["https://batch.core.windows.net/"];
+    let credential = Arc::new(AzureCliCredential {});
+    let client = azure_svc_batch::ClientBuilder::new(credential)
+        .endpoint(endpoint)
+        .scopes(scopes)
+        .build();
+
+    let pool_info = PoolInformation {
+        pool_id: Some(pool_id),
+        ..PoolInformation::new()
+    };
+
+    println!("creating job");
+    let job_params = JobAddParameter::new(job_id.clone(), pool_info);
+    client.job().add(job_params).into_future().await?;
+
+    println!("creating task");
+    let command_line = "echo hello there".to_string();
+    let task = TaskAddParameter::new(task_id.to_string(), command_line);
+    client.task().add(job_id, task).into_future().await?;
+
+    Ok(())
+}
+
+/*
+The eyre crate is recommended for printing the report with the full error chain.
+You can use it instead of the below print_error_chain.
+
+#[tokio::main]
+async fn main() -> eyre::Result<()> {
+    Ok(run().await?)
+}
+*/
+
+#[tokio::main]
+async fn main() {
+    match run().await {
+        Ok(_) => (),
+        Err(error) => {
+            print_error_chain(error);
+            std::process::exit(1);
+        }
+    }
+}
+
+fn print_error_chain(error: impl std::error::Error) {
+    println!("- {}", error.to_string());
+    if let Some(source) = error.source() {
+        print_error_chain(source);
+    }
+}