iterative · 0x2b3bfa0 · Apr 15, 2022 · Apr 10, 2022 · Apr 10, 2022 · Apr 10, 2022
diff --git a/README.md b/README.md
@@ -8,19 +8,21 @@
 
 TPI is a [Terraform](https://terraform.io) plugin built with machine learning in mind. Full lifecycle management of computing resources (including GPUs and respawning spot instances) from several cloud vendors (AWS, Azure, GCP, K8s)... without needing to be a cloud expert.
 
-- **Provision Resources**: create cloud compute (CPU, GPU, RAM) & storage resources without reading pages of documentation
-- **Sync & Execute**: easily sync & run local data & code in the cloud
+- **Easy to use**: create cloud compute (CPU, GPU, RAM) & storage resources without reading pages of documentation
 - **Low cost**: transparent auto-recovery from interrupted low-cost spot/preemptible instances
+- **No cloud vendor lock-in**: switch between several cloud vendors with ease due to concise unified configuration
+- **Seamless developer experience**: easily sync & run data & code in the cloud as easily as on a local laptop
 - **No waste**: auto-cleanup unused resources (terminate compute instances upon job completion/failure & remove storage upon download of results)
-- **No lock-in**: switch between several cloud vendors with ease due to concise unified configuration
 
-Supported cloud vendors include:
+Supported cloud vendors [include][auth]:
 
 - Amazon Web Services (AWS)
 - Microsoft Azure
 - Google Cloud Platform (GCP)
 - Kubernetes (K8s)
 
+[auth]: https://registry.terraform.io/providers/iterative/iterative/latest/docs/guides/authentication
+
 ## Usage
 
 ### Requirements
@@ -36,7 +38,7 @@ Supported cloud vendors include:
     sudo apt-add-repository "deb [arch=amd64] https://apt.releases.hashicorp.com $(lsb_release -cs) main"
     sudo apt-get update && sudo apt-get install terraform
     ```
-- Create an account with any supported cloud vendor and expose its [authentication credentials via environment variables](https://registry.terraform.io/providers/iterative/iterative/latest/docs/guides/authentication)
+- Create an account with any supported cloud vendor and expose its [authentication credentials via environment variables][auth]
 
 ### Define a Task
 
@@ -59,8 +61,17 @@ resource "iterative_task" "example" {
   }
   script = <<-END
     #!/bin/bash
-    mkdir results
-    echo "Hello World!" > results/greeting.txt
+
+    # create output directory if needed
+    mkdir -p results
+    # read last result (in case of spot/preemptible instance recovery)
+    if [[ -f results/epoch.txt ]]; then EPOCH="$(cat results/epoch.txt)"; fi
+
+    # (re)start training loop up to 42 epochs
+    for epoch in $(seq ${EPOCH:-1} 10); do
+      sleep 1
+      echo "$epoch" > results/epoch.txt
+    done
   END
 }
 ```
@@ -119,6 +130,38 @@ Instead of using the latest stable release, a local copy of the repository must
    ```
 3. Use `source = "github.com/iterative/iterative"` in your `main.tf` to use the local repository (`source = "iterative/iterative"` will download the latest release instead), and run `terraform init --upgrade`
 
+This diagram may also help to see what TPI does under-the-hood:
+
+```mermaid
+flowchart LR
+subgraph tpi [what TPI manages]
+direction LR
+    subgraph you [what you manage]
+        direction LR
+        A([Personal Computer])
+    end
+    B[("Cloud Storage (low cost)")]
+    C{{"Cloud Orchestrator (zero cost)"}}
+    D[["Cloud (spot) Instance"]]
+    A ---> |create cloud storage| B
+    A --> |create cloud orchestrator| C
+    A ==> |upload script & workdir| B
+    A -.-> |"offline (lunch break)"| A
+    C -.-> |"(re)provision instance"| D
+    D ==> |run script| D
+    B <-.-> |persistent workdir cache| D
+    D ==> |script end,\nshutdown instance| B
+    D -.-> |outage| C
+    B ==> |download output| A
+end
+style you fill:#fff,stroke:#13ADC7
+style tpi fill:#fff,stroke:#fff,stroke-width:0px
+style A fill:#13ADC7,stroke:#333
+style B fill:#945DD5,stroke:#333
+style D fill:#F46737,stroke:#333
+style C fill:#7B61FF,stroke:#333
+```
+
 ## Copyright
 
 This project and all contributions to it are distributed under [![Apache-2.0][licence-badge]][licence-file]

diff --git a/docs/guides/authentication.md b/docs/guides/authentication.md
@@ -13,6 +13,8 @@ TF_LOG_PROVIDER=INFO terraform apply
 
 ## Amazon Web Services
 
+[Create an AWS account](https://aws.amazon.com/premiumsupport/knowledge-center/create-and-activate-aws-account/) if needed, and then set these environment variables:
+
 - `AWS_ACCESS_KEY_ID` - Access key identifier.
 - `AWS_SECRET_ACCESS_KEY` - Secret access key.
 - `AWS_SESSION_TOKEN` - (Optional) Session token.
@@ -29,6 +31,8 @@ export AWS_SECRET_ACCESS_KEY="$(terraform output --raw aws_secret_access_key)"
 
 ## Microsoft Azure
 
+[Create an Azure account](https://docs.microsoft.com/en-us/learn/modules/create-an-azure-account/) if needed, and then set these environment variables:
+
 - `AZURE_CLIENT_ID` - Client identifier.
 - `AZURE_CLIENT_SECRET` - Client secret.
 - `AZURE_SUBSCRIPTION_ID` - Subscription identifier.
@@ -48,6 +52,8 @@ export AZURE_CLIENT_SECRET="$(terraform output --raw azure_client_secret)"
 
 ## Google Cloud Platform
 
+[Create a GCP account](https://cloud.google.com/free) if needed, and then set the environment variable:
+
 - `GOOGLE_APPLICATION_CREDENTIALS` - Path to (or contents of) a service account JSON key file.
 
 See the [GCP documentation](https://cloud.google.com/docs/authentication/getting-started#creating_a_service_account) to obtain these variables directly.

diff --git a/docs/guides/getting-started.md b/docs/guides/getting-started.md
@@ -45,8 +45,17 @@ resource "iterative_task" "example" {
   }
   script = <<-END
     #!/bin/bash
-    mkdir results
-    echo "Hello World!" > results/greeting.txt
+
+    # create output directory if needed
+    mkdir -p results
+    # read last result (in case of spot/preemptible instance recovery)
+    if [[ -f results/epoch.txt ]]; then EPOCH="$(cat results/epoch.txt)"; fi
+
+    # (re)start training loop up to 42 epochs
+    for epoch in $(seq ${EPOCH:-1} 10); do
+      sleep 1
+      echo "$epoch" > results/epoch.txt
+    done
   END
 }
 ```
@@ -115,7 +124,7 @@ This command will:
 1. Download the `output` directory from the cloud.
 2. Delete all the cloud resources created by `terraform apply`.
 
-In this example, after running `terraform destroy`, the `results` directory should contain a file named `greeting.txt` with the text `Hello, World!`
+In this example, after running `terraform destroy`, the `results` directory should contain a file named `epoch.txt` with the text `10`.
 
 -> **Note:** A large `output` directory may take a long time to download.
 

diff --git a/docs/index.md b/docs/index.md
@@ -7,21 +7,23 @@
 
 TPI is a [Terraform](https://terraform.io) plugin built with machine learning in mind. Full lifecycle management of computing resources (including GPUs and respawning spot instances) from several cloud vendors (AWS, Azure, GCP, K8s)... without needing to be a cloud expert.
 
-- **Provision Resources**: create cloud compute (CPU, GPU, RAM) & storage resources without reading pages of documentation
-- **Sync & Execute**: easily sync & run local data & code in the cloud
+- **Easy to use**: create cloud compute (CPU, GPU, RAM) & storage resources without reading pages of documentation
 - **Low cost**: transparent auto-recovery from interrupted low-cost spot/preemptible instances
+- **No cloud vendor lock-in**: switch between several cloud vendors with ease due to concise unified configuration
+- **Seamless developer experience**: easily sync & run data & code in the cloud as easily as on a local laptop
 - **No waste**: auto-cleanup unused resources (terminate compute instances upon job completion/failure & remove storage upon download of results)
-- **No lock-in**: switch between several cloud vendors with ease due to concise unified configuration
 
-Supported cloud vendors include:
+Supported cloud vendors [include][auth]:
 
 - Amazon Web Services (AWS)
 - Microsoft Azure
 - Google Cloud Platform (GCP)
 - Kubernetes (K8s)
 
+[auth]: https://registry.terraform.io/providers/iterative/iterative/latest/docs/guides/authentication
+
 ## Links
 
 - [Getting Started](https://registry.terraform.io/providers/iterative/iterative/latest/docs/guides/getting-started)
-  - [Authentication](https://registry.terraform.io/providers/iterative/iterative/latest/docs/guides/authentication)
+  - [Authentication][auth]
 - [Full reference](https://registry.terraform.io/providers/iterative/iterative/latest/docs/resources/task)
diff --git a/docs/resources/task.md b/docs/resources/task.md
@@ -27,6 +27,7 @@ resource "iterative_task" "example" {
   }
   script = <<-END
     #!/bin/bash
+    mkdir -p results
     echo "$GREETING" | tee results/$(uuidgen)
   END
   # or: script = file("example.sh")