Lab 8 Final Step

I was able to resolve this by modifying sacc.go and re-deploying:
1. Add import "github.com/hyperledger/fabric-contract-api-go/contractapi"
2. Make SimpleAsset extend/implement contractapi.Contract
3. Make get/set methods public and methods of SimpleAsset
4. Accept contractapi.TransactionContextInterface as first argument to Get/Set
5. Replace calls to stub with ctx.GetStub()
6. Delete extraneous code

/*
 * Copyright IBM Corp All Rights Reserved
 *
 * SPDX-License-Identifier: Apache-2.0
 */

package main

import (
    "fmt"

    "github.com/hyperledger/fabric-contract-api-go/contractapi"
)

// SimpleAsset implements a simple chaincode to manage an asset
type SimpleAsset struct {
    contractapi.Contract
}


// Set stores the asset (both key and value) on the ledger. If the key exists,
// it will override the value with the new one
func (sc *SimpleAsset) Set(ctx contractapi.TransactionContextInterface, args []string) (string, error) {
    if len(args) != 2 {
        return "", fmt.Errorf("Incorrect arguments. Expecting a key and a value")
    }

    err := ctx.GetStub().PutState(args[0], []byte(args[1]))
    if err != nil {
        return "", fmt.Errorf("Failed to set asset: %s", args[0])
    }
    return args[1], nil
}

// Get returns the value of the specified asset key
func (sc *SimpleAsset) Get(ctx contractapi.TransactionContextInterface, args []string) (string, error) {
    if len(args) != 1 {
        return "", fmt.Errorf("Incorrect arguments. Expecting a key")
    }

    value, err := ctx.GetStub().GetState(args[0])
    if err != nil {
        return "", fmt.Errorf("Failed to get asset: %s with error: %s", args[0], err)
    }
    if value == nil {
        return "", fmt.Errorf("Asset not found: %s", args[0])
    }
    return string(value), nil
}

// main function starts up the chaincode in the container during instantiate
func main() {
    simpleAsset := new(SimpleAsset)

    cc, err := contractapi.NewChaincode(simpleAsset)
    if err != nil {
        panic(err.Error())
    }

    if err := cc.Start(); err != nil {
            panic(err.Error())
        }
}

Due to the nature of the peer CLI and the json ctor argument, invoking was a bit difficult, but I finally accomplished that with the following:
peer chaincode invoke -C allarewelcome -c '{"function":"set","args":["[\"key1\", \"value1\"]"]}' -n sacc --tls --cafile $ORDERER_TLS_CA